Nanomaterials

19 pages, 4143 KiB

Open AccessArticle

Anisotropic Elasticity, Spin–Orbit Coupling, and Topological Properties of ZrTe₂ and NiTe₂: A Comparative Study for Spintronic and Nanoscale Applications

by Yasaman Fazeli, Zahra Nourbakhsh, Shahram Yalameha and Daryoosh Vashaee

Nanomaterials 2025, 15(2), 148; https://doi.org/10.3390/nano15020148 - 20 Jan 2025

Viewed by 567

Abstract

The present work investigates the interfacial and atomic layer-dependent mechanical properties, SOC-entailing phonon band structure, and comprehensive electron-topological–elastic integration of ZrTe₂ and NiTe₂. The anisotropy of Young’s modulus, Poisson’s ratio, and shear modulus are analyzed using density functional theory with [...] Read more.

The present work investigates the interfacial and atomic layer-dependent mechanical properties, SOC-entailing phonon band structure, and comprehensive electron-topological–elastic integration of ZrTe₂ and NiTe₂. The anisotropy of Young’s modulus, Poisson’s ratio, and shear modulus are analyzed using density functional theory with the TB-mBJ approximation. NiTe₂ has higher mechanical property values and greater anisotropy than ZrTe₂. Phonon dispersion analysis with SOC effects predicts the dynamic stability of both compounds. Thus, the current research unifies electronic band structure analysis, topological characterization, and elastic property calculation to reveal how these transition metal dichalcogenides are influenced by their structural, electronic, and mechanical properties. The results obtained in this work can be used in the further development of spintronic and nanoelectronic devices. Full article

(This article belongs to the Topic Advances in Computational Materials Sciences)

► Show Figures

Figure 1

25 pages, 7520 KiB

Open AccessReview

AgGaS₂ and Derivatives: Design, Synthesis, and Optical Properties

by Guansheng Xing and Bing Chen

Nanomaterials 2025, 15(2), 147; https://doi.org/10.3390/nano15020147 - 20 Jan 2025

Viewed by 516

Abstract

Silver gallium sulfide (AgGaS₂) is a ternary A^(I)B^(III)X^(VI)₂-type semiconductor featuring a direct bandgap and high chemical stability. Structurally resembling diamond, AgGaS₂ has gained considerable attention as a highly promising material for nonlinear optical [...] Read more.

Silver gallium sulfide (AgGaS₂) is a ternary A^(I)B^(III)X^(VI)₂-type semiconductor featuring a direct bandgap and high chemical stability. Structurally resembling diamond, AgGaS₂ has gained considerable attention as a highly promising material for nonlinear optical applications such as second harmonic generation and optical parametric oscillation. In attempts to expand the research scope, on the one hand, AgGaS₂-derived bulk materials with similar diamond-like configurations have been investigated for the enhancement of nonlinear optics performance, especially the improvement of laser-induced damage thresholds and/or nonlinear coefficients; on the other hand, nanoscale AgGaS₂ and its derivatives have been synthesized with sizes as low as the exciton Bohr radius for the realization of potential applications in the fields of optoelectronics and lighting. This review article focuses on recent advancements and future opportunities in the design of both bulk and nanocrystalline AgGaS₂ and its derivatives, covering structural, electronic, and chemical aspects. By delving into the properties of AgGaS₂ in bulk and nanocrystalline states, this review aims to deepen the understanding of chalcopyrite materials and maximize their utilization in photon conversion and beyond. Full article

(This article belongs to the Special Issue Nonlinear Optics and Ultrafast Lasers in Nanosystems)

► Show Figures

Figure 1

15 pages, 4343 KiB

Open AccessArticle

A Low-Cost Electrochemical Cell Sensor Based on MWCNT-COOH/α-Fe₂O₃ for Toxicity Detection of Drinking Water Disinfection Byproducts

by Ying Liu, Zhipeng Zhang, Yuling Wu, Huan Yang, Jiao Qu and Xiaolin Zhu

Nanomaterials 2025, 15(2), 146; https://doi.org/10.3390/nano15020146 - 20 Jan 2025

Viewed by 484

Abstract

The disinfection of drinking water is essential for eliminating pathogens and preventing waterborne diseases. However, this process generates various disinfection byproducts (DBPs), which toxicological research indicates can have detrimental effects on living organisms. Moreover, the safety of these DBPs has not been sufficiently [...] Read more.

The disinfection of drinking water is essential for eliminating pathogens and preventing waterborne diseases. However, this process generates various disinfection byproducts (DBPs), which toxicological research indicates can have detrimental effects on living organisms. Moreover, the safety of these DBPs has not been sufficiently assessed, underscoring the need for a comprehensive evaluation of their toxic effects and associated health risks. Compared to traditional methods for studying the toxicity of pollutants, emerging electrochemical sensing technologies offer advantages such as simplicity, speed, and sensitivity, presenting an effective means for toxicity research on pollutants. However, challenges remain in this field, including the need to improve electrode sensitivity and reduce electrode costs. In this study, a pencil graphite electrode (PGE) was modified with carboxylated multi-walled carbon nanotubes (MWCNT-COOH) and nano-iron (III) oxide (α-Fe₂O₃) to fabricate a low-cost electrode with excellent electrocatalytic performance for cell-active substances. Subsequently, a novel cellular electrochemical sensor was constructed for the sensitive detection of the toxicity of three drinking water DBPs. The half inhibitory concentration (IC₅₀) values of 2-chlorophenylacetonitrile (2-CPAN), 3-chlorophenylacetonitrile (3-CPAN), and 4-chlorophenylacetonitrile (4-CPAN) for HepG2 cells were 660.69, 831.76, and 812.83 µM, respectively. This study provides technical support and scientific evidence for the toxicity detection and safety assessment of emerging contaminants. Full article

(This article belongs to the Special Issue Nanomaterials for Environmental Sensors and Pollutant Control)

► Show Figures

Figure 1

12 pages, 3252 KiB

Open AccessArticle

A Cu(I)-Based MOF with Nonlinear Optical Properties and a Favorable Optical Limit Threshold

by Jing Cui, Zhaohui Yang, Yu Zhang, Zhaoxuan Fan, Jianquan Wang, Xiaoyun Qin, Lijun Gao, Haoran Yang, Shuangliang Liu, Liming Zhou, Shaoming Fang and Zhen Zhang

Nanomaterials 2025, 15(2), 145; https://doi.org/10.3390/nano15020145 - 20 Jan 2025

Viewed by 420

Abstract

The exploitation of high-performance third-order nonlinear optical (NLO) materials that have a favorable optical limit (OL) threshold is essential due to a rise in the application of ultra-intense lasers. In this study, a Cu-based MOF (denoted as Cu-bpy) was synthesized, and its third-order [...] Read more.

The exploitation of high-performance third-order nonlinear optical (NLO) materials that have a favorable optical limit (OL) threshold is essential due to a rise in the application of ultra-intense lasers. In this study, a Cu-based MOF (denoted as Cu-bpy) was synthesized, and its third-order NLO and OL properties were investigated using the Z-scan technique with the nanosecond laser pulse excitation set at 532 nm. The Cu-bpy exhibits a typical rate of reverse saturable absorption (RSA) with a third-order nonlinear absorption coefficient of 100 cm GW⁻¹ and a favorable OL threshold of 0.75 J cm⁻² (at a concentration of 1.6 mg mL⁻¹), which is lower than that of most NLO materials that have been reported on so far. In addition, a DFT calculation was performed and was in agreement with our experimental results. Furthermore, the mechanism of the third-order NLO properties was illustrated as one-photon absorption (1PA). These results investigate the relationship between the structure and the nonlinear optical properties of Cu-bpy, and provide an experimental and theoretical basis for its use in optical limiting applications. Full article

(This article belongs to the Section Nanocomposite Materials)

► Show Figures

Figure 1

11 pages, 2797 KiB

Open AccessArticle

Controllable Nano-Crystallization in Fluoroborosilicate Glass Ceramics for Broadband Visible Photoluminescence

by Yuanhang Xiang, Yi Long, Peiying Cen, Sirang Liu, Zaijin Fang and Renjie Jiao

Nanomaterials 2025, 15(2), 144; https://doi.org/10.3390/nano15020144 - 20 Jan 2025

Viewed by 447

Abstract

A transparent fluoroborosilicate glass ceramic was designed for the controllable precipitation of fluoride nanocrystals and to greatly enhance the photoluminescence of active ions. Through the introduction of B₂O₃ into fluorosilicate glass, the melting temperature was decreased from 1400 to 1050 [...] Read more.

A transparent fluoroborosilicate glass ceramic was designed for the controllable precipitation of fluoride nanocrystals and to greatly enhance the photoluminescence of active ions. Through the introduction of B₂O₃ into fluorosilicate glass, the melting temperature was decreased from 1400 to 1050 °C, and the abnormal crystallization in the fabrication process of fluorosilicate glass was avoided. More importantly, the controlled crystallizations of KZnF₃ and KYb₃F₁₀ in fluoroborosilicate glass ceramics enhanced the emission of Mn²⁺ and Mn²⁺–Yb³⁺ dimers by 6.7 and 54 times, respectively. Moreover, the upconversion emission color of glass ceramic could be modulated from yellow to white and blue by adjusting the Yb³⁺ concentration. The well-designed glass ceramic is a novel and significant compound to simultaneously provide efficiently coordinated sites for transition metal and rare earth ions. More importantly, the design strategy opens a new way for engineering high-quality oxy-fluoride glass ceramics with properties of excellent stability, controllable nano-crystallization and high-efficiency photoluminescence. Full article

(This article belongs to the Section Nanocomposite Materials)

► Show Figures

Figure 1

17 pages, 3144 KiB

Open AccessArticle

Antifungal Potential of Biogenic Zinc Oxide Nanoparticles for Controlling Cercospora Leaf Spot in Mung Bean

by Zill-e-Huma Aftab, Faisal Shafiq Mirza, Tehmina Anjum, Humaira Rizwana, Waheed Akram, Muzamil Aftab, Muhammad Danish Ali and Guihua Li

Nanomaterials 2025, 15(2), 143; https://doi.org/10.3390/nano15020143 - 19 Jan 2025

Viewed by 680

Abstract

Agricultural growers worldwide face significant challenges in promoting plant growth. This research introduces a green strategy utilizing nanomaterials to enhance crop production. While high concentrations of nanomaterials are known to be hazardous to plants, this study demonstrates that low doses of biologically synthesized [...] Read more.

Agricultural growers worldwide face significant challenges in promoting plant growth. This research introduces a green strategy utilizing nanomaterials to enhance crop production. While high concentrations of nanomaterials are known to be hazardous to plants, this study demonstrates that low doses of biologically synthesized zinc oxide nanoparticles (ZnO NPs) can serve as an effective regulatory tool to boost plant growth. These nanoparticles were produced using Nigella sativa seed extract and characterized through UV-Vis spectroscopy, FT-IR, X-ray diffraction, and scanning electron microscopy (SEM). The antifungal properties of ZnO NPs were evaluated against Cercospora canescens, the causative agent of Cercospora leaf spot in mung bean. Application of ZnO NPs significantly improved plant metrics, including shoot, root, pod, leaf, and root nodule counts, as well as plant length, fresh weight, and dry weight—all indicators of healthy growth. Moreover, low-dose ZnO NPs positively influenced enzymatic activity, physicochemical properties, and photosynthetic parameters. These findings suggest that biologically synthesized ZnO NPs offer a promising approach for enhancing crop yield and accelerating plant growth. Full article

(This article belongs to the Special Issue Interplay between Nanomaterials and Plants)

► Show Figures

Figure 1

15 pages, 6891 KiB

Open AccessArticle

Reactions of Hydrogen-Passivated Silicon Vacancies in α-Quartz with Electron Holes and Hydrogen

by Teofilo Cobos Freire, Jack Strand and Alexander L. Shluger

Nanomaterials 2025, 15(2), 142; https://doi.org/10.3390/nano15020142 - 19 Jan 2025

Viewed by 520

Abstract

We used density functional theory with a hybrid functional to investigate the structure and properties of [4H]_Si (hydrogarnet) defects in α-quartz as well as the reactions of these defects with electron holes and extra hydrogen atoms and ions. The results demonstrate [...] Read more.

We used density functional theory with a hybrid functional to investigate the structure and properties of [4H]_Si (hydrogarnet) defects in α-quartz as well as the reactions of these defects with electron holes and extra hydrogen atoms and ions. The results demonstrate the depassivation mechanisms of hydrogen-passivated silicon vacancies in α-quartz, providing a detailed understanding of their stability, electronic properties, and behaviour in different charge states. While fully hydrogen passivated silicon vacancies are electrically inert, the partial removal of hydrogen atoms activates these defects as hole traps, altering the defect states and influencing the electronic properties of the material. Our calculations of the hydrogen migration mechanisms predict the low energy barriers for H⁺, H⁰, and H⁻, with the lowest barrier of 0.28 eV for neutral hydrogen migration between parallel c-channels and a similar barrier for H⁺ migration along the c-channels. The reactions of electron holes and hydrogen species with [4H]_Si defects lead to the breaking of O–H bonds and the formation of non-bridging oxygen hole centres (NBOHCs) within the Si vacancies. The calculated optical absorption energies of these centres are close to those attributed to individual NBOHCs in glass samples. These findings can be useful for understanding the role of [4H]_Si defects in bulk and nanocrystalline quartz as well as in SiO₂-based electronic devices. Full article

(This article belongs to the Section Theory and Simulation of Nanostructures)

► Show Figures

Figure 1

12 pages, 2825 KiB

Open AccessArticle

Digital Mini-LED Lighting Using Organic Thin-Film Transistors Reaching over 100,000 Nits of Luminance

by Chia-Hung Tsai, Yang-En Wu, Chien-Chi Huang, Li-Yin Chen, Fang-Chung Chen and Hao-Chung Kuo

Nanomaterials 2025, 15(2), 141; https://doi.org/10.3390/nano15020141 - 17 Jan 2025

Viewed by 528

Abstract

This paper demonstrates the use of organic thin-film transistors (OTFTs) to drive active digital mini light-emitting diode (mini-LED) backlights, aiming to achieve exceptional display performance. Our findings reveal that OTFTs can effectively power mini-LED backlights, reaching brightness levels exceeding 100,000 nits. This approach [...] Read more.

This paper demonstrates the use of organic thin-film transistors (OTFTs) to drive active digital mini light-emitting diode (mini-LED) backlights, aiming to achieve exceptional display performance. Our findings reveal that OTFTs can effectively power mini-LED backlights, reaching brightness levels exceeding 100,000 nits. This approach not only enhances image quality but also improves energy efficiency. OTFTs offer a flexible and lightweight alternative to conventional silicon-based transistors, enabling innovative and versatile display designs. The integration of mini-LED technology with OTFTs produces displays with superior contrast ratios, enhanced color brightness, and lower power consumption. This technological advancement is poised to revolutionize high-dynamic-range (HDR) displays, including those in televisions, smartphones, and wearable devices, where the demand for high brightness and energy efficiency is paramount. Full article

(This article belongs to the Special Issue Nanostructured Materials for Perovskite Solar Cells and Light-Emitting Diodes)

► Show Figures

Figure 1

21 pages, 7804 KiB

Open AccessArticle

In Situ X-Ray Study During Thermal Cycle Treatment Combined with Complementary Ex Situ Investigation of InGaN Quantum Wells

by Ewa Grzanka, Sondes Bauer, Artur Lachowski, Szymon Grzanka, Robert Czernecki, Byeongchan So, Tilo Baumbach and Mike Leszczyński

Nanomaterials 2025, 15(2), 140; https://doi.org/10.3390/nano15020140 - 17 Jan 2025

Viewed by 594

Abstract

In situ X-ray reciprocal space mapping was performed during the interval heating and cooling of InGaN/GaN quantum wells (QWs) grown via metal–organic vapor phase epitaxy (MOVPE). Our detailed in situ X-ray analysis enabled us to track changes in the peak intensities and radial [...] Read more.

In situ X-ray reciprocal space mapping was performed during the interval heating and cooling of InGaN/GaN quantum wells (QWs) grown via metal–organic vapor phase epitaxy (MOVPE). Our detailed in situ X-ray analysis enabled us to track changes in the peak intensities and radial and angular broadenings of the reflection. By simulating the radial diffraction profiles recorded during the thermal cycle treatment, we demonstrate the presence of indium concentration distributions (ICDs) in the different QWs of the heterostructure (1. QW, bottom, 2. QW, middle, and 3. QW, upper). During the heating process, we found that the homogenization of the QWs occurred in the temperature range of 850 °C to 920 °C, manifesting in a reduction in ICDs in the QWs. Furthermore, there is a critical temperature (T = 940 °C) at which the mean value of the indium concentration starts to decrease below 15% in 1. QW, indicating the initiation of decomposition in 1. QW. Moreover, further heating up to 1000 °C results in extended diffuse scattering along the angular direction of the diffraction spot, confirming the propagation of the decomposition and the formation of trapezoidal objects, which contain voids and amorphous materials (In-Ga). Heating InGaN QWs up to T = 1000 °C led to a simultaneous decrease in the indium content and ICDs. During the cooling phase, there was no significant variation in the indium concentrations in the different QWs but rather an increase in the defect area, which contributes to the amplification of diffuse scattering. A comparison of ex situ complementary high-resolution transmission microscopy (Ex-HRTEM) measurements performed at room temperature before and after the thermal cycle treatment provides proof of the formation of four different types of defects in the QWs, which result from the decomposition of 1. QW during the heating phase. This, in turn, has strongly influenced the intensity of the photoluminescence emission spectra without any detectable shift in the emission wavelength λ_MQWs. Full article

(This article belongs to the Section Synthesis, Interfaces and Nanostructures)

► Show Figures

Figure 1

16 pages, 6768 KiB

Open AccessArticle

Mid-Infrared High-Power InGaAsSb/AlGaInAsSb Multiple-Quantum-Well Laser Diodes Around 2.9 μm

by Hongguang Yu, Chengao Yang, Yihang Chen, Jianmei Shi, Juntian Cao, Zhengqi Geng, Zhiyuan Wang, Haoran Wen, Enquan Zhang, Yu Zhang, Hao Tan, Donghai Wu, Yingqiang Xu, Haiqiao Ni and Zhichuan Niu

Nanomaterials 2025, 15(2), 139; https://doi.org/10.3390/nano15020139 - 17 Jan 2025

Viewed by 406

Abstract

Antimonide laser diodes, with their high performance above room temperature, exhibit significant potential for widespread applications in the mid-infrared spectral region. However, the laser’s performance significantly degrades as the emission wavelength increases, primarily due to severe quantum-well hole leakage and significant non-radiative recombination. [...] Read more.

Antimonide laser diodes, with their high performance above room temperature, exhibit significant potential for widespread applications in the mid-infrared spectral region. However, the laser’s performance significantly degrades as the emission wavelength increases, primarily due to severe quantum-well hole leakage and significant non-radiative recombination. In this paper, we put up an active region with a high valence band offset and excellent crystalline quality with high luminescence to improve the laser’s performance. The miscibility gap of the InGaAsSb alloy was systematically investigated by calculating the critical temperatures based on the delta lattice parameter model. As the calculation results show, In_0.54Ga_0.46As_0.23Sb_0.77, with a compressive strain of 1.74%, used as the quantum well, is out of the miscibility gap with no spinodal decomposition. The quantum wells exhibit high crystalline quality, as evidenced by distinct satellite peaks in XRD curves with a full width at half maximum (FWHM) of 56 arcseconds for the zeroth-order peak, a smooth surface with a root mean square (RMS) roughness of 0.19 nm, room-temperature photoluminescence with high luminous efficiency and narrow FHWM of 35 meV, and well-defined interfaces. These attributes effectively suppress non-radiative recombination, thereby enhancing internal quantum efficiency in the antimonide laser. Furthermore, a novel epitaxial laser structure was designed to acquire low optical absorption loss by decreasing the optical confinement factor in the cladding layer and implementing gradient doping in the p-type cladding layer. The continuous-wave output power of 310 mW was obtained at an injection current of 4.6 A and a heatsink temperature of 15 °C from a 1500 × 100 μm² single emitter. The external quantum efficiency of 53% was calculated with a slope efficiency of 0.226 W/A considering both of the uncoated facets. More importantly, the lasing wavelength of our laser exhibited a significant blue shift from 3.4 μm to 2.9 μm, which agrees with our calculated results when modeling the interdiffusion process in a quantum well. Therefore, the interdiffusion process must be considered for proper design and epitaxy to achieve mid-infrared high-power and high-efficiency antimonide laser diodes. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

► Show Figures

Figure 1

14 pages, 5347 KiB

Open AccessArticle

A Microfabrication Technique for High-Performance Diffractive Optical Elements Tailored for Numerical Simulation

by Xingang Dai, Yanjun Hu, Bowen Niu, Qun Dai, Yu Ao, Hongru Zhang, Gaoshan Jing, Yuan Li and Guofang Fan

Nanomaterials 2025, 15(2), 138; https://doi.org/10.3390/nano15020138 - 17 Jan 2025

Viewed by 481

Abstract

Diffractive optical elements (DOEs) are specialized optical components that manipulate light through diffraction for various applications, including holography, spectroscopy, augmented reality (AR) and virtual reality (VR), and light detection and ranging (LiDAR). The performance of DOEs is highly determined by fabricated materials and [...] Read more.

Diffractive optical elements (DOEs) are specialized optical components that manipulate light through diffraction for various applications, including holography, spectroscopy, augmented reality (AR) and virtual reality (VR), and light detection and ranging (LiDAR). The performance of DOEs is highly determined by fabricated materials and fabrication methods, in addition to the numerical simulation design. This paper presents a microfabrication technique optimized for DOEs, enabling precise control of critical parameters, such as refractive index (RI) and thickness. Using photolithography, we fabricated high-precision photoresist patterns on silicon and sapphire substrates, with 3 × 3 and 3 × 5 DOE beam splitter as examples. The results show a strong match between simulation and experimental data, with discrepancies of just 0.53% and 0.57% for DOE on silicon and sapphire substrates, respectively. This approach offers potential for advancing high-performance DOE devices in semiconductor manufacturing, supporting next-generation optical systems. Full article

(This article belongs to the Special Issue Advanced Manufacturing on Nano- and Microscale)

► Show Figures

Figure 1

12 pages, 2296 KiB

Open AccessArticle

Effects of Homogeneous Doping on Electron–Phonon Coupling in SrTiO₃

by Minwoo Park and Suk Bum Chung

Nanomaterials 2025, 15(2), 137; https://doi.org/10.3390/nano15020137 - 17 Jan 2025

Viewed by 515

Abstract

Bulk n-type SrTiO₃ (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying adiabatic assumption. However, recent experimental reports have set [...] Read more.

Bulk n-type SrTiO₃ (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying adiabatic assumption. However, recent experimental reports have set the pairing gap to the critical temperature (

T_{c}

) ratio at the BCS value for superconductivity in Nb-doped STO, even though the adiabaticity condition the BCS pairing requires is satisfied over the entire superconducting dome only by the lowest branch of optical phonons. In spite of the strong implications these reports have on specifying the pairing glue, they have not proved sufficient in explaining the magnitude of the optimal doping. This motivated us to apply density functional theory to Nb-doped STO to analyze how the phonon band structures and the electron–phonon coupling evolve with doping. To describe the very low doping concentration, we tuned the homogeneous background charge, from which we obtained a first-principles result on the doping-dependent phonon frequency that is in good agreement with experimental data for Nb-doped STO. Using the EPW code, we obtain the doping-dependent phonon dispersion and the electron–phonon coupling strength. Within the framework of our calculation, we found that the electron–phonon coupling forms a dome in a doping range lower than the experimentally observed superconducting dome of the Nb-doped STO. Additionally, we examined the doping dependence of both the orbital angular momentum quenching in the electron–phonon coupling and the phonon displacement correlation length and found the former to have a strong correlation with our electron–phonon coupling in the overdoped region. Full article

(This article belongs to the Special Issue Low-Dimensional Perovskite Materials and Devices)

► Show Figures

Figure 1

14 pages, 5938 KiB

Open AccessArticle

Facile Synthesis of Functional Mesoporous Organosilica Nanospheres and Adsorption Properties Towards Pb(II) Ions

by Liping Deng, Shichun Gu, Ruyi Wang, Yapeng He, Hairong Dong and Xue Wang

Nanomaterials 2025, 15(2), 136; https://doi.org/10.3390/nano15020136 - 17 Jan 2025

Viewed by 428

Abstract

We successfully synthesize monodisperse sulfhydryl-modified mesoporous organosilica nanospheres (MONs-SH) via one-step hydrolytic condensation, where cetyltrimethylammonium chloride and dodecyl sulfobetaine are employed as dual-template agents with (3-mercaptopropyl)triethoxysilane and 1,2-bis(triethoxysilyl)ethane as the precursors and concentrated ammonia as the alkaline catalyst. The prepared MONs-SHs deliver a [...] Read more.

We successfully synthesize monodisperse sulfhydryl-modified mesoporous organosilica nanospheres (MONs-SH) via one-step hydrolytic condensation, where cetyltrimethylammonium chloride and dodecyl sulfobetaine are employed as dual-template agents with (3-mercaptopropyl)triethoxysilane and 1,2-bis(triethoxysilyl)ethane as the precursors and concentrated ammonia as the alkaline catalyst. The prepared MONs-SHs deliver a large specific surface area (729.15 m² g⁻¹), excellent monodispersity, and homogeneous particle size. The introduction of ethanol into the reaction systems could expand the particle size of the synthesized MONs-SH materials from 18 to 182 nm. Moreover, the successful modification of -SH groups endowed MONs-SHs with an excellent adsorption capacity (297.12 mg g⁻¹) for Pb²⁺ ions in aqueous solution through ion exchange and complexation function. In addition, the established isotherm model and kinetic analyses reveal that the adsorption of Pb²⁺ ions on MONs-SHs follows the secondary reaction kinetic models, where both physisorption and chemisorption contribute to the adsorption of Pb²⁺ ions. The favorable recyclability of MONs-SHs is demonstrated with the maintained adsorption efficiency of 85.35% after six cycles. The results suggest that the synthesized MONs-SHs exhibit considerable application prospects for effectively eliminating Pb²⁺ ions from aqueous solutions. Full article

(This article belongs to the Special Issue Nanostructured Mesoporous and Zeolite-Based Materials: 2nd Edition)

► Show Figures

Figure 1

11 pages, 3283 KiB

Open AccessArticle

Foamy Melamine Resin–Silica Aerogel Composite-Derived Thermal Insulation Coating

by Dongfang Wang, Yabin Ma, Yingjie Ma, Baolei Liu, Dewen Sun and Qianping Ran

Nanomaterials 2025, 15(2), 135; https://doi.org/10.3390/nano15020135 - 17 Jan 2025

Viewed by 541

Abstract

A novel class of SiO₂ aerogel-based resin composite with a self-formed foamy structure and an extremely low thermal conductivity, as well as excellent fire resistance, was fabricated via a room temperature and atmospheric pressure route. The self-formed foamy structure was achieved by [...] Read more.

A novel class of SiO₂ aerogel-based resin composite with a self-formed foamy structure and an extremely low thermal conductivity, as well as excellent fire resistance, was fabricated via a room temperature and atmospheric pressure route. The self-formed foamy structure was achieved by utilizing SiO₂ aerogel particles not only as a thermal insulative functional additive filler but also as nano-sized solid particles in a Picking emulsion system, adjusting the surface tension as a stabilizer at the interface between the two immiscible phases (liquid and air in this case). The results of foamy structure analyses via scanning electron microscopy, micro-CT, and N₂ adsorption–desorption isotherms validate the successful generation of a micro-scale porous structure with the enhancement of the aerogel nano-scale solid particles at the wall as a stabilizer. A combination of multiscale pores imbues the aerogel-based foamy coating with a low thermal conductivity, as well as a high cohesive strength. For the foamy coating studied, with variable emulsion/foaming agent/aerogel ratios of 1/2/x, the thermal conductivity decreases from 0.141 to 0.031 W/m·K, and the cohesive strength increases from being non-detectable to 0.41 MPa. The temperature difference, which is a direct indicator of the thermal insulation behavior of the foamy coating, can increase from 12.1 °C to 48.6 °C under an 80 °C hot plate. Full article

(This article belongs to the Section Nanocomposite Materials)

► Show Figures

Graphical abstract

12 pages, 2211 KiB

Open AccessCommunication

4D-Printed Magnetic Responsive Bilayer Hydrogel

by Yangyang Li, Yuanyi Li, Jiawei Cao, Peng Luo, Jianpeng Liu, Lina Ma, Guo-Lin Gao and Zaixing Jiang

Nanomaterials 2025, 15(2), 134; https://doi.org/10.3390/nano15020134 - 17 Jan 2025

Viewed by 667

Abstract

Despite its widespread application in targeted drug delivery, soft robotics, and smart screens, magnetic hydrogel still faces challenges from lagging mechanical performance to sluggish response times. In this paper, a methodology of in situ generation of magnetic hydrogel based on 3D printing of [...] Read more.

Despite its widespread application in targeted drug delivery, soft robotics, and smart screens, magnetic hydrogel still faces challenges from lagging mechanical performance to sluggish response times. In this paper, a methodology of in situ generation of magnetic hydrogel based on 3D printing of poly-N-isopropylacrylamide (PNIPAM) is presented. A temperature-responsive PNIPAM hydrogel was prepared by 3D printing, and Fe₂O₃ magnetic particles were generated in situ within the PNIPAM network to generate the magnetic hydrogel. By forming uniformly distributed magnetic particles in situ within the polymer network, 3D printing of customized magnetic hydrogel materials was successfully achieved. The bilayer hydrogel structure was designed according to the different swelling ratios of temperature-sensitive hydrogel and magnetic hydrogel. Combined with the excellent mechanical properties of PNIPAM and printable magnetic hydrogel, 4D-printed remote magnetic field triggered shape morphing of bilayers of five-petal flower-shaped hydrogels was presented, and the deformation process was finished within 300 s. Full article

(This article belongs to the Special Issue Magnetization and Magnetic Disorder at the Nanoscale)

► Show Figures

Figure 1

21 pages, 6661 KiB

Open AccessReview

Doxorubicin-Conjugated Nanoparticles for Potential Use as Drug Delivery Systems

by Alua Imantay, Nariman Mashurov, Balnur A. Zhaisanbayeva and Ellina A. Mun

Nanomaterials 2025, 15(2), 133; https://doi.org/10.3390/nano15020133 - 17 Jan 2025

Viewed by 664

Abstract

Doxorubicin (DOX) is one of the most widely used chemotherapy drugs in the treatment of both solid and liquid tumors in patients of all age groups. However, it is likely to produce several side effects that include doxorubicin cardiomyopathy. Nanoparticles (NPs) can offer [...] Read more.

Doxorubicin (DOX) is one of the most widely used chemotherapy drugs in the treatment of both solid and liquid tumors in patients of all age groups. However, it is likely to produce several side effects that include doxorubicin cardiomyopathy. Nanoparticles (NPs) can offer targeted delivery and release of the drug, potentially increasing treatment efficiency and alleviating side effects. This makes them a viable vector for novel drug delivery systems. Currently, DOX is commonly conjugated to NPs by non-covalent conjugation–physical entrapping of the drug using electrostatic interactions, van der Waals forces, or hydrogen bonding. The reported downside of these methods is that they provide a low drug loading capacity and a higher drug leakage possibility. In comparison to this, the covalent conjugation of DOX via amide (typically formed by coupling carboxyl groups on DOX with amine groups on the nanoparticle or a linker, often facilitated by carbodiimide reagents), hydrazone (which results from the reaction between hydrazines and carbonyl groups, offering pH-sensitive cleavage for controlled release), or disulfide bonds (formed through the oxidation of thiol groups and cleavable by intracellular reducing agents such as glutathione) is more promising as it offers greater bonding strength. This review covers the covalent conjugation of DOX to three different types of NPs—metallic, silica/organosilica, and polymeric—including their corresponding release rates and mechanisms. Full article

(This article belongs to the Topic Application of Nanomaterials and Nanobiotechnology in Cancer)

► Show Figures

Figure 1

29 pages, 9920 KiB

Open AccessArticle

Controlled Capture of Magnetic Nanoparticles from Microfluidic Flows by Ferromagnetic Antidot and Dot Nanostructures

by Reyne Dowling and Mikhail Kostylev

Nanomaterials 2025, 15(2), 132; https://doi.org/10.3390/nano15020132 - 16 Jan 2025

Viewed by 545

Abstract

The capture of magnetic nanoparticles (MNPs) is essential in the separation and detection of MNPs for applications such as magnetic biosensing. The sensitivity of magnetic biosensors inherently depends upon the distribution of captured MNPs within the sensing area. We previously demonstrated that the [...] Read more.

The capture of magnetic nanoparticles (MNPs) is essential in the separation and detection of MNPs for applications such as magnetic biosensing. The sensitivity of magnetic biosensors inherently depends upon the distribution of captured MNPs within the sensing area. We previously demonstrated that the distribution of MNPs captured from evaporating droplets by ferromagnetic antidot nanostructures can be controlled via an external magnetic field. In this paper, we demonstrate the capture of magnetic nanoparticles from a microfluidic flow by four variants of antidot array nanostructures etched into 30 nm thick Permalloy films. The nanostructures were exposed to 130 nm MNP clusters passing through microfluidic channels with square cross-sections of 400 μm × 400 μm. In the presence of a parallel magnetic field, up to 83.1% of nanoparticles were captured inside the antidot holes. Significantly higher proportions of nanoparticles were captured within the antidots from the flow than when applying the nanoparticles via droplets. In the parallel field configuration, MNPs can be focused into the regularly spaced antidot indents in the nanostructure, which may be useful when detecting or observing MNPs and their conjugates. Conversely, up to 84% of MNPs were caught outside of antidots under a perpendicular magnetic field. Antidot nanostructures under this perpendicular configuration show potential for MNP filtration applications. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Sensing and Detection (2nd Edition))

► Show Figures

Figure 1

10 pages, 1806 KiB

Open AccessArticle

Controlled Oxidation of Metallic Molybdenum Patterns via Joule Heating for Localized MoS₂ Growth

by Norah Aldosari, William Poston, Gregory Jensen, Maryam Bizhani, Muhammad Tariq and Eric Stinaff

Nanomaterials 2025, 15(2), 131; https://doi.org/10.3390/nano15020131 - 16 Jan 2025

Viewed by 634

Abstract

High-quality two-dimensional transition metal dichalcogenides (2D TMDs), such as molybdenum disulfide (MoS₂), have significant potential for advanced electrical and optoelectronic applications. This study introduces a novel approach to control the localized growth of MoS₂ through the selective oxidation of bulk [...] Read more.

High-quality two-dimensional transition metal dichalcogenides (2D TMDs), such as molybdenum disulfide (MoS₂), have significant potential for advanced electrical and optoelectronic applications. This study introduces a novel approach to control the localized growth of MoS₂ through the selective oxidation of bulk molybdenum patterns using Joule heating, followed by sulfurization. By passing an electric current through molybdenum patterns under ambient conditions, localized heating induced the formation of a molybdenum oxide layer, primarily MoO₂ and MoO₃, depending on the applied power and heating duration. These oxides act as nucleation sites for the subsequent growth of MoS₂. The properties of the grown MoS₂ films were investigated using Raman spectroscopy and photoluminescence measurements, showing promising film quality. This study demonstrates that Joule heating can be an effective method for precise control over TMD growth, offering a scalable approach for producing high-quality 2D materials that have the potential to be integrated into next-generation electrical and optoelectronic technologies. Full article

(This article belongs to the Special Issue Functional Two-Dimensional Materials, Thin Films and Coatings)

► Show Figures

Figure 1

23 pages, 7326 KiB

Open AccessArticle

Significance of Tool Coating Properties and Compacted Graphite Iron Microstructure for Tool Selection in Extreme Machining

by Anna Maria Esposito, Qianxi He, Jose M. DePaiva and Stephen C. Veldhuis

Nanomaterials 2025, 15(2), 130; https://doi.org/10.3390/nano15020130 - 16 Jan 2025

Viewed by 589

Abstract

This study aims to determine the extent to which coating composition and workpiece properties impact machinability and tool selection when turning Compacted Graphite Iron (CGI) under extreme roughing conditions. Two CGI workpieces, differing in pearlite content and graphite nodularity, were machined at a [...] Read more.

This study aims to determine the extent to which coating composition and workpiece properties impact machinability and tool selection when turning Compacted Graphite Iron (CGI) under extreme roughing conditions. Two CGI workpieces, differing in pearlite content and graphite nodularity, were machined at a cutting speed of 180 m/min, feed rate of 0.18 mm/rev, and depth of cut of 3 mm. To assess the impact of tool properties across a wide range of commercially available tools, four diverse multilayered cemented carbide tools were evaluated: Tool A and Tool B with a thin AlTiSiN PVD coating, Tool C with a thick Al₂O₃-TiCN CVD coating, and Tool D with a thin Al₂O₃-TiC PVD coating. The machinability of CGI and wear mechanisms were analyzed using pre-cutting characterization, in-process optical microscopy, and post-test SEM analysis. The results revealed that CGI microstructural variations only affected tool life for Tool A, with a 110% increase in tool life between machining CGI Grade B and Grade A, but that the effects were negligible for all other tools. Tool C had a 250% and 70% longer tool life compared to the next best performance (Tool A) for CGI Grade A and CGI Grade B, respectively. With its thick CVD-coating, Tool C consistently outperformed the others due to its superior protection of the flank face and cutting edge under high-stress conditions. The cutting-induced stresses played a more significant role in the tool wear process than minor differences in workpiece microstructure or tool properties, and a thick CVD coating was most effective in addressing the tool wear effects for the extreme roughing conditions. However, differences in tool life for Tool A showed that tool behavior cannot be predicted based on a single system parameter, even for extreme conditions. Instead, tool properties, workpiece properties, cutting conditions, and their interactions should be considered collectively to evaluate the extent that an individual parameter impacts machinability. This research demonstrates that a comprehensive approach such as this can allow for more effective tool selection and thus lead to significant cost savings and more efficient manufacturing operations. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications for Nanostructured Alloys)

► Show Figures

Figure 1

13 pages, 10081 KiB

Open AccessArticle

Preparation and Gas-Sensitive Properties of SnO₂@Bi₂O₃ Core-Shell Heterojunction Structure

by Jin Liu, Yixin Gao, Yuanyuan Lv, Mengdi Yang, Haoru Guo, Neng Li, Danyang Bai and Anyi Wang

Nanomaterials 2025, 15(2), 129; https://doi.org/10.3390/nano15020129 - 16 Jan 2025

Viewed by 548

Abstract

The SnO₂@Bi₂O₃ core-shell heterojunction structure was designed and synthesized via a hydrothermal method, and the structure and morphology of the synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Based [...] Read more.

The SnO₂@Bi₂O₃ core-shell heterojunction structure was designed and synthesized via a hydrothermal method, and the structure and morphology of the synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Based on the conclusions from XRD and SEM, it can be observed that as the hydrothermal temperature increases, the content of Bi₂O₃ coated on the surface of SnO₂ spheres gradually increases, and the diameter of Bi₂O₃ nanoparticles also increases. At a hydrothermal temperature of 160 °C, the SnO₂ spheres are fully coated with Bi₂O₃ nanoparticles. This paper investigated the gas-sensitive performance of the SnO₂@Bi₂O₃ sensor towards ethanol gas. Gas sensitivity tests at the optimal operating temperature of 300 °C showed that the composite prepared at 160 °C achieved a response value of 19.7 for 100 ppm ethanol. Additionally, the composite exhibited excellent response to 100 ppm ethanol, with a response time of only 4 s, as well as good repeatability. The excellent gas-sensitive performance of the SnO₂@Bi₂O₃ core-shell heterojunction towards ethanol gas is attributed to its p-n heterojunction material properties. Its successful preparation contributes to the realization of high-performance heterostructure ethanol gas sensors. Full article

(This article belongs to the Special Issue Harvesting Electromagnetic Fields with Nanomaterials: Selected Papers from the International Forum on Micro-Nano Technology and Composites)

► Show Figures

Figure 1

14 pages, 7136 KiB

Open AccessArticle

Mesoporous Nitrogen-Doped Carbon Support from ZIF-8 for Pt Catalysts in Oxygen Reduction Reaction

by Sangyeup Park, Jong Gyeong Kim, Youngin Cho and Chanho Pak

Nanomaterials 2025, 15(2), 128; https://doi.org/10.3390/nano15020128 - 16 Jan 2025

Viewed by 541

Abstract

Zeolitic imidazolate framework-8 (ZIF-8) has been extensively studied as a precursor for nitrogen-doped carbon (NC) materials due to its high surface area, tunable porosity, and adjustable nitrogen content. However, the intrinsic microporous structure of the ZIF-8 limits mass transport and accessibility of reactants [...] Read more.

Zeolitic imidazolate framework-8 (ZIF-8) has been extensively studied as a precursor for nitrogen-doped carbon (NC) materials due to its high surface area, tunable porosity, and adjustable nitrogen content. However, the intrinsic microporous structure of the ZIF-8 limits mass transport and accessibility of reactants to active sites, reducing its effectiveness in electrochemical applications. In this study, a soft templating approach using a triblock copolymer was used to prepare mesoporous ZIF-8-derived NC (Meso-ZIF-NC) samples. The hierarchical porous structure was investigated by varying the ratios of Pluronic F-127, NaClO₄, and toluene. The resulting Meso-ZIF-NC exhibited widespread pore size distribution with an enhanced mesopore (2–50 nm) volume according to the composition of the reaction mixtures. Pt nanoparticles were uniformly dispersed on the Meso-ZIF-NC to form Pt/Meso-ZIF-NC catalysts, which presented a high electrochemical surface area and improved oxygen reduction reaction activity. The study highlights the important role of mesopore structure and nitrogen doping in enhancing catalytic performance, providing a pathway for advanced fuel cell catalyst design. Full article

(This article belongs to the Collection Micro/Nanoscale Open Framework Materials (OFMs))

► Show Figures

Figure 1

17 pages, 4204 KiB

Open AccessArticle

Preparation and Gas-Sensitive Properties of Square–Star-Shaped Leaf-Like BiVO₄ Nanomaterials

by Jin Liu, Mengdi Yang, Yuanyuan Lv, Yixin Gao, Danyang Bai, Neng Li, Haoru Guo and Anyi Wang

Nanomaterials 2025, 15(2), 127; https://doi.org/10.3390/nano15020127 - 16 Jan 2025

Viewed by 488

Abstract

In this study, square–star-shaped leaf-like BiVO₄ nanomaterials were successfully synthesized using a conventional hydrothermal method. The microstructure, elemental composition, and gas-sensing performance of the materials were thoroughly investigated. Morphological analysis revealed that BiVO₄ prepared at different reaction temperatures exhibited square–star-shaped leaf-like [...] Read more.

In this study, square–star-shaped leaf-like BiVO₄ nanomaterials were successfully synthesized using a conventional hydrothermal method. The microstructure, elemental composition, and gas-sensing performance of the materials were thoroughly investigated. Morphological analysis revealed that BiVO₄ prepared at different reaction temperatures exhibited square–star-shaped leaf-like structures, with the most regular and dense structures formed at 150 °C, exhibiting a large specific surface area of 2.84 m²/g. The response performance of the BiVO₄ gas sensors to different target gases was evaluated, and the results showed that the prepared BiVO₄ gas sensor exhibited a strong response to NH₃. At the optimal operating temperature of 300 °C, its sensitivity to 5 ppm NH₃ reached 13.3, with a response time of 28 s and a recovery time of 16 s. Moreover, the gas sensor exhibited excellent repeatability and anti-interference performance. These findings indicate that square–star-shaped leaf-like BiVO₄ holds great potential in environmental monitoring and industrial safety detection, offering new insights for the development of high-performance gas sensors. Full article

(This article belongs to the Special Issue Harvesting Electromagnetic Fields with Nanomaterials: Selected Papers from the International Forum on Micro-Nano Technology and Composites)

► Show Figures

Figure 1

41 pages, 3621 KiB

Open AccessReview

Chitosan and Its Nanoparticles: A Multifaceted Approach to Antibacterial Applications

by Emir Akdaşçi, Hatice Duman, Furkan Eker, Mikhael Bechelany and Sercan Karav

Nanomaterials 2025, 15(2), 126; https://doi.org/10.3390/nano15020126 - 16 Jan 2025

Viewed by 656

Abstract

Chitosan, a multifaceted amino polysaccharide biopolymer derived from chitin, has extensive antibacterial efficacy against diverse pathogenic microorganisms, including both Gram-negative and Gram-positive bacteria, in addition to fungi. Over the course of the last several decades, chitosan nanoparticles (NPs), which are polymeric and bio-based, [...] Read more.

Chitosan, a multifaceted amino polysaccharide biopolymer derived from chitin, has extensive antibacterial efficacy against diverse pathogenic microorganisms, including both Gram-negative and Gram-positive bacteria, in addition to fungi. Over the course of the last several decades, chitosan nanoparticles (NPs), which are polymeric and bio-based, have garnered a great deal of interest as efficient antibacterial agents. This is mostly due to the fact that they are used in a wide variety of applications, including medical treatments, food, chemicals, and agricultural products. Within the context of the antibacterial mechanism of chitosan and chitosan NPs, we present a review that provides an overview of the synthesis methods, including novel procedures, and compiles the applications that have been developed in the field of biomedicine. These applications include wound healing, drug delivery, dental treatment, water purification, agriculture, and food preservation. In addition to this, we focus on the mechanisms of action and the factors that determine the antibacterial activity of chitosan and its derivatives. In conjunction with this line of inquiry, researchers are strongly urged to concentrate their efforts on developing novel and ground-breaking applications of chitosan NPs. Full article

(This article belongs to the Special Issue Biomass-Based Functional Nanomaterials: Synthesis and Application)

► Show Figures

Figure 1

22 pages, 11357 KiB

Open AccessArticle

Enhancement of Fracture Toughness of NiTi Alloy by Controlling Grain Size Gradient

by Kai Huang, Zhongzheng Deng and Hao Yin

Nanomaterials 2025, 15(2), 125; https://doi.org/10.3390/nano15020125 - 16 Jan 2025

Viewed by 446

Abstract

Fracture toughness is a critical indicator for the application of NiTi alloys in medical fields. We propose to enhance the fracture toughness of NiTi alloys by controlling the spatial grain size (GS) gradient. Utilizing rolling processes and heat treatment technology, three categories of [...] Read more.

Fracture toughness is a critical indicator for the application of NiTi alloys in medical fields. We propose to enhance the fracture toughness of NiTi alloys by controlling the spatial grain size (GS) gradient. Utilizing rolling processes and heat treatment technology, three categories of NiTi alloys with distinct spatial GS distributions were fabricated and subsequently examined through multi-field synchronous fracture tests. It is found that the one with a locally ultra-high GS gradient (20 nm−3.4 μm) has significantly enhanced fracture toughness, which is as high as 412% of that of the normally distributed nano-grains with an average GS of 8 nm and 178% of that of the coarse-grains with an average GS of 100 nm. Theoretical analysis reveals that in such a gradient structure, phase transition in the coarse-grained matrix greatly absorbs the surface energy of subcritical and stable propagation. Meanwhile, the locally non-uniform GS distribution leads to deviation and tortuosity of the crack path, increasing the critical fracture stress. Furthermore, the nanocrystalline clusters distributed in the form of network nodes reduce the stress intensity factor due to their higher elastic modulus compared to the coarse-grained matrix. This work provides guidance for developing new gradient nanostructured NiTi alloys with high fracture toughness. Full article

(This article belongs to the Special Issue Mechanical Properties and Applications for Nanostructured Alloys)

► Show Figures

Figure 1

15 pages, 3561 KiB

Open AccessArticle

High-Performance Hydrogen Sensing at Room Temperature via Nb-Doped Titanium Oxide Thin Films Fabricated by Micro-Arc Oxidation

by Chilou Zhou, Zhiqiu Ye, Yue Tan, Zhenghua Wu, Xinyi Guo, Yinglin Bai, Xuying Xie, Zilong Wu, Ji’an Feng, Yao Xu, Bo Deng and Hao Wu

Nanomaterials 2025, 15(2), 124; https://doi.org/10.3390/nano15020124 - 16 Jan 2025

Viewed by 413

Abstract

Metal oxide semiconductor (MOS) hydrogen sensors offer advantages, such as high sensitivity and fast response, but their challenges remain in achieving low-cost fabrication and stable operation at room temperature. This study investigates Nb-doped TiO₂ (NTO) thin films prepared via a one-step micro-arc [...] Read more.

Metal oxide semiconductor (MOS) hydrogen sensors offer advantages, such as high sensitivity and fast response, but their challenges remain in achieving low-cost fabrication and stable operation at room temperature. This study investigates Nb-doped TiO₂ (NTO) thin films prepared via a one-step micro-arc oxidation (MAO) with the addition of Nb₂O₅ nanoparticles into the electrolyte for room-temperature hydrogen sensing. The characterization results revealed that the incorporation of Nb₂O₅ altered the film’s morphology and phase composition, increasing the Nb content and forming a homogeneous composite thin film. Hydrogen sensing tests demonstrated that the NTO samples exhibited significantly improved sensitivity, selectivity, and stability compared to undoped TiO₂. Among the fabricated samples, NTO thin film prepared at Nb₂O₅ concentration of 6 g/L (NTO-6) showed the best performance, with a broad detection range, excellent sensitivity, rapid response, and good specificity to hydrogen. A strong linear relationship between response values and hydrogen concentration (10–1000 ppm) highlights its potential for precise hydrogen detection. The enhanced hydrogen sensing mechanism of NTO thin films primarily stems from the influence of Nb₂O₅; nanoparticles doping in the anatase-phase TiO₂ structure on the semiconductor surface depletion layer, as well as the improved charge transfer and additional adsorption sites provided by the Nb/Ti composite metal oxides, such as TiNb₂O₇ and Ti_0.95Nb_0.95O₄. This study demonstrates the potential of MAO-fabricated Nb-doped TiO₂ thin films as efficient and reliable hydrogen sensors operating at room temperature, offering a pathway for novel gas-sensing technologies to support clean energy applications. Full article

(This article belongs to the Special Issue Nano Surface Engineering: 2nd Edition)

► Show Figures

Figure 1

13 pages, 5858 KiB

Open AccessArticle

Temperature Sensing in Agarose/Silk Fibroin Translucent Hydrogels: Preparation of an Environment for Long-Term Observation

by Maria Micheva, Stanislav Baluschev and Katharina Landfester

Nanomaterials 2025, 15(2), 123; https://doi.org/10.3390/nano15020123 - 16 Jan 2025

Viewed by 459

Abstract

Environmental changes, such as applied medication, nutrient depletion, and accumulation of metabolic residues, affect cell culture activity. The combination of these factors reflects on the local temperature distribution and local oxygen concentration towards the cell culture scaffold. However, determining the temporal variation of [...] Read more.

Environmental changes, such as applied medication, nutrient depletion, and accumulation of metabolic residues, affect cell culture activity. The combination of these factors reflects on the local temperature distribution and local oxygen concentration towards the cell culture scaffold. However, determining the temporal variation of local temperature, independent of local oxygen concentration changes in biological specimens, remains a significant technological challenge. The process of triplet–triplet annihilation upconversion (TTA-UC), performed in a nanoconfined environment with a continuous aqueous phase, appears to be a possible solution to these severe sensing problems. This process generates two optical signals (delayed emitter fluorescence (dF) and residual sensitizer phosphorescence (rPh)) in response to a single external stimulus (local temperature), allowing the application of the ratiometric-type sensing procedure. The ability to incorporate large amounts of sacrificial singlet oxygen scavenging materials, without altering the temperature sensitivity, allows long-term protection against photo-oxidative damage to the sensing moieties. Translucent agarose/silk fibroin hydrogels embedding non-ionic micellar systems containing energetically optimized annihilation couples simultaneously fulfill two critical functions: first, to serve as mechanical support (for further application as a cell culture scaffold); second, to allow tuning of the material response window to achieve a maximum temperature sensitivity better than 0.5 K for the physiologically important region around 36 °C. Full article

(This article belongs to the Section Nanoelectronics, Nanosensors and Devices)

► Show Figures

Figure 1

24 pages, 10552 KiB

Open AccessReview

Nano-Oncologic Vaccine for Boosting Cancer Immunotherapy: The Horizons in Cancer Treatment

by Chao Chen, Yue Xu, Hui Meng, Hongyi Bao, Yong Hu, Chunjian Li and Donglin Xia

Nanomaterials 2025, 15(2), 122; https://doi.org/10.3390/nano15020122 - 16 Jan 2025

Viewed by 646

Abstract

Nano-oncologic vaccines represent a groundbreaking approach in the field of cancer immunotherapy, leveraging the unique advantages of nanotechnology to enhance the effectiveness and specificity of cancer treatments. These vaccines utilize nanoscale carriers to deliver tumor-associated antigens and immunostimulatory adjuvants, facilitating targeted immune activation [...] Read more.

Nano-oncologic vaccines represent a groundbreaking approach in the field of cancer immunotherapy, leveraging the unique advantages of nanotechnology to enhance the effectiveness and specificity of cancer treatments. These vaccines utilize nanoscale carriers to deliver tumor-associated antigens and immunostimulatory adjuvants, facilitating targeted immune activation and promoting robust antitumor responses. By improving antigen presentation and localizing immune activation within the tumor microenvironment, nano-oncologic vaccines can significantly increase the efficacy of cancer immunotherapy, particularly when combined with other treatment modalities. This review highlights the mechanisms through which nano-oncologic vaccines operate, their potential to overcome existing limitations in cancer treatment, and ongoing advancements in design. Additionally, it discusses the targeted delivery approach, such as EPR effects, pH response, ultrasonic response, and magnetic response. The combination therapy effects with photothermal therapy, radiotherapy, or immune checkpoint inhibitors are also discussed. Overall, nano-oncologic vaccines hold great promise for changing the landscape of cancer treatment and advancing personalized medicine, paving the way for more effective therapeutic strategies tailored to individual patient needs. Full article

(This article belongs to the Special Issue Applications of Functional Nanomaterials in Biomedical Science)

► Show Figures

Figure 1

18 pages, 12286 KiB

Open AccessArticle

Effects of Annealing Conditions on the Catalytic Performance of Anodized Tin Oxide for Electrochemical Carbon Dioxide Reduction

by Nicolò B. D. Monti, Juqin Zeng, Micaela Castellino, Samuele Porro, Mitra Bagheri, Candido F. Pirri, Angelica Chiodoni and Katarzyna Bejtka

Nanomaterials 2025, 15(2), 121; https://doi.org/10.3390/nano15020121 - 16 Jan 2025

Viewed by 530

Abstract

The electrochemical reduction of CO₂ (CO₂RR) to value-added products has garnered significant interest as a sustainable solution to mitigate CO₂ emissions and harness renewable energy sources. Among CO₂RR products, formic acid/formate (HCOOH/HCOO⁻) is particularly attractive [...] Read more.

The electrochemical reduction of CO₂ (CO₂RR) to value-added products has garnered significant interest as a sustainable solution to mitigate CO₂ emissions and harness renewable energy sources. Among CO₂RR products, formic acid/formate (HCOOH/HCOO⁻) is particularly attractive due to its industrial relevance, high energy density, and potential candidate as a liquid hydrogen carrier. This study investigates the influence of the initial oxidation state of tin on CO₂RR performance using nanostructured SnO_x catalysts. A simple, quick, scalable, and cost-effective synthesis strategy was employed to fabricate SnO_x catalysts with controlled oxidation states while maintaining consistent morphology and particle size. The catalysts were characterized using SEM, TEM, XRD, Raman, and XPS to correlate structure and surface properties with catalytic performance. Electrochemical measurements revealed that SnO_x catalysts annealed in air at 525 °C exhibited the highest formate selectivity and current density, attributed to the optimized oxidation state and the presence of oxygen vacancies. Flow cell tests further demonstrated enhanced performance under practical conditions, achieving stable formate production with high faradaic efficiency over prolonged operation. These findings highlight the critical role of tin oxidation states and surface defects in tuning CO₂RR performance, offering valuable insights for the design of efficient catalysts for CO₂ electroreduction to formate. Full article

(This article belongs to the Section Energy and Catalysis)

► Show Figures

Figure 1

18 pages, 7024 KiB

Open AccessArticle

Effect of Sodium Sulfate Solution Coupled with Wetting–Drying Cycles on the Properties of Nano-Alumina-Modified Concrete

by Kai Gao, Dun Chen, Chunqing Li, Guoyu Li, Yuncheng Mao, Xuyang Wu, Anshuang Su, Hang Zhang and Xu Wang

Nanomaterials 2025, 15(2), 120; https://doi.org/10.3390/nano15020120 - 15 Jan 2025

Viewed by 673

Abstract

The degradation of concrete caused by sulfate attack poses a significant challenge to its durability. Using nanomaterials to enhance the mechanical and durability properties of concrete is a promising solution. A study of the durability of nano-alumina (NA)-modified concrete by sulfate erosion was [...] Read more.

The degradation of concrete caused by sulfate attack poses a significant challenge to its durability. Using nanomaterials to enhance the mechanical and durability properties of concrete is a promising solution. A study of the durability of nano-alumina (NA)-modified concrete by sulfate erosion was carried out. The results showed that the compressive strength, quality, and permeability of concrete to chloride ions decreased during its long-term erosion by a sodium sulfate solution. The NA-modified concrete exhibited higher resistance to erosion by the sodium sulfate than ordinary concrete (OPC), the rate of reduction in its tensile strength was low, and the resistance of sample NA1 to penetration by chloride ions decreased only by one-fifth compared with that of OPC. The results of mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests showed that erosion had severely damaged the pore characteristics and micromorphology of concrete. The total porosities of the OPC and NA1 samples increased from 12.68% and 10.29% to 16.03% and 12.71%, respectively. Their microscopic morphology revealed loose particles and poor compactness. The leading causes of damage to concrete due to erosion by the sodium sulfate were its crystallization pressure and the swelling-induced stress caused by the deposition of crystals in its pores. This study demonstrates that NA can significantly enhance the durability of concrete against sulfate attack, offering valuable insights for strategic applications of NA in concrete materials. Full article

(This article belongs to the Section Nanofabrication and Nanomanufacturing)

► Show Figures

Figure 1

16 pages, 49523 KiB

Open AccessArticle

Study on Crack Resistance Mechanism of Helical Carbon Nanotubes in Nanocomposites

by Zhiwu Bie, Xuefeng Liu, Yajie Deng, Xian Shi and Xiaoqiao He

Nanomaterials 2025, 15(2), 119; https://doi.org/10.3390/nano15020119 - 15 Jan 2025

Viewed by 514

Abstract

Helical carbon nanotubes (HCNTs) with different geometrical properties were constructed and incorporated into nanocomposites for the investigation of the anti-crack mechanism. The interfacial mechanical properties of the nanocomposites reinforced with straight carbon nanotubes and various types of HCNTs were investigated through the pullout [...] Read more.

Helical carbon nanotubes (HCNTs) with different geometrical properties were constructed and incorporated into nanocomposites for the investigation of the anti-crack mechanism. The interfacial mechanical properties of the nanocomposites reinforced with straight carbon nanotubes and various types of HCNTs were investigated through the pullout of HCNTs in the crack propagation using molecular dynamics (MD). The results show that the pullout force of HCNTs is much higher than that of CNTs because the physical interlock between HCNTs and matrices is much stronger than the van der Waals (vdW) interactions between CNTs and matrices. Remarkably, HCNTs with a large pitch length can not only effectively prevent the initiation of breakages but also hinder the growth of cracks, while HCNTs with a small diameter and tube radius cannot even effectively prevent the initiation of cracks, which is similar to straight CNTs. Moreover, the shear resistance of HCNTs increases with the increase in the helix angle, which remains at a high level when the helix angle reaches the critical value. However, HCNTs with a small helix angle and large diameter can carry out more polymer chains, while snake-like HCNTs and HCNTs with a small diameter and helix angle can hardly carry out any polymer chain during the pullout process and show similar interfacial properties to the straight CNTs. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Nanomaterials, Volume 15, Issue 2 (January-2 2025) – 70 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI