Nanomaterials

Research

19 pages, 3343 KiB

Open AccessArticle

Insight into the Roles of Metal Loading on CO₂ Photocatalytic Reduction Behaviors of TiO₂

by Darika Permporn, Rattabal Khunphonoi, Jetsadakorn Wilamat, Pongtanawat Khemthong, Prae Chirawatkul, Teera Butburee, Weradesh Sangkhun, Kitirote Wantala, Nurak Grisdanurak, Jirapat Santatiwongchai, Pussana Hirunsit, Wantana Klysubun and Mark Daniel G. de Luna

Nanomaterials 2022, 12(3), 474; https://doi.org/10.3390/nano12030474 - 29 Jan 2022

Cited by 16 | Viewed by 3694

Abstract

The photocatalytic reduction of carbon dioxide (CO₂) into value-added chemicals is considered to be a green and sustainable technology, and has recently gained considerable research interest. In this work, titanium dioxide (TiO₂) supported Pt, Pd, Ni, and Cu catalysts [...] Read more.

The photocatalytic reduction of carbon dioxide (CO₂) into value-added chemicals is considered to be a green and sustainable technology, and has recently gained considerable research interest. In this work, titanium dioxide (TiO₂) supported Pt, Pd, Ni, and Cu catalysts were synthesized by photodeposition. The formation of various metal species on an anatase TiO₂ surface, after ultraviolet (UV) light irradiation, was investigated insightfully by the X-ray absorption near edge structure (XANES) technique. CO₂ reduction under UV-light irradiation at an ambient pressure was demonstrated. To gain an insight into the charge recombination rate during reduction, the catalysts were carefully investigated by the intensity modulated photocurrent spectroscopy (IMPS) and photoluminescence spectroscopy (PL). The catalytic behaviors of the catalysts were investigated by density functional theory using the self-consistent Hubbard U-correction (DFT+U) approach. In addition, Mott–Schottky measurement was employed to study the effect of energy band alignment of metal-semiconductor on CO₂ photoreduction. Heterojunction formed at Pt-, Pd-, Ni-, and Cu-TiO₂ interface has crucial roles on the charge recombination and the catalytic behaviors. Furthermore, it was found that Pt-TiO₂ provides the highest methanol yield of 17.85 µmol/g_cat/h, and CO as a minor product. According to the IMPS data, Pt-TiO₂ has the best charge transfer ability, with the mean electron transit time of 4.513 µs. We believe that this extensive study on the junction between TiO₂ could provide a profound understanding of catalytic behaviors, which will pave the way for rational designs of novel catalysts with improved photocatalytic performance for CO₂ reduction. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Figure 1

11 pages, 2168 KiB

Open AccessArticle

Three-Dimensional Hierarchical Porous TiO₂ for Enhanced Adsorption and Photocatalytic Degradation of Remazol Dye

by Jitpisut Poolwong, Tanya Kiatboonyarit, Supakit Achiwawanich, Teera Butburee, Pongtanawat Khemthong and Sutasinee Kityakarn

Nanomaterials 2021, 11(7), 1715; https://doi.org/10.3390/nano11071715 - 29 Jun 2021

Cited by 22 | Viewed by 2668

Abstract

Three-dimensional hierarchical mesoporous structures of titanium dioxide (3D-HPT) were synthesized by self-assembly emulsion polymerization. Polymethyl methacrylate (PMMA) and pluronic 123 (P123) were used as the soft templates and co-templates for assisting the formation of hierarchical 3D porous structures. The TiO₂ crystal structure, [...] Read more.

Three-dimensional hierarchical mesoporous structures of titanium dioxide (3D-HPT) were synthesized by self-assembly emulsion polymerization. Polymethyl methacrylate (PMMA) and pluronic 123 (P123) were used as the soft templates and co-templates for assisting the formation of hierarchical 3D porous structures. The TiO₂ crystal structure, morphology, and Remazol red dye degradation were investigated. The 3D-HPT and normal three-dimensional titanium dioxide (3D-T) presented the good connection of the nanoparticle-linked honeycomb within the form of anatase. The 3D-HPT structure showed greatly enhanced adsorption of Remazol dye, and facilitated the efficient photocatalytic breakdown of the dye. Surprisingly, 3D-HPT can adsorb approximately 40% of 24 ppm Remazol dye in the dark, which is superior to 3D-T and the commercial anatase at the same condition (approx. 5%). Moreover, 3D-HPT can completely decolorize Remazol dye within just 20 min, which is more than three folds faster than the commercial anatase, making it one of the most active photocatalysts that have been reported for degradation of Remazol dye. The superior photocatalytic performance is attributed to the higher specific surface area, amplified light-harvesting efficiency, and enhanced adsorption capacity into the hierarchical 3D inverse opal structure compared to the commercial anatase TiO₂. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Graphical abstract

14 pages, 4491 KiB

Open AccessArticle

Characteristics of P-Type and N-Type Photoelectrochemical Biosensors: A Case Study for Esophageal Cancer Detection

by Joseph-Hang Leung, Hong-Thai Nguyen, Shih-Wei Feng, Sofya B. Artemkina, Vladimir E. Fedorov, Shang-Chin Hsieh and Hsiang-Chen Wang

Nanomaterials 2021, 11(5), 1065; https://doi.org/10.3390/nano11051065 - 21 Apr 2021

Cited by 5 | Viewed by 2709

Abstract

P-type and N-type photoelectrochemical (PEC) biosensors were established in the laboratory to discuss the correlation between characteristic substances and photoactive material properties through the photogenerated charge carrier transport mechanism. Four types of human esophageal cancer cells (ECCs) were analyzed without requiring additional bias [...] Read more.

P-type and N-type photoelectrochemical (PEC) biosensors were established in the laboratory to discuss the correlation between characteristic substances and photoactive material properties through the photogenerated charge carrier transport mechanism. Four types of human esophageal cancer cells (ECCs) were analyzed without requiring additional bias voltage. Photoelectrical characteristics were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis reflectance spectroscopy, and photocurrent response analyses. Results showed that smaller photocurrent was measured in cases with advanced cancer stages. Glutathione (L-glutathione reduced, GSH) and Glutathione disulfide (GSSG) in cancer cells carry out redox reactions during carrier separation, which changes the photocurrent. The sensor can identify ECC stages with a certain level of photoelectrochemical response. The detection error can be optimized by adjusting the number of cells, and the detection time of about 5 min allowed repeated measurement. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Figure 1

13 pages, 4462 KiB

Open AccessArticle

Efficient and Rapid Photocatalytic Degradation of Methyl Orange Dye Using Al/ZnO Nanoparticles

by Piangjai Peerakiatkhajohn, Teera Butburee, Jung-Hoon Sul, Supphasin Thaweesak and Jung-Ho Yun

Nanomaterials 2021, 11(4), 1059; https://doi.org/10.3390/nano11041059 - 20 Apr 2021

Cited by 56 | Viewed by 5194

Abstract

ZnO and Aluminum doped ZnO nanoparticles (Al/ZnO NPs) were successfully synthesized by the sol-gel method. Together with the effect of calcination temperatures (200, 300 and 400 °C) and Al dosage (1%, 3%, 5% and 10%) on structural, morphological and optical properties of Al/ZnO [...] Read more.

ZnO and Aluminum doped ZnO nanoparticles (Al/ZnO NPs) were successfully synthesized by the sol-gel method. Together with the effect of calcination temperatures (200, 300 and 400 °C) and Al dosage (1%, 3%, 5% and 10%) on structural, morphological and optical properties of Al/ZnO NPs, their photocatalytic degradation of methyl orange (MO) dye was investigated. The calcination temperatures at 200, 300 and 400 °C in forming structure of ZnO NPs led to spherical nanoparticle, nanorod and nanoflake structures with a well-crystalline hexagonal wurtzite, respectively. The ZnO NPs calcined at 200 °C exhibited the highest specific surface area and light absorption property, leading to the MO removal efficiency of 80% after 4 h under the Ultraviolet (UV) light irradiation. The MO removal efficiency was approximately two times higher than the nanoparticles calcined at 400 °C. Furthermore, the 5% Al/ZnO NPs exhibited superior MO removal efficiency of 99% in only 40 min which was approximately 20 times enhancement in photocatalytic activity compared to pristine ZnO under the visible light irradiation. This high degradation performance was attributed to the extended light absorption, narrowed band gap and effective suppression of electron–hole recombination through an addition of Al metal. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Figure 1

14 pages, 45410 KiB

Open AccessArticle

GABr Post-Treatment for High-Performance MAPbI₃ Solar Cells on Rigid Glass and Flexible Substrate

by Tingting Chen, Rui He, Fan Zhang, Xia Hao, Zhipeng Xuan, Yunfan Wang, Wenwu Wang, Dewei Zhao, Jingquan Zhang and Lili Wu

Nanomaterials 2021, 11(3), 750; https://doi.org/10.3390/nano11030750 - 16 Mar 2021

Cited by 7 | Viewed by 3381

Abstract

Perovskite solar cells have exhibited astonishing photoelectric conversion efficiency and have shown a promising future owing to the tunable content and outstanding optoelectrical property of hybrid perovskite. However, the devices with planar architecture still suffer from huge V_oc loss and severe hysteresis [...] Read more.

Perovskite solar cells have exhibited astonishing photoelectric conversion efficiency and have shown a promising future owing to the tunable content and outstanding optoelectrical property of hybrid perovskite. However, the devices with planar architecture still suffer from huge V_oc loss and severe hysteresis effect. In this research, Guanidine hydrobromide (GABr) post-treatment is carried out to enhance the performance of MAPbI₃ n-i-p planar perovskite solar cells. The detailed characterization of perovskite suggests that GABr post-treatment results in a smoother absorber layer, an obvious reduction of trap states and optimized energy level alignment. By utilizing GABr post-treatment, the V_oc loss is reduced, and the hysteresis effect is alleviated effectively in MAPbI₃ solar cells. As a result, solar cells based on glass substrate with efficiency exceeding 20%, V_oc of 1.13 V and significantly mitigated hysteresis are fabricated successfully. Significantly, we also demonstrate the effectiveness of GABr post-treatment in flexible device, whose efficiency is enhanced from 15.77% to 17.57% mainly due to the elimination of V_oc loss. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Figure 1

14 pages, 7244 KiB

Open AccessArticle

Novel Two-Dimensional Layered MoSi₂Z₄ (Z = P, As): New Promising Optoelectronic Materials

by Hui Yao, Chao Zhang, Qiang Wang, Jianwei Li, Yunjin Yu, Fuming Xu, Bin Wang and Yadong Wei

Nanomaterials 2021, 11(3), 559; https://doi.org/10.3390/nano11030559 - 24 Feb 2021

Cited by 62 | Viewed by 4346

Abstract

Very recently, two new two-dimensional (2D) layered semi-conducting materials MoSi

_{2}

N

_{4}

and WSi

_{2}

N

_{4}

were successfully synthesized in experiments, and a large family of these two 2D materials, namely MA

_{2}

Z

_{4}

, was also predicted theoretically (Science, [...] Read more.

Very recently, two new two-dimensional (2D) layered semi-conducting materials MoSi

_{2}

N

_{4}

and WSi

_{2}

N

_{4}

were successfully synthesized in experiments, and a large family of these two 2D materials, namely MA

_{2}

Z

_{4}

, was also predicted theoretically (Science, 369, 670 (2020)). Motivated by this exciting family, in this work, we systematically investigate the mechanical, electronic and optical properties of monolayer and bilayer MoSi

_{2}

P

_{4}

and MoSi

_{2}

As

_{4}

by using the first-principles calculation method. Numerical results indicate that both monolayer and bilayer MoSi

_{2}

Z

_{4}

(Z = P, As) present good structural stability, isotropic mechanical parameters, moderate bandgap, favorable carrier mobilities, remarkable optical absorption, superior photon responsivity and external quantum efficiency. Especially, due to the wave-functions of band edges dominated by d orbital of the middle-layer Mo atoms are screened effectively, the bandgap and optical absorption hardly depend on the number of layers, providing an added convenience in the experimental fabrication of few-layer MoSi

_{2}

Z

_{4}

-based electronic and optoelectronic devices. We also build a monolayer MoSi

_{2}

Z

_{4}

-based 2D optoelectronic device, and quantitatively evaluate the photocurrent as a function of energy and polarization angle of the incident light. Our investigation verifies the excellent performance of a few-layer MoSi

_{2}

Z

_{4}

and expands their potential application in nanoscale electronic and optoelectronic devices. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Figure 1

9 pages, 2841 KiB

Open AccessArticle

Preparation of Monodispersed Cs_0.33WO₃ Nanocrystals by Mist Chemical Vapor Deposition for Near-Infrared Shielding Application

by Lei Huang, Hua Tang, Youjun Bai, Yong Pu, Lu Li and Jiang Cheng

Nanomaterials 2020, 10(11), 2295; https://doi.org/10.3390/nano10112295 - 20 Nov 2020

Cited by 11 | Viewed by 2993

Abstract

In this study, single-phase Cs_0.33WO₃ nanocrystals were synthesized by a novel mist chemical vapor deposition method. As prepared, Cs_0.33WO₃ nanocrystals exhibited a microsphere-like appearance constructed with angular crystal grains with an average size of about 30–40 nm. [...] Read more.

In this study, single-phase Cs_0.33WO₃ nanocrystals were synthesized by a novel mist chemical vapor deposition method. As prepared, Cs_0.33WO₃ nanocrystals exhibited a microsphere-like appearance constructed with angular crystal grains with an average size of about 30–40 nm. Characterization by X-ray photoelectron spectroscopy indicated that Cs_0.33WO₃ nanocrystals consisted of mixed chemical valence states of tungsten ions W⁶⁺ and W⁵⁺, inducing many free electrons, which could scatter and absorb near-infrared (NIR) photons by plasmon resonance. These Cs_0.33WO₃ microspheres consisted of a loose structure that could be crushed to nanoscale particles and was easily applied for producing long-term stable ink after milling. Herein, a Cs_0.33WO₃/polymer composite was successfully fabricated via the ultrasonic spray coating method using mixed Cs_0.33WO₃ ink and polyurethane acrylate solution. The composite coatings exhibited excellent IR shielding properties. Remarkably, only 0.9 mg cm⁻² Cs_0.33WO₃ could shield more than 70% of NIR, while still maintaining the visible light transmittance higher than 75%. Actual measurement results indicate that it has really good heat insulation properties and shows good prospect in heat insulation window applications. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures

Graphical abstract

8 pages, 1701 KiB

Open AccessCommunication

Surface Degradation Mechanism on CH₃NH₃PbBr₃ Hybrid Perovskite Single Crystal by a Grazing E-Beam Irradiation

by Heriyanto Syafutra, Jung-Ho Yun, Yuya Yoshie, Miaoqiang Lyu, Sakura Nishino Takeda, Masakazu Nakamura, Lianzhou Wang and Min-Cherl Jung

Nanomaterials 2020, 10(7), 1253; https://doi.org/10.3390/nano10071253 - 28 Jun 2020

Cited by 13 | Viewed by 3302

Abstract

To start a step such as some realization of minimized and integrated devices, it requires simply understanding the surface status of hybrid perovskite on the e-beam irradiation because many commercial semiconductor devices are performed with a surface patterning process using e-beam or etching [...] Read more.

To start a step such as some realization of minimized and integrated devices, it requires simply understanding the surface status of hybrid perovskite on the e-beam irradiation because many commercial semiconductor devices are performed with a surface patterning process using e-beam or etching gas. The surface status of CH₃NH₃PbBr₃ (MAPbBr₃) single crystal was studied after a grazing e-beam irradiation in an ultra-high vacuum. The prepared hybrid perovskite single crystal was irradiated by the 3 degree-grazing e-beam with energy of 15 kV for 10 min using a reflection high-electron energy diffraction technique. The e-beam irradiation on the MAPbBr₃ hybrid perovskite single crystal induced the deformation from MAPbBr₃ into MABr, Br₂, and Pb on the surface. The gas phases of MABr and Br₂ are depleted from the surface and the Pb element has remained on the surface. As a result of the e-beam irradiation, it formed a polycrystalline-like phase and Pb metal particles on the surface, respectively. Full article

(This article belongs to the Special Issue Photoelectrochemical Properties of Nanomaterials and Applications in Energy Conversion and Environmental Remediation)

► Show Figures