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19 pages, 4732 KiB

Open AccessArticle

Enhancement of Methylene Blue Photodegradation Rate Using Laser Synthesized Ag-Doped ZnO Nanoparticles

by Damjan Blažeka, Rafaela Radičić, Dejan Maletić, Sanja Živković, Miloš Momčilović and Nikša Krstulović

Nanomaterials 2022, 12(15), 2677; https://doi.org/10.3390/nano12152677 - 4 Aug 2022

Cited by 23 | Viewed by 2574

Abstract

In this work, Ag-doped ZnO nanoparticles are obtained via pulsed laser ablation of the Ag-coated ZnO target in water. The ratio of Ag dopant in ZnO nanoparticles strongly depends on the thickness of the Ag layer at the ZnO target. Synthesized nanoparticles were [...] Read more.

In this work, Ag-doped ZnO nanoparticles are obtained via pulsed laser ablation of the Ag-coated ZnO target in water. The ratio of Ag dopant in ZnO nanoparticles strongly depends on the thickness of the Ag layer at the ZnO target. Synthesized nanoparticles were characterized by XRD, XPS, SEM, EDS, ICP-OES, and UV–VIS spectrophotometry to obtain their crystal structure, elemental composition, morphology and size distribution, mass concentration, and optical properties, respectively. The photocatalytic studies showed photodegradation of methylene blue (MB) under UV irradiation. Different ratios of Ag dopant in ZnO nanoparticles influence the photodegradation rate. The ZnO nanoparticles doped with 0.32% silver show the most efficient photodegradation rate, with the chemical reaction constant of 0.0233 min⁻¹. It exhibits an almost twice as large photodegradation rate compared to pure ZnO nanoparticles, showing the doping effect on the photocatalytic activity. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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16 pages, 3797 KiB

Open AccessArticle

Synthesis and Characterization of N and Fe-Doped TiO₂ Nanoparticles for 2,4-Dimethylaniline Mineralization

by Emerson Faustino, Thalita Ferreira da Silva, Rebeca Fabbro Cunha, Diego Roberto Vieira Guelfi, Priscila Sabioni Cavalheri, Silvio César de Oliveira, Anderson Rodrigues Lima Caires, Gleison Antonio Casagrande, Rodrigo Pereira Cavalcante and Amilcar Machulek Junior

Nanomaterials 2022, 12(15), 2538; https://doi.org/10.3390/nano12152538 - 24 Jul 2022

Cited by 5 | Viewed by 2145

Abstract

The present study aimed to evaluate the feasibility of developing low-cost N- and Fe-doped TiO₂ photocatalysts for investigating the mineralization of 2,4-dimethylaniline (2,4-DMA). With a single anatase phase, the photocatalysts showed high thermal stability with mass losses of less than 2%. The [...] Read more.

The present study aimed to evaluate the feasibility of developing low-cost N- and Fe-doped TiO₂ photocatalysts for investigating the mineralization of 2,4-dimethylaniline (2,4-DMA). With a single anatase phase, the photocatalysts showed high thermal stability with mass losses of less than 2%. The predominant oxidative state is Ti⁴⁺, but there is presence of Ti³⁺ associated with oxygen vacancies. In materials with N, doping was interstitial in the NH₃/NH⁴⁺ form and for doping with Fe, there was a presence of Fe-Ti bonds (indicating substitutional occupations). With an improved band gap energy from 3.16 eV to 2.82 eV the photoactivity of the photocatalysts was validated with an 18 W UVA lamp (340–415 nm) with a flux of 8.23 × 10⁻⁶ Einstein s⁻¹. With a size of only 14.45 nm and a surface area of 84.73 m² g⁻¹, the photocatalyst doped with 0.0125% Fe mineralized 92% of the 2,4-DMA in just 180 min. While the 3% N photocatalyst with 12.27 nm had similar performance at only 360 min. Factors such as high surface area, mesoporous structure and improved E_bg, and absence of Fe peak in XPS analysis indicate that doping with 0.0125% Fe caused a modification in TiO₂ structure. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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13 pages, 4448 KiB

Open AccessArticle

AuAg Nanoparticles Grafted on TiO₂@N-Doped Porous Carbon: Improved Depletion of Ciprofloxacin under Visible Light through Plasmonic Photocatalysis

by Marta Jiménez-Salcedo, Miguel Monge and María Teresa Tena

Nanomaterials 2022, 12(15), 2524; https://doi.org/10.3390/nano12152524 - 22 Jul 2022

Cited by 3 | Viewed by 1691

Abstract

TiO₂ nanoparticles (NPs) were modified to obtain photocatalysts with different composition sophistication and displaying improved visible light activity. All of them were evaluated in the photodegradation of ciprofloxacin. The band gap of TiO₂ NPs was successfully tailored by the formation of [...] Read more.

TiO₂ nanoparticles (NPs) were modified to obtain photocatalysts with different composition sophistication and displaying improved visible light activity. All of them were evaluated in the photodegradation of ciprofloxacin. The band gap of TiO₂ NPs was successfully tailored by the formation of an N-doped porous carbon (NPC)-TiO₂ nanohybrid through the pyrolysis of melamine at 600 °C, leading to a slight red-shift of the absorption band edge for nanohybrid NPC-TiO₂ 1. In addition, the in-situ formation and grafting of plasmonic AuAg NPs at the surface of NPC sheets and in close contact with TiO₂ NPs leads to AuAg-NPC-TiO₂ nanohybrids 2–3. These nanohybrids showed superior photocatalytic performance for the degradation of ciprofloxacin under visible light irradiation, compared to pristine P25 TiO₂ NPs or to AuAg-PVP-TiO₂ nanohybrid 4 in which polyvinylpyrrolidone stabilized AuAg NPs were directly grafted to TiO₂ NPs. The materials were characterized by transmission electron microscope (TEM), High Angle Annular Dark Field—Scanning Transmission Electron Microscopy—Energy Dispersive X-ray Spectroscopy HAADF-STEM-EDS, X-ray photoelectron spectroscopy and solid UV-vis spectroscopy. Moreover, the active species involved in the photodegradation of ciprofloxacin using AuAg-NCS-TiO₂ nanohybrids were evaluated by trapping experiments to propose a mechanism for the degradation. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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17 pages, 2740 KiB

Open AccessArticle

Facile Synthesis of ZnO-CeO₂ Heterojunction by Mixture Design and Its Application in Triclosan Degradation: Effect of Urea

by Antonia Cáceres-Hernández, Jose Gilberto Torres-Torres, Adib Silahua-Pavón, Srinivas Godavarthi, David García-Zaleta, Rafael Omar Saavedra-Díaz, Renan Tavares-Figueiredo and Adrián Cervantes-Uribe

Nanomaterials 2022, 12(12), 1969; https://doi.org/10.3390/nano12121969 - 8 Jun 2022

Viewed by 2023

Abstract

In this study, simplex centroid mixture design was employed to determine the effect of urea on ZnO-CeO. The heterojunction materials were synthesized using a solid-state combustion method, and the physicochemical properties were evaluated using X-ray diffraction, nitrogen adsorption/desorption, and UV–Vis spectroscopy. Photocatalytic activity [...] Read more.

In this study, simplex centroid mixture design was employed to determine the effect of urea on ZnO-CeO. The heterojunction materials were synthesized using a solid-state combustion method, and the physicochemical properties were evaluated using X-ray diffraction, nitrogen adsorption/desorption, and UV–Vis spectroscopy. Photocatalytic activity was determined by a triclosan degradation reaction under UV irradiation. According to the results, the crystal size of zinc oxide decreases in the presence of urea, whereas a reverse effect was observed for cerium oxide. A similar trend was observed for ternary samples, i.e., the higher the proportion of urea, the larger the crystallite cerium size. In brief, urea facilitated the co-existence of crystallites of CeO and ZnO. On the other hand, UV spectra indicate that urea shifts the absorption edge to a longer wavelength. Studies of the photocatalytic activity of TCS degradation show that the increase in the proportion of urea favorably influenced the percentage of mineralization. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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12 pages, 5262 KiB

Open AccessArticle

Constructing Co₃O₄/La₂Ti₂O₇ p-n Heterojunction for the Enhancement of Photocatalytic Hydrogen Evolution

by Haodong Wen, Wenning Zhao and Xiuxun Han

Nanomaterials 2022, 12(10), 1695; https://doi.org/10.3390/nano12101695 - 16 May 2022

Cited by 12 | Viewed by 2393

Abstract

Layered perovskite-type semiconductor La₂Ti₂O₇ has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and [...] Read more.

Layered perovskite-type semiconductor La₂Ti₂O₇ has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and the low separation efficiency of photogenerated carriers limit its photocatalytic activity. Herein, plate-like La₂Ti₂O₇ with uniform crystal morphology was synthesized in molten NaCl salt. A p-n heterojunction was then constructed through the in situ hydrothermal growth of p-type Co₃O₄ nanoparticles on the surface of n-type plate-like La₂Ti₂O₇. The effects of Co₃O₄ loading on photocatalytic hydrogen evolution performance were investigated in detail. The results demonstrate that composite Co₃O₄/La₂Ti₂O₇ possesses much better photocatalytic activity than the pure component. The composite photocatalyst with 1 wt% Co₃O₄ exhibits the highest hydrogen evolution rate of 79.73 μmol·g⁻¹·h⁻¹ and a good cycling stability. The photoelectrochemistry characterizations illustrate that the improvement of photocatalytic activity is mainly attributed to both the enhanced light absorption from the Co₃O₄ ornament and the rapid separation of photogenerated electron-hole pairs driven by the built-in electric field close to the p-n heterojunction. The results may provide further insights into the design of high-efficiency La₂Ti₂O₇-based heterojunctions for photocatalytic hydrogen evolution. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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13 pages, 3849 KiB

Open AccessArticle

Electrospun Donor/Acceptor Nanofibers for Efficient Photocatalytic Hydrogen Evolution

by Xiaoyu Lin, Yuanying Liang, Zhicheng Hu, Xi Zhang, Youcai Liang, Zhengwei Hu, Fei Huang and Yong Cao

Nanomaterials 2022, 12(9), 1535; https://doi.org/10.3390/nano12091535 - 2 May 2022

Cited by 1 | Viewed by 2134

Abstract

We prepared a series of one-dimensional conjugated-material-based nanofibers with different morphologies and donor/acceptor (D/A) compositions by electrospinning for efficient photocatalytic hydrogen evolution. It was found that homogeneous D/A heterojunction nanofibers can be obtained by electrospinning, and the donor/acceptor ratio can be easily controlled. [...] Read more.

We prepared a series of one-dimensional conjugated-material-based nanofibers with different morphologies and donor/acceptor (D/A) compositions by electrospinning for efficient photocatalytic hydrogen evolution. It was found that homogeneous D/A heterojunction nanofibers can be obtained by electrospinning, and the donor/acceptor ratio can be easily controlled. Compared with the single-component-based nanofibers, the D/A-based nanofibers showed a 34-fold increase in photocatalytic efficiency, attributed to the enhanced exciton dissociation in the nanofibrillar body. In addition, the photocatalytic activity of these nanofibers can be easily optimized by modulating the diameter. The results show that the diameter of the nanofibers can be conveniently controlled by the electrospinning feed rate, and the photocatalytic effect increases with decreasing fiber diameter. Consequently, the nanofibers with the smallest diameter exhibit the most efficient photocatalytic hydrogen evolution, with the highest release rate of 24.38 mmol/(gh). This work provides preliminary evidence of the advantages of the electrospinning strategy in the construction of D/A nanofibers with controlled morphology and donor/acceptor composition, enabling efficient hydrogen evolution. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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14 pages, 4528 KiB

Open AccessArticle

Preparation and Photocatalytic Properties of Anatase TiO₂ with Hollow Hexagonal Frame Structure

by Mengyuan Teng, Haixia Liu, Bensheng Lin, Xiangzhu Zhou and Wei Zhou

Nanomaterials 2022, 12(9), 1409; https://doi.org/10.3390/nano12091409 - 20 Apr 2022

Cited by 2 | Viewed by 1943

Abstract

Titanium dioxide (TiO₂) has been widely used to solve energy and environmental pollution problems due to its excellent properties. In this study, the precursor (HTiOF₃) with a spherical structure composed of hexagonal prisms was prepared via a simple solvothermal [...] Read more.

Titanium dioxide (TiO₂) has been widely used to solve energy and environmental pollution problems due to its excellent properties. In this study, the precursor (HTiOF₃) with a spherical structure composed of hexagonal prisms was prepared via a simple solvothermal method using tetrabutyl titanate, hydrofluoric acid, glacial acetic acid and isopropanol as raw materials. Then, the calcination time and temperature of the precursor were controlled to prepare anatase TiO₂ with different morphologies, and the photocatalytic performance of the prepared catalysts was studied. When the precursor was calcined at 600 °C for 7 h, the prepared TiO₂ had a unique hexagonal framework structure and exhibited excellent photocatalytic performance. The degradation rate of the RhB solution was 98.58% at 40 min and the rate of hydrogen evolution was 2508.12 μmol g⁻¹ h⁻¹. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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14 pages, 5180 KiB

Open AccessEditor’s ChoiceArticle

Highly Efficient Photothermal Reduction of CO₂ on Pd₂Cu Dispersed TiO₂ Photocatalyst and Operando DRIFT Spectroscopic Analysis of Reactive Intermediates

by Munirathinam Elavarasan, Willie Yang, Sethupathi Velmurugan, Jyy-Ning Chen, Thomas C.-K. Yang and Toshiyuki Yokoi

Nanomaterials 2022, 12(3), 332; https://doi.org/10.3390/nano12030332 - 21 Jan 2022

Cited by 11 | Viewed by 3244

Abstract

The photocatalytic conversion of CO₂ to fuels using solar energy presents meaningful potential in the mitigation of global warming, solar energy conversion, and fuel production. Photothermal catalysis is one promising approach to convert chemically inert CO₂ into value-added chemicals. Herein, we [...] Read more.

The photocatalytic conversion of CO₂ to fuels using solar energy presents meaningful potential in the mitigation of global warming, solar energy conversion, and fuel production. Photothermal catalysis is one promising approach to convert chemically inert CO₂ into value-added chemicals. Herein, we report the selective hydrogenation of CO₂ to ethanol by Pd₂Cu alloy dispersed TiO₂ (P25) photocatalyst. Under UV-Vis irradiation, the Pd₂Cu/P25 showed an efficient CO₂ reduction photothermally at 150 °C with an ethanol production rate of 4.1 mmol g⁻¹ h⁻¹. Operando diffuse reflectance infrared Fourier transform (DRIFT) absorption studies were used to trace the reactive intermediates involved in CO₂ hydrogenation in detail. Overall, the Cu provides the active sites for CO₂ adsorption and Pd involves the oxidation of H₂ molecule generated from P25 and C–C bond formation. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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14 pages, 1633 KiB

Open AccessArticle

Preparation and Application of Nb₂O₅ Nanofibers in CO₂ Photoconversion

by A. C. F. Prado, J. O. D. Malafatti, J. A. Oliveira, C. Ribeiro, M. R. Joya, A. P. Luz and E. C. Paris

Nanomaterials 2021, 11(12), 3268; https://doi.org/10.3390/nano11123268 - 1 Dec 2021

Cited by 15 | Viewed by 2570

Abstract

Increasing global warming due to NO

_{x}

, CO

_{2}

, and CH

_{4}

, is significantly harming ecosystems and life worldwide. One promising methodology is converting pollutants into valuable chemicals via photocatalytic processes (by reusable photocatalysts). In this context, the present work [...] Read more.

Increasing global warming due to NO

_{x}

, CO

_{2}

, and CH

_{4}

, is significantly harming ecosystems and life worldwide. One promising methodology is converting pollutants into valuable chemicals via photocatalytic processes (by reusable photocatalysts). In this context, the present work aimed to produce a Nb

_{2}

O

_{5}

photocatalyst nanofiber system by electrospinning to convert CO

_{2}

. Based on the collected data, the calcination at 600

^{\circ}

C for 2 h resulted in the best condition to obtain nanofibers with homogeneous surfaces and an average diameter of 84 nm. As a result, the Nb

_{2}

O

_{5}

nanofibers converted CO

_{2}

mostly into CO and CH

_{4}

, reaching values around 8.5

μ

mol g

^{- 1}

and 0.55

μ

mol g

^{- 1}

, respectively. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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15 pages, 3624 KiB

Open AccessArticle

Solar Light Photoactive Floating Polyaniline/TiO₂ Composites for Water Remediation

by Ermelinda Falletta, Anna Bruni, Marta Sartirana, Daria C. Boffito, Giuseppina Cerrato, Alessia Giordana, Ridha Djellabi, Erfan S. Khatibi and Claudia L. Bianchi

Nanomaterials 2021, 11(11), 3071; https://doi.org/10.3390/nano11113071 - 15 Nov 2021

Cited by 11 | Viewed by 2505

Abstract

In the present study, the development of innovative polyurethane-polyaniline/TiO₂ modified floating materials applied in the sorption and photodegradation of rhodamine B from water matrix under solar light irradiation is reported. All the materials were fabricated with inexpensive and easy approaches and were [...] Read more.

In the present study, the development of innovative polyurethane-polyaniline/TiO₂ modified floating materials applied in the sorption and photodegradation of rhodamine B from water matrix under solar light irradiation is reported. All the materials were fabricated with inexpensive and easy approaches and were properly characterized. The effect of the kind of polyaniline (PANI) dopant on the materials’ behavior was investigated, as well as the role of the conducting polymer in the pollutant abatement on the basis of its physico-chemical characteristics. Rhodamine B is removed by adsorption and/or photodegradation processes depending on the type of doping agent used for PANI protonation. The best materials were subjected to recycle tests in order to demonstrate their stability under the reaction conditions. The main transformation products formed during the photodegradation process were identified by ultraperformance liquid chromatography-mass spectrometry (UPLC/MS). The results demonstrated that photoactive floating PANI/TiO₂ composites are useful alternatives to common powder photocatalysts for the degradation of cationic dyes. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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15 pages, 5009 KiB

Open AccessArticle

Synthesis and Enhanced Light Photocatalytic Activity of Modulating Band BiOBr_XI_1−X Nanosheets

by Bingke Zhang, Shengwen Fu, Dongbo Wang, Shujie Jiao, Zhi Zeng, Xiangyu Zhang, Zhikun Xu, Yaxin Liu, Chenchen Zhao, Jingwen Pan, Donghao Liu and Jinzhong Wang

Nanomaterials 2021, 11(11), 2940; https://doi.org/10.3390/nano11112940 - 2 Nov 2021

Cited by 10 | Viewed by 1943

Abstract

The photocatalysis technique has been proven to be a promising method to solve environmental pollution in situations of energy shortage, and has been intensively investigated in the field of pollutant degradation. In this work, a band structure-controlled solid solution of BiOBr_XI [...] Read more.

The photocatalysis technique has been proven to be a promising method to solve environmental pollution in situations of energy shortage, and has been intensively investigated in the field of pollutant degradation. In this work, a band structure-controlled solid solution of BiOBr_XI_1−X (x = 0.00, 0.05, 0.10, 0.15, 0.20, 1.00) with highly efficient light-driven photocatalytic activities was successfully synthesized via simple solvothermal methods. The phase composition, crystal structure, morphology, internal molecular vibration, optical properties, and energy band structure were characterized and analyzed by XRD, SEM, HRTEM, XPS, Raman, and UV Vis DRS. To evaluate the photocatalytic activity of BiOBr_XI_1−X, rhodamine B was selected as an organic pollutant. In particular, BiOBr_0.15I_0.85 displayed significantly enhanced photocatalytic activity by virtue of modulating the energy band position, optimizing redox potentials, and accelerating carrier separation. Moreover, the enhancement mechanism was elucidated on the basis of band structure engineering, which provides ideas for the design of highly active photocatalysts for practical application in the fields of environmental issues and energy conservation. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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14 pages, 4218 KiB

Open AccessArticle

Novel, Simple and Low-Cost Preparation of Ba-Modified TiO₂ Nanotubes for Diclofenac Degradation under UV/Vis Radiation

by Mario Bohač, Tihana Čižmar, Vedran Kojić, Jan Marčec, Krunoslav Juraić, Ivana Grčić and Andreja Gajović

Nanomaterials 2021, 11(10), 2714; https://doi.org/10.3390/nano11102714 - 14 Oct 2021

Cited by 4 | Viewed by 2056

Abstract

A novel low-cost synthesis of barium-modified TiO₂ nanotube (TNT) arrays was used to obtain an immobilized photocatalyst for degradation of diclofenac. TNT arrays were prepared by electrochemical anodization of titanium thin films deposited on fluorine-doped tin oxide (FTO) coated glass by magnetron [...] Read more.

A novel low-cost synthesis of barium-modified TiO₂ nanotube (TNT) arrays was used to obtain an immobilized photocatalyst for degradation of diclofenac. TNT arrays were prepared by electrochemical anodization of titanium thin films deposited on fluorine-doped tin oxide (FTO) coated glass by magnetron sputtering, ensuring transparency and immobilization of the nanotubes. The Ba-modifications were obtained by annealing solutions of Ba(OH)₂ spin coated on top of TNT. Three different concentrations of Ba(OH)₂ were used (12.5 mM, 25 mM and 50 mM). The crystalline structure, morphology and presence of Ba were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Ba-modified TiO₂ nanotubes (BTNT) were tested for photocatalytic degradation of diclofenac under UV/Vis radiation and it was proven that all of the Ba-modified samples showed an increase in photocatalytic activity with respect to the unmodified TNTs. The most efficient photocatalyst was the sample prepared with 25 mM Ba(OH)₂ which showed 90% diclofenac degradation after 60 min. This result was in agreement with cyclic voltammetry measurements that showed the largest increase in photo-oxidation current densities for the same sample due to the increased generation of ^•OH radicals obtained by a more efficient photogenerated charge separation. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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14 pages, 4196 KiB

Open AccessArticle

Photocatalytic Degradation of Sulfamethoxazole, Nitenpyram and Tetracycline by Composites of Core Shell g-C₃N₄@ZnO, and ZnO Defects in Aqueous Phase

by Godfred Kwesi Teye, Jingyu Huang, Yi Li, Ke Li, Lei Chen and Williams Kweku Darkwah

Nanomaterials 2021, 11(10), 2609; https://doi.org/10.3390/nano11102609 - 4 Oct 2021

Cited by 12 | Viewed by 2559

Abstract

The synthesis of photocatalysts with high charge separation and transfer efficiency are of immense significance in the process of using photocatalysis technology for wastewater treatment. In this study core shell g-C₃N₄@ZnO, and ZnO defects photocatalysts presented an improved morphology [...] Read more.

The synthesis of photocatalysts with high charge separation and transfer efficiency are of immense significance in the process of using photocatalysis technology for wastewater treatment. In this study core shell g-C₃N₄@ZnO, and ZnO defects photocatalysts presented an improved morphology in its characterization using techniques such as SEM, DRS, PL, MS, EIS, and XRD, and enhanced photodegradation of sulfamethoxazole, Nitenpyram and Tetracycline. Different composites were obtained as confirmed by the various characterization techniques studied, including core shell g-C₃N₄@ZnO, and ZnO defects photocatalyst. The synthesized photocatalysts showed high visible light absorption efficiency within a range of ~655 to 420 nm. Core shell g-C₃N₄@ZnO, and ZnO defects photocatalysts demonstrated high photocatalytic activity ascribed to high load separation and transition as shown in PL, Photocurrent reaction and EIS. It is understandable that core shell g-C₃N₄@ZnO, and ZnO defects photocatalysts have been confirmed to be one of the ultimate promising entrants for photocatalyst scheming. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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9 pages, 4441 KiB

Open AccessArticle

Enhanced Photocatalytic Antibacterial Properties of TiO₂ Nanospheres with Rutile/Anatase Heterophase Junctions and the Archival Paper Protection Application

by Yingying Qin, Xinyu Wang, Pengyuan Qiu and Jian Tian

Nanomaterials 2021, 11(10), 2585; https://doi.org/10.3390/nano11102585 - 30 Sep 2021

Cited by 16 | Viewed by 2090

Abstract

TiO₂ has been generally studied for photocatalytic sterilization, but its antibacterial activities are limited. Herein, TiO₂ nanospheres with rutile/anatase heterophase junctions are prepared by a wet chemical/annealing method. The large BET surface area and pore size are beneficial for the absorption [...] Read more.

TiO₂ has been generally studied for photocatalytic sterilization, but its antibacterial activities are limited. Herein, TiO₂ nanospheres with rutile/anatase heterophase junctions are prepared by a wet chemical/annealing method. The large BET surface area and pore size are beneficial for the absorption of bacteria. The rutile/anatase heterojunctions narrow the bandgap, which enhances light absorption. The rutile/anatase heterojunctions also efficiently promote the photogenerated carriers’ separation, finally producing a high yield of radical oxygen species, such as •O₂⁻ and •OH, to sterilize bacteria. As a consequence, the obtained TiO₂ nanospheres with rutile/anatase heterojunctions present an improved antibacterial performance against E. coli (98%) within 3 h of simulated solar light irradiation, exceeding that of TiO₂ nanospheres without annealing (amorphous) and TiO₂ nanospheres annealing at 350 and 550 °C (pure anatase). Furthermore, we design a photocatalytic antibacterial spray to protect the file paper. Our study reveals that the TiO₂ nanospheres with rutile/anatase heterojunctions are a potential candidate for maintaining the durability of paper in the process of archival protection. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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15 pages, 10436 KiB

Open AccessArticle

Effects of Electrospinning Parameters on the Microstructure of PVP/TiO₂ Nanofibers

by Wan-Tae Kim, Dong-Cheol Park, Wan-Hee Yang, Churl-Hee Cho and Won-Youl Choi

Nanomaterials 2021, 11(6), 1616; https://doi.org/10.3390/nano11061616 - 20 Jun 2021

Cited by 34 | Viewed by 4711

Abstract

Titanium dioxide has excellent chemical, electrical, and optical properties, as well as good chemical stability. For that reason, it is widely used in many fields of study and industry, such as photocatalysts, organic solar cells, sensors, dental implants, and other applications. Many nanostructures [...] Read more.

Titanium dioxide has excellent chemical, electrical, and optical properties, as well as good chemical stability. For that reason, it is widely used in many fields of study and industry, such as photocatalysts, organic solar cells, sensors, dental implants, and other applications. Many nanostructures of TiO₂ have been reported, and electrospinning is an efficient practical technique that has a low cost and high efficiency. In various studies on improving performance, the researchers created nanofibers with suitable microstructures by changing various properties and the many process parameters that can be controlled. In this study, PVP/TiO₂ nanofibers were fabricated by the electrospinning process. The diameters of the nanofibers were controlled by various parameters. To understand the effects on the diameter of the nanofibers, various process parameters were controlled: the molecular weight and concentration of the polymers, deionized water, applied voltage, fluid velocity, and concentration of titanium precursor. The average diameter of the PVP nanofibers was controlled in a range of 42.3 nm to 633.0 nm. The average diameter of the PVP/TiO₂ nanofibers was also controlled in a range of 63.5 nm to 186.0 nm after heat treatment. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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Review

Jump to: Research

26 pages, 1773 KiB

Open AccessReview

Antimicrobial Effectiveness of Innovative Photocatalysts: A Review

by Giusy Lofrano, Francesca Ubaldi, Luisa Albarano, Maurizio Carotenuto, Vincenzo Vaiano, Federica Valeriani, Giovanni Libralato, Gianluca Gianfranceschi, Ilaria Fratoddi, Sureyya Meric, Marco Guida and Vincenzo Romano Spica

Nanomaterials 2022, 12(16), 2831; https://doi.org/10.3390/nano12162831 - 17 Aug 2022

Cited by 24 | Viewed by 2227

Abstract

Waterborne pathogens represent one of the most widespread environmental concerns. Conventional disinfection methods, including chlorination and UV, pose several operational and environmental problems; namely, formation of potentially hazardous disinfection by-products (DBPs) and high energy consumption. Therefore, there is high demand for effective, low-cost [...] Read more.

Waterborne pathogens represent one of the most widespread environmental concerns. Conventional disinfection methods, including chlorination and UV, pose several operational and environmental problems; namely, formation of potentially hazardous disinfection by-products (DBPs) and high energy consumption. Therefore, there is high demand for effective, low-cost disinfection treatments. Among advanced oxidation processes, the photocatalytic process, a form of green technology, is becoming increasingly attractive. A systematic review was carried out on the synthesis, characterization, toxicity, and antimicrobial performance of innovative engineered photocatalysts. In recent decades, various engineered photocatalysts have been developed to overcome the limits of conventional photocatalysts using different synthesis methods, and these are discussed together with the main parameters influencing the process behaviors. The potential environmental risks of engineered photocatalysts are also addressed, considering the toxicity effects presented in the literature. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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35 pages, 8455 KiB

Open AccessReview

g-C₃N₄: Properties, Pore Modifications, and Photocatalytic Applications

by Jiaqi Dong, Yue Zhang, Muhammad Irfan Hussain, Wenjie Zhou, Yingzhi Chen and Lu-Ning Wang

Nanomaterials 2022, 12(1), 121; https://doi.org/10.3390/nano12010121 - 30 Dec 2021

Cited by 78 | Viewed by 8276

Abstract

Graphitic carbon nitride (g-C₃N₄), as a polymeric semiconductor, is promising for ecological and economical photocatalytic applications because of its suitable electronic structures, together with the low cost, facile preparation, and metal-free feature. By modifying porous g-C [...] Read more.

Graphitic carbon nitride (g-C₃N₄), as a polymeric semiconductor, is promising for ecological and economical photocatalytic applications because of its suitable electronic structures, together with the low cost, facile preparation, and metal-free feature. By modifying porous g-C₃N₄, its photoelectric behaviors could be facilitated with transport channels for photogenerated carriers, reactive substances, and abundant active sites for redox reactions, thus further improving photocatalytic performance. There are three types of methods to modify the pore structure of g-C₃N₄: hard-template method, soft-template method, and template-free method. Among them, the hard-template method may produce uniform and tunable pores, but requires toxic and environmentally hazardous chemicals to remove the template. In comparison, the soft templates could be removed at high temperatures during the preparation process without any additional steps. However, the soft-template method cannot strictly control the size and morphology of the pores, so prepared samples are not as orderly as the hard-template method. The template-free method does not involve any template, and the pore structure can be formed by designing precursors and exfoliation from bulk g-C₃N₄ (BCN). Without template support, there was no significant improvement in specific surface area (SSA). In this review, we first demonstrate the impact of pore structure on photoelectric performance. We then discuss pore modification methods, emphasizing comparison of their advantages and disadvantages. Each method’s changing trend and development direction is also summarized in combination with the commonly used functional modification methods. Furthermore, we introduce the application prospects of porous g-C₃N₄ in the subsequent studies. Overall, porous g-C₃N₄ as an excellent photocatalyst has a huge development space in photocatalysis in the future. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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22 pages, 3043 KiB

Open AccessReview

Recent Advances of Photocatalytic Application in Water Treatment: A Review

by Guangmin Ren, Hongtao Han, Yixuan Wang, Sitong Liu, Jianyong Zhao, Xiangchao Meng and Zizhen Li

Nanomaterials 2021, 11(7), 1804; https://doi.org/10.3390/nano11071804 - 12 Jul 2021

Cited by 277 | Viewed by 18013

Abstract

Photocatalysis holds great promise as an efficient and sustainable oxidation technology for application in wastewater treatment. Rapid progress developing novel materials has propelled photocatalysis to the forefront of sustainable wastewater treatments. This review presents the latest progress on applications of photocatalytic wastewater treatment. [...] Read more.

Photocatalysis holds great promise as an efficient and sustainable oxidation technology for application in wastewater treatment. Rapid progress developing novel materials has propelled photocatalysis to the forefront of sustainable wastewater treatments. This review presents the latest progress on applications of photocatalytic wastewater treatment. Our focus is on strategies for improving performance. Challenges and outlooks in this promising field are also discussed. We hope this review will help researchers design low-cost and high-efficiency photocatalysts for water treatment. Full article

(This article belongs to the Special Issue Semiconductor-Based Nanomaterials for Photocatalytic Applications)

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