Nanomaterials

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12 pages, 2544 KiB

Open AccessArticle

Nano-MnO₂ Decoration of TiO₂ Microparticles to Promote Gaseous Ethanol Visible Photoremoval

by Marta Stucchi, Daria C. Boffito, Eleonora Pargoletti, Giuseppina Cerrato, Claudia L. Bianchi and Giuseppe Cappelletti

Nanomaterials 2018, 8(9), 686; https://doi.org/10.3390/nano8090686 - 3 Sep 2018

Cited by 26 | Viewed by 3887

Abstract

TiO₂-based photocatalysis under visible light is an attractive way to abate air pollutants. Moreover, developing photocatalytic materials on a large-scale requires safe and low-cost precursors. Both high-performance TiO₂ nanopowders and visible-light active noble metals do not match these requirements. Here, [...] Read more.

TiO₂-based photocatalysis under visible light is an attractive way to abate air pollutants. Moreover, developing photocatalytic materials on a large-scale requires safe and low-cost precursors. Both high-performance TiO₂ nanopowders and visible-light active noble metals do not match these requirements. Here, we report the design of novel Mn-decorated micrometric TiO₂ particles. Pigmentary TiO₂ replaced unsafe nano-TiO₂ and firmly supported MnO_x particles. Mn replaced noble metals such as Au or Ag, opening the way for the development of lower cost catalysts. Varying Mn loading or pH during the impregnation affected the final activity, thus giving important information to optimize the synthesis. Photocatalytic activity screening occurred on the gas-phase degradation of ethanol as a reference molecule, both under ultraviolet (UV) (6 h) and Light Emitting Diode (LED) (24 h) irradiation. Mn-doped TiO₂ reached a maximum ethanol degradation of 35% under visible light after 24 h for the sample containing 20% of Mn. Also, we found that an acidic pH increased both ethanol degradation and mineralization to CO₂, while an alkaline pH drastically slowed down the reaction. A strict correlation between photocatalytic results and physico-chemical characterizations of the synthesized powders were drawn. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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14 pages, 3936 KiB

Open AccessArticle

Synergistic Effects of Active Sites’ Nature and Hydrophilicity on the Oxygen Reduction Reaction Activity of Pt-Free Catalysts

by Mariangela Longhi, Camilla Cova, Eleonora Pargoletti, Mauro Coduri, Saveria Santangelo, Salvatore Patanè, Nicoletta Ditaranto, Nicola Cioffi, Anna Facibeni and Marco Scavini

Nanomaterials 2018, 8(9), 643; https://doi.org/10.3390/nano8090643 - 22 Aug 2018

Cited by 12 | Viewed by 4017

Abstract

This work highlights the importance of the hydrophilicity of a catalyst’s active sites on an oxygen reduction reaction (ORR) through an electrochemical and physico-chemical study on catalysts based on nitrogen-modified carbon doped with different metals (Fe, Cu, and a mixture of them). BET, [...] Read more.

This work highlights the importance of the hydrophilicity of a catalyst’s active sites on an oxygen reduction reaction (ORR) through an electrochemical and physico-chemical study on catalysts based on nitrogen-modified carbon doped with different metals (Fe, Cu, and a mixture of them). BET, X-ray Powder Diffraction (XRPD), micro-Raman, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and hydrophilicity measurements were performed. All synthesized catalysts are characterized not only by a porous structure, with the porosity distribution centered in the mesoporosity range, but also by the presence of carbon nanostructures. In iron-doped materials, these nanostructures are bamboo-like structures typical of nitrogen carbon nanotubes, which are better organized, in a larger amount, and longer than those in the copper-doped material. Electrochemical ORR results highlight that the presence of iron and nitrogen carbon nanotubes is beneficial to the electroactivity of these materials, but also that the hydrophilicity of the active site is an important parameter affecting electrocatalytic properties. The most active material contains a mixture of Fe and Cu. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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14 pages, 4480 KiB

Open AccessArticle

Band Gap Implications on Nano-TiO₂ Surface Modification with Ascorbic Acid for Visible Light-Active Polypropylene Coated Photocatalyst

by Chiara Anna D’Amato, Rita Giovannetti, Marco Zannotti, Elena Rommozzi, Marco Minicucci, Roberto Gunnella and Andrea Di Cicco

Nanomaterials 2018, 8(8), 599; https://doi.org/10.3390/nano8080599 - 7 Aug 2018

Cited by 51 | Viewed by 6603

Abstract

The effect of surface modification using ascorbic acid as a surface modifier of nano-TiO₂ heterogeneous photocatalyst was studied. The preparation of supported photocatalyst was made by a specific paste containing ascorbic acid modified TiO₂ nanoparticles used to cover Polypropylene as a [...] Read more.

The effect of surface modification using ascorbic acid as a surface modifier of nano-TiO₂ heterogeneous photocatalyst was studied. The preparation of supported photocatalyst was made by a specific paste containing ascorbic acid modified TiO₂ nanoparticles used to cover Polypropylene as a support material. The obtained heterogeneous photocatalyst was thoroughly characterized (scanning electron microscope (SEM), RAMAN, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and Diffuse Reflectance Spectra (DRS) and successfully applied in the visible light photodegradation of Alizarin Red S in water solutions. In particular, this new supported TiO₂ photocatalyst showed a change in the adsorption mechanism of dye with respect to that of only TiO₂ due to the surface properties. In addition, an improvement of photocatalytic performances in the visible light photodegration was obtained, showing a strict correlation between efficiency and energy band gap values, evidencing the favorable surface modification of TiO₂ nanoparticles. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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16 pages, 2688 KiB

Open AccessArticle

Morphology, Optical Properties and Photocatalytic Activity of Photo- and Plasma-Deposited Au and Au/Ag Core/Shell Nanoparticles on Titania Layers

by Alexander Müller, Sandra Peglow, Michael Karnahl, Angela Kruth, Henrik Junge, Volker Brüser and Christina Scheu

Nanomaterials 2018, 8(7), 502; https://doi.org/10.3390/nano8070502 - 6 Jul 2018

Cited by 13 | Viewed by 4998

Abstract

Titania is a promising material for numerous photocatalytic reactions such as water splitting and the degradation of organic compounds (e.g., methanol, phenol). Its catalytic performance can be significantly increased by the addition of co-catalysts. In this study, Au and Au/Ag nanoparticles were deposited [...] Read more.

Titania is a promising material for numerous photocatalytic reactions such as water splitting and the degradation of organic compounds (e.g., methanol, phenol). Its catalytic performance can be significantly increased by the addition of co-catalysts. In this study, Au and Au/Ag nanoparticles were deposited onto mesoporous titania thin films using photo-deposition (Au) and magnetron-sputtering (Au and Au/Ag). All samples underwent comprehensive structural characterization by grazing incidence X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Nanoparticle distributions and nanoparticle size distributions were correlated to the deposition methods. Light absorption measurements showed features related to diffuse scattering, the band gap of titania and the local surface plasmon resonance of the noble metal nanoparticles. Further, the photocatalytic activities were measured using methanol as a hole scavenger. All nanoparticle-decorated thin films showed significant performance increases in hydrogen evolution under UV illumination compared to pure titania, with an evolution rate of up to 372 μL H₂ h⁻¹ cm⁻² representing a promising approximately 12-fold increase compared to pure titania. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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17 pages, 4612 KiB

Open AccessArticle

Facile Synthesis of Novel CaIn₂S₄/ZnIn₂S₄ Composites with Efficient Performance for Photocatalytic Reduction of Cr(VI) under Simulated Sunlight Irradiation

by Siyu Xu, Jun Dai, Juan Yang, Jun You and Jingyi Hao

Nanomaterials 2018, 8(7), 472; https://doi.org/10.3390/nano8070472 - 27 Jun 2018

Cited by 33 | Viewed by 5210

Abstract

A series of novel and efficient heterostructured composites CaIn₂S₄/ZnIn₂S₄ have been synthesized using a facile hydrothermal method. XRD patterns indicate the as-prepared catalysts are two-phase composites of cubic phase CaIn₂S₄ and hexagonal phase [...] Read more.

A series of novel and efficient heterostructured composites CaIn₂S₄/ZnIn₂S₄ have been synthesized using a facile hydrothermal method. XRD patterns indicate the as-prepared catalysts are two-phase composites of cubic phase CaIn₂S₄ and hexagonal phase ZnIn₂S₄. FESEM (field emission scanning electron microscope) images display that the synthesized composites are composed of flower-like microspheres with wide diameter distribution. UV–Vis diffuse reflectance spectra (DRS) show that the optical absorption edges of the CaIn₂S₄/ZnIn₂S₄ composites shift toward longer wavelengths with the increase of the CaIn₂S₄ component. The photocatalytic activities of the as-synthesized composites are investigated by using the aqueous-phase Cr(VI) reduction under simulated sunlight irradiation. This is the first report on the application of the CaIn₂S₄/ZnIn₂S₄ composites as stable and efficient photocatalysts for the Cr(VI) reduction. The fabricated CaIn₂S₄/ZnIn₂S₄ composites possess higher photocatalytic performance in comparison with pristine CaIn₂S₄ or ZnIn₂S₄. The CaIn₂S₄/ZnIn₂S₄ composite with a CaIn₂S₄ molar content of 30% exhibits the optimum photocatalytic activity. The primary reason for the significantly enhanced photoreduction activity is proved to be the substantially improved separation efficiency of photogenerated electrons/holes caused by forming the CaIn₂S₄/ZnIn₂S₄ heterostructured composites. The efficient charge separation can be evidenced by steady-state photoluminescence spectra (PLs) and transient photocurrent response. Based on the charge transfer between CaIn₂S₄ and ZnIn₂S₄, an enhancement mechanism of photocatalytic activity and stability for the Cr(VI) reduction is proposed. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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13 pages, 3062 KiB

Open AccessArticle

Construction of g-C₃N₄-mNb₂O₅ Composites with Enhanced Visible Light Photocatalytic Activity

by Meiyin Wang, Hui Wang, Yuanhang Ren, Cheng Wang, Zhewei Weng, Bin Yue and Heyong He

Nanomaterials 2018, 8(6), 427; https://doi.org/10.3390/nano8060427 - 12 Jun 2018

Cited by 15 | Viewed by 4289

Abstract

A series of composites consisting of g-C₃N₄ sheet and mesoporous Nb₂O₅ (mNb₂O₅) microsphere were fabricated by in situ hydrolysis deposition of NbCl₅ onto g-C₃N₄ sheet followed by solvothermal treatment. [...] Read more.

A series of composites consisting of g-C₃N₄ sheet and mesoporous Nb₂O₅ (mNb₂O₅) microsphere were fabricated by in situ hydrolysis deposition of NbCl₅ onto g-C₃N₄ sheet followed by solvothermal treatment. The samples were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N₂ adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of the composites was studied by degradation of rhodamine B (RhB) and tetracycline hydrochloride (TC-HCl) in aqueous solution under visible light irradiation (λ > 420 nm). Compared with g-C₃N₄ and mNb₂O₅, g-C₃N₄-mNb₂O₅ composites have higher photocatalytic activity due to synergistic effect between g-C₃N₄ and mNb₂O₅. Among these composites, 4% g-C₃N₄-mNb₂O₅ has the highest efficiency and good recyclability for degradation of both RhB and TC-HCl. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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14 pages, 4278 KiB

Open AccessArticle

A Facile Approach for the Synthesis of Zn₂SnO₄/BiOBr Hybrid Nanocomposites with Improved Visible-Light Photocatalytic Performance

by Tiekun Jia, Ming Liu, Dongsheng Yu, Fei Long, Shuyi Mo, Zhao Deng and Weimin Wang

Nanomaterials 2018, 8(5), 313; https://doi.org/10.3390/nano8050313 - 9 May 2018

Cited by 26 | Viewed by 4076

Abstract

In this study, a novel Zn₂SnO₄/BiOBr hybrid photocatalyst was prepared via a mild hydrothermal synthesis combined with a chemical deposition method. The morphological structure, chemical composition, crystal structure, and optical properties were comprehensively characterized by a series of measurement [...] Read more.

In this study, a novel Zn₂SnO₄/BiOBr hybrid photocatalyst was prepared via a mild hydrothermal synthesis combined with a chemical deposition method. The morphological structure, chemical composition, crystal structure, and optical properties were comprehensively characterized by a series of measurement techniques. Morphological observation showed that fine Zn₂SnO₄ nanoparticles were anchored on the nanoplate surface of a flower-like BiOBr 3D hierarchical structure. The experimental results of UV-vis diffuse reflection spectroscopy revealed that the visible-light absorptive capacity of the Zn₂SnO₄/BiOBr hybrid photocatalyst was promoted, as compared to that of pure Zn₂SnO₄. Evidenced by electro-negativity theoretical calculation, Zn₂SnO₄ and BiOBr possessed matched band edges for accelerating photogenerated charge separation at the interface. The Zn₂SnO₄/BiOBr hybrid photocatalyst exhibited enhanced photocatalytic performance in the degradation of Rhodamine B (RhB) under visible light irradiation. According to the band energy structure and the experimental results, the enhanced photocatalytic performance was ascribed to the improved visible-light absorptive capacity and the contact interface between Zn₂SnO₄ nanoparticles and BiOBr nanoplates, being able to favor the prompt charge migration and suppress the recombination of photogenerated carriers in the hybrid system. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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11 pages, 3576 KiB

Open AccessArticle

Enhanced Photocatalytic Activity of {110}-Faceted TiO₂ Rutile Nanorods in the Photodegradation of Hazardous Pharmaceuticals

by Tran Thi Thuong Huyen, Tran Thi Kim Chi, Nguyen Duc Dung, Hendrik Kosslick and Nguyen Quang Liem

Nanomaterials 2018, 8(5), 276; https://doi.org/10.3390/nano8050276 - 25 Apr 2018

Cited by 31 | Viewed by 5715

Abstract

Rutile TiO₂ with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple [...] Read more.

Rutile TiO₂ with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple hydrothermal synthesis of rutile TiO₂ nanorods with highly exposed {110} facets. The obtained rutile was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. The main contribution to the photocatalytic activity comes from rutile nanorods with highly dominant active {110} facets, which were studied in the photodegradation of reactive cinnamic acid and more recalcitrant ibuprofen. The contribution of active species was also investigated. The present work further confirmed the hydrothermal synthesis route for controlling the preparation of highly crystalline and active rutile nanocrystals. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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11 pages, 5436 KiB

Open AccessArticle

Effect of Organic Substrates on the Photocatalytic Reduction of Cr(VI) by Porous Hollow Ga₂O₃ Nanoparticles

by Jin Liu, Huihui Gan, Hongzhang Wu, Xinlei Zhang, Jun Zhang, Lili Li and Zhenling Wang

Nanomaterials 2018, 8(4), 263; https://doi.org/10.3390/nano8040263 - 22 Apr 2018

Cited by 4 | Viewed by 4670

Abstract

Porous hollow Ga₂O₃ nanoparticles were successfully synthesized by a hydrolysis method followed by calcination. The prepared samples were characterized by field emission scanning electron microscope, transmission electron microscope, thermogravimetry and differential scanning calorimetry, UV-vis diffuse reflectance spectra and Raman spectrum. [...] Read more.

Porous hollow Ga₂O₃ nanoparticles were successfully synthesized by a hydrolysis method followed by calcination. The prepared samples were characterized by field emission scanning electron microscope, transmission electron microscope, thermogravimetry and differential scanning calorimetry, UV-vis diffuse reflectance spectra and Raman spectrum. The porous structure of Ga₂O₃ nanoparticles can enhance the light harvesting efficiency, and provide lots of channels for the diffusion of Cr(VI) and Cr(III). Photocatalytic reduction of Cr(VI), with different initial pH and degradation of several organic substrates by porous hollow Ga₂O₃ nanoparticles in single system and binary system, were investigated in detail. The reduction rate of Cr(VI) in the binary pollutant system is markedly faster than that in the single Cr(VI) system, because Cr(VI) mainly acts as photogenerated electron acceptor. In addition, the type and concentration of organic substrates have an important role in the photocatalytic reduction of Cr(VI). Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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21 pages, 34606 KiB

Open AccessArticle

A Facile Method for the Preparation of Colored Bi₄Ti₃O_12−x Nanosheets with Enhanced Visible-Light Photocatalytic Hydrogen Evolution Activity

by Yizeng Zhang, Zhiwu Chen and Zhenya Lu

Nanomaterials 2018, 8(4), 261; https://doi.org/10.3390/nano8040261 - 21 Apr 2018

Cited by 31 | Viewed by 5363

Abstract

Bi₄Ti₃O_12−x nanosheet photocatalysts with abundant oxygen vacancies are fabricated by a facile solid-state chemical reduction method for the first time. This method is simple in operation, has short reaction time, and can be conducted at mild temperatures [...] Read more.

Bi₄Ti₃O_12−x nanosheet photocatalysts with abundant oxygen vacancies are fabricated by a facile solid-state chemical reduction method for the first time. This method is simple in operation, has short reaction time, and can be conducted at mild temperatures (300~400 °C). The electron paramagnetic resonance, thermogravimetric analysis, X-ray photoelectron spectrometer, and positron annihilation lifetime spectra results indicate that oxygen vacancies are produced in Bi₄Ti₃O_12−x, and they can be adjusted by tuning the reduction reaction conditions. Control experiments show that the reduction time and temperature have great influences on the photocatalytic activities of Bi₄Ti₃O_12−x. The optimal Bi₄Ti₃O_12−x is the sample undergoing the reduction treatment at 350 °C for 60 min and it affords a hydrogen evolution rate of 129 μmol·g⁻¹·h⁻¹ under visible-light irradiation, which is about 3.4 times that of the pristine Bi₄Ti₃O₁₂. The Bi₄Ti₃O_12−x photocatalysts have good reusability and storage stability and can be used to decompose formaldehyde and formic acid for hydrogen production. The surface oxygen vacancies states result in the broadening of the valence band and the narrowing of the band gap. Such energy level structure variation helps promote the separation of photo-generated electron-hole pairs thus leading to enhancement in the visible-light photocatalytic hydrogen evolution. Meanwhile, the narrowing of the band gap leads to a broader visible light absorption of Bi₄Ti₃O_12−x. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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16 pages, 32722 KiB

Open AccessArticle

A Facile Approach to Prepare Black TiO₂ with Oxygen Vacancy for Enhancing Photocatalytic Activity

by Shihao Chen, Yang Xiao, Yinhai Wang, Zhengfa Hu, Hui Zhao and Wei Xie

Nanomaterials 2018, 8(4), 245; https://doi.org/10.3390/nano8040245 - 16 Apr 2018

Cited by 146 | Viewed by 13197

Abstract

Black TiO₂ has triggered worldwide research interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships and a more effective, facile and versatile method to produce it remain great challenges. We have developed a facile approach to synthesize [...] Read more.

Black TiO₂ has triggered worldwide research interest due to its excellent photocatalytic properties. However, the understanding of its structure–property relationships and a more effective, facile and versatile method to produce it remain great challenges. We have developed a facile approach to synthesize black TiO₂ nanoparticles with significantly improved light absorption in the visible and infrared regions. The experimental results show that oxygen vacancies are the major factors responsible for black coloration. More importantly, our black TiO₂ nanoparticles have no Ti³⁺ ions. These oxygen vacancies could introduce localized states in the bandgap and act as trap centers, significantly decreasing the electron–hole recombination. The photocatalytic decomposition of both rhodamine B and methylene blue demonstrated that, under ultraviolet light irradiation, better photocatalytic performance is achieved with our black TiO₂ nanoparticles than with commercial TiO₂ nanoparticles. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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20 pages, 29056 KiB

Open AccessArticle

In-Situ Synthesis of Hydrogen Titanate Nanotube/Graphene Composites with a Chemically Bonded Interface and Enhanced Visible Photocatalytic Activity

by Juan Yang, Jun You, Jun Dai, Yumei Chen and Yao Li

Nanomaterials 2018, 8(4), 229; https://doi.org/10.3390/nano8040229 - 8 Apr 2018

Cited by 6 | Viewed by 4734

Abstract

Hydrogen titanate nanotube (HTT)/graphene nanocomposites are synthesized by hydrothermal reduction of graphene oxide (GO) and simultaneous preparation of nanotubular HTT via an alkaline hydrothermal process. By using this facile in-situ compositing strategy, HTT are densely supported upon the surface of graphene sheets with [...] Read more.

Hydrogen titanate nanotube (HTT)/graphene nanocomposites are synthesized by hydrothermal reduction of graphene oxide (GO) and simultaneous preparation of nanotubular HTT via an alkaline hydrothermal process. By using this facile in-situ compositing strategy, HTT are densely supported upon the surface of graphene sheets with close interface contacts. The as-prepared HTT/graphene nanocomposites possess significantly enhanced visible light catalytic activity for the partial oxidation of benzylic alcohols. The amount of graphene has significant influence on catalytic activity and the optimal content of graphene is 1.0 wt %, giving a normalized rate constant k of 1.71 × 10⁻³ g/m²·h, which exceeds that of pure HTT and HTT/graphene-1.0% mixed by a factor of 7.1 or 5.2. Other than the general role of graphene as a high-performance electron acceptor or transporter, the observed enhancement in photocatalytic activity over HTT/graphene can be ascribed to the improved interfacial charge migration from enhanced chemical bonding (Ti–C bonds) during the in-situ compositing process. The formation of Ti–C bonds is confirmed by XPS analysis and the resulting enhanced separation of photoinduced charge carriers is demonstrated by electrochemical impedance spectra and transient photocurrent response. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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15 pages, 2520 KiB

Open AccessArticle

Zinc Tantalum Oxynitride (ZnTaO₂N) Photoanode Modified with Cobalt Phosphate Layers for the Photoelectrochemical Oxidation of Alkali Water

by Prabhakarn Arunachalam, Maged N. Shaddad, Mohamed A. Ghanem, Abdullah M. Al-Mayouf and Mark T. Weller

Nanomaterials 2018, 8(1), 48; https://doi.org/10.3390/nano8010048 - 18 Jan 2018

Cited by 16 | Viewed by 6048

Abstract

Photoanodes fabricated by the electrophoretic deposition of a thermally prepared zinc tantalum oxynitride (ZnTaO₂N) catalyst onto indium tin oxide (ITO) substrates show photoactivation for the oxygen evolution reaction (OER) in alkaline solutions. The photoactivity of the OER is further boosted by [...] Read more.

Photoanodes fabricated by the electrophoretic deposition of a thermally prepared zinc tantalum oxynitride (ZnTaO₂N) catalyst onto indium tin oxide (ITO) substrates show photoactivation for the oxygen evolution reaction (OER) in alkaline solutions. The photoactivity of the OER is further boosted by the photodeposition of cobalt phosphate (CoPi) layers onto the surface of the ZnTaO₂N photoanodes. Structural, morphological, and photoelectrochemical (PEC) properties of the modified ZnTaO₂N photoanodes are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet visible (UV−Vis) diffuse reflectance spectroscopy, and electrochemical techniques. The presence of the CoPi layer significantly improved the PEC performance of water oxidation in an alkaline sulphate solution. The photocurrent-voltage behavior of the CoPi-modified ZnTaO₂N anodes was improved, with the influence being more prominent at lower oxidation potentials. A stable photocurrent density of about 2.3 mA·cm⁻² at 1.23 V vs. RHE was attained upon visible light illumination. Relative to the ZnTaO₂N photoanodes, an almost three-fold photocurrent increase was achieved at the CoPi/ZnTaO₂N photoelectrode. Perovskite-based oxynitrides are modified using an oxygen-evolution co-catalyst of CoPi, and provide a new dimension for enhancing the photoactivity of oxygen evolution in solar-assisted water-splitting reactions. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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