{"title":"An anisotropically crystallized and nitrogen-doped CuWO4 photoanode for efficient and robust visible-light-driven water oxidation","authors":"Tomohiro Katsuki, Zaki Zahran, Norihisa Hoshino, Yuta Tsubonouchi, Debraj Chandra, Masayuki Yagi","doi":"10.1039/d4ta04120h","DOIUrl":null,"url":null,"abstract":"A nitrogen-doped CuWO<small><sub>4</sub></small> (N-CuWO<small><sub>4</sub></small>) photoanode for photoelectrochemical (PEC) water oxidation was synthesized by a mixed metal-imidazole casting (MiMIC) method with 1-butylimidazole (BIm). The N-CuWO<small><sub>4</sub></small> electrode attained PEC water oxidation at the longer wavelength of 540 nm by 40 nm compared to the film (neat-CuWO<small><sub>4</sub></small>) prepared without BIm due to the N-doping, which was conscientiously characterized by spectroscopic and theoretical investigations. The N-CuWO<small><sub>4</sub></small> surface was compactly covered with worm-like particles of 100-500 nm in diameter, which is responsible for the N-CuWO<small><sub>4</sub></small> film adhering rigidly on the substrate. The N-CuWO<small><sub>4</sub></small> film showed anisotropic crystallization of triclinic CuWO<small><sub>4</sub></small> with predominant growth to [010] and [100] directions, in contrast to isotropic crystallization for the neat-CuWO<small><sub>4</sub></small> film. The N-CuWO<small><sub>4</sub></small> electrode demonstrated the superior performance for PEC water oxidation with incident photon-to-electron conversion efficiency (IPCE) of 5.6% contributed from charge separation efficiency (<em>η</em><small><sub>sep</sub></small>) of 12.3% and catalytic efficiency (<em>η</em><small><sub>cat</sub></small>) of 51.9% (at 420 nm and 1.23 V), Faraday efficiency (FE<small><sub>O2</sub></small>) of 97% for O<small><sub>2</sub></small> evolution, and significant stability for 40 h, which compares advantageously with those for the state-of-the-art CuWO<small><sub>4</sub></small>-based photoanodes. The water oxidation rate constant (<em>k</em><small><sub>O2</sub></small> = 1.6 × 10<small><sup>2</sup></small> s<small><sup>-1</sup></small>) at the surface for the N-CuWO<small><sub>4</sub></small> electrode was higher than that (6.8 s<small><sup>-1</sup></small>) for the neat-CuWO<small><sub>4</sub></small> electrode by 2 orders of magnitude, which is responsible for the high IPCE and <em>η</em><small><sub>cat</sub></small> for the N-CuWO<small><sub>4</sub></small> electrode. The higher <em>k</em><small><sub>O2</sub></small> for the N-CuWO<small><sub>4</sub></small> electrode is ascribable to the higher active site on the (100) facet for water oxidation at the surface.","PeriodicalId":82,"journal":{"name":"Journal of Materials Chemistry A","volume":null,"pages":null},"PeriodicalIF":10.7000,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Materials Chemistry A","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1039/d4ta04120h","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
A nitrogen-doped CuWO4 (N-CuWO4) photoanode for photoelectrochemical (PEC) water oxidation was synthesized by a mixed metal-imidazole casting (MiMIC) method with 1-butylimidazole (BIm). The N-CuWO4 electrode attained PEC water oxidation at the longer wavelength of 540 nm by 40 nm compared to the film (neat-CuWO4) prepared without BIm due to the N-doping, which was conscientiously characterized by spectroscopic and theoretical investigations. The N-CuWO4 surface was compactly covered with worm-like particles of 100-500 nm in diameter, which is responsible for the N-CuWO4 film adhering rigidly on the substrate. The N-CuWO4 film showed anisotropic crystallization of triclinic CuWO4 with predominant growth to [010] and [100] directions, in contrast to isotropic crystallization for the neat-CuWO4 film. The N-CuWO4 electrode demonstrated the superior performance for PEC water oxidation with incident photon-to-electron conversion efficiency (IPCE) of 5.6% contributed from charge separation efficiency (ηsep) of 12.3% and catalytic efficiency (ηcat) of 51.9% (at 420 nm and 1.23 V), Faraday efficiency (FEO2) of 97% for O2 evolution, and significant stability for 40 h, which compares advantageously with those for the state-of-the-art CuWO4-based photoanodes. The water oxidation rate constant (kO2 = 1.6 × 102 s-1) at the surface for the N-CuWO4 electrode was higher than that (6.8 s-1) for the neat-CuWO4 electrode by 2 orders of magnitude, which is responsible for the high IPCE and ηcat for the N-CuWO4 electrode. The higher kO2 for the N-CuWO4 electrode is ascribable to the higher active site on the (100) facet for water oxidation at the surface.
期刊介绍:
The Journal of Materials Chemistry A, B & C covers a wide range of high-quality studies in the field of materials chemistry, with each section focusing on specific applications of the materials studied. Journal of Materials Chemistry A emphasizes applications in energy and sustainability, including topics such as artificial photosynthesis, batteries, and fuel cells. Journal of Materials Chemistry B focuses on applications in biology and medicine, while Journal of Materials Chemistry C covers applications in optical, magnetic, and electronic devices. Example topic areas within the scope of Journal of Materials Chemistry A include catalysis, green/sustainable materials, sensors, and water treatment, among others.