Nanoscale Heterogeneities and Composition–Reactivity Relationships in Copper Vanadate Photoanodes
| Autor: | Ian D. Sharp, Francesca M. Toma, Jason K. Cooper, Chang-Ming Jiang, Johanna Eichhorn |
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| Rok vydání: | 2021 |
| Předmět: |
Materials science
Photoelectrochemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Solar fuel 01 natural sciences 0104 chemical sciences Chemical engineering Water splitting General Materials Science Chemical stability Thin film 0210 nano-technology Ternary operation Chemical composition Stoichiometry |
| Zdroj: | ACS Applied Materials & Interfaces. 13:23575-23583 |
| ISSN: | 1944-8252 1944-8244 |
| Popis: | The photoelectrochemical performance of thin film photoelectrodes can be impacted by deviations from the stoichiometric composition, both at the macroscale and at the nanoscale. This issue is especially pronounced for the class of ternary compounds that are currently investigated for simultaneously achieving the optoelectronic characteristics and chemical stability required for solar fuel generation. Here, we combine macroscopic photoelectrochemical testing with atomic force microscopy (AFM) and scanning transmission X-ray microscopy (STXM) to reveal relationships between photoelectrochemical activity, nanoscale morphology, and local chemical composition in copper vanadate (CVO) thin films as a model system. For films with varying Cu/(Cu + V) ratios around the ideal stoichiometry of stoiberite Cu5V2O10, AFM resolves submicrometer morphology variations, which correlate with variations of the Cu content resolved by STXM. Both stoichiometric and Cu-deficient films exhibit a clear photoresponse, which indicates electronic tolerance to reduced Cu content. While both films exhibit homogeneous O and V content, they are also characterized by local regions of Cu enrichment and depletion that extend beyond individual grains. By contrast, Cu-rich photoelectrodes exhibit a tendency toward CuO secondary phase formation and a significantly reduced photoelectrochemical activity, indicating a significantly poor electronic tolerance to Cu-enrichment. These findings highlight that the average film composition at the macroscale is insufficient for defining structure-function relationships in complex ternary compounds. Rather, correlating microscopic variations in chemical composition to macroscopic photoelectrochemical performance provides insights into photocatalytic activity and stability that are otherwise not apparent from pure macroscopic characterization. |
| Databáze: | OpenAIRE |
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