2022 Fiscal Year Annual Research Report
Si-based photoelectrochemical carbon dioxide reduction for value-added chemicals
| Project/Area Number |
22F22366
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| Allocation Type | Single-year Grants |
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
押切 光丈 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, 主幹研究員 (20354368)
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| Co-Investigator(Kenkyū-buntansha) |
LI SIJIE 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, 外国人特別研究員
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| Project Period (FY) |
2022-11-16 – 2025-03-31
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| Keywords | photoelectrocatalysis / carbon dioxide reduction / silicon photocathode / photoanode / cocatalysts / surface and interface |
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| Outline of Annual Research Achievements |
This project aims at developing Si-based photocathodes and potential photoanodes for solar-driven synergistic reaction of CO2 reduction and water oxidation. In the past year, we converted planner p-Si semiconductors into p-Si pyramid-textured semiconductors as photocathodes by a liquid-phase etching method. The large specific surface area of p-Si pyramid-structure is conducive to the loading of cocatalysts and facilitates the separation and migration of photogenerated carriers. The photocathode performance was evaluated after loading cocatalyst. Compared with planner p-Si, the photoelectrochemical (PEC) CO2 reduction performance of p-Si pyramid was significantly improved, which proves that the PEC CO2 reduction performance of Si-based photocathodes is closely related to the semiconductor surface structure and the interface connection of semiconductor/cocatalyst.
On the other hand, we also tried to form transition metal oxide BiVO4 semiconductors on transparent conductive substrate (fluorine-doped tin oxide: FTO) based on a liquid-phase synthesis strategy. It was confirmed that BiOI was electrodeposited on the substrate first, and then transformed into BiVO4 semiconductors by heat treatment. The chemical composition, morphology, and crystal structure of BiVO4 semiconductor with porous nanostructure were analyzed and evaluated. Since the as-prepared BiVO4 porous nanostructured semiconductor exhibits n-type semiconducting properties, we set out to try to optimize it as a potential photoanode for assisting PEC CO2 reduction.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Focusing on the proposed research plan, we have constructed Si nanostructures as photocathodes for PEC CO2 reduction. Current results indicated that the surface modification of Si semiconductors is beneficial to the loading of cocatalysts in the later stage and exhibits better PEC catalytic performance. In addition, we analyzed the morphology, chemical composition, and crystal structure of the as-prepared BiVO4 porous nanostructured semiconductor, confirming that it is a strong candidate for the desired n-type semiconductor photoanode. In the water oxidation performance test, the BiVO4 photoanode also showed gratifying performance. Therefore, we have made smooth progress in fabricating the Si-based semiconductor photocathode and its potential photoanode, which provides a good foundation for subsequently constructing the synergistic reaction device of CO2 reduction and water oxidation.
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| Strategy for Future Research Activity |
On the basis of the previous year's research, future research will mainly focus on three issues. First, we will continue to systematically study and optimize the surface structure of Si-based semiconductor photocathode to further improve the separation and migration of photogenerated carriers. Second, we will design and optimize CO2 reduction cocatalysts to achieve a superior adhesion at the cocatalyst/Si semiconductor interface, thereby constructing a Si-based photocathode system with low onset potential and high photocurrent. The third is the further structure improvement and performance evaluation of the n-type BiVO4 photoanode to help to achieve unbiased CO2 reduction.
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