Si-based photoelectrochemical carbon dioxide reduction for value-added chemicals

该项目旨在开发硅基光阴极和潜在的光阳极，用于太阳能驱动的二氧化碳还原和水氧化协同反应。在过去的一年中，我们通过液相刻蚀方法将计划p-Si半导体转化为p-Si金字塔结构半导体作为光电阴极。p-Si金字塔结构的大比表面积有利于助催化剂的负载，有利于光生载体的分离和迁移。对负载助催化剂后的光电阴极性能进行了评价。与计划物p-Si相比，p-Si金字塔的光电化学（PEC） CO2还原性能显著提高，这证明si基光电阴极的PEC CO2还原性能与半导体表面结构和半导体/助催化剂的界面连接密切相关。另一方面，我们也尝试基于液相合成策略在透明导电衬底（氟掺杂氧化锡：FTO）上形成过渡金属氧化物BiVO4半导体。证实了BiVO4是先电沉积在衬底上，然后经过热处理转化为BiVO4半导体。对具有多孔纳米结构的BiVO4半导体的化学成分、形貌和晶体结构进行了分析和评价。由于制备的BiVO4多孔纳米结构半导体具有n型半导体特性，我们开始尝试优化其作为辅助PEC二氧化碳还原的潜在光阳极。

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.