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

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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.