Construction of Heterostructured Sn/TiO₂/Si Photocathode for Efficient Photoelectrochemical CO₂ Reduction

Using renewable energy to convert CO₂ into liquid products, as a sustainable way to produce fuels and chemicals, has attracted intense attention. Herein, a novel heterostructured photocathode composed of Si wafer, TiO₂ layer, and Sn metal particles has been successfully fabricated by combining of a facile hydrothermal and electrodeposition method. The obtained Sn/TiO₂/Si photocathode shows enhanced light absorption performance by the surface plasmon resonance effect of Sn metal. Especially, the Sn/TiO₂/Si photocathode together with rich oxygen vacancy defects jointly promote photoelectrochemical CO₂ reduction, harvesting a high faradaic efficiency of HCOOH and a desirable average current density (−4.72 mA cm⁻²) at −1.0 V vs. reversible hydrogen electrode. Significantly, the photocathode Sn/TiO₂/Si also shows good stability due to the design of protecting layer TiO₂. This study provides a facile strategy of constructing an efficient photocathode to improve the light absorption performance and the electron transfer efficiency, exhibiting great potential in the CO₂ reduction.