Synergistically Interface-Engineered Inorganic Halide Perovskite Photocathodes for Photoelectrochemical CO₂ Reduction

Halide perovskite materials have shown immense potential for photovoltaics and photocatalytic CO2 reduction as a result of their excellent optoelectronic properties. However, the rational way to directly apply these materials to photoelectrochemical (PEC) CO2 reduction remains unclear. Herein, on the basis of stepwise optimized interface-engineering strategies, we synthesize CsPbBr3 (CPB) thin-film photocathode catalysts using a two-step spin-coating method and modify the perovskites with synergizing 5% fluorine (F) doping, Nafion (N) solution, and 15 nm Au coating, sequentially. It is demonstrated that, with the synergistic effect of the interface-engineering approaches, the optimal photocathode (CPB-F-N-Au) achieves greatly enhanced light absorption and charger transfer capability compared to the pristine CPB-based photocathode. As a result, the as-fabricated CPB-F-N-Au photocathode exhibits the maximum photocurrent of -0.23 mA cm(-2) at a bias of -0.5 V versus E-Ag/AgCl under the 4.13 mW cm(-2) light illumination, which is twice that of the pristine CPB device. This work demonstrates the practicability of directly applying halide perovskites into PEC CO2 reduction and proposes useful interface-engineering strategies for tuning the relevant device performance, which can also be extended to other fields, like photovoltaics and photodetectors.