Enhancing photocatalytic hydrogen production efficiency in all-inorganic lead-free double perovskites via silver doping-induced efficient separation of photogenerated carriers

All-inorganic halide perovskites are renowned for their extensive light absorption range, prolonged carrier lifetime, and minimal exciton binding energy, collectively rendering them promising candidates for solar lightdriven hydrogen production. Nevertheless, their inherent poor stability poses a significant challenge, constraining their practical application in photocatalytic hydrogen generation. Herein, we controlled synthesized highly stable all-inorganic lead-free bimetallic perovskites Cs6Cu3AgBr10 and Cs3Cu2Br5, and in-depth studied their photocatalytic hydrogen production properties. The introduction of Ag+ ions expanded the light absorption range, significantly reduced the exciton binding energy and improved the separation efficiency of the photogenerated carrier, thereby enhancing its stability and the H2 evolution ability. The photocatalytic hydrogen production efficiencies of Cs6Cu3AgBr10 and Cs3Cu2Br5 were determined to be 14.64 mu mol h- 1 and 10.07 mu mol h- 1, respectively. Density functional theory (DFT) calculations demonstrate that Ag+ ion doping significantly enhances the photocatalytic hydrogen production efficiency of perovskite materials, revealing that the Cu/Ag sites function as active centers for electron and proton transfer during the photocatalytic process. This research paves the way for developing all-inorganic lead-free double perovskites with enhanced stability and high efficiency in photocatalytic hydrogen production.