Cu-Mediated (CH3NH3)PbI3 Perovskite Photocatalysts Achieving >1% Solar-to-Hydrogen Efficiency

Abstract Organolead halide perovskites, with their exceptional optoelectronic properties and intrinsic defect tolerance, have emerged as promising candidates for photovoltaics and photocatalysis. Yet, their photocatalytic activity remains hindered by severe nonradiative charge recombination. Herein, we introduce copper (Cu) atoms into methylammonium lead iodide ((CH3NH3)PbI3) during synthesis, directing the transformation of irregular crystals into well-defined dodecahedra. Comprehensive characterizations reveal that Cu mediation significantly promotes charge separation and transfer, leading to a remarkable 60-fold enhancement in hydrogen evolution compared to pristine (CH3NH3)PbI3. When coupled with a Ru/H2–TiO2 cocatalyst, the Cu-mediated (CH3NH3)PbI3 (100 mg) delivers 1.29 mmol of H2 within 6 h under simulated sunlight (AM 1.5G, 100 mW cm–2) and achieves a solar HI-splitting efficiency of 1.21% with an irradiation area of π·cm2. This work not only demonstrates a record-level photocatalytic performance of halide perovskites, but also provides mechanistic insights into how composition modulation and crystallographic engineering can unlock their potential for solar-driven hydrogen generation.