Lead-Free Cs2AgBiBr6 Perovskite with Enriched Surface Defects for Efficient Photocatalytic Hydrogen Evolution

In recent years, lead halide perovskites have been widely used as appealing candidates in solar energy conversion. However, further development of these materials is restricted by their instability and toxicity. Therefore, searching for efficient lead-free perovskites with excellent photoelectric properties is highly anticipated. We report a postsynthesis visible light irradiation on Cs2AgBiBr6 to form a defect-rich Cs2AgBiBr6 via inducing surface defects in Cs2AgBiBr6. The formation of surface defects can promote surface charge separation by tuning the local atomic arrangement and electronic structure and optimizing the surface structure, thereby boosting the photocatalytic efficiency of the defect-rich Cs2AgBiBr6. The photocatalytic hydrogen evolution efficiency is enhanced by about 5.27, 5.51, and 5.48 times compared to the bulk Cs2AgBiBr6 , Cs2AgBiBr6/Pt, and Cs2AgBiBr6/Mo3S132-, respectively. This defect-rich Cs2AgBiBr6 presents strong stability with no performance decrease even after an 80 h photocatalytic reaction. These findings provide an accessible strategy for preparing highly efficient and stable lead-free perovskites.