Lead-free perovskite Cs3Bi2Br9 heterojunctions for highly efficient and selective photocatalysis under mild conditions

Lead halide perovskites possess excellent photoelectric properties and are promising for photocatalysis. However, the toxicity of lead in these perovskites has hindered their application. We designed a stable, lead-free heterojunction to enhance the photocatalytic efficiency of the perovskite. A production rate of 1465 µmol/g/h for the selective oxidation of benzyl alcohol was achieved, which was the highest among all inorganic catalysts without zero-valent metal cocatalyst in the atmosphere at room temperature. In addition, the heterojunction degraded 74.7% of 10 ppm 2-mercaptobenzothiazole within 10 min, and achieving a final degradation rate exceeding 99.9% in 20 min, which is the best degradation efficiency among all reported studies. Detailed optical characterisation proved that the high efficiency stems from band matching and charge transfer between Cs3Bi2Br9 and TiO2. This result will inspire the design of additional lead-free perovskites for photocatalysis.