Bismuth-doped methylamine lead bromide perovskite CH₃NH₃PbBr₃ single crystals for efficient hydrogen evolution via hydrobromic acid splitting

Organic-inorganic hybrid halide perovskites have emerged as promising photocatalysts for hydrogen production because of their high absorption coefficients and large carrier diffusion lengths. However, the synthesis and development of organic–inorganic perovskite bromide photocatalysts have not been fully explored. Herein, we report on a novel high-activity Bismuth (Bi) doped CH₃NH₃PbBr₃ (MAPbBr₃) photocatalyst that was successfully synthesized using the reverse-temperature crystallization method. This material exhibited a reduced band gap and increased free-carrier concentration compared to pure MAPbBr₃. Molecular dynamics and lattice changes within the photocatalyst were systematically investigated using solid-state nuclear magnetic resonance spectroscopy (NMR). The photocatalyst employs hypophosphorous acid (H₃PO₂) as a stabilizer and platinum (Pt) as a co-catalyst in the photocatalytic hydrogen bromide (HBr) splitting system, achieving a hydrogen evolution rate of 3946.52 μmol·g⁻¹·h⁻¹ under visible light irradiation. Our experimental results suggest that the enhanced photocatalytic performance is attributed to Bi doping, which modifies the charge distribution in the region of the lead (Pb) octahedron, thereby promoting effective charge separation and improving the hydrogen production efficiency. This study provides new insights into the photocatalytic hydrogen production capabilities of organic–inorganic hybrid bromide perovskites.