Composites of Reduced Graphene Oxide and MAPbI₃ Crystals for Photocatalytic Hydrogen Generation

Lead halide perovskite has emerged as an alternate material for photocatalytic hydrogen (H2) evolution owing to its excellent optoelectronic properties. However, designing an efficient and stable perovskite photocatalyst system still remains a challenging task. Pristine MAPbI3 exhibited a lesser H2 evolution activity due to the lack of reactive sites and its faster degradation. Herein, reduced graphene oxides (RGOs) with varied chemical reduction were integrated with MAPbI3 microcrystals by in situ coupling to construct a robust and effective heterostructure resulting into a strong interconnection between MAPbI3 and RGO. Careful selection of cocatalysts with appropriate bandgaps and proper alignment of band positions are the key steps for successful photocatalytic H2 generation. This work highlights that facile and easy photogenerated charge separation and migration can be achieved for MAPbI3/RGO heterostructures where chemically modified RGOs having favorable bandgap and band positions were incorporated with MAPbI3 via unusual improved in situ crystallization resulting into remarkable mmol scale photocatalytic H2 evolution in aqueous HI medium under white light LED illumination. Under optimal reaction conditions, the H2 evolution rate can reach 4493 μmol g–1 h–1.