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

Lead halide perovskite has emerged as an alternate material for photocatalytic hydrogen (H 2 ) evolution owing to its excellent optoelectronic properties. However, designing an efficient and stable perovskite photocatalyst system still remains a challenging task. Pristine MAPbI 3 exhibited a lesser H 2 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 MAPbI 3 microcrystals by in situ coupling to construct a robust and effective heterostructure resulting into a strong interconnection between MAPbI 3 and RGO. Careful selection of cocatalysts with appropriate bandgaps and proper alignment of band positions are the key steps for successful photocatalytic H 2 generation. This work highlights that facile and easy photogenerated charge separation and migration can be achieved for MAPbI 3 /RGO heterostructures where chemically modified RGOs having favorable bandgap and band positions were incorporated with MAPbI 3 via unusual improved in situ crystallization resulting into remarkable mmol scale photocatalytic H 2 evolution in aqueous HI medium under white light LED illumination. Under optimal reaction conditions, the H 2 evolution rate can reach 4493 μmol g –1 h –1 .