Composite of CH3NH3PbI3 with Reduced Graphene Oxide as a Highly Efficient and Stable Visible-Light Photocatalyst for Hydrogen Evolution in Aqueous HI Solution

A facile and efficient photoreduction method is employed to synthesize the composite of methylammonium lead iodide perovskite (MAPbI(3)) with reduced graphene oxide (rGO). This MAPbI(3)/rGO composite is shown to be an outstanding visible-light photocatalyst for H-2 evolution in aqueous HI solution saturated with MAPbI(3). Powder samples of MAPbI(3)/rGO (100 mg) show a H-2 evolution rate of 93.9 mu mol h(-1), which is 67 times faster than that of pristine MAPbI(3), under 120 mW cm(-2) visible-light (lambda >= 420 nm) illumination, and the composite is highly stable showing no significant decrease in the catalytic activity after 200 h (i.e., 20 cycles) of repeated H-2 evolution experiments. The electrochemiluminescence performance of MAPbI(3) is investigated to explore the charge transfer process, to find that the photogenerated electrons in MAPbI(3) are transferred to the rGO sites, where protons are reduced to H-2.