In-situ construction of lead-free halide perovskite CsCu₂I₃/g-C₃N₄ heterojunction for photocatalytic H₂ generation

Lead-free halide perovskites have enormous superiority in photoelectric devices, but low photocatalytic hydrogen evolution (PHE) hinders their application in photocatalysis. Here, a heterojunction composed of CsCu2I3 (CCI) perovskite and graphite carbon nitride (CN) is constructed by in-situ hot-injection method for the first time. The resultant CCI/CN presents a significantly enhanced PHE performance from hydroiodic acid (HI) splitting with a PHE rate of 2212 umol/g/h, which is four times higher than CCI and nearly ten times higher than CN. It is revealed that a unique N-I bond is formed by the connection of N in CN and I in CCI at the interface between CN and CCI, which serves as a fast channel for the transfer of photogenerated electrons to establish a type II mechanism, effectively promoting the PHE performance. This study provides ideas and methods for the construction of type II photocatalyst for hydrogen production using lead-free halide perovskite.