Photoinduced In Situ Spontaneous Formation of a Reduced Graphene Oxide-Enwrapped Cu–Cu₂O Nanocomposite for Solar Hydrogen Evolution

The fast recombination of photogenerated charge carriers and poor stability have impeded the application of many narrow band gap semiconductors with otherwise excellent photocatalytic performance. A metal–semiconductor Schottky junction is a promising strategy to accelerate charge separation and enhance catalytic efficiency. However, the preparation of these structures often involves intricate processes and harsh conditions, which will inevitably destroy the electronic structures of the semiconductors and ruin their original properties in practical applications. In this study, a reduced graphene oxide (RGO)-enwrapped Cu–Cu2O nanocomposite (Cu–Cu2O@RGO) spontaneously evolved from an aqueous alcoholic solution containing cupric ions and graphene oxide (GO) under simulated sunlight irradiation. During this process, GO reduction and Cu–Cu2O nanoparticles growth occurred simultaneously in conjunction with in situ RGO encapsulation. Benefiting from the superior intrinsic semiconductor characteristic retention under mild reaction conditions, strong component interactions, and efficient interfacial charge transfer, the distinctive Cu–Cu2O@RGO nanocomposite supplied multiple channels for rapid electron transfer to substantially enhance the charge carrier separation efficiency and provide perfect chemical protection to effectively prevent Cu2O photocorrosion. This product also greatly suppressed self-aggregation to decrease the size of nanoparticles. Based on these merits, the Cu–Cu2O@RGO nanocomposite offered promising advances in photoelectrochemical and photocatalytic H2 evolution. This work provides an innovative photoinduced strategy for constructing an RGO-enwrapped semiconductor nanocomposite with efficient charge transfer interfaces while providing novel insights for the efficient solar energy utilization.