A striking interfacial interaction between Cu2O and black phosphorus boosts solar-to-hydrogen conversion

We designed a high-performance photocatalyst by a selective in situ growth of Cu2O nanoparticles (NP) on the surface of black phosphorus (BP) nanosheets. Our ad-hoc procedure for generating Cu2O-BP nanohybrids, counting on a careful choice of the reducing agents and the reaction conditions, ensured the unaltered integrity of BP nanosheets and prevented the over-oxidation to Cu(II) or the reduction to Cu(0). Additionally, an improved ambient stability of BP was ascertained once embedded in the Cu2O-BP nanohybrid. By integrating the latter with TiO2 NPs, a new ternary photocatalyst was obtained, outperforming pristine TiO2 in the photocatalytic hydrogen production rate more than one hundred times. Next to the characterization of the materials, an in-depth study of the newly created interfaces, Cu2O-BP and TiO2–Cu2O-BP, was carried out at the multiscale atomistic level by joining quantum chemistry and classical reactive molecular dynamics simulations, allowing an explicit evaluation of the electronic band alignment and the investigation of Cu2O NPs formation and interfacial H2 evolution.