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 Cu 2 O nanoparticles (NP) on the surface of black phosphorus (BP) nanosheets. Our ad-hoc procedure for generating Cu 2 O-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 Cu 2 O-BP nanohybrid. By integrating the latter with TiO 2 NPs, a new ternary photocatalyst was obtained, outperforming pristine TiO 2 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, Cu 2 O-BP and TiO 2 –Cu 2 O-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 Cu 2 O NPs formation and interfacial H 2 evolution. • Surface functionalization of black phosphorus (BP) with nanostructured Cu 2 O. • Integration of BP-Cu 2 O with TiO 2 and study of the opto-electronic properties. • Solar-to-hydrogen conversion resulted much higher for the ternary hybrid respect with bare TiO 2 . • Computational study unravels the interfacial interactions in TiO 2 –Cu 2 O-BP and evidences the formation of an S-Scheme.