High-efficiency photocatalyst based on Au nanoparticles loaded on defective ZnO nanorods

Abstract

Optimizing the semiconductor-metal interaction is the key to developing metal single-atom cocatalysts with 100 % metal atom utilization and unique electronic properties. Metal atom sites are exclusively coordinated with semiconductor, featuring a chemical-bond-driven tunable interaction. Here vacancy defect-rich ZnO nanorods (NRs) are fabricated by a facile hydrothermal approach. Au nanoparticles (NPs) are preferentially anchored on surface zinc vacancy sites of ZnO NRs in an ultra-low concentration (10−4 mol/L) of HAuCL4 solution. The Au/ZnO nanohybrids exhibit an excellent photocatalytic activity toward removal of Rhodamine B and levofloxacin. Combining ferromagnetism and valence-band XPS spectra analysis, it is demonstrated that the strong interaction of surface vacancy defects in ZnO and Au generates a distinct upshift of the valence band edge, resulting from the antibonding interaction between O 2p and Au 5d orbitals which significantly weakens the Au–O bonds. This facilitates the release of the lattice oxygen and thus generates more oxygen vacancies. The remarkable photoactivity of defective Au/ZnO is due to the synergistic interaction between the intrinsic oxygen vacancy and Au. Optimizing the hybridization of transition metal d and O 2p states at the atomic scale can induce more active-sites, improve atomic utilization efficiency and thus provide a new approach for enhancing photoactivity.