Enhancing CO Oxidation Activity via Tuning a Charge Transfer between Gold Nanoparticles and Supports

Charge transfer from the supports to nanoparticles at the interface is one of the key factors to determine the catalytic performances of supported nanoparticles. In this work, we showed in a systematic way that the charge transfer from semiconductor supports to Au nanoparticle catalysts can lower the onset temperature toward CO oxidation. For this study, a novel Au/SiO2/Si composite system synthesized by the helium droplet deposition method with precisely tuned SiO2 layer thickness was fabricated to control the magnitude of interfacial charge transfer. With the support of X-ray photoelectron spectroscopy and numerical simulations, it was demonstrated that the Schottky barrier formed across the Au/SiO2/Si heterojunction led to a negative charge accumulation on the surface of Au nanoparticles. In turn, this additional charge can be transferred to the antibonding orbital of adsorbed O2 molecules to activate the O-O bonds, leading to enhanced CO oxidation. In addition to the charge transfer mechanism, the role of a strong electric field arising from the formation of the Schottky barrier was also explored to explain the observed enhancement of catalytic reactivity. Overall, this work highlights an important pathway for systematically tuning metal-support interactions to accelerate catalytic reactions and designing the next generation of nanocatalysts.