Tandem catalysis for Enhanced CO Oxidation over the Bi-Au-SiO2 Interface

Bimetallic catalysts typically exploit unique synergetic effects between two metal species to achieve their catalytic . Understanding the mechanism of CO oxidation using hybrid heterogeneous catalysts is important for effective catalyst design and environmental protection. Herein, we report a Bi-Au/SiO2 tandem bimetallic catalyst for CO oxidation reaction over the Au/SiO2 surface, which was monitored using near-ambient-pressure X-ray photoelectron spectroscopy. The Au-decorated SiO2 catalyst exhibited scarce activity in the CO oxidation reaction; However, the introduction of Bi to the Au/SiO2 system promoted the catalytic activity. The mechanism is thought to involve the dissociation O2 molecules in the presence of Bi, which results in spillover of the O species to adjacent Au atoms, thereby forming Auδ+. Further CO adsorption, followed by thermal treatment, facilitated the oxidation of CO at the Au-Bi interface, resulting in a reversible reversion to the neutral Au valence state. Our work provides insight into the mechanism of CO oxidation on tandem surfaces and will facilitate the rational design of other Au-based catalysts.