Environmental TEM Study of the Dispersion of Au/α-MoC: From Nanoparticles to Two-Dimensional Clusters
Bowen He, Xin Tao, Lina Li, Xi Liu, Liwei Chen
Abstract
The synthesis of highly dispersed Au nanoclusters that are stable under elevated temperatures in heterogeneous catalysis is challenging. Here, we directly observe a strong metal–support interaction (SMSI)-induced dispersion of Au nanoparticles (NPs) on α-MoC using an environmentally atomically resolved secondary imaging technique. Under a realistic environment, Au NPs flatten and spread out on the α-MoC to form two-dimensional atomic layered clusters. The formed highly dispersed Au/α-MoC catalyst shows excellent stability at 600 °C for 160 h in the reverse water–gas shift reaction. The X-ray photoelectron spectrum and extended X-ray absorption fine structure results show that Au NPs gradually become low-coordination-number cluster species and lose electrons to become Au δ+; these form chemical bonds with the α-MoC support and are responsible for the dispersion behavior. This work provides an insightful understanding of dispersion behavior and promotes the rational design and synthesis of reverse sintering catalysts.