Direct Operando Visualization of Metal Support Interactions Induced by Hydrogen Spillover During CO 2 Hydrogenation.

The understanding of catalyst active sites is a fundamental challenge for the future rational design of optimized and bespoke catalysts. For instance, the partial reduction of Ce 4+ surface sites to Ce 3+ and the formation of oxygen vacancies are critical for CO 2 hydrogenation, CO oxidation and the water gas shift reaction. Furthermore, metal nanoparticles, the reducible support, and metal support interactions are prone to evolve under reaction conditions, therefore a catalyst structure must be characterized under operando conditions to identify active states and deduce structure-activity relationships. In the present work, we investigate temperature-induced morphological and chemical changes in Ni nanoparticle-decorated mesoporous CeO 2 by means of in situ quantitative multimode electron tomography and in situ heating electron energy loss spectroscopy, respectively. Moreover, we employ operando electron energy loss spectroscopy using a windowed gas cell and reveal the role of Ni-induced hydrogen spillover on active Ce 3+ site formation and enhancement of the overall catalytic performance. This article is protected by copyright. All rights reserved.