Facet-Dependent Adsorbate-Mediated Strong Metal-Support Interaction in Ni/TiO2
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Despite the growing significance of adsorbate-mediated strong metal-support interaction (A-SMSI) in various catalytic processes, a comprehensive mechanistic understanding of its formation and effective strategies for its precise modulation remain elusive. Herein, by constructing three well-defined model Ni/TiO 2 catalysts with distinct exposed facets, we directly visualize a facet-dependent A-SMSI behavior in CO 2 hydrogenation via in-situ environmental transmission electron microscopy (ETEM) at the atomic level. The in-situ results reveal distinct formation behaviors of TiO 2 − x overlayers: complete, partial, and no encapsulation of Ni nanoparticles (NPs) on the {100}, {101}, and {001} TiO 2 facets, respectively. Complementary in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray absorption spectroscopy (XAS) demonstrate interfacial electron transfer from TiO 2 − x to Ni, which is pivotal in stabilizing COOH * intermediates that dehydroxylate to form CO. Guided by these mechanistic insights, facet-dependent A-SMSI enables remarkable selectivity modulation, yielding CH₄ selectivity exceeding 89% on Ni/TiO 2 -{001} and CO selectivity over 83% on Ni/TiO 2 -{100}. These findings advance the fundamental understanding of A-SMSI and offer a rational framework for designing oxide-supported catalysts with tailored interfacial properties.
