Strong Metal–Support Interactions between Nickel and Iron Oxide during CO₂ Hydrogenation

Abstract

Understanding the interaction of metal with metal oxides is essential for establishing the structure–activity relationship in heterogeneous catalysis. Herein, a series of nickel–iron-based bimetallic catalysts are systematically investigated to unveil the nature of active sites for the CO2 hydrogenation reaction. An environmental-sensitive strong metal–support interaction between Ni nanoparticles and iron oxides is revealed by a series of characterizations, including HR-TEM, H2-TPR, quasi in situ XPS, and time-resolved in situ DRIFTS. Iron oxides migrate and entirely cover the metallic Ni nanoparticles during the reaction, yielding a more active core–shell-type structure with much-improved reducibility. Such a reconstruction process is also indirectly monitored in a time-resolved manner by in situ DRIFTS and confirmed to complete within 30 min of the reaction.