Restructuring of titanium oxide overlayers over nickel nanoparticles during catalysis

Gaining insights into the workings of catalysts is complicated by the often harsh reaction environments they operate in. The hurdle is especially high for tools that allow us to obtain fundamental level knowledge of the atomistic and electronic structure. In a paper published in Science, we utilize advances in microscopy and spectroscopy to follow strong-metal support interaction (SMSI) in a Ni-TiO_x catalyst under CO₂ hydrogenation conditions. SMSI affects the exposure of the active metal in the catalyst and its interfacing. Our findings reveal non-trivial interplay between the reaction environment and the structure of the catalyst that calls into question the usefulness of ex-situ studies for understanding heterogeneously catalyzed reactions. Most importantly, a specific ensemble of active sites is present in the catalyst only under reaction conditions. Advances in multimodal probing tools now allow us to apply the same approach to an extensive set of catalytic reactions, opening a pathway to revising our static understanding of structure-activity relationships.