Reaction-induced modification of Co nanoclusters driven by Co-Mn interfacial sites to control selectivity in CO2 hydrogenation

Controlling the selectivity of chemical products on small Co nanoparticles is crucial in many catalytic applications. Reaction-driven structural changes offer an alternative methodology to regulate their properties. Herein, carbon-induced surface restructuring occurs on a 2Co/MnOₓ catalyst (cobalt nanoclusters with 2% mass loading on manganese oxide) during thermal CO₂ hydrogenation, driven by the formation of bridging Co-C-O-Mn interfacial sites. This leads to a shift in selectivity from methane to CO, with a remarkable enhancement of the CO/CH₄ product ratio from 0.89 to 13.4. Such a Co/MnO_x system has unique interfacial properties, including strong carbonophilic and oxophilic characteristics. It chemisorbs reaction-derived CO and facilitates C-O bond breaking, promoting rapid CO dissociation and subsequent carbon coverage on Co nanoclusters. This restructuring of Co nanoclusters suppresses the hydrogenation of CO intermediates to methane. This effect is unique to 2Co/MnOₓ and absent at higher/lower Co loadings or other oxide supports. This insight shows how structural evolution during catalysis enables precise surface engineering, overcoming the structure-sensitivity limits of Co nanoclusters.