Zonal activation of molecular carbon dioxide and hydrogen over dual sites Ni-Co-MgO catalyst for CO2 methanation: Synergistic catalysis of Ni and Co species

Abstract

An in-depth mechanism in zonal activation of CO2 and H2 molecular over dual-active sites has not been revealed yet. Here, Ni-Co-MgO was rationally constructed to elucidate the CO2 methanation mechanism. The abundant surface nickel and cobalt components as active sites led to strong Ni-Co interaction with charge transfer from nickel to cobalt. Notably, electron-enriched Coδ− species participated in efficient chemisorption and activation of CO2 to generate monodentate carbonate. Simultaneously, plentiful available Ni0 sites facilitated H2 dissociation, thus CO2 and H2 were smoothly activated at zones of Coδ− species and Ni0, respectively. Detailed in situ DRIFTS, quasi situ XPS, TPSR, and DFT calculations substantiated a new formate evolution mechanism via monodentate carbonate instead of traditional bidentate carbonate based on synergistic catalysis of Coδ− species and Ni0. The zonal activation of CO2 and H2 by tuning electron behaviors of double-center catalysts can boost heterogeneous catalytic hydrogenation performance.