Single-atom Co-N-C catalysts for high-efficiency reverse water-gas shift reaction

Abstract

Designing efficient non-precious metal catalysts for CO2 hydrogenation is a significant challenge. Cobalt-based catalysts often failed to catalyze the reverse water-gas shift (RWGS) reaction with high CO selectivity and stability. Herein, nitrogen-doped carbon (N-C) immobilized single-atom Co-N4 catalyst with 5% Co loading were prepared by anchoring strategy through regulating the cobalt species coordination structure. The stable single-atom catalyst achieves almost 100% CO selectivity and a high CO2 conversion of 52.4% at 500 °C during CO2 hydrogenation, while the 20% Co-N-C nanoparticle catalyst favored CH4 formation. The experiments and density functional theory (DFT) calculations revealed that atomically dispersed Co-N4 site followed the hydrogen-assisted pathway in which the intermediate COOH* was desorbed and dissociated into CO, whereas the Co nanoparticle catalysts mainly followed the direct dissociation. This study provided a new strategy for designing Co-based RWGS catalysts with excellent performance.