KI-Doped α-Mo₂C Stably Catalyze Near-Equilibrium CO₂ to CO Beyond 1000 Hours

Abstract

α-Mo₂C has demonstrated excellent potential in the catalytic conversion of CO₂ to CO. However, it tends to be reduced to thermodynamically stable β-Mo₂C under H₂ atmosphere, leading to deactivation during reverse water–gas shift (RWGS) reaction. In addition, α-Mo₂C cannot achieve an equilibrium CO yield below 500°C. This work first found that KI-doped α-Mo₂C can achieve near-equilibrium CO yields beyond 1000 h at 400°C, 4 bar in the RWGS reaction while maintaining the original α-Mo₂C crystal structure. Further research indicates that the doped KI effectively stabilized the oxygen content in α-Mo₂C, which is critical for stable catalytic activity. This modification not only reduces the formation-desorption energy barriers for CO and H₂O, but also markedly suppresses methane side reaction. Moreover, the incorporation of the KI reduces the oxidation state of Mo, thereby enhancing the surface alkalinity. This enhancement leads to an increased CO₂ conversion rate, thereby achieving near-equilibrium CO yields at 400°C, 4 bar.

Keywords

KI doping / near-equilibrium CO yield / RWGS reaction / α-Mo₂C

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