In Situ Surface Restructuring of γ-Mo₂N for Enhanced Reverse Water-GasShift Reaction

In heterogeneous catalytic systems, catalyst activation induced by reactants or products, often attributed to surface restructuring, represents a compelling phenomenon. The catalytic nature and reaction mechanism of the molybdenum nitride system in the reverse water-gas shift reaction (RWGS) remain subjects of ongoing debate, with no consensus reached to date. In this work, we demonstrate that γ-Mo2N can be effectively activated via in situ treatment under the RWGS reaction atmosphere at 500 °C, leading to a significant enhancement of its catalytic activity. A deep investigation revealed that surface restructuring is the underlying mechanism responsible for the activation of γ-Mo2N. During the RWGS process, Mo6+ species on the surface of γ-Mo2N are converted into Mo4+ under the induction of the reaction atmosphere, thereby enhancing the activation of H2 and improving the catalytic activity. Notably, the surface restructuring effect enables γ-Mo2N to achieve catalytic activity and stability comparable to those of metal-based catalysts reported in the literature. This work provides significant insight into the real active site and the pivotal role of γ-Mo2N in RWGS reactions.