Breaking activity-selectivity-stability trade-offs in reverse water-gas shift reaction via high-energy micro-faceted Mo2N nanocrystals

The reverse water-gas shift reaction (RWGSR) is essential for converting CO2 into fuels using renewable hydrogen, but it remains challenged by the difficulty of simultaneously maximizing catalyst activity, selectivity, and stability. These limitations stem from thermodynamic constraints – specifically, the Gibbs-Curie-Wulff theorem - which restricts the synthetic accessibility of high-energy micro-faceted nanocrystals via conventional methods. To address this, we introduce a near-surface “quasi-hyperbaric” ammonia strategy that integrates atmospheric-pressure processing with in-situ ammonia decomposition. This approach enables the controlled synthesis of molybdenum nitride nanocrystals with preferentially exposed high-energy (112) microfacets. These facets promote CO2 activation through a hydrogen-assisted redox mechanism, driven by geometrically confined and stabilized Mo-N/M-O hybrid active sites. The resulting catalyst outperforms the benchmark Pt/CeO₂, which typically suffers from CO selectivity below 92%. Our catalyst achieves near-equilibrium conversion (56%) at a space velocity (24000 ml/gcat/h), with 100% CO selectivity and outstanding stability (≤ 1% deactivation over 250 hours). The reverse water–gas shift reaction is crucial for CO₂ conversion using renewable hydrogen, but simultaneously achieving high activity, selectivity, and stability in catalysts remains a challenge. Here, the authors introduce a near-surface “quasi-hyperbaric” ammonia strategy that integrates atmospheric-pressure processing with in situ ammonia decomposition to synthesize a high-energy Mo₂N-based catalyst capable of overcoming these trade-offs.