A recent study by Academician Bao Xinhe and Researcher Fu Qiang's team at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, has made a breakthrough in the research of dynamic evolution of catalytic surface structures induced by reactions. They discovered that the products of the reverse water-gas shift reaction, water and carbon monoxide, sequentially dominate the surface activation of molybdenum nitride catalysts, leading to the restructuring of the surface into more active oxide molybdenum and carbide molybdenum structures. This further enhances catalytic activity, promotes surface carbide formation, and reveals a positive feedback correlation between catalytic activity, surface carbide formation, and catalyst activation. The related findings have been published in Nature Communications.
In most cases, the surface structures of catalysts undergo dynamic changes during reactions, a process closely related to the local gas microenvironment around the catalyst. In recent years, the team has made a series of advancements in the study of atmosphere-induced dynamic evolution of catalytic surface structures, revealing that reaction atmospheres can induce the dynamic dispersion of metal catalysts and the monodispersion of oxide catalysts, significantly enhancing catalytic performance.
In this study, based on in situ and quasi-in situ XPS characterization in the reaction environment, researchers found that the surface structure of molybdenum nitride catalysts in the reverse water-gas shift reaction highly depends on the reaction products, namely the partial pressure or concentration of carbon monoxide and water, rather than on the reactants carbon dioxide and hydrogen. The research indicates that at the initial stage of the reaction with low product concentrations or partial pressures, water dominates the oxidation of the molybdenum nitride surface, forming an active oxide molybdenum surface layer. As the reaction progresses and the product concentrations and partial pressures increase, carbon monoxide then dominates surface carbide formation, creating an active carbide molybdenum surface layer. This process facilitates the reaction and generates higher partial pressures of carbon monoxide, further promoting the surface carbide formation of molybdenum nitride.
This work demonstrates a positive feedback mechanism between catalytic activity and structural evolution of the catalyst during the reaction process.
For more information, please refer to the related paper: https://doi.org/10.1038/s41467-024-47550-8
