Recent progress on oxygen vacancies in selective catalytic reduction of nitrogen oxides

Selective catalytic reduction (SCR) is among the most promising technologies for the denitrification (de-NO_x) of nitrogen oxides (NO_x), with the performance of catalysts serving as the decisive factor governing its efficiency and durability. In recent years, engineering and modulation of oxygen vacancies (OVs) within SCR catalysts have emerged as a forefront strategy to enhance de-NO_x activity. This review summarizes major strategies for constructing OVs in SCR catalysts. In parallel, advanced characterization and simulation techniques are summarized to elucidate the intrinsic relationships between OV structures and catalytic behavior. Furthermore, particular emphasis is placed on the pivotal roles of OVs in promoting reactant adsorption and activation, strengthening redox capacity, and enhancing resistance to sulfur, water, and alkali-metal poisoning. Their contributions to lowering reaction energy barriers and optimizing catalytic pathways are also analyzed in detail. Finally, the challenges and future perspectives of OV engineering in SCR catalysis are critically discussed. This review seeks to offer theoretical and strategic guidance for the rational design of SCR catalysts through the precise modulation of OVs to improve their stability and durability.