Carbides and nitrides in CO2 thermocatalysis: Phase stability, active-site engineering, and structure-performance relationships

The continued rise in CO 2 emissions has intensified the search for carbon-neutral processes. One promising route to mitigate CO 2 emissions is its thermocatalytic conversion to fuels and chemicals, and carbides and nitrides have emerged as an attractive class of catalysts for this purpose. These materials stand out due to their tunable catalytic properties, high thermal stability, and the ability to activate CO 2 at relatively low cost compared to noble metals. Pristine carbides and nitrides have certain limitations, including low surface areas, poor product selectivity, and susceptibility to oxidation or deactivation under reaction conditions, necessitating rational structural and compositional modifications. In this review, we examine the roles of carbides/nitrides as active catalysts, supports, and co-catalysts for a series of CO 2 conversion reactions, including the reverse water gas shift (rWGS), dry reforming of methane (DRM), and CO 2 hydrogenation. The influence of structural parameters, including phase composition, defect formation, morphology, and support integration, on catalytic activity and product selectivity is discussed in depth. Despite notable advances, challenges such as catalyst deactivation, oxycarbide formation, selectivity-conversion trade-offs, and complex synthesis protocols remain. Future research directions to overcome such limitations are outlined and discussed to guide the rational design of next-generation carbide- and nitride-based catalysts for efficient and selective CO 2 utilization.