Insights into N2O decomposition in environmental catalysis: evaluation and an advanced outlook

Abstract

Nitrous oxide (N₂O) is a potent greenhouse gas and a significant contributor to stratospheric ozone depletion. Its emission arises from a combination of natural and anthropogenic sources, including microbial processes such as nitrification, denitrification, nitrifier denitrification and abiotic chemical pathways such as chemodenitrification and hydroxylamine oxidation. Effective decomposition of N₂O into harmless nitrogen and oxygen is therefore critical for climate mitigation. This review provides a comprehensive overview of the current state of N₂O decomposition, with a focus on mechanisms, catalyst composition and material design strategies. Catalysts are systematically classified based on their decomposition pathways i.e. direct catalytic decomposition (DCD), selective catalytic reduction (SCR), and surface-mediated redox processes. In addition, they are further classified on the basis of their compositional attributes, encompassing both precious as well as and non-precious metal-based catalysts systems. Furthermore, a progress-based classification is presented, encompassing classical metal oxides, spinel oxides, layered double hydroxides, MXenes, and metal–organic frameworks (MOFs). Emerging systems such as antenna-reactor catalysts and quantum dots have also been discussed based on their unique properties and potential. Mechanistic insights into N₂O activation, including thermal, surface-catalysed, Mars–van Krevelen-type redox, radical and photocatalytic pathways, are explored in depth. This review highlights the significance of catalyst design, oxygen vacancy engineering and atomically dispersed active sites in enhancing activity and selectivity. Future perspectives emphasize the development of low-cost, thermally stable and environmentally benign catalysts, along with gaining a mechanistic understanding through in situ studies and computational modelling. This review aims to guide the rational design of next-generation catalysts for efficient N₂O abatement across industrial and environmental systems.