Strategies for effective nitrous oxide capture: From materials to mechanisms

Nitrous oxide (N₂O) is a potent greenhouse gas and ozone-depleting substance, with industrial sources particularly nitric acid and adipic acid production being the major anthropogenic contributions to its emissions. Given the environmental risks coupled with its significant potential for economic value, it is essential to explore methods for N₂O capture. This review provides a comprehensive assessment of recent advancements in N₂O capture, focusing on adsorptive and absorptive materials and their underlying mechanisms. Silica, biochar, activated carbon, metal-organic frameworks (MOFs), and zeolites, are evaluated for their adsorption efficiency, while organic absorbents and ionic liquids are analyzed for their absorption properties. Mechanistic insights reveal the interactions between N₂O and metal cations, strong electron donors, frustrated Lewis pairs (FLPs), and physical absorption in ionic liquids. Additionally, mechanisms for selectively separating N₂O from CO₂, including hydrogen bonding, Lewis acidity tuning, and gate-opening effects, are also explored. Recent research highlights the significance of microenvironment modulation around capture sites in enhancing N₂O uptake. Microenvironments into four levels: molecular, nano/microscale confinements, surface and field effects offer new opportunities for rational material design. Advancements in in-situ characterization technologies and computational simulations further facilitate the understanding of N₂O capture mechanisms. This detailed analysis offers guidance on selective N₂O recovery, enrichment, and valorization, with a focus on improving cost-efficiency and enhancing environmental sustainability. Future directions include advancing material design, cost reduction, and novel capture mechanisms to foster sustainable N₂O mitigation strategies.