Current challenges and developments of inorganic/organic materials for the abatement of toxic nitrogen oxides (NOx) – A critical review

Nitrogen oxides (NOx) are toxic gases produced from various anthropogenic and natural sources. It causes acid rain, ozone depletion, photochemical smog, corrosion of buildings, and various health hazards. The removal of these toxic gases is vital to safeguard the health of living organisms and the air quality on the earth. These can be done by complying with government regulations and using efficient gas capture techniques in industries. However, the challenge remains in arresting these toxic gases with high efficiency, selectivity, and sustainability using low-cost materials. The present review summarizes the recent advances in the detention and diminution of NOx (NO₂, NO, and N₂O) by inorganic and organic materials. We have discussed different processes for capturing nitrogen dioxides (NO₂) using various materials namely metal-organic framework, activated carbon, functionalized metal oxides, transition metals, and zeolites. Moreover, a variety of materials such as ionic liquid, deep eutectic liquid, and selective catalytic reduction-based materials, including metal oxides and zeolites, are described for the abatement of nitric oxides (NO). Finally, the methods of capturing nitrous oxides (N₂O) are deliberated, including direct and photocatalytic decomposition, followed by various adsorbent materials. Overall, different materials/methods and mechanisms for NOx detention and/or abatement are well presented and their efficiency is compared in this review. The present article also showcases all the examples of recently developed high-performance materials for efficient NOx capturing/abating.