Valorization of nitrous oxide (N₂O), a potent greenhouse gas, through the oxidative dehydrogenation of light alkanes such as methane and propane to produce light olefins (ethylene and propylene), presents a promising technique for both environmental mitigation and valuable chemical production. This review provides a systematic analysis of the differences between N₂O and O₂ as oxidants, emphasizing the distinctive advantages of N₂O as a mild oxidant for olefin production. It delves into key technologies, such as oxidative dehydrogenation of propane (ODHP) to propylene and oxidative coupling of methane (OCM) to ethylene, focusing on the underlying reaction mechanisms and recent advancements in catalyst development. A major challenge in these reactions is the trade-off between activity and selectivity. To address this, we propose an innovative strategy–redox center separation–to enhance catalytic performance. This comprehensive review offers valuable insights for the rational design of catalysts, advancing sustainable chemical engineering processes that utilize N₂O, while addressing critical environmental and industrial challenges.

Graphitic carbon nitride (g-C₃N₄, CN) exhibits inefficient charge separation, deficient CO₂ adsorption and activation sites, and sluggish surface reaction kinetics, which have been recognized as the main barriers to its application in CO₂ photocatalytic reduction. In this work, carbon quantum dot (CQD) decoration and oxygen atom doping were applied to CN by a facile one-step hydrothermal method. The incorporated CQDs not only facilitate charge transfer and separation, but also provide alternative CO₂ adsorption and activation sites. Further, the oxygen-atom-doped CN (OCN), in which oxygen doping is accompanied by the formation of nitrogen defects, proves to be a sustainable H⁺ provider by facilitating the water dissociation and oxidation half-reactions. Because of the synergistic effect of the hybridized binary CQDs/OCN addressing the three challenging issues of the CN based materials, the performance of CO₂ photocatalytic conversion to CH₄ over CQDs/OCN-x (x represents the volume ratio of laboratory-used H₂O₂ (30 wt.%) in the mixed solution) is dramatically improved by 11 times at least. The hybrid photocatalyst design and mechanism proposed in this work could inspire more rational design and fabrication of effective photocatalysts for CO₂ photocatalytic conversion with a high CH₄ selectivity.