Recent progress in green catalysis for C N bond construction toward sustainable chemical production

The efficient construction of carbon–nitrogen (C N) bonds is a central challenge in organic synthesis, underpinning the production of pharmaceuticals, agrochemicals, and functional materials. Catalytic strategies that enable direct formation of C N bonds from abundant carbon- and nitrogen-containing feedstocks offer sustainable pathways for synthesizing high-value compounds such as urea, amides, and amino acids, while contributing to carbon neutrality and environmental remediation. Although previous reviews have focused separately on electrocatalysis, photocatalysis, or enzymatic catalysis, a comprehensive analysis that integrates electrocatalysis, photocatalysis, photoelectrocatalysis and photoenzymatic catalysis remains absent. In this review, we systematically summarize recent advances across these four catalytic paradigms, with emphases on mechanistic understanding, catalyst design and reactor engineering. We highlight emerging strategies for broadening the scope of carbon and nitrogen sources, while also identifying persistent challenges that limit scalability, selectivity and energy efficiency. Finally, we outline future directions aimed at guiding the development of next-generation catalytic systems for sustainable C N bond formation. • Comparative review of four catalytic systems for sustainable C N coupling. • Unified mechanistic framework linking electro-, photo-, and bio-catalysis. • Key intermediates and electron–proton transfer pathways identified. • Design principles for metal–ligand coordination in C N bond activation. • Outlook for integrating artificial and enzymatic catalytic strategies.