Anchoring Co Single Atoms on Nitrogen‐Vacancies‐Enriched Carbon Nitride for Efficient Photocatalytic Acetylene Semihydrogenation

Comprehensive Summary Photocatalytic semihydrogenation of coal‐derived acetylene using water as a hydrogen source under ambient conditions offers a sustainable and petroleum‐independent route for ethylene production, yet suffers from the utilization of expensive photosensitizers, weak acetylene adsorption and insufficient generation of active hydrogen (H*). Herein, we fabricate a Co single‐atom catalyst anchored on nitrogen‐vacancy‐rich carbon nitride (Co/C 3 N 4 ‐V N ) via in‐situ co‐polymerization. Owing to enhanced light absorption and charge separation efficiency, the Co/C 3 N 4 ‐V N exhibits a considerably high ethylene production rate of 3916.5 μmol·g cat −1 ·h −1 under 420 nm light‐emitting diode (LED) illumination without photosensitizers, surpassing bulk C 3 N 4 by 53‐folds and outperforming previously reported photocatalysts. The photocatalytic experiments, acetylene temperature‐programmed desorption analysis, in‐situ photo‐chemical infrared spectra and theoretical simulations together reveal that N vacancies and Co single atoms in Co/C 3 N 4 ‐V N synergistically promote the acetylene adsorption, H* generation from water dissociation and acetylene hydrogenation, thereby accelerating the kinetics of photocatalytic acetylene semihydrogenation.