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

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/C₃N₄-V_N) via in-situ co-polymerization. Owing to enhanced light absorption and charge separation efficiency, the Co/C₃N₄-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 C₃N₄ 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/C₃N₄-V_N synergistically promote the acetylene adsorption, H* generation from water dissociation and acetylene hydrogenation, thereby accelerating the kinetics of photocatalytic acetylene semihydrogenation.