Defect Engineering Metal‐Free Polymeric Carbon Nitride Electrocatalyst for Effective Nitrogen Fixation under Ambient Conditions

Abstract Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions provides an intriguing picture for the conversion of N 2 into NH 3 . However, electrocatalytic NRR mainly relies on metal‐based catalysts, and it remains a grand challenge in enabling effective N 2 activation on metal‐free catalysts. Here we report a defect engineering strategy to realize effective NRR performance (NH 3 yield: 8.09 μg h −1 mg −1 cat. , Faradaic efficiency: 11.59 %) on metal‐free polymeric carbon nitride (PCN) catalyst. Illustrated by density functional theory calculations, dinitrogen molecule can be chemisorbed on as‐engineered nitrogen vacancies of PCN through constructing a dinuclear end‐on bound structure for spatial electron transfer. Furthermore, the N−N bond length of adsorbed N 2 increases dramatically, which corresponds to “strong activation” system to reduce N 2 into NH 3 . This work also highlights the significance of defect engineering for improving electrocatalysts with weak N 2 adsorption and activation ability.