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

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions provides an intriguing picture for the conversion of N-2 into NH3. 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 (NH3 yield: 8.09gh(-1)mg(cat.)(-1), 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 NH3. This work also highlights the significance of defect engineering for improving electrocatalysts with weak N-2 adsorption and activation ability.