Photocatalytic Dinitrogen Fixation with Water on High-Phosphorus-Doped Carbon Nitride with Surface Nitrogen Vacancies.

Sunlight-driven photocatalytic dinitrogen (N) fixation with water at ambient conditions is of vital importance for a sustainable energy society. The efficiency of this reaction, however, is still low because of the difficulty in promoting both water oxidation and N reduction reactions. Herein, we report that a high-phosphorus-doped carbon nitride with surface nitrogen vacancies (PCN(V)) synthesized by thermal condensation under a hydrogen (H) atmosphere using phosphorus oxide (PO) as a phosphorus source efficiently promotes N fixation. The large numbers of the doped P atoms on the PCN(V)-PO catalysts enhance the oxidation of water, while the N vacancies reduce N, facilitating efficient ammonia (NH) generation with an apparent quantum yield at 420 nm of 3.4%. Simulated sunlight illumination of the catalyst in water under N bubbling produces NH with a solar-to-chemical conversion efficiency of 0.16%, which is the highest efficiency among the previously reported powder photocatalysts.