Formation of BNC Coordination to Stabilize the Exposed Active Nitrogen Atoms in g‐C3N4 for Dramatically Enhanced Photocatalytic Ammonia Synthesis Performance

Abstract It is an important issue that exposed active nitrogen atoms (e.g., edge or amino N atoms) in graphitic carbon nitride (g‐C 3 N 4 ) could participate in ammonia (NH 3 ) synthesis during the photocatalytic nitrogen reduction reaction (NRR). Herein, the experimental results in this work demonstrate that the exposed active N atoms in g‐C 3 N 4 nanosheets can indeed be hydrogenated and contribute to NH 3 synthesis during the visible‐light photocatalytic NRR. However, these exposed N atoms can be firmly stabilized through forming BNC coordination by means of B‐doping in g‐C 3 N 4 nanosheets (BCN) with a B‐doping content of 13.8 wt%. Moreover, the formed BNC coordination in g‐C 3 N 4 not only effectively enhances the visible‐light harvesting and suppresses the recombination of photogenerated carriers in g‐C 3 N 4 , but also acts as the catalytic active site for N 2 adsorption, activation, and hydrogenation. Consequently, the as‐synthesized BCN exhibits high visible‐light‐driven photocatalytic NRR activity, affording an NH 3 yield rate of 313.9 µmol g −1 h −1 , nearly 10 times of that for pristine g‐C 3 N 4 . This work would be helpful for designing and developing high‐efficiency metal‐free NRR catalysts for visible‐light‐driven photocatalytic NH 3 synthesis.