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

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