It is an important issue that exposed active nitrogen atoms (e.g., edge or amino N atoms) in graphitic carbon nitride (g-C3 N4 ) could participate in ammonia (NH3 ) synthesis during the photocatalytic nitrogen reduction reaction (NRR). Herein, the experimental results in this work demonstrate that the exposed active N atoms in g-C3 N4 nanosheets can indeed be hydrogenated and contribute to NH3 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-C3 N4 nanosheets (BCN) with a B-doping content of 13.8 wt%. Moreover, the formed BNC coordination in g-C3 N4 not only effectively enhances the visible-light harvesting and suppresses the recombination of photogenerated carriers in g-C3 N4 , but also acts as the catalytic active site for N2 adsorption, activation, and hydrogenation. Consequently, the as-synthesized BCN exhibits high visible-light-driven photocatalytic NRR activity, affording an NH3 yield rate of 313.9 µmol g-1 h-1 , nearly 10 times of that for pristine g-C3 N4 . This work would be helpful for designing and developing high-efficiency metal-free NRR catalysts for visible-light-driven photocatalytic NH3 synthesis.

中文翻译：

---

BNC配位的形成，以稳定g-C3 N4中暴露的活性氮原子，从而显着增强了光催化氨的合成性能。

一个重要的问题是，在石墨化碳氮化物（g-C3 N4）中暴露的活性氮原子（例如边缘N或氨基N原子）可能在光催化氮还原反应（NRR）期间参与氨（NH3）的合成。在本文中，这项工作的实验结果表明，在可见光光催化NRR过程中，g-C3 N4纳米片中暴露的活性N原子确实可以被氢化并有助于NH3的合成。然而，这些暴露的N原子可以通过在B掺杂含量为13.8 wt％的g-C3 N4纳米片（BCN）中通过B掺杂形成BNC配位而牢固地稳定。而且，在g-C3 N4中形成的BNC配位不仅有效地增强了可见光的收集，而且抑制了g-C3 N4中光生载流子的重组，而且还充当N2吸附，活化和氢化的催化活性中心。因此，合成后的BCN表现出高可见光驱动的光催化NRR活性，提供的NH3收率为313.9 µmol g-1 h-1，几乎是原始g-C3 N4的10倍。这项工作将有助于设计和开发用于可见光驱动的光催化NH3合成的高效无金属NRR催化剂。