The challenge of activating the inert dinitrogen molecule has greatly hindered the development of efficient catalysts for electrochemical C–N coupling. Herein, we propose a novel design idea of a polar B–V atom-pair catalyst (APC) embedded into two-dimensional (2D) g-CN (B–V@g-CN) for activating and polarizing the inert NN bond and accelerating the electrochemical C–N coupling process. Our work shows that B–V@g-CN is a promising electrocatalyst for the urea synthesis reaction with an ultra-low limiting potential (U_L) of −0.21 V. The synergistic side-on adsorption configuration of N₂ at the polar B–V dual-site triggers unbalanced electron transfer via a two-channel pathway, i.e., the σ donation–π backdonation of electron transfer through B–N and V–N bonds, which results in sufficient activation of the NN bond. The electronegativity difference between B and V atoms enables the polarization of non-polar N₂. Protonation of *N₂ to a *NH*NH intermediate further weakens the NN bond, which leads to a lower energy barrier for *NH*NH dissociation to 2*NH species (0.75 eV) than for the direct dissociation of *N₂ (1.45 eV). Subsequently, the coupling of CO and 2*NH species generates the key urea precursor *NHCO*NH with a low barrier of 0.45 eV. Furthermore, the B–V@g-CN APC demonstrates good thermodynamic and electrochemical stability, as well as excellent dispersibility of its dual-active sites. The construction of polar non-metal/metal APCs in this work provides a new avenue for designing high-performance catalysts in energy conversion reactions.

中文翻译：

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用于电化学 C-N 偶联的极性原子对催化剂


活化惰性二氮分子的挑战极大地阻碍了用于电化学 C-N 偶联的高效催化剂的开发。在此，我们提出了一种新的设计思路，将极性 B-V 原子对催化剂 （APC） 嵌入二维 （2D） g-CN （B-V@g-CN） 中，以活化和极化惰性 N N 键并加速电化学 C-N 耦合过程。我们的研究表明，B-V@g-CN 是一种很有前途的尿素合成反应电催化剂，具有 -0.21 V 的超低限位电位 （U_L）。N₂ 在极性 B-V 双位点的协同侧向吸附构型通过双通道途径触发不平衡电子转移，即通过 B-N 和 V-N 键进行电子转移的σ供π回供，从而导致 N N 键的充分激活。B 和 V 原子之间的电负性差使非极性 N₂ 的极化成为可能。*N₂ 质子化为 *NH*NH 中间体进一步削弱了 N N 键，这导致 *NH*NH 解离为 2*NH 物质的能量势垒 （0.75 eV） 低于 *N₂ 的直接解离 （1.45 eV）。随后，CO 和 2*NH 物质的偶联产生了关键的尿素前驱体 *NHCO*NH，具有 0.45 eV 的低阻挡层。此外，B–V@g-CN APC 表现出良好的热力学和电化学稳定性，以及其双活性位点的优异分散性。这项工作中极性非金属/金属 APC 的构建为在能量转换反应中设计高性能催化剂提供了一条新途径。