Feng Xueting, Liu Jiyuan, Chen Long, Kong Ya, Zhang Zedong, Zhang Zixuan, Wang Dingsheng, Liu Wen, Li Shuzhou, Tong Lianming, Zhang Jin
Center for Nanochemistry, Beijing Science and Engineering Center for Nanocarbons, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
J Am Chem Soc. 2023 May 10;145(18):10259-10267. doi: 10.1021/jacs.3c01319. Epub 2023 Apr 25.
Realizing efficient hydrogenation of N molecules in the electrocatalytic nitrogen reduction reaction (NRR) is crucial in achieving high activity at a low potential because it theoretically requires a higher equilibrium potential than other steps. Analogous to metal hydride complexes for N reduction, achieving this step by chemical hydrogenation can weaken the potential dependence of the initial hydrogenation process. However, this strategy is rarely reported in the electrocatalytic NRR, and the catalytic mechanism remains ambiguous and lacks experimental evidence. Here, we show a highly efficient electrocatalyst (ruthenium single atoms anchored on graphdiyne/graphene sandwich structures) with a hydrogen radical-transferring mechanism, in which graphdiyne (GDY) generates hydrogen radicals (H), which can effectively activate N to generate NNH radicals (NNH). A dual-active site is constructed to suppress competing hydrogen evolution, where hydrogen preferentially adsorbs on GDY and Ru single atoms serve as the adsorption site of NNH to promote further hydrogenation of NH synthesis. As a result, high activity and selectivity are obtained simultaneously at -0.1 V versus a reversible hydrogen electrode. Our findings illustrate a novel hydrogen transfer mechanism that can greatly reduce the potential and maintain the high activity and selectivity in NRR and provide powerful guidelines for the design concept of electrocatalysts.
在电催化氮还原反应（NRR）中实现N分子的高效氢化对于在低电位下实现高活性至关重要，因为从理论上讲，该步骤比其他步骤需要更高的平衡电位。类似于用于氮还原的金属氢化物配合物，通过化学氢化实现这一步骤可以减弱初始氢化过程对电位的依赖性。然而，这种策略在电催化NRR中鲜有报道，其催化机理仍不明确且缺乏实验证据。在此，我们展示了一种具有氢自由基转移机制的高效电催化剂（锚定在石墨炔/石墨烯夹心结构上的钌单原子），其中石墨炔（GDY）产生氢自由基（H），它可以有效地活化N以生成NNH自由基（NNH）。构建了双活性位点以抑制竞争性析氢，其中氢优先吸附在GDY上，而Ru单原子作为NNH的吸附位点以促进NH合成的进一步氢化。结果，相对于可逆氢电极，在-0.1 V时同时获得了高活性和选择性。我们的研究结果阐明了一种新型的氢转移机制，该机制可以大大降低电位并在NRR中保持高活性和选择性，并为电催化剂的设计理念提供了有力的指导。
