Hydrogen Radical-Induced Electrocatalytic N2 Reduction at a Low Potential
Hydrogen Radical-Induced Electrocatalytic N2 Reduction at a Low Potential
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DOI：
10.1021/jacs.3c01319
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发表时间：
2023-04-25
影响因子：
15
通讯作者：
Zhang, Jin
中科院分区：
文献类型：
--
作者：
Feng, Xueting;Liu, Jiyuan;Zhang, Jin
在电催化氮气还原反应(NRR)中实现氮气分子的高效加氢是实现低电势高活性的关键，因为理论上它需要比其他步骤更高的平衡电势。类似于金属氢化物还原氮气，通过化学加氢实现这一步骤可以削弱初始加氢过程的潜在依赖性。然而，这一策略在电催化NRR中的报道很少，其催化机制仍不明确，缺乏实验证据。在这里，我们展示了一种高效的电催化剂(固定在石墨二炔/石墨烯夹心结构上的Ru单原子)，它具有氢自由基转移机制，其中石墨二炔(GDY)产生氢自由基(H中心点)，它可以有效地活化N_2生成NNH自由基(中心点NNH)。构建了一个双活性中心来抑制竞争析氢，氢优先吸附在GDY上，Ru单原子作为中心点NNH的吸附中心，促进NH3合成的进一步加氢。结果表明，与可逆氢电极相比，在-0.1V下同时获得了高的活性和选择性。我们的发现说明了一种新的氢转移机理，它可以极大地降低NRR的电位，并保持其高活性和高选择性，为电催化剂的设计概念提供了有力的指导。
Realizing efficient hydrogenation of N2 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 N2 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 center dot), which can effectively activate N2 to generate NNH radicals (center dot 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 center dot NNH to promote further hydrogenation of NH3 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.