Electro-catalytic reductive amination is an environmentally friendly and sustainable route to synthesize amines. In this paper, we prepared the 2Ru/NiPOx catalyst by incipient wetness impregnation using nickel phosphate as a support with Ru loading of 2% (w) and applied it for the electro-catalytic reductive amination of benzaldehyde and cyclohexylamine. The reaction was carried out in an undivided cell with tetrabutylammonium bromide (TBAB) as electrolyte and dimethyl sulfoxide (DMSO) as both H donor and solvent. When 2Ru/NiPOx on carbon paper was used as the cathode and Pt sheet as the anode, N-benzylcyclohexylamine was obtained in 95.1% yield with a Faraday efficiency of 64.7%. The Faraday efficiency started to decrease when the loading of Ru exceeded 2% (w), which is due to the fact that the excessive Ru accelerated the self-reaction of DMSO, thus decreased the Faraday efficiency. Electrochemical impedance spectroscopy (EIS) results showed that loading Ru on NiPOx could significantly improve the electron transfer rate during the reductive amination reaction. The cyclic voltammetry (CV) test showed that -4 V was the optimal potential for the 2Ru/NiPOx catalyst as the cathode during the electro-catalytic reduction of amination, which the paired anodic reaction was the oxidation of DMSO. The diffuse reflectance infrared Fourier transform (DRIFT) results showed that the self-reaction of DMSO by 2Ru/NiPOx was weaker than those of the other Ru-based catalysts, resulting in its high Faraday efficiency. The C=N adsorbed on 2Ru/NiPOx had a higher electron cloud density, which was favorable for the attack of N by the H + generated from water splitting, thus promoting the reductive amination. Free radical trapping experiments proved that free radicals were involved in the reaction process. Isotope labeling experiments confirmed that DMSO is the H atom donor of the radical intermediate. Finally, a possible reaction mechanism was presented: the imine from benzaldehyde and cyclohexylamine reacting spontaneously was adsorbed on the surface of the 2Ru/NiPOx catalyst at the cathode, and then was attacked by H + and electrons to generate a free radical, which abstracted H from DMSO to produce the N-benzylcyclohexylamine product and one DMSO free radical, and the DMSO free radical gets H + and electrons at the cathode to regenerate DMSO. Keywords electro-catalytic reductive amination; N-benzylcyclohexylamine; Ru-based catalyst; nickel phosphate; free radical reaction 1 引言 胺是一种广泛应用于化学、生物学、医学、材料科 学、环境工程以及可持续能源等领域的高价值化学品 [1][2][3] . 此外, 胺可作为合成高级化学品、药品、生物大分子、 农用化学品和聚合物的关键前体或中间体 [4][5] . 合成胺 类物质的方法有直接 C-H 键胺化 [6][7][8][9] 、 使用氢气或等量 还原剂, 将醛或酮与氨或胺进行还原胺化反应 [10][11][12][13][14] .还原胺化分两步完成: 醛或者酮首先缩合形成亚 胺, 之后亚胺上的 C=N 键被还原生成胺 [15] . 虽然生成 亚胺的反应可以在温和的条件下自发进行 [16] , 但是 C= N 键的还原却具有较高的能垒. 因此研究人员一直致力