Tang Shangfeng, Guo Na, Chen Cheng, Yao Bingqing, Liu Xuan, Ma Chi, Liu Qiyuan, Ren Shan, He Chi, Liu Bin, Li Xinzhe
Department of Environmental Science and Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, 710072, China.
Department of Physics, National University of Singapore, Singapore, 119077, Singapore.
Angew Chem Int Ed Engl. 2025 Aug 4:e202510192. doi: 10.1002/anie.202510192.
Electrocatalytic alkyne semi-hydrogenation (EASH) powered by renewable electricity using water as a hydrogen donor provides a sustainable alternative to conventional thermocatalysis. However, the current EASH systems predominantly follow hydrogen atom transfer (HAT) pathways, which are prone to over-hydrogenation and at the same time compete with the hydrogen evolution reaction. In this work, we report a proton-coupled electron transfer (PCET) mechanism enabled on Cu(111) surface for highly efficient and selective EASH. Well-defined two-dimensional Cu nanosheets with exposed (111) facets achieve > 98% selectivity for electrochemical semi-hydrogenation of 4-aminophenylacetylene to 4-vinylphenylamine in a membrane electrode assembly reactor. The Cu nanosheets can also efficiently remove 1%-8% alkyne impurities in alkene and exhibit broad substrate scope, stereoselectivity, as well as operational stability. In situ Raman spectroscopy measurements reveal that, during the PCET-mediated EASH, the covalent adsorption of alkynes and their conversion to weakly bound planar intermediates facilitate the EASH process and suppress over-hydrogenation. Interfacial K-structured and linearly hydrogen-bonded water species further enhance EASH selectivity via proton supply and steric modulation. Radical scavenging and kinetic isotope effect studies, along with theoretical calculations, corroborate a PCET-dominated mechanism on Cu(111) surface. This work establishes a PCET-driven paradigm for selective hydrogenation beyond the conventional HAT pathways.
利用水作为氢供体，由可再生电力驱动的电催化炔烃半氢化反应（EASH）为传统热催化提供了一种可持续的替代方法。然而，目前的EASH体系主要遵循氢原子转移（HAT）途径，这种途径容易发生过度氢化，同时还会与析氢反应竞争。在这项工作中，我们报道了一种在Cu(111)表面实现的质子耦合电子转移（PCET）机制，用于高效且选择性的EASH。具有暴露（111）晶面的明确二维Cu纳米片在膜电极组装反应器中对4-氨基苯乙炔电化学半氢化为4-乙烯基苯胺的选择性>98%。Cu纳米片还能有效去除烯烃中1%-8%的炔烃杂质，具有广泛的底物范围、立体选择性以及操作稳定性。原位拉曼光谱测量表明，在PCET介导的EASH过程中，炔烃的共价吸附及其向弱结合平面中间体的转化促进了EASH过程并抑制了过度氢化。界面K结构和线性氢键合水物种通过质子供应和空间调制进一步提高了EASH的选择性。自由基清除和动力学同位素效应研究以及理论计算证实了Cu(111)表面以PCET为主导的机制。这项工作建立了一种超越传统HAT途径的PCET驱动的选择性氢化范式。
