Manipulating interfacial hydrogen atom transfer for electrocatalytic CO2 reduction to ethylene in bicarbonate electrolyte

Cu-based catalysts have been considered promising electrocatalysts for converting CO 2 into multi-carbon products (C 2+ products). However, achieving selectivity toward a specific C 2+ product remains challenging, necessitating the delicate design of catalytic sites to regulate the energy preference of reaction pathways. Herein, we introduced catalytic sites that evolve active hydrogen atoms (*H) on Cu surfaces to regulate electrocatalytic CO 2 hydrogenation pathways to achieve the selective production of ethylene. Ru single-atom site (Ru 1 ) was theoretically screened from 17 elements with 51 structures, exhibiting optimal activity in promoting hydrogenation of CO 2 reduction intermediates. The accordingly synthesized Ru 1 -doped oxide-derived Cu (Ru 1 -ODCu) catalyst delivered an ethylene selectivity of 82% in C 2+ products with a Faradaic efficiency of 58.9% and a partial current density of 353.4 mA cm –2 in KHCO 3 electrolyte. Kinetic isotope and in situ spectroscopic analyses evidenced that the Ru 1 sites effectively promote intermediate hydrogenation by regulating *H transfer to intermediates, facilitating the energy-preferred pathway to ethylene production. These results provide insights into the design of Cu catalysts with intermediate hydrogenation sites for converting CO 2 into specific products.