Selective CO2 Electroreduction to Multi-Carbon Products on Organic-Functionalized CuO Nanoparticles by Local Micro-Environment Modulation

Abstract Surface functionalization of Cu-based catalysts has demonstrated promising potential for enhancing the electrochemical CO 2 reduction reaction (CO 2 RR) toward multi-carbon (C 2+ ) products, primarily by suppressing the parasitic hydrogen evolution reaction and facilitating a localized CO 2 /CO concentration at the electrode. Building upon this approach, we developed surface-functionalized catalysts with exceptional activity and selectivity for electrocatalytic CO 2 RR to C 2+ in a neutral electrolyte. Employing CuO nanoparticles coated with hexaethynylbenzene organic molecules (HEB-CuO NPs), a remarkable C 2+ Faradaic efficiency of nearly 90% was achieved at an unprecedented current density of 300 mA cm −2 , and a high FE (> 80%) was maintained at a wide range of current densities (100–600 mA cm −2 ) in neutral environments using a flow cell. Furthermore, in a membrane electrode assembly (MEA) electrolyzer, 86.14% FE C2+ was achieved at a partial current density of 387.6 mA cm −2 while maintaining continuous operation for over 50 h at a current density of 200 mA cm −2 . In-situ spectroscopy studies and molecular dynamics simulations reveal that reducing the coverage of coordinated K⋅H 2 O water increased the probability of intermediate reactants (CO) interacting with the surface, thereby promoting efficient C–C coupling and enhancing the yield of C 2+ products. This advancement offers significant potential for optimizing local micro-environments for sustainable and highly efficient C 2+ production.