Nickel-Doped Facet-Selective Copper Nanowires for Activating CO-to-Ethanol Electrosynthesis

Ethanol isa promising energy vector for closing the anthropogenic carbon cycle through reversible electrochemical redox. Currently, ethanol electrosynthesissuffers from low product selectivity due to the competitive advantage of ethylene in CO /CO electroreduction. Here, a facet-selective metal-doping strategy is reported, tuning the reaction kinetics of CO reduction paths and thus enhancing the ethanol selectivity. The theoretical calculations reveal that nickel (Ni)doped Cu(100) surface facilitates water dissociation to form adsorbed hydrogen, which promotesselective electrochemical hydrogenation of a key C intermediate ( CHCOH) toward ethanol path over ethylene path. Experimentally, a solution-phase synthesis of a Ni-doped {100}-dominated Copper nanowires (Cu NWs) catalyst is reported, enabling an ethanol Faradaic efficiency of 56% and a selectivity ratio of ethanol to ethylene of 2.7, which are ≈4 and 15 times larger than those of undoped Cu NWs, respectively. The operando spectroscopic characterizations confirm that Ni-doping in Cu NWs can alter the interfacial water activity and thus regulate the C product selectivity. With further electrode engineering, a membrane electrode assembly electrolyzer using Ni-doped Cu NWs catalysts demonstrates an ethanol Faradaic efficiency over 50% at 300 mA cm with a full cell voltage of ≈2.7 V and operates stably for over 300 h.