Ultrastable Cu Catalyst for CO2 Electroreduction to Multicarbon Liquid Fuels by Tuning C-C Coupling with CuTi Subsurface.

Production of multicarbon (C 2+ ) liquid fuels is a challenging task for electrocatalytic CO 2 reduction, mainly limited by the stabilization of reaction intermediates and their subsequent C-C couplings. In this work, we report a unique catalyst, the coordinatively unsaturated Cu sites on amorphous CuTi alloy (a-CuTi@Cu) toward electrocatalytic CO 2 reduction to multicarbon (C 2-4 ) liquid fuels. Remarkably, the electrocatalyst yields ethanol, acetone and n-butanol as major products with a total C 2-4 faradaic efficiency of about 49% at -0.8 V vs. reversible hydrogen electrode (RHE), which can be maintained for at least 3 months. Theoretical simulation together with in-situ characterization reveals that subsurface Ti atoms can increase the electron density of surface Cu sites and enhance the adsorption of *CO intermediate, which in turn reduces the energy barriers required for *CO dimerization and trimerization. This work refreshes the concept that the catalytically inactive element can maneuver the behaviour of catalytic sites in electrocatalytic C-C coupling from the angle of electron density.