Liquid/Solid EGaIn@Ag Heterostructure Catalyst Enabling CO 2 Electroreduction to CO in a Three‐Membrane Electrolyzer With Co‐Production of K 2 CO 3 and Cl 2

Abstract

Electrochemical carbon dioxide reduction reaction (CO 2 RR) powered by renewable electricity offers a sustainable route for producing value‐added carbonaceous chemicals. Herein, a three‐membrane electrolyzer was employed to directly co‐generate carbon monoxide (CO), chlorine (Cl 2 ), and potassium carbonate (K 2 CO 3 ) from the electrolysis of CO 2 and potassium chloride (KCl), achieving net CO 2 utilization while simultaneously supporting downstream chemical processes such as phosgene synthesis. To enhance the catalytic performance, a core–shell EGaIn@Ag metal–metal heterostructure catalyst was designed, in which a solid Ag shell encapsulates a liquid eutectic gallium–indium (EGaIn) core. This liquid–solid architecture enables efficient CO 2 ‐to‐CO conversion, delivering a CO partial current density of 182.66 mA cm −2 and a Faradaic efficiency of 95.29% at −2.4 V versus SHE during prolonged electrolysis. Experimental results combined with density functional theory (DFT) calculations show that the GaIn/Ag heterointerface exhibits an electron spillover effect, which facilitates charge transfer from the GaIn core to the Ag shell and enhances the adsorption of CO 2 RR intermediates, thereby improving the selectivity for CO production. Finite‐element method (FEM) simulations in COMSOL suggest locally strengthened electrostatic fields and enhanced transport–reaction responses for EGaIn@Ag relative to EGaIn under identical boundary conditions. This work elucidates the liquid‐metal‐induced interfacial mechanism and provides a feasible strategy for designing high‐performance liquid metal catalysts for efficient CO 2 electroreduction.