Synergistic Promotion Strategy of “Dual-Site” and “Dual-Path” to Enhance the C–C Coupling Between CO2 and HCHO Driven by Photoelectrocatalysis

Photoelectrocatalytic coupling CO2 and volatile organic compounds (VOCs) is a promising green strategy for the synergistic conversion of the two carbon-containing resources to C-2 products. The catalytic efficiency is always at the mercy of chemical inertness of CO2 and the competitive hydrogen evolution of H2O. Herein, a modified g-C3N4/ZnAl-LDH Z-scheme heterojunction catalyst with dual reaction site was rationally designed and precisely constructed. The Faraday efficiency of ethanol reached 68.67% with a corresponding formation rate of 227.3 mu mol g(-1) h(-1). As revealed by in-situ characterizations and density functional theory calculations, CO2 and HCHO were absorbed at Zn site and N site, respectively. Then, *CO generated from CO2 and HCHO was converted to *CH3O and *CHO on the dual-active-site heterojunction. The detailed reaction mechanism experiments indicated that C-C coupling only occurred between *CO and *CH3O in electrocatalysis process. Apart from the "*CO + *CH3O" path, another "*CO + *CHO" coupling path was also detected in photoelectrocatalytic process. The selectivity of ethanol was significantly enhanced due to the synthesis of dual-site catalyst and the dual-path coupling path between CO2 and HCHO simultaneously driven by light and electricity.