Synergistic promotion strategy of “dual-site” and “dual-path” to enhance the C–C coupling between CO2 and HCHO driven by photoelectrocatalysis

Photoelectrocatalytic coupling CO 2 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 CO 2 and the competitive hydrogen evolution of H 2 O. Herein, a modified g-C 3 N 4 /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 μmol g −1 h −1 . As revealed by in-situ characterizations and density functional theory calculations, CO 2 and HCHO were absorbed at Zn site and N site, respectively. Then, *CO generated from CO 2 and HCHO was converted to *CH 3 O and *CHO on the dual-active-site heterojunction. The detailed reaction mechanism experiments indicated that C–C coupling only occurred between *CO and *CH 3 O in electrocatalysis process. Apart from the “*CO + *CH 3 O” 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 CO 2 and HCHO simultaneously driven by light and electricity.