Toward an Understanding of the Enhanced CO2 Electroreduction in NaCl Electrolyte over CoPc Molecule‐Implanted Graphitic Carbon Nitride Catalyst

Abstract Direct CO 2 electrolysis in seawater enables the simultaneous conversion of CO 2 into CO and the chlorine ions into Cl 2 , further meeting downstream industry needs such as phosgene synthesis and also facilitating the net consumption of CO 2 . As a result, the direct implementation of CO 2 electrolysis in seawater is urgently required. Herein, a CoPc molecule‐implanted graphitic carbon nitride nanosheets (CoPc/g‐C 3 N 4 ) electrocatalyst is prepared via a simple mechanochemistry method. The CoPc/g‐C 3 N 4 with a negatively charged surface and preferential adsorption capability for Na + can achieve appreciable faradaic efficiency (FE, 89.5%) toward CO with a current density of 16.0 mA cm −2 in natural seawater and also realize long‐term operation for 25 h in simulated seawater. Process monitoring further reveals that the chlorine ions in NaCl electrolyte can modulate the reaction microenvironment around the anode, which in turn has positive effects on the CO 2 RR in cathode. The CO 2 RR overall splitting in the simulated seawater exhibits a maximum FE of 98.1% towards CO at cell voltage of 3 V. This work describes the development of a carbon‐coupled CoPc molecular catalyst that can drive the CO 2 electrolysis in simulated seawater and provides a promising and energy‐saving coupled reaction system for direct coproduction of CO and Cl 2 .