Electrochemical graphitization conversion of CO2 through soluble NaVO3 homogeneous catalyst in carbonate molten salt

Electrochemical conversion of CO2 to carbon in molten salts is a promising route for the high-value utilization of greenhouse gases. Low graphitization degree of carbon materials is the limiting issue for potential applications. In the past, catalytic effect for the electrochemical conversion of CO2 was not achieved in molten salts due to carbon coverage on heterogeneous solid electrode. A novel and feasible homogeneous catalytic strategy by soluble NaVO3 in carbonate molten salt was proposed for the enhanced electrochemical conversion of CO2 to carbon with high graphitization degree. It was found that graphite consisting of carbon nanotubes and sheets were more easily produced by adding NaVO3 into molten salt. The graphitization degree of carbon products was obviously improved and ID/IG value was only 0.428. During CO2 electrolysis, vanadate in the form of V2O74− will be co-electroreduced to V2O3. Meanwhile, V2O74− ions can be regenerated by the spontaneous reaction between the newly-formed V2O3 and carbonate, which also accelerates the production of graphite. Therefore, a continuous homogeneous in-situ catalytic cycle was achieved for the enhanced graphitization conversion of CO2. It provides a novel and effective way to prepare carbon materials with high graphitization degree from CO2.