The emergence of liquid metal catalysts endows electrocatalytic processes with enhanced efficiencies by eliminating coking issues that rapidly deactivate conventional solid catalysts. Alloying them with trace amounts of redox-active metal additives can further improve their catalytic activity. Here we report a vanadium-liquid metal alloy with superior activity that can drive electrochemical reduction of CO₂ into solid carbon. The reaction mechanism has been thoroughly investigated and discussed. In addition, artificial neural networks trained by machine learning have been demonstrated to be powerful in predicting performance of LM alloys with various compositions.