Carbon-loaded metal nanoparticles (NPs) are widely employed as functional materials for electrocatalysis. In this study, a rapid thermal shock method was developed to load various metal nanoparticles onto carbon supports. Compared to conventional pyrolysis processes, Joule heating enables rapid heating to elevated temperatures within a short period, effectively preventing the migration and aggregation of metal atoms. Simultaneously, the anchoring effect of defective carbon carriers ensures the uniform distribution of NPs on the carbon supports. Additionally, nitrogen doping can significantly enhance the electronic conductivity of the carbon matrix and strengthen the metal-carbon interactions, thereby synergistically improving catalyst performance. When used as electrocatalysts for electrocatalytic CO2 reduction, bismuth-, indium-, and tin/carbon-carrier-based catalysts exhibit excellent Faraday efficiencies of 92.8%, 86.4%, and 73.3%, respectively, for formate generation in flow cells. The influence of different metals and calcination temperatures on catalytic performance was examined to provide valuable insights into the rational design of carbon-based electrocatalysts with enhanced electrocatalytic activity.