Electrocatalytic CO₂ Reduction over Pyridinic Nitrogen-Doped Carbon as a Metal-Free Catalyst

The electrochemical reduction of CO₂ to CO is an environmentally friendly method of carbon utilization, as it can convert greenhouse gases like CO₂ into high value-added chemicals. However, current catalysts suffer from low catalytic activity and poor CO selectivity. Herein, we report a facile and template-free synthesis of nonmetallic nitrogen-doped carbon (N-C) catalysts via the pyrolysis of a conductive carbon black/melamine/polyvinylpyrrolidone precursor. Electrochemical evaluation demonstrated that the N-C 700 catalyst (pyrolyzed at 700 °C) achieved a 94% CO Faraday efficiency at -1.2 V vs RHE, and the CO partial current density was 11 times higher than that of C 700 control. Comprehensive characterization reveals that the pyrolysis temperature critically governs the relative content of multiple nitrogen species (pyridinic, pyrrolic, graphitic) and the concomitant creation of carbon defects. These structural modifications enhanced the CO₂-to-CO conversion efficiency, while density functional theory (DFT) calculations further confirmed the significant role of pyridinic nitrogen in promoting CO₂ reduction performance.