Molecular Evidence for Metallic Cobalt Boosting CO₂ Electroreduction on Pyridinic Nitrogen

Abstract

Nitrogen-doped carbon materials (N-C_mat ) are emerging as low-cost metal-free electrocatalysts for the electrochemical CO₂ reduction reaction (CO₂ RR), although the activities are still unsatisfactory and the genuine active site is still under debate. We demonstrate that the CO₂ RR to CO preferentially takes place on pyridinic N rather than pyrrolic N using phthalocyanine (Pc) and porphyrin with well-defined N-C_mat configurations as molecular model catalysts. Systematic experiments and theoretic calculations further reveal that the CO₂ RR performance on pyridinic N can be significantly boosted by electronic modulation from in-situ-generated metallic Co nanoparticles. By introducing Co nanoparticles, Co@Pc/C can achieve a Faradaic efficiency of 84 % and CO current density of 28 mA cm^-2 at -0.9 V, which are 18 and 47 times higher than Pc/C without Co, respectively. These findings provide new insights into the CO₂ RR on N-C_mat , which may guide the exploration of cost-effective electrocatalysts for efficient CO₂ reduction.