Figure 5. (a) KIE of Co1-NC and Co1-SNC measured at -0.8 V (vs. RHE). (b) Effect of electrolyte pH on CO2RR performance over the Co1-SNC at -0.8 V (vs. RHE). (c) EIS Nyquist plot of the Co1-NC and Co1-SNC catalysts. (d) Theoretically computed model of CoN4 and CoN3S. (e) The calculated free energy diagrams of CO2-to-CO conversion. (f) The calculated density of states for Co 3d orbital of CoN4 and CoN3S. (g) Differential charge density distribution between the catalyst (CoN4 and CoN3S) and *COOH intermediate.
Conclusions
In summary, Co1-SNC catalyst with a Co1-N3S structure has been successfully prepared through a facile pyrolysis method, which exhibits a greatly enhanced CO2RR to CO performance compared to Co1-NC. In situ ATR-SEIRAS and KIE analyses demonstrate accelerated water dissociation over the Co1-SNC catalyst. Furthermore, DFT calculations indicate that the introduction of S into Co1-NC can adjust the electronic structure of Co active center, facilitating the adsorption and activation of CO2.
Experimental