Boosting electrochemical CO2 reduction on ternary heteroatoms-doped porous carbon

Abstract

Electroreduction of CO2 to value-added chemicals using metal-free carbon catalysts is attractive, but single N-doped carbons suffer from poor efficiency (<90%) and low current density (<2 mA cm−2). Herein, we report a facile and scalable preparation of ternary heteroatoms (N, S, P)-doped carbon electrocatalyst to enhance electrochemical activity, because the multi-heteroatoms with different sizes and electronegativities can modulate the electronic properties to facilitate CO2 localization and provide abundant active sites with enhanced charge-carrier concentrations. It exhibits high activity toward CO2 electroreduction to CO activity with 92% CO Faradaic efficiency (FECO) at −0.7 VRHE and low onset overpotential of 270 mV. The promising potential of industrial application is manifested by the high current density of 245 mA cm−2 and stable FECO above 98% in a flow-cell configuration. Moreover, in-situ Raman spectroscopy demonstrates that *COOH is the key intermediate in CO2-to-CO conversion. Density functional theory calculations reveal that the synergistic effect of N, S, and P heteroatoms boosts the catalytic activity by greatly decreasing the free energy barrier of *COOH formation. Furthermore, the morphological benefit of hierarchically porous structures plays a synergistic role in improving the CO2 reduction activity.