Electroreduction of low concentration CO2 at atomically dispersed Ni-N-C catalysts with nanoconfined ionic liquids

Abstract

Most studies on electrochemical CO2 reduction reaction use pure CO2, which requires extra energy for CO2 capture and enrichment from atmosphere. Herein, nanoconfined ionic liquids are introduced into porous atomically dispersed nickel-nitrogen-carbon (Ni-N-C) catalysts to enrich local CO2 concentration and increase the CO2RR kinetics. A series of high-CO2-solubility ionic liquids (ILs) were impregnated into the pores of the columnar Ni-N-C catalyst to alter the CO2-Ni sites interactions and create a solid/liquid interface with high CO2 concentration. The optimal Ni-N-C/[Bmim][PF6] composite outperforms the Ni-N-C catalyst for pure CO2 electroreduction with a maximum FECO of 99.6% and 2.7-fold larger jCO. The high solubility of CO2 in ILs compared to aqueous electrolyte enables direct electrolysis of CO2 at low concentrations. When fed with 5–10% (v/v) CO2, the Ni-N-C/[Bmim][PF6] composite exhibited up to 1.5-fold higher FECO and a 68% increase of jCO, in comparison to Ni-N-C, and robust stability over 30 h.