Cobalt-nitrogen-carbon sites on carbon aerogels for enhanced electrocatalytic CO2 activity

Developing highly-efficient electrocatalysts with metal-nitrogen-carbon (M- NxC) sites for electrochemical CO2 reduction reaction (CO2RR) towards carbon monoxide (CO) is an effective way towards carbon neutralization. Herein, nitrogen-doped carbon aerogels (N-CA) supported Co-NxC sites with cobalt phthalocyanine (CoPc) as precursor via pyrolysis (500 celcius) strategy is reported. The CoPc@N-CA-500 catalyst with the average pore size of 8.57 nm, displays a wide potential window from-0.5 to-0.9 V vs. RHE with the CO Faradaic efficiency (FECO) over 80%. It also exhibits the maximal FECO of 92.48%, the CO partial current density of 21.72 mA cm-2, CO turnover frequency (TOFCO) of 1.23 s-1 and stability over 20 h (under-0.8 V vs. RHE), which is significantly higher than that of CoPc@CB-500 (53.91%, 4.47 mA cm-2, 0.14 s- 1) with the average pore size of 2.54 nm, while selecting commercial carbon black (CB) as the carrier. The superior activity of CoPc@N-CA-500 could be attributed to its unique porous system, which not only promotes the mass transfer of CO2 molecules to facilitate the CO2RR kinetic, but is beneficial to expose Co active sites. Meanwhile, a home-made zinc-CO2 battery with CoPc@N-CA-500 as cathode achieved a peak power density of 0.69 mW cm-2 and maximum FECO of 87.41%.