Effective electrocatalytic conversion of CO2 to CO on CoO-NC supported iron oxide heterostructure

Abstract

Electrocatalytic CO₂ reduction reaction (eCO₂RR) generates valuable chemical feedstocks but exhibits slow kinetics due to its proton-coupled electron transfer (PCET) process. Transition metal oxides, including iron oxides (FeO) and cobalt oxides (CoO), are economically feasible, non-toxic, and widely accessible materials for various electrochemical applications. Yet, they demonstrate near inactivity in eCO₂RR. Our study reveals a notable boost in the activity and selectivity of FeO to reduce CO₂ to CO when it is supported on cobalt oxide embedded nitrogen doped carbon nanotubes (CoO-NC). By varying the concentration of FeO, a series of FeO based electrocatalysts has been synthesized. The optimum ratio denoted as FeO/CoO-NC(0.16) exhibits a significant current density (j) of 38 mAcm^-2 which is 3.8 times greater when FeO is deposited over commercial multiwalled carbon nanotubes (FeO/MWCNTs). Moreover, FeO/CoO-NC(0.16) shows a remarkably lower overpotential (η) of only 0.251 V_RHE than FeO/MWCNTs (0.446 V_RHE). The Faraday efficiency (FE) for electrocatalytic CO₂ to CO conversion on the surface of FeO/CoO-NC(0.16) reaches ≈ 79 % at −0.70 V_RHE which is quantitively monitored by a GC-TCD. The present study offers a new avenue for the use of Fe as an efficient candidate for eCO₂RR.