Electrochemical Oxygen-Reduction Activity and Carbon Monoxide Tolerance of Iron Phthalocyanine Functionalized with Graphene Quantum Dots: A Density Functional Theory Approach

Abstract

We examined the catalytic activities of iron phthalocyanine integrated with graphene quantum dots (FePc/GQDs) and the pure iron phthalocyanine (FePc) system toward oxygen reduction from both thermodynamics and kinetics perspectives. In addition, density functional theory is used to understand the tolerances of the FePc and FePc/GQD catalysts toward carbon monoxide (CO). The four-electron pathway was determined to be energetically favorable for the oxygen-reduction reactions (ORRs) catalyzed by both FePc and FePc/GQD. With a high cell potential of 0.70 V, FePc/GQD is a potential alternative nonplatinum group metal (PGM) catalyst to Pt/C (0.79 V) for the ORR. The formation of OH* was the rate-limiting step on FePc/GQD, whereas the hydrogenation of chemisorbed O-2 is the rate-determining step on the FePc-monolayer catalyst. Remarkably, the CO-adsorption energy on FePc/GQD was positive at 2.39 eV, demonstrating that FePc/GQD is reasonably tolerant to CO, unlike the FePc system. Our study showed that FePc/GQD can be a practical catalyst candidate in the polymer electrolyte membrane fuel cells in that it exhibits high O-2-reduction activity and CO tolerance.