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.

Theoretical Investigation of the Active Sites in N-Doped Graphene Bilayer for the Oxygen Reduction Reaction in Alkaline Media in PEMFCs

“…The exchange–correlation interactions were calculated using the generalized gradient approximation (GGA) within the Perdew–Burke–Ernzerhof (PBE) exchange–correlation . The GGA-PBE functional has been shown to be reasonable for carbon-based systems. ,,− The optimized lattice unit cell for graphene was 2.459 × 2.459 Å. The hydrogenated zigzag nanoribbon was applied to represent the edge pyridinic-N3-doped graphene structures because in an alkaline medium, this structure is more active and energetically favorable for the ORR ,− than the oxygenated structure.…”

“…Owing to the escalating global climate change and environmental pollution, studies related to green energy technology are receiving significant attention, with a focus on polymer electrolyte membrane fuel cells (PEMFCs). − The electrochemical oxygen reduction reaction (ORR) during the discharge process is a critical factor influencing cell efficiency. , Effective and cost-friendly ORR electrocatalysts have been proposed as alternatives to Pt-based electrocatalysts. Heteroatom-doped carbon materials such as carbon nanotubes, graphene quantum dots, − and graphene , have been extensively investigated as metal-free catalysts. Graphene doped with N, − B, , or S , shows excellent electrocatalytic performance and is more economical than Pt-based group metals (PGMs).…”

Graphene quantum dot-porphyrin/phthalocyanine multifunctional hybrid systems: from interfacial dialogue to application

“…Thus, all these characteristics make FePc-GQD an efficient electrocatalyst for the ORR, which can be used for commercial application in fuel cells. 255 Reduced GQDs (rGQD) show better electrocatalytic activity than amino-functionalized GQDs given that the reduction process involves the elimination of carboxyl, epoxy, and hydroxy groups on the surface of GQDs, which results in narrowing of the energy band gap of GQDs, thus enhancing electron transfer properties. 252 Centane et al conjugated rGQD covalently and non-covalently with cobalt phthalocyanine (CoPc), where CoPc has three tert-butyl substituents, acting as electron donating groups ( push), and a single COOH as an electronwithdrawing group ( pull).…”