Fe–N-doped graphene as a superior catalyst for H2O2 reduction reaction in neutral solution

Abstract

Fe–N-doped graphene containing 0.3at% of Fe and 1.9 of N with an active specific surface area of 77.5±4m2g−1 is synthesized in two steps: first N-doped graphene is produced by thermal dissociation of methane in an inductively coupled thermal plasma (ICP) reactor and subsequently the product is converted to Fe–N-doped graphene by a wet chemical method. The catalytic activity of this catalyst toward H2O2 reduction reaction (HPRR) is studied by rotating disk electrode for fuel cell applications. Although the mechanism of HPRR on Fe–N-doped graphene, N-doped graphene and graphene is similar, Fe–N-doped graphene shows the highest catalytic activity toward HPRR. The exchange current density based on the active surface area (j0A) of Fe–N-doped graphene in Na2SO4 solution is (4.4±0.2)×10−8Acm−2, which is 5 times greater than j0A of the N-doped graphene. Direct reduction of H2O2, H2O2 decomposition, O2 reduction, and O2 desorption are predicted as the reactions involved in the HPRR while O2 reduction and O2 desorption are negligible at low and high overpotentials, respectively. Investigation of the effect of the electrolyte and catalyst loading reveals that HPRR on Fe–N-doped graphene suffers from kinetic limitations especially at low catalyst lodgings, fast rotation rates, and strong acidic and basic solutions.