MnO2-modified ZIF-67 supported on doped reduced graphene oxide as highly active catalyst for the oxygen reduction reaction.

Abstract

In this investigation, ZIF-67 supported on non-doped reduced graphene oxide (rGO), nitrogen- and sulphur-doped reduced graphene oxide (SN-rGO), and manganese-modified ZIF-67/SN-rGO are synthetized and compared as electrocatalysts for the oxygen reduction reaction (ORR) in alkaline conditions. XPS, SEM, XRD and Raman spectroscopy techniques are used to physiochemically characterize the materials. Cyclic and linear sweep voltammetry unveil kinetic parameters, including rate constants, Tafel slopes, and exchange current density, providing insights into the reaction mechanism. Nitrogen and sulphur doping of graphene reduces hydrogen peroxide production, lowering overpotential and enhancing cathodic currents. Manganese modification further enhances performance, matching cathodic currents with Pt/C and achieving a potential of 0.85 V vs RHE at −1 mA·cm−2 demonstrating superior efficiency. The study highlights the impact of graphene doping and manganese incorporation on ORR activity, contributing to a comprehensive understanding of these electrocatalytic systems.