Contribution of B,N-co-doped reduced graphene oxide as a catalyst support to the activity of iridium oxide for oxygen evolution reaction

Abstract

The current research deals with the study of boron and nitrogen co-doped reduced graphene oxide (BN-rGO) as a support material for iridium oxide (IrO₂) nanoparticles for oxygen evolution reaction (OER) catalysis. The synthetic approach for the IrO₂–BN-rGO catalyst involves the combination of pyrolysis and hydrothermal methods used for hierarchical nanostructures. BN-rGO possesses B–N, B–C, and N–C functional groups to support and stabilize the IrO₂ catalyst nanoparticles. The altered electronic states of IrO₂ on the BN-rGO support are compared with those of IrO₂ on a non-doped support, rGO (IrO₂–rGO), and on commercial BN sheets (IrO₂–c-BN). The catalyst shows a low overpotential (300 mV at 10 mA cm⁻²), high current density (55 mA cm⁻² at 1.65 V), and significantly high durability (12 350 cycles; 45 h) in an acidic environment. The high stability of IrO₂–BN-rGO may result from the presence of a chemically and electrochemically stable B–N bond. We confirm that other functional groups (B–C and N–C) and the rGO framework are equally crucial for better attachment of IrO₂ nanoparticles.