Effect of Calcination Temperatures on the Electrocatalytic Performance of IrO2@RGO for Oxygen Evolution Reaction

In this study, IrO2 was loaded on graphene oxide (GO) by a hydrothermal method, and an optimal temperature was established for the calcination step. The structure of IrO2@RGO calcined at different temperatures was determined by TEM and XRD. The results have revealed that the best dispersion of IrO2 on RGO was achieved after calcination at 350 ℃; IrO2 particles were evenly spread over the entire surface of the graphene substrate. Regular spherical nanostructures of IrO2@RGO were used as a working electrode for electrochemical analysis. The results confirmed that the performance of IrO2@RGO material at 350 ℃ was superior to composite materials at other temperatures in terms of activity in the oxygen evolution reaction (OER). IrO2@RGO-350 ℃ showed better catalytic activity with an overpotential of 50 mV at the current density of 10 mA/cm−2 with a low Tafel slope of 85.1 mV dec−1. The outstanding OER performance is ascribed to the introduction of the RGO, which not only act as a support to prevent agglomeration of IrO2 nanoparticles that produces high surface area of catalytic sites, but also facilitates electron transfer between IrO2 nanoparticles and RGO. Therefore, this work provides a method to synthesize the IrO2@RGO catalyst for applications in OER.