Investigation of oxygen evolution reaction kinetic process and kinetic parameters on iridium electrode by electrochemistry impedance spectroscopy analysis

Abstract

Though metallic iridium catalyst is broadly used as an efficient OER catalyst due to its high OER activity, however, there is a current dearth of researches on its OER mechanism and kinetic parameters. The present study aims to investigate the OER kinetic process and obtain kinetic parameters of the iridium catalyst. The OER rate determining step was investigated by EIS measurements. Meanwhile, OER kinetic parameters were obtained by both steady-state polarization curve measurement and microkinetic modelling. Results show that the rate determining step of OER is the adsorption of Ir-OHads species on active sites. Values of both Tafel slope and exchange current density are important kinetic parameters which are about 48.6 mV/dec and 1.88 × 10−11 A/cm2 according to the microkinetic modelling. The obtained parameters could be referred in the novel OER catalysts investigation. The approaches for OER kinetic process study and kinetic parameters evaluation are useful in the investigation of other catalysts.