Kinetic Analysis of Oxygen Evolution on Spin-Coated Thin-Film Electrodes via Electrochemical Impedance Spectroscopy

Sustainable and renewable energy technologies have attracted significant attention for reducing greenhouse emissions in the shift from fossil fuels. The production of green hydrogen from water electrolysis is considered an environmentally friendly strategy for a decarbonized economy. We examine the activities of the hydrogen and oxygen evolution reactions (HER and OER) using spin-coated thin-film electrodes with Pt/C and IrO2 nano-electrocatalysts under acidic conditions. The nano-electrocatalysts are characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The electrocatalytic activities of nanoscale Pt/C and IrO2 are close to those of commercial Pt/C and superior to commercial IrO2, resulting in improved overall water splitting performance. Furthermore, the OER kinetics analysis using the IrO2 electrode is conducted using EIS measurements with distribution of relaxation time (DRT) analysis, resulting in a comparable exchange current density to that from the Tafel slope method (6.7 × 10−2 mA/cm2 versus 5.1 × 10−2 mA/cm2), demonstrating the validity of the kinetics analysis. This work provides a general strategy for preparing novel and highly active OER electrode materials for water electrolysis.