Microwave-Assisted Synthesis of Ir-Ni Electrocatalysts for the Oxygen Evolution Reaction in Acidic Electrolyte

This study investigates a microwave-assisted synthesis method for producing Ir-Ni bimetallic catalysts for the oxygen evolution reaction in acidic environment. Due to the high cost of iridium-based catalysts used in the anodes of proton-exchange membrane electrolyzers, reducing the noble metal content while maintaining high performance is crucial. In this work, materials with various Ir-Ni atomic ratios are synthesized and their impact on the catalyst microstructure, phase composition, and electrochemical performance is evaluated. The results reveal a synergistic effect between the two metals, with 60 at% Ni identified as the optimal nominal composition. This catalyst achieves an overpotential of 274 mV at 10 mA cm(-2) and a Tafel slope of 49 mV dec(-1) in 0.5 M H2SO4 electrolyte, outperforming commercial IrO2 (320 mV at 10 mA cm(-2) and 56 mV dec(-1)). The higher activity is retained after both a 6 h chronoamperometry and an accelerated degradation test, during which Ni acts as a sacrificial component and the electrochemically surface area of the films increases. Overall, this study demonstrates the potential of microwave-assisted synthesis, a greener and faster alternative to conventional methods, for developing low Ir-content catalysts with enhanced performance.