Comparison of IrO₂@FeVS and IrO₂@Co–FeVS catalysts in PEM electrolysis at different temperatures

In this study, FeVS and Co–FeVS nanoparticles synthesized via a hydrothermal method using sunflower shell extract were employed as support materials for IrO₂ catalysts prepared by the Adams method. The resulting IrO₂@FeVS and IrO₂@Co–FeVS catalysts were calcined at various temperatures (500–800 °C) and evaluated as anode catalysts in the proton exchange membrane electrolyzer cell (PEMEC). The catalysts calcined at 500 °C were further examined at operating temperatures between 20 and 70 °C. The results showed that increasing the operating temperature enhanced proton conductivity and reaction kinetics, thereby reducing the cell voltage; the optimum performance was achieved at 70 °C. In terms of calcination temperature, the best electrochemical activity was obtained for catalysts treated at 500–600 °C, while higher temperatures (700–800 °C) led to performance loss due to particle growth and reduced surface area. Structural analyses confirmed uniform dispersion of IrO₂ on the FeVS support. Co incorporation decreased crystallite size, improved electrical conductivity, and enhanced interfacial stability, resulting in superior catalytic performance. Overall, the optimum PEMEC performance was achieved at 500–600 °C calcination and 70 °C operating temperature, yielding high current densities at lower voltages. The optimal conditions for PEMEC operation were determined to be a calcination temperature of 500–600 °C and a cell operating temperature of 70 °C. Under these conditions, high current densities were achieved at lower cell voltages, indicating improved catalytic efficiency at elevated temperatures.