Mixed iridium-tungsten oxides as highly active and stable anode electrode for proton exchange membrane water electrolyzers

Water electrolysis using proton exchange membrane (PEM) technology is one of the most promising processes to produce green hydrogen. However, for its industrialization, the anode catalyst must be improved to provide high activity and stability with low iridium content. In this work, a catalyst consisting of a composite with mixed iridium-tungsten oxides ( ca . 30 wt% of iridium, denoted IrO x -WO 3 ) was prepared and tested in a PEM electrolyzer. The performance of this new catalyst was benchmarked with an iridium-based commercial catalyst from Premetek. The results obtained in the rotating disk electrode (RDE) demonstrated that the IrO x -WO 3 catalyst can achieve an OER activity of 113.6 mA mg Ir −1 at 1.55 V RHE and was stable in 0.1 M HClO 4 during 2 h. The prepared catalyst was further studied in a single-cell electrolyzer, according to an EU test protocol, displaying excellent performance indicators with a catalyst load of 0.2 mg Ir cm −2 – 1.69 V @ 1 A cm −2 and a stability of over 500 h @ 1.5 A cm −2 . Therefore, the prepared catalyst is a promising anode catalyst for PEM electrolyzers. • IrO x -WO 3 ( ca. 30 wt % of Ir) was successfully prepared to conduct the acidic OER. • IrO x -WO 3 outperforms the commercial benchmark in catalytic activity and stability. • MEAs with 0.2 mg Ir cm −2 of IrO x -WO 3 performed stably during 500 h of operation. • IrO x -WO 3 is a promising alternative for anode catalysts of PEM electrolyzers.