Directly Coated Iridium Nickel Oxide on Porous‐Transport Layer as Anode for High‐Performance Proton‐Exchange Membrane Water Electrolyzers

Developing a high‐performance anode design is important for a low‐cost proton‐exchange membrane water electrolyzer (PEMWE). In this study, an iridium nickel oxide directly coated anode (IrNiOx electrode) for high‐efficient PEMWE is reported. Five IrNiOx electrodes with different Ir‐to‐Ni ratios are developed using co‐electrodeposition. The resulting electrodes contain a thin IrNiOx layer on the carbon substrate. To develop the PEMWE incorporating IrNiOx electrode, the effect of fabrication methods, catalyst compositions, and porous transport layer are investigated. Consequently, the IrNiOx electrode prepared with 7:3 precursor solution (Ir0.5Ni0.5Ox) exhibits higher oxygen evolution reaction activity with a smaller overpotential than the electrode prepared with 10:0 precursor solution (IrOx) and the commercial IrO2. Furthermore, the performance of the PEMWE is higher with the Ir0.5Ni0.5Ox electrode than that with the sprayed electrode with commercial IrO2 nanoparticles. This enhancement is attributed to the high electrochemical surface area caused by introducing Ni in IrOx. Additionally, the performance of the directly coated Ir0.5Ni0.5Ox PEMWE is the highest reported in the literature.