The effect of iridium content in boron carbide-supported iridium catalyst on the activity and stability of proton exchange membrane water electrolyzer

One of the major obstacles to proton exchange membrane water electrolyzer (PEMWE) for large-scale applications is the cost of iridium for oxygen evolution reaction (OER). To resolve this issue, boron carbide-supported iridium catalysts are prepared by varying the iridium content from 10 to 60 wt%. Increasing the iridium content on the boron carbide support affects the physical properties of the catalysts and the electronic structure of iridium. At the content of 40%, Ir/B₄C showed the highest catalytic activity mainly due to its high electrochemical surface area. 40%-Ir/B₄C showed outstanding cell performance of 1.0 A/cm² at 1.61 V with a loading of 0.5 mg⋅_Ir/cm² which has the same performance with 3.0 mg⋅_Ir/cm² of unsupported commercial catalyst. 40%-Ir/B₄C also showed excellent durability in a half-cell as well as in a single cell. The presence of Ir (IV) and the metal-support interaction help 40%-Ir/B₄C to be stable.