Support-free iridium hydroxide for high-efficiency proton-exchange membrane water electrolysis
Yubo Chen, Chencheng Dai, Qian Wu, Haiyan Li, Shibo Xi, Justin Zhu Yeow Seow, Songzhu Luo, Fanxu Meng, Yaolong Bo, Yanghong Xia, Yansong Jia, Adrian C. Fisher, Zhichuan J. Xu
Abstract
The large-scale implementation of proton-exchange membrane water electrolyzers relies on high-performance membrane-electrode assemblies that use minimal iridium (Ir). In this study, we present a support-free Ir catalyst developed through a metal-oxide-based molecular self-assembly strategy. The unique self-assembly of densely isolated single IrO6H8 octahedra leads to the formation of μm-sized hierarchically porous Ir hydroxide particles. The support-free Ir catalyst exhibits a high turnover frequency of 5.31 s⁻¹ at 1.52 V in the membrane-electrode assembly. In the corresponding proton-exchange membrane water electrolyzer, notable performance with a cell voltage of less than 1.75 V at 4.0 A cm⁻² (Ir loading of 0.375 mg cm⁻²) is achieved. This metal-oxide-based molecular self-assembly strategy may provide a general approach for the development of advanced support-free catalysts for high-performance membrane-electrode assemblies. Next-generation proton exchange membrane electrolyzers rely on high-performance anodes. Here, the authors report a metal-oxide-based molecular self-assembly strategy toward a support-free iridium hydroxide catalyst for an advanced anode with low-iridium loading and enhanced mass transport.