One-dimensional iridium catalyst for enhanced interfacial electron transport in proton exchange membrane water electrolysis

Abstract

Iridium, the most-used oxygen evolution reaction (OER) catalyst substance, needs to be used at minimal expense due to its high price and limited supply. However, abnormally large cell polarizations restrict the use of low iridium-loaded anode in proton exchange membrane water electrolysis (PEMWE). Herein, we present one-dimensional iridium nanofiber that enables a high current density operation of 3 A cm-2 at 1.86 V even at ultralow loading (as low as 0.07 mgIr cm-2). Our nanofiber catalyst circumvents the interfacial electron transport problem posed by the native oxide on Ti porous transport layer. We attributed this to the low work function and low ionomer exposure that does not create the upward band bending in the native oxides. Besides, outstanding pore distribution and in-plane electron conductivity enhanced the two-phase transport and catalyst utilization, respectively, which enables the high current operation. This work highlights the efficacy of the one-dimensional iridium nanofiber as an anode catalyst of PEMWE especially at low loading.