Self-Supported Iridium Oxide Nanostructures for Electrocatalytic Water Oxidation in Acidic Media

One major obstacle in the advancement of proton exchange membrane (PEM) technology is the development of highly active and durable electrocatalysts for the oxygen evolution reaction (OER) in an acid environment. In comparison with conventional catalysts in the powdery form, the self-supported nanostructures are more promising for practical applications. However, the preparation of self-supported nanocatalysts with high stability in acidic media remains challenging. Herein, IrO x nanostructures anchored on carbon cloth were prepared by a facile two-step method, which involved a fast dip-coating process and a subsequent annealing treatment under different temperatures. High hydroxide contents and mixed valence of iridium were observed for the obtained samples. By optimizing the annealing temperature, we achieved a low overpotential of 220 mV at the current density of 20 mA cm –2 . The optimal activity was attributed to a balance between hydroxide content and electrochemical surface area. Moreover, the self-supported IrO x nanostructure showed a good stability over 50 h.