Activity and stability of Ir-based gas diffusion electrode for proton exchange membrane water electrolyzer

Abstract

The low performance and high cost of oxygen-evolution electrodes limit an efficient hydrogen production using the proton exchange membrane water electrolyzer (PEMWE). Here, a facile strategy to fabricate Ir-based gas diffusion electrodes (GDEs) is proposed using electrochemical methods and subsequent oxidation processes. In brief, the spontaneous displacement of Ir on Ni supported by a carbon paper facilitates the simple fabrication of a metallic Ir GDE with an Ir loading mass of 53.9 μgIr/cm2. Further, electrochemical and thermochemical oxidation processes enable modulation of the Ir oxidation state. Based on half-cell measurements, it is revealed that the Ir3+ and Ir4+ ratios play an important role in the activity and stability, respectively, of the oxygen evolution reaction. Compared with the state-of-the-art Ir-based anodes, the Ir-based GDE employed as an anode for PEMWE single-cell operation demonstrates a superior mass activity of 6.8 A/mgIr at a cell voltage of 1.6 Vcell, originating from the structural advantage of GDEs for achieving high Ir utilization. Moreover, the PEMWE shows acceptable stability during long-term (12 h) operations at a current density of 1.00 A/cm2. © 2020 Elsevier B.V.