Potential Dependence of Ir Dissolution Using Time-Resolved Measurements

Electrocatalysis efforts in low temperature, PEM-based electrolysis tend to focus on the oxygen evolution reaction (OER) since it is several orders of magnitude kinetically slower than its counterpart, the hydrogen evolution reaction (HER). 1 In comparison to other OER catalysts, Ir-based metal oxides (IrO x ) 2-6 are regarded as the best PEM electrolyzer electrocatalysts as they are both active and are relatively stable. 7, 8 However, even Ir-based electrocatalysts slowly undergo dissolution under the operating conditions of the electrolyzer anode. 9-10, 7 Considering the low Earth abundance and high-cost of Ir, understanding the kinetics and mechanism of its electrochemical dissolution is of vital importance to develop strategies targeting high activity, long-term stability, and limited metal dissolution in acidic media. Mechanistic studies of both OER and dissolution at the solid–liquid interface are more challenging, as they typically require detection of reaction intermediates with short lifetimes. An electrochemical cell coupled to a highly-sensitive analytical technique provides a platform for detection of dissolution products and may help to resolve the degradation pathway of Ir and its oxides and the correlation to the OER mechanism. In this work, we aim to understand the structure-durability relation for different Ir oxides. An electrochemical flow cell system connected to an inductively-coupled plasma-mass spectrometer (ICP-MS) capable of detecting trace concentrations (更多