Highly effective IrxSn1−xO2 electrocatalysts for oxygen evolution reaction in the solid polymer electrolyte water electrolyser

We developed an advanced surfactant-assistant method for the IrxSn1−xO2 (0 < x ≤ 1) nanoparticle (NP) preparation, and examined the OER performances by a series of half-cell and full-cell tests. In contrast to the commercial Ir black, the collective data confirmed the outstanding activity and stability of the fabricated IrxSn1−xO2 (x = 1, 0.67 and 0.52) NPs, which could be ascribed to the amorphous structure, good dispersion, high pore volume, solid-solution state and Ir-rich surface for bi-metal oxides, and relatively large size (10–11 nm), while Ir0.31Sn0.69 exhibited poor electro-catalytic activity because of the separated two phases, a SnO2-rich phase and an IrO2-rich phase. Furthermore, compared with highly active IrO2, the improved durability, precious-metal Ir utilization efficiency and correspondingly reduced Ir loading were realized by the addition of Sn component. When the Ir0.52Sn0.48O2 cell operated at 80 °C using Nafion® 115 membrane and less than 0.8 mg cm−2 of the noble-metal Ir loading, the cell voltages we achieved were 1.631 V at 1000 mA cm−2, and 1.821 V at 2000 mA cm−2. The IR-free voltage at the studied current density was very close to the onset voltage of oxygen evolution. The only 50 μV h−1 of voltage increased for the 500 h durability test at 500 mA cm−2. In fact, these results are exceptional compared to the performances for OER in SPEWE cells known so far. This work highlights the potential of using highly active and stable IrO2–SnO2 amorphous NPs to enhance the electrolysis efficiency, reduce the noble-metal Ir loading and thus the cost of hydrogen production from the solid polymer electrolyte water electrolysis.