%0 Publication %T Water Electrolysis Using a Porous IrO2/Ti/IrO2 Catalyst Electrode and Nafion Membranes at Elevated Temperatures %A Akihiro Ohira; Je-Deok Kim %8 03/03/2023 %I MDPI AG %U https://mdr.nims.go.jp/concern/publications/ht24wn655 %( https://doi.org/10.3390/membranes11050330 %X Porous IrO2/Ti/IrO2 catalyst electrodes were obtained by coating IrO2 on three types of porous Ti powder sheets (sample 1, sample 2, and sample 3) using different surface treatment methods, and a hydrogen evolution catalyst electrode was obtained by coating Pt/C on carbon gas diffusion layers. A Nafion115 membrane was used as an electrolyte for the membrane electrode assemblies (MEA). Water electrolysis was investigated at cell temperatures up to 150 °C, and the electrical characteristics of the three types of porous IrO2/Ti/IrO2 catalyst electrodes were investigated. The sheet re-sistance of sample 1 was higher than those of samples 2 and 3, although during water electrolysis, a high current density was observed due to the nanostructure of the IrO2 catalyst. In addition, the structural stabilities of Nafion and Aquivion membranes up to 150 °C were investigated by using small angle X-ray scattering (SAXS). The polymer structures of Nafion and Aquivion membranes were stable up to 80 °C, whereas the crystalline domains grew significantly above 120 °C. In other words, the initial polymer structure does not recover after the sample is heated above the glass transition temperature. %G English %9 Article %K elevated temperature; nafion membrane; polymer electrolyte; porous IrO2/Ti/IrO2 catalyst electrode; water electrolysis %~ MDR: NIMS Materials Data Repository %W National Institute for Materials Science