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In this study, antimony-doped tin oxide (ATO) support materials for a Pt anode catalyst in direct methanol fuel cells were prepared and electrochemically evaluated. When the heating temperature was increased from 300 to 400 °C, the ATO samples exhibited a slightly decreased specific surface area and increased electrical conductivity. In particular, the ATO sample heated at 350 °C in an air atmosphere showed improved electrical conductivity (1.3 S cm−1) with an optimum specific surface area of ~34 m2 g−1. The supported Pt catalysts were synthesized using a polyol process with as-prepared and heated ATO samples and Vulcan XC-72R as supports (denoted as Pt/ATO, Pt/ATO-350, and Pt/C, respectively). In the methanol oxidation reaction (MOR), compared to Pt/C and Pt/ATO, Pt/ATO-350 exhibited the best electrocatalytic activity and stability for MOR, which could be attributed to Pt nanoparticles on the relatively stable oxide support with high electrical conductivity and interaction between the Pt catalyst and the heated ATO support.

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In water splitting, anode catalysts for the oxygen evolution reaction (OER), which is the rate‐determining step, are more critical than cathode catalysts. Herein, the authors prepare Ni‐IrOx composite catalysts consisting of NiO and IrO2 for the OER by a solid‐state reaction with different ratios of NiO to IrO2 and reaction temperatures. In particular, Ni‐IrOx‐400 with a molar ratio of NiO/IrO2 = 1:1 heated at 400 °C shows the best OER performance. In the overall water splitting test using an anion exchange membrane (AEM) water electrolyzer, the single cell with Ni‐IrOx‐400 as the anode catalyst shows current densities of 1454.8 mA cm−2, respectively, measured at 1.8 V. Furthermore, the stability tests of the AEM single cells are carried out at 50 °C under a constant current density of 500 mA cm−2. The single cell with Ni‐IrOx‐400 shows only a slight increase in the overpotential (rate: 2.0 mV h−1) for 100 h owing to the enhanced stability of Ni‐IrOx‐400 compared to IrO2 (12.5 mV h−1). The improved OER performance of the Ni‐IrOx‐400 may be attributed to a composite structure that can prevent particle agglomeration and thus preserve the active sites during the OER.