Synthesis and activities of IrO2/Ti1−xWxO2 electrocatalyst for oxygen evolution in solid polymer electrolyte water electrolyzer

Abstract

Novel IrO2/Ti1−xWxO2 electrocatalysts for the oxygen evolution reaction (OER) in a solid polymer electrolyte (SPE) water electrolyzer were synthesized using the Adams fusion method and the evaporation-induced self-assembly method. Physical and chemical characterizations of the sample—including Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and polarization curves for single cells—were performed. The W-doped TiO2 support with various doping amounts (0, 5, 10, and 20at.%) exhibited a single-phase anatase structure and a large BET surface area. Furthermore, with annealing at a reducing atmosphere, a phase change from anatase to rutile occurred, trace α-W was precipitated from the crystal lattice of the Ti0.8W0.2O2 sample, and the BET surface area decreased accordingly. On the other hand, the conductivities of the W-doped support exhibited an increasing trend, indicating a significant impact of the W dopant on the enhancement of the TiO2 conductivity. The voltammetric charge of 40IrO2/Ti0.9W0.1O2 (1754mC (cm2mg)−1) was higher than that of unsupported IrO2, and 40IrO2/Ti0.9W0.1O2 exhibited enhanced electrochemical activity for the OER process. A single-cell performance of 1.79V was achieved by using 80IrO2/Ti0.9W0.1O2 as an anode for the minimum charge-transfer resistance and ohmic resistance. Electrocatalysts with the Ti0.9W0.1O2 support exhibited good durability. Thus, Ti0.9W0.1O2 is a promising anode electrocatalyst support for SPE water electrolysis.