Activity of IrO2 supported on tantalum-doped TiO2 electrocatalyst for solid polymer electrolyte water electrolyzer

Abstract

TiO₂ doped tantalum was successfully synthesized via an evaporation-induced self-assembly method (EISA) as a support of IrO₂ for a solid polymer electrolyte water electrolyzer (SPEWE). The IrO₂ was synthesized on the surface of Ta-doped TiO₂ support by using the Adams fusion method. The samples were characterized by BET, XRD, SEM, TEM, CV, EIS and polarization curves of single cells. The doping amount of Tantalum (5, 10, 20, 30 at%) was thoroughly investigated to evaluate the effects on structure, electric conductivity and oxygen evolution reaction (OER) activity of Ta-doped titania supported IrO₂. The results indicated that a significant effect of the Ta dopant on the phase composition and conductivity. Among all the catalysts, with the optimized catalyst IrO₂ loading, the terminal applied potential was 1.849 V at 1000 mA cm⁻² and 80 °C in a SPE water electrolysis cell using 80IrO₂/Ti_0.7Ta_0.3O₂ as anode. IrO₂ loading 80% IrO₂/Ti_0.7Ta_0.3O₂ showed better performance than that of the pristine IrO₂ after normalizing the current density for IrO₂ loading. The increased performance can be attributed to the better dispersion of the IrO₂ on Ti_0.7Ta_0.3O₂ resulting in smaller crystallites and large surface area. In closing, Ti_0.7Ta_0.3O₂ showed outstanding promise as an electrocatalyst support in SPE water electrolysis.