Enhanced oxygen evolution reaction activity of iridium oxide supported on tantalum-doped tin oxide for acidic water electrolysis

Abstract

In the research process of proton exchange membrane electrolysis, Ir-based catalysts exhibit sluggish dynamics of reaction and the poor durability in strongly acidic medium, as well as the high cost greatly limit their commercialization. In this paper, in order to decrease the Ir amount and improve precious metal utilization, Ta-doped tin oxide (SnO₂) was prepared by sol-gel method in this paper as a support and loaded with iridium dioxide (IrO₂). The results indicate that the Ta doping increased conductivity of SnO₂ by two orders of magnitude and inhibited particle size growth. The introduction of 2Ta-SnO₂ supports improved the electric charge transfer dynamics during the catalytic reaction process, and the mass activity of the 40 wt% IrO₂/2Ta-SnO₂ catalyst reached 835.39 A g⁻¹ IrO₂, which was 3.6 times higher than that of commercial IrO₂. The overpotential of the 40 wt% IrO₂/2Ta-SnO₂ catalyst was 264 mV at a current density of 10 mA cm⁻², which is due to the prominent dispersion effect of the support as well as the interaction of the support surface with the active substance. Its stability is better than that of commercial IrO₂ in a stability test over 20,000 s. Therefore, Ta-doped SnO₂ supported IrO₂ catalysts have a promising application by reducing the cost of precious metal catalysts and enhancing the electrocatalytic properties of OER catalysts.