Electrolysis of water into oxygen and hydrogen fuels has been considered as a viable strategy to convert and store energy renewably, but has been hampered by the slow kinetics of the oxygen evolution reaction (OER). Hence there is an urgent need to improve the performance of currently used materials and/or develop new materials. Iridium oxide is an effective stable electrocatalyst with low over-potential and high current for efficient fuel generation technologies. To further improve its activity, here ultrafine iridium oxide nanocrystals (IrO2 NCs) with tunable size were successfully synthesized using a facile one-step molten salt synthesis process at 650 oC in air. The structure and morphology of these IrO2 NRs were characterized by powder X-ray diffraction, Raman spectroscopy, Infrared spectroscopy, X-ray photoelectron spectroscopy, and electron microscopic techniques. The electrocatalytic performance of these IrO2 NCs for OER in acidic media was compared with that of commercial IrO2 nanoparticles (NPs) in terms of specific capacitance, total charge, most accessible charge, electrochemically active surface area, and roughness factor. The as-synthesized IrO2 NCs show enhanced electrocatalytic OER activity in 0.5 M H2SO4 media compared to the commercial IrO2 NPs. Moreover, compared to commercial IrO2 NPs and previous reports, the as-synthesized IrO2 nanorods show enhanced electrocatalytic activity to both OER and HER by passing either N2 or O2 gas in a 0.5 M KOH electrolyte before electrochemical measurements, including cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Our results are comparable with, and in most cases, higher than reported data in the literature. Therefore, the current study reported a novel, reliable and scalable synthetic process for IrO2 nanostructures, but also a type of highly electrocatalytic efficient IrO2 nanostructures. It is expected that these IrO2 NCs can serve as a benchmark in the development of active OER and HER (photo)electrocatalysts for various applications in the near future.

Iridium dioxide nanocrystals synthesized by molten-salt method for oxygen and hydrogen evolution reactions

255th National Meeting (2018)

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