Study of TaC Supported Ir-Based Oxygen Evolution Reaction Electrocatalysts Synthesized by Surfactant-Mediated Method

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Rezaei, Nafiseh
OER Electrocatalyst , Surfactant-Mediated Method , OER Support , PEM Water Electrolysis
The physical and electrochemical properties of Tantalum carbide (TaC) as a potential support for oxygen evolution reaction (OER) electrocatalysts were investigated. It was first ball milled for 7 and 14 days in order to decrease the particle size and increase the surface area. The larger the surface area of a support, the better the dispersion of the electrocatalyst on the support. This implies a larger number of available active sites. The TaC that was ball milled for 14 days showed smaller particle size and larger surface area in comparison with that which was ball milled for 7 days and unmilled TaC. The long term electrochemical stability of the ball-milled TaC was evaluated under OER conditions. The ball-milled TaC was found to be a promising support for OER electrocatalysts in order to reduce the loading of precious metal. Unsupported and TaC supported Iridium-based electrocatalysts were synthesized via a surfactant-mediated method. The advantage of this method is that no heating is required. The synthesized electrocatalysts were analyzed using physical, chemical, and electrochemical characterization methods to see the effect of the ball-milled TaC on the performance of the Ir-based electrocatalyst. The synthesized unsupported electrocatalyst consisted of 1.8 nm particles. Both the unsupported and supported electrocatalysts were a mixture of Ir0, Ir+3 and Ir+4 oxidation states. It was observed that due to less agglomeration and better dispersion of the supported electrocatalyst on the TaC support, the surface area of the supported electrocatalyst was larger than the unsupported electrocatalyst. Electrochemical properties of the electrocatalysts were studied in a 3 electrode system. The supported electrocatalyst showed larger voltammetric charge and mass activity, and better durability compared to the unsupported electrocatalyst. The supported electrocatalyst also showed lower charge transfer resistance at the end of the long-term stability test. By supporting the Ir-based electrocatalyst on the ball-milled TaC, the Ir loading was decreased and the utilization of Ir for OER electrocatalysis was enhanced.
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