Evaluation of Pt-Ru-Ir as Bifunctional Electrocatalysts for the Oxygen Electrode in a Unitized Regenerative Fuel Cell

The Unitized Regenerative Fuel Cell (URFC) is a device that works as a Fuel Cell (FC) to produce electric energy and as a Water Electrolyzer (WE) to produce the oxygen and hydrogen for the FC operation mode. One of the challenges for URFC's is the development of bifunctional electrocatalysts capable of carrying out efficiently the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), since those electrocatalysts that performs well the oxygen reduction have also poor oxygen evolution performance. The objective of this paper is to evaluate the efficiency of four different atomic composition electrocatalytic materials, based on Pt-Ru-Ir, to carry out the oxygen reduction and evolution reactions. The studies of the performance for this material were made in a Proton Exchange Membrane Fuel Cell (PEMFC), using the linear voltammetry technique at 30, 60 and 80°C in FC and WE mode. The Membrane Electrode Assembly (MEA) was prepared by the Hot-Spray technique for the oxygen electrode without using an electrocatalysts support; meanwhile the hydrogen electrode was prepared using the paste technique over the gas diffusion layer. The electrocatalyst loading was 3-5 mg·cm-2 on the oxygen electrode and 0.5-1 mg Pt·cm-2 on the hydrogen side.