PtIr/Ti4O7 as a bifunctional electrocatalyst for improved oxygen reduction and oxygen evolution reactions

A unitized regenerative fuel cell (URFC) that combines a fuel cell with a water electrolyzer is attractive as a portable power source. To enhance the efficiency of the URFC, a bifunctional oxygen catalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) needs to be developed. In this study, Ti4O7 supported Pt-based catalysts were prepared for a bifunctional oxygen catalyst (BOC) in URFC. Ti4O7 support was prepared using a low-temperature process with TiO2 and cobalt chloride hexahydrate at 950 °C under an H2 atmosphere. The metal catalysts (60 wt%) were deposited on a Ti4O7 support using a borohydride reduction method. The catalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Compared to Pt/C and Pt/Ti4O7, PtIr/Ti4O7 exhibited enhanced activity and stability in ORR and OER. The improved electrocatalytic performance of PtIr alloy supported by Ti4O7 might be attributed to the PtIr alloy phase, the highly stable Ti4O7 support in an acid medium, and the interaction between catalyst and support.