Preparation of Pt/Irx(IrO2)10-x bifunctional oxygen catalyst for unitized regenerative fuel cell

Bifunctional Pt/Ir-x(IrO2)(10-x) (x < 10) catalyst for unitized regenerative fuel cell (URFC) has been prepared by depositing Pt on Ir-x(IrO2)(10-x) support which is obtained initially from Adams fusion method. X-ray diffraction and transmission electron microscopy show that ultrafine and narrow distributed Pt/Ir-3(IrO2)(7) nanocomposites are formed. Electrochemical measurements demonstrate that among the series of catalysts studied, Pt/Ir-3(Iro(2))(7) catalyst possesses the highest electrochemical surface area (24.74 m(2) g(-1)) and the highest activity towards oxygen reduction reaction (ORR) (21.71 mA mg(-1) at 0.85 V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35 mA mg(-1) at 1.55V) is also observed for Pt/Ir-3(IrO2)(7) catalyst. Kinetic analyses indicate that ORR on Pt/Ir-3(IrO2)(7) catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC. (C) 2012 Elsevier B.V. All rights reserved.