Synthesis and electrochemical properties of nano-composite IrO2/TiO2 anode catalyst for SPE electrolysis cell

Abstract

A composite catalyst of nano-grade IrO2/TiO2 powder is synthesized by Adams’ fusion method for reducing overvoltage of solid polymer electrolyte (SPE) cell and cost-down of noble metal catalyst, simultaneously. The IrO2/TiO2 catalysts, which has a porous composite nanostructure, are prepared according to molar ratio of Ir and Ti element with a specific surface area of 34.1–55.3 m2 g−1. It is found that crystal structure of TiO2 is more dominated by the rutile phase than by Anatase. For a SPE system, total catalyst loading of anode which made of TiO2 and IrO2 is prepared as low as 0.77 mg cm−2 or less, in which the loading amount of the IrO2 only is set to 0.6 mg cm−2 or less. The anode catalyst layer of about 10 ㎛ thickness is coated on the membrane (Nafion 212) for the membrane electrode assembly (MEA) by the decal method. The strong adhesion between the catalyst electrode the membrane is observed by Scanning electron microscopy (SEM). Linear sweep voltammetry (LSV) results shows that the nano-composite IrO2/TiO2 catalysts has better oxygen evolution reaction (OER) than that of the synthesis IrO2 only. Finally, the IrO2/TiO2 catalysts is applied as anode electrode for SPE cells and it is observed that in spite of the lower loading amount of the IrO2 less than 0.5 mg cm−2, working voltage of 1.68 V is observed at a current density of 1 A cm−2 and operating temperature of 80 °C.