Preparation of IrO2 nanoparticles with SBA-15 template and its supported Pt nanocomposite as bifunctional oxygen catalyst.

In the present work, we report the syntheses of IrO 2 nanoparticles with SBA-15 template (s-IrO 2 ), and s-IrO 2 supported Pt nanocomposite (Pt/s-IrO 2 ) as bifunctional oxygen catalyst. Physical characterizations including X-ray diffraction and transmission electron microscopy demonstrate that s-IrO 2 catalyst has excellent uniformity and regularity in particle shape and much ordered distribution in geometric space, and Pt/s-IrO 2 catalyst shows a uniform Pt dispersion on the surface of the s-IrO 2 particles. Electrochemical analyses prove that s-IrO 2 catalyst possesses superior OER activity at operating potentials; and that Pt/s-IrO 2 catalyst, in comparison to Pt/commercial IrO 2 , has higher ESA value and ORR catalytic performance with a mechanism of four-electron pathway and a high ORR efficiency. And as a bifunctional oxygen catalyst, Pt/s-IrO 2 also exhibits more remarkable OER performance than the commercial one. The s-IrO 2 nanoparticles will be a promising active component (for OER), and suitable for Pt support (for ORR). [ABSTRACT FROM AUTHOR]