Issue 37, 2013

Oxidation-state dependent electrocatalytic activity of iridium nanoparticles supported on graphene nanosheets

Abstract

Nanocomposites of iridium nanoparticles (Ir NPs), supported on graphene nanosheets, are synthesized and their electrocatalytic acitivities in the oxygen reduction reaction (ORR) are studied depending on their Ir oxidation state. Graphene functionalized with poly(vinyl pyrrolidone) (pRGO) is a suitable support for Ir NPs, producing well-monodispersed Ir NPs anchored strongly on the pRGO surface (Ir NP/pRGO) with a very high density. This was confirmed by scanning electron microscopy and transmission electron microscopy. The ORR activity of the Ir NP/pRGO nanocomposites in 0.5 M H2SO4 solution was observed to be dependent on the oxidation state of the immobilized Ir NPs. In fact, the nanocomposite composed of Ir(0) metal NPs, rather than Ir oxide (IrOx) NPs, exhibits higher ORR activity, such as more positive onset potential, higher and flatter limiting current density, a greater n value, and a sharper curve shape in the rotating disk electrode voltammetry experiments. Higher ORR activity of Ir is ascribed to the stronger adsorption of oxygen on the surface of Ir compared to IrOx. The practical stability of the Ir NP/pRGO composite was also confirmed under O2 saturated/acidic conditions.

Graphical abstract: Oxidation-state dependent electrocatalytic activity of iridium nanoparticles supported on graphene nanosheets

Supplementary files

Article information

Article type
Paper
Submitted
26 Apr 2013
Accepted
11 Jul 2013
First published
16 Jul 2013

Phys. Chem. Chem. Phys., 2013,15, 15365-15370

Oxidation-state dependent electrocatalytic activity of iridium nanoparticles supported on graphene nanosheets

J. H. Shim, J. E. Kim, Y. Cho, C. Lee and Y. Lee, Phys. Chem. Chem. Phys., 2013, 15, 15365 DOI: 10.1039/C3CP51780B

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