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

Jun Ho Shim, Ji Eon Kim, Yun Bin Cho, Chongmok Lee, Youngmi Lee

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


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. This journal is

Original languageEnglish
Pages (from-to)15365-15370
Number of pages6
JournalPhysical Chemistry Chemical Physics
Issue number37
StatePublished - 7 Oct 2013


Dive into the research topics of 'Oxidation-state dependent electrocatalytic activity of iridium nanoparticles supported on graphene nanosheets'. Together they form a unique fingerprint.

Cite this