Growth of Highly Single
Crystalline IrO<sub>2</sub> Nanowires and Their Electrochemical
Applications
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Abstract
We present the facile growth of highly single crystalline
iridium
dioxide (IrO<sub>2</sub>) nanowires on SiO<sub>2</sub>/Si and Au substrates
via a simple vapor phase transport process under atmospheric pressure
without any catalyst. Particularly, high-density needle-like IrO<sub>2</sub> nanowires were readily obtained on a single Au microwire,
suggesting that the melted surface layer of Au might effectively enhance
the nucleation of gaseous IrO<sub>3</sub> precursors at the growth
temperature. In addition, all the electrochemical observations of
the directly grown IrO<sub>2</sub> nanowires on a single Au microwire
support favorable electron-transfer kinetics of [Fe(CN<sub>6</sub>)]<sup>4–/3–</sup> as well as Ru(NH<sub>3</sub>)<sub>6</sub><sup>3+/2+</sup> at the highly oriented crystalline IrO<sub>2</sub> nanowire surface. Furthermore, stable pH response is shown,
revealing potential for use as a miniaturized pH sensor, confirmed
by the calibration curve exhibiting super-Nernstian behavior with
a slope of 71.6 mV pH<sup>–1</sup>