Template-assisted synthesis of ruthenium oxide nanoneedles: electrical and electrochemical properties

Abstract

We here demonstrate the formation of bundles of RuO₂ nanoneedles (ca. 100 nm diameter) by a template-assisted electrodeposition from aqueous RuCl₃ solution under potentiostatic conditions at room temperature. Cyclic voltammetric measurements in 0.5 M H₂SO₄ show significantly higher redox-related charging behavior for the RuO₂ nanoneedles compared to that of the commercial sample, which is also supported by the electrochemical impedance data. A comparison of the specific capacitance reveals a higher value for nanoneedles (3 F/g instead of 0.4 F/g for the bulk), which has been explained on the basis of enhanced reactivity. More interestingly, electrical transport measurements reveal a transition from metallic to semiconducting behavior especially at low-temperature caused by an impurity scattering mechanism. We anticipate that the present simple route for the fabrication of RuO₂ nanostructures will be useful to exploit their potentials in various fields such as electrocatalysis, nanoelectronics, and more importantly for designing supercapacitors.