Two convenient methods for the fabrication of ruthenium oxide nanowires are reported. In one method, nanowire clusters are obtained by electrodeposition from an aqueous plating solution onto the step edges present on the surface of highly oriented pyrolytic graphite (HOPG) as an electrode. The electrodeposition was performed in perchloric acid solution containing 20 µM RuCl₃ as precursor, with continuous scanning of the potential of the underlying electrode. Under optimized conditions, the nucleation of ruthenium oxide occurs selectively at the step edges present on the HOPG surface, with continued and somewhat aligned growth of nuclei that were 7-15 nm in diameter; the nuclei tend to coalesce with adjacent ones along the step edge to form nanowire-like features as evidenced by atomic force microscopy, Figure 1. More ordered arrays can be obtained using the tip of an atomic force microscope and the nanoscratching method on a pre-deposited layer of non-conductive hydrophobic organic polymer mask on an indium tin oxide (ITO) substrate. The comparison of the two methods and the performance of the resulting nanowires as nanosensors in the detection of nitric oxide will be presented and discussed.

Figure 1. AFM image of the electrodeposited ruthenium oxide nanowires on a HOPG surface