Highly Branched RuO₂ Nanoneedles on Electrospun TiO₂ Nanofibers as an Efficient Electrocatalytic Platform

Highly single-crystalline ruthenium dioxide (RuO₂) nanoneedles were successfully grown on polycrystalline electrospun titanium dioxide (TiO₂) nanofibers for the first time by a combination of thermal annealing and electrospinning from RuO₂ and TiO₂ precursors. Single-crystalline RuO₂ nanoneedles with relatively small dimensions and a high density on electrospun TiO₂ nanofibers are the key feature. The general electrochemical activities of RuO₂ nanoneedles-TiO₂ nanofibers and Ru(OH)₃-TiO₂ nanofibers toward the reduction of [Fe(CN)₆]^3- were carefully examined by cyclic voltammetry carried out at various scan rates; the results indicated favorable charge-transfer kinetics of [Fe(CN)₆]^3- reduction via a diffusion-controlled process. Additionally, a test of the analytical performance of the RuO₂ nanoneedles-TiO₂ nanofibers for the detection of a biologically important molecule, hydrogen peroxide (H₂O₂), indicated a high sensitivity (390.1 ± 14.9 μA mM^-1 cm^-2 for H₂O₂ oxidation and 53.8 ± 1.07 μA mM^-1 cm^-2 for the reduction), a low detection limit (1 μM), and a wide linear range (1-1000 μM), indicating H₂O₂ detection performance better than or comparable to that of other sensing systems.