Electrochemical properties of core-shell TiC–TiO2nanoparticle films immobilized at ITO electrode surfaces

Abstract

Titanium carbide (TiC) nanoparticles are readily deposited onto tin-doped indium oxide (ITO) electrodes in the form of thin porous films. The nanoparticle deposits are electrically highly conducting and electrochemically active. In aqueous media (at pH 7) and at applied potentials positive of 0.3 V vs. SCE partial anodic surface oxidation and formation (at least in part) of novel core-shell TiC–TiO₂ nanoparticles is observed. Significant thermal oxidation of TiC nanoparticles by heating in air occurs at a temperature of 250 °C and leads first to core-shell TiC–TiO₂ nanoparticles, next at ca. 350 °C to TiO₂ (anatase), and finally at temperatures higher than 750 °C to TiO₂ (rutile). Electrochemically and thermally partially oxidized TiC nanoparticles still remain very active and for some redox systems electrocatalytically active. Scanning and transmission electron microscopy (SEM and TEM), temperature dependent XRD, quartz crystal microbalance, and voltammetric measurements are reported. The electrocatalytic properties of the core-shell TiC–TiO₂ nanoparticulate films are surveyed for the oxidation of hydroquinone, ascorbic acid, and dopamine in aqueous buffer media. In TiC–TiO₂ core-shell nanoparticle films TiO₂ surface reactivity can be combined with TiC conductivity.