Hydroxide ion oxidation using low-symmetry mesoporous titanium dioxide (lsm-TiO2) electrode

This work reports the direct oxidation of hydroxide ion at low-symmetry mesoporous titanium dioxide (lsm-TiO2) electrode. The mesoporous TiO2 electrode with a short-range order of mesopores, the surface area of 200 m2 g−1, the average pore size of 2.7 nm, and semi-crystalline anatase walls is prepared by using a surfactant self-assembly template followed by a two-step calcination process. The electrochemical behaviour of the hydroxide ion solution at the lsm-TiO2 electrode is studied, and a novel and well-defined oxidation peak around the potential of 0.85 V (vs. SCE) is revealed. The oxidation process is irreversible, under diffusion control, and the peak current linearly increases with [OH−] within the concentration range 1.0–50 mm. The hydroxide ion detection limit of 0.05 mm is achieved, based on 3σ calculations, along with an extraordinary current sensitivity of 0.180 mA mm−1. This hydroxide oxidation process can be performed in nitrate, fluoride, chloride, or sulfate-containing supporting electrolytes, which makes the lsm-TiO2 electrode very selective for the voltammetric hydroxide ion determination. [Display omitted] •Low-symmetry mesoporous TiO2 electrode prepared by a surfactant self-assembly template.•The electrode shows a novel hydroxide oxidation peak at 0.85 V (vs. SCE).•The peak current linearly increases with [OH−] with detection limit of 0.05 mM and sensitivity of 0.180 mA mM−1.