A carbon needle microelectrode decorated with TiO₂ nanosheets dominated by reactive facets as a highly electrocatalytic sensing element.

We demonstrate a highly efficient electrocatalytic activity of TiO 2 nanosheets with reactive (001) facets grown on a carbon needle microelectrode (TiO 2 -CNE). This microelectrode is prepared by a simple hydrothermal process. Scanning electron microscopy, high-resolution transmission electron microscopy, and electrochemical impedance spectroscopy were used to characterize as-prepared TiO 2 -CNE. These methods confirm that the surface area-to-volume ratio and electron transfer rate of TiO 2 -CNE are considerably greater than those of the bare electrode. In addition, the amperometric response for acetaminophen (AP) oxidation is remarkably facilitated by 13.9 times at the TiO 2 -CNE by the enlarged surface area-to-volume ratio, as well as the exposure of high-energy (001) facets. Furthermore, the constructed electrochemical sensor displays excellent analytical performance for AP detection over a range of 0.002–100.0   μM, with a detection limit of 0.83   nM ( S / N =3). The electrode was applied for the in vitro determination of AP in fish blood 30   min after injection in the abdominal cavity. Consequently, the present approach shows feasibility and great potential in constructing highly sensitive and low-consumption miniaturized electrochemical sensors in the field of biological applications.