TiO2 sol-embedded in electroless Ni–P coating: a novel approach for an ultra-sensitive sorbitol sensor

Abstract

A Ni–P–TiO₂ coating was readily prepared by direct incorporation of nano-TiO₂ sol into a Ni–P solution followed by electroless deposition. This coating was applied as a working electrode in an electrochemical sensor for the first time. The morphologies of the TiO₂ sol and the coated surface were well characterized by TEM, SEM and AFM. The high hydrophilicity of this surface was verified by contact angles of 40.7/41.8. Here, the appropriate amount of TiO₂ within the nanocomposite was optimized (2 g L⁻¹) prior to applying as an electrode. Interestingly, the electrocatalytic activity of the coating towards the oxidation of alcoholic compounds was investigated by linear sweep voltammetry. Apparently, incorporation of TiO₂ into the composites substantially improved the electrocatalytic activity of Ni–P and 2 layers of Ni–P/Ni–P–TiO₂ coating provided the highest sensitivity for all analytes, especially for sorbitol. A low LOD value of 1.0 nM and a wide linear range of 2.0 nM to 0.2 mM were achieved for sorbitol. Furthermore, a high stability and high reproducibility (2.96% RSD) for this system were obtained. Owing to ultra-high sensitivity, wide linearity, high stability, easy preparation and low cost, it might be a promising tool for early diagnosis of diabetes via sorbitol detection.