Ti/TiO₂Nanotube Array/Ni Composite Electrodes for Nonenzymatic Amperometric Glucose Sensing

Abstract

TiO2 nantube arrays (NTAs) with a tube diameter of about 100 nm were prepared by anodic oxidation, and a Ni layer about several tens of micrometers thick was electrodeposited on the surface of TiO2 NTAs. The synthesized Ti/TiO2 NTA/Ni composite electrodes were used for nonenzymatic glucose detection. The behavior of the anodic TiO2 NTA/substrate Ti metal is analogous to characteristics of an n-type semiconductor/metal Schottky barrier diode. The characteristic would enhance the rapid transport of surface reaction electrons to the metal substrate, thereby enhancing the performance of biosensors. Cyclic voltammogram investigations indicate that calcined Ti/TiO2 NTAs have a wider work potential window than that of Ti/TiO2 NTAs without calcinations and Ti foils. Moreover, the low saturated current in alkaline solutions under a constant potential makes Ti/TiO2 NTAs favorable as substrate materials for biosensors. For the Ti/TiO2 NTA/Ni composite electrodes, the relationship between the linear range and the potential was investigated. The positive line scans and the amperometric response curves to glucose indicated that a potential of 0.5−0.6 V would be favorable to get a wide linear range for detecting glucose. The sensitivity of the composite electrodes can reach a value as high as 200 μA mM−1 cm−2, and the detection limit was about 4 μM with a signal-to-noise ratio of 3 (S/N = 3). The present Ti/TiO2 NTA/Ni composite nonenzymatic amperometric glucose sensor could find potential applications in a good biosensing platform for other redox proteins and enzymes.