Study Of Non-enzymatic Glucose Sensor Based On TiO₂Nanotube Array Loaded Pt Nanoparticles

In this paper, a novel non-enzymatic glucose sensor was developed based on TiO2nanotube array as a substrate material and loading Pt nanoparticles on TiO2nanotube array (NTA). The regular orientation perpendicular TiO2NTA was prepared by method of anodization with properties of containing large specific surface area, thermal and acid-base tolerance and photocatalytic degradation ability, being a excellent suppoting material. The Pt particles were loaded on TiO2in situ by ion-exchange and the particle size of Pt was5nm with large specific surface area and high catalytic activity. Pt/TiO2NTA composite electrode showed high catalytic activity to glucose, negative detection potential (-0.5V vs. SCE)and highly self-cleaning ability, which provides a new possibility for developing new glucose sensors and has promising applications in blood glucose measurement and meidiator-free anodes for glucose biofuel cells.Two kinds of non-enzymatic glucose sensors were fabricated:One-time calcination electrode was developed based on TiO2NTA as supporting material prepared by anodizaton, calcined for3h in air atmosphere and treated by base-acid. Pt(NH3)4Cl2, as the Pt precursor, was ion-exchanged on the TiO2nanotube surface and reduced by NaBH4and the Pt/TiO2electrode was prepared well. SEM was carried out to investigate TiO2NTA morphology. The results of SEM show that the tube diameter and length were200nm and4um; TEM was carried out to investigate the Pt nanoparticles dispersion, of which the results demonstrate that the Pt nanoparticles uniformly deposited on TiO2surface with average grain size of5nm. XRD was used to characterzize TiO2crystal form. The anodized TiO2was amorphous, while the calcined TiO2was anatase. XPS was performed to investigate the valence state of Pt, of which the results showed that the deposited Pt was zero valent. The Pt/TiO2electrode can detect glucose at an applied potential of-0.5V(vs. SCE) with a linear range of1-15mM, a sensitivity of63.77μA·mM-1· cm-2and a detection limit of0.2mM at a signal-to-noise ratio of3. The interfering current ratio of0.1mM uric acid (UA) was0.2%, while that of0.1mM ascorbic acid (AA) was6.7%; The current response of1mM glucose only decreased by3%after2weeeks of regular measurements, showing good stability.Two-time calcination electrode was developed based on TiO2NTA as supporting material prepared by anodizaton, calcined for3h in N2atmosphere and treated by base-acid. Pt(NH3)4Cl2, as the Pt precursor, was ion-exchanged on the TiO2nanotube surface and subsequently calcined for3h in N2atmosphere again and finally reduced by NaBH4, and the Pt/TiO2electrode was prepared well. SEM, TEM, XRD, XPS characterizations were the same to that of above. The Pt/TiO2electrode can detect glucose at an applied potential of-0.4V(vs. SCE) with a linear range of0.5-4.5mM, a sensitivity of1.01386μ·AmM-1·cm-2and a detection limit of0.2mM (S/N=3). The interfering current ratio of0.1mM UA was0.93%and that of0.1mM AA was4.99%; The current response to1mM glucose only decreased by2.22%after2weeeks of regular measurements. Meanwhile, glucose electrocatalytic oxidation mechanism on the surface electrode was investigated. The oxidation peak current linearly increased with the square root of the scan rate, which indicated that the electrode reaction of glucose was a typical diffusion-controlled process. The glucose electrocatalytic oxidation was two-electron and two-proton process. The electrochemical impedance spectroscopy was carried out to detailed self-cleaning process research, of which the result indicated Pt/TiO2electrode contained the excellent photoeletrocatalysis ability and ensured the electrocatalytic oxidation ability of electreode to glucose.