Study On The Fabrication Of Metal Composite Materials Based On TiO₂Nanotube Arrays And Sensing Properties

Titanium dioxide nanotubes arrays （TiO₂NTs） which possesses unique structure,physical and chemical properties, have attracted considerable interests due to its wideapplications such as photoelectricity, catalysis, chemical sensors and biomedical science.Depositing a metal material （such as Ni, Ag, Cu, Au） onto the TiO₂NTs to formnanocomposites is an effective method to improve its electrochemical properties. In thispaper, based on the researches of metal/TiO₂NTs composites at home and abroad,TiO₂NTs was used as a substrate electrode which was modified by metal in order toimprove the electrochemical properties of TiO₂NTs electrode. The modified compositeelectrode was used to electrocatalyte insulin and ethanol. The main contents of thispaper are as follows:①The Ni nanoparticles modified TiO₂NTs composite electrode was synthesizedby pulse electrodeposition （PED） technique and the multi-voltage step technique. Themorphology, phase structure, elemental analysis and composition of the samples wereinvestigated by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, energydispersive X-ray spectroscopy （EDX） and X-ray photoelectron spectroscopy （XPS）,respectively. SEM image shows that spherical Ni nanoparticles were well dispersed andembedded on and in the TiO₂NTs. XPS shows that the surface of Ni/TiO₂NTscomposite electrode is made up of Nickel and nickel hydroxide. The effect of differentdeposition time and different cycles on the morphology and electrochemical propertiesof Ni/TiO₂NTs electrode has been investigated.②Ni/TiO₂NTs composite electrode prepared by PED was used to detect insulin.Its electrocatalysis properties were also been investigated. The experimental resultsshowed that, the Ni/TiO₂NTs composite electrode had a good electrochemical responseto the insulin. The response mechanism was mainly based on the formation of aNi（Ⅱ）/Ni（Ⅲ） redox in alkaline medium. In the0.1mol/L NaOH electrolyte, theelectrode had a remarkable response to insulin. The insulin detector exhibited excellentsensitivity (0.49×10^-3A/（μmol/L.cm²）), the detection limit down to0.28μmol/L, linearrange （0.8¹.6μmol/L）. Otherwise, the composite electrode had good reproducibilityand stability.③Ni/TiO₂NTs composite electrode prepared by multi-voltage step technique wasused to detect and analyte ethanol.The effect of different concentrations of KOH electrolyte and scanning rates on the detection of ethanol were investigated by cyclicvoltammetry （CV）. The results showed that under the optimistic conditions, the Ni/TiO₂NTs composite electrode had a good response to ethanol. The sensitivity was0.0602A/（mol/L·cm²） and the linear range was from2.0×10^-3mol/L to2.0×10^-2mol/Lwith detection limit of1.27mmol/L（S/N=3）. The electrode also had sood reproducibility andlong service life. The simple preparation method, good analytical performance and lowcost make this composite electrode promising for the electroanalysis and sensing.