Study On The Fabrication Of V₂O₅/TiO₂Nanotubes And Its Electrochemical Applications

One-dimension TiO₂nanotubes, which possesses unique structure, physical andchemical properties, has attracted considerable interests due to its wide applicationssuch as sensors, photocatalytic water spliting, Li ion batteries， electrochemicalcapacitors. To improve its functional properties, depositing a metallic oxide material（such as WO3, V₂O₅）onto the TiO₂nanotubes to form nanocomposites is an effectivemethod because the metal element can modify the surface properties of the TiO₂such assurface structure and catalytic activity. This paper carried out following the research ofmetallic oxide/TiO₂nanotube composites at home and abroad. In this paper, a V₂O₅nanoparticle-TiO₂nanotube composite was synthesized by a pulse electrodeposition（PED） technique. The morphology and phase structure of the as-prepared products wereinvestigated by field emission scanng electron microscopy （FESEM） and X-raydiffraction （XRD）. The electrochemical properties of V₂O₅/TiO₂composite and itscapacitance performance were investigated. The main results of this paper are asfollowing:â‘ The pulse electrodeposition parameters （current density, current off-time,current on-time, deposition time and electrolyte concentration） play key roles incontrolling the size and distribution of V₂O₅nanoparticles on the TiO₂nanotubes. In abath containg0.2mol/L VOSO4·6H2O, V₂O₅nanoparticles with average size rangingfrom10nm to60nm were obtained by changing current density （35mA/cm2¹40mA/cm2）. The particle size of V₂O₅deposited at different current off-time（10ms¹00ms） was in the range of10nm to70nm. V₂O₅nanoparticles （5nm³5nm）were obtained by controlling the current on-time between8ms and16ms. The particlesize of V₂O₅deposited at deposition time （20min⁶0min） was in the range of5nm to110nm. V₂O₅nanoparticles （5nm³5nm） were obtained by changing the electrolyteconcentration （0.01～0.2mol/L）.â‘¡The electrochemical properties of V₂O₅/TiO₂composite were investigated bycyclic voltammetry （CV）. The CV results indicated a quasi-reversible electron transferprocess. The size, distribution, loading of the electroactive materials V₂O₅and thecrystalline structure of TiO₂nanotube had a strong effect on the electrochemicalproperties of V₂O₅/TiO₂composite. Large current density of V₂O₅/TiO₂composite wereobtained by decreasing V₂O₅particle size and increasing distribution and loading of the V₂O₅nanoparticles.â‘¢The effect of deposition conditions on the lithium ions intercalation ofV₂O₅/TiO₂composite was investigated by chronopotentiometry measurements. Theresults indiacted a specific capacitance of of V₂O₅/TiO₂composite can be increased byoptimizing deposition conditions. A maximum discharge specific capacitance wasobtained for the V₂O₅/TiO₂composite synthesized at current of35mA/cm2. Bymodulating deposition time （20min⁶0min）, the V₂O₅/TiO₂prepared at40min had amaximum discharge specific capacitance. Under different current off-time（10ms,50ms,100ms）, the V₂O₅/TiO₂prepared at100ms had a maximum dischargespecific capacitance. The capacity retention was70.8%after25cycles. The V₂O₅/TiO₂composite exhibited excellent cycle stability...