Preparation Of TiO₂ Nanotube Array And Preliminary Study On Its Electrocatalytic Performance For Hydrogen Evolution

Nanotube arrays have a highly regular,high specific surface area array structure that can significantly improve the material exchange efficiency.However,TiO₂ nanotube arrays have great potential for hydrogen evolution from electrolyzed water,but due to their wide bandgap?Eg=3.2 eV for anatase,Eg=3.0 eV for rutile?and lower quantum efficiency,hydrogen evolution reduced performance.In view of the above problems,in this paper,TiO₂ nanotube arrays were prepared by two anodizing methods using ammonium fluoride glycol solution as the electrolyte,and TiO₂ nanotubes were used as the base material for composite modification.X-ray Diffraction?XRD?,Scanning Electron Microscopy?SEM?and Transmission Electron Microscopy?TEM?were used to characterize the samples.The TiO₂ nanotube array was used as the working electrode.Electrochemical workstation was used to test the hydrogen evolution performance of electrolyzed water.The anodic oxidation method was used to prepare TiO₂ nanotube arrays with high vertical regularity and uniform diameter.The effects of oxidation time,oxidation voltage and electrolyte concentration on the morphology of nanotubes and the formation mechanism of TiO₂ nanotube arrays were studied.The XRD results showed that the annealed nanotube arrays were anatase crystals with high crystallinity.Through the test of hydrogen evolution performance of the sample electrolyzed water,the voltage in the range of-1.8^-0.3 V vs Hg/HgO,the current density of the TiO₂ nanotube array is 20.5 mA cm^-2 at the current density of 0 mA cm^-2 The overpotential relative to the standard hydrogen electrode?0 V vs.NHE?is 0.44 V.The CuO-TiO₂ nanotube arrays were prepared by calcining the TiO₂ nanotube arrays by thermal decomposition reaction of Cu?NO₃?₂ with TiO₂ nanotube array as the base material.The results show that CuO is successfully loaded on the surface of the nanotube array and inside the tube,and progressively decreases from the top of the tube to the bottom of the tube.The hydrogen evolution performance test shows that the current density of the CuO-TiO₂ nanotube array reaches 56.5 mA cm^-2,which is 2.75 times that of the pure TiO₂ nanotube array,and the slope of the current density-voltage characteristic curve of the CuO-TiO₂ nanotube array is higher than that of the TiO₂.The nanotubes become larger,and when the current density is 0 mA cm^-2,the overpotential decreases by0.18 V.Compared with TiO₂ nanotube arrays,CuO-TiO₂ nanotube arrays have significant hydrogen evolution properties in electrolyzed water.Using TiO₂ nanotube arrays as the base material,V₂O₅-TiO₂ nanotube arrays were prepared by hydrothermal method.The morphology of V₂O₅-TiO₂ nanotube arrays is regular.XRD results show that the V₂O₅-TiO₂ nanotube array still maintains the anatase phase structure of TiO₂.The hydrogen evolution performance test showed that when the concentration of NH₄VO₃ solution was 5 g/L,the V₂O₅-TiO₂ nanotube array exhibited a lower hydrogen evolution overpotential of 0.13 V,which was 0.31 V lower than that of the TiO₂ nanotube array.