Preparation of Lotus Root-like TiO2 Nanotube Arrays in NH4F-(NH4)2SO4 Composite Electrolyte and Its Photogenerated Cathodic Protection Performance
At present,TiO2,as a low-cost and non-polluting N-type semiconductor material,has been applied to photogenerated cathodic protection technology due to its excellent photoelectric conver-sion performance.In comparison with the ordinary nanotube arrays,the highly ordered lotus root-like TiO2 nanotube arrays(TNTAs)present much larger specific surface area and more effective photoreaction sites,which is conductive to enhancing the photoelectrochemical properties of TiO2 nanotube arrays.In this paper,lotus root-like TiO2 nanotube arrays were prepared by a two-step anodization process in NH4F-(NH4)2SO4 composite electrolyte.The effect of different anodization voltages on the performance of TiO2 nanotube photoanodes was studied.The structure,morphology and separation rate of photogenerated carriers of TNTAs prepared by different appllied anodic oxidation voltages were studied by XRD,SEM and photoluminescence spectra(PL).At the same time,under the irradiation of a simulated sunlight,the photoelectrochemical performance was evaluated by the photocurrent density measurement,and the ca-thodic protection effect of the photoanode on 304 stainless steel was evaluated by measurements of open circuit potential and Tafel polarization potential,as well as by fitting EIS curves.The results show that when the anodic oxidation voltage is 25 V,TNTAs have clear lotus root-like shape,high regularity,high photogenerated carrier separation rate and high photogenerated current density.Accordingly,the prepared TNTAs present lower open circuit potential,while better cathodic protection effect for 304 stain-less steel substrates.
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