| Stainless steel corrosion is mainly caused by the presence of a large number of chloride ions in the environment,ocean solution as a strong corrosion electrolyte bring much harm to stainless steel.Therefore,developing a kind of economic,environment friendly,safe and non-toxic anticorrosion measures has become the key to solve marine corrosion problems.In recent years,the photocathodic protection of TiO2 nanomaterials has attracted a lot of attention due to its reproducibility.However,the wide band-gap of TiO2 is large,the utilization rate of sunlight is low and the light carrier is easy to compound,resulting in low light quantum efficiency.In order to improve the defects of TiO2 nanomaterials,this paper utilizes two-step anodized oxidation to prepare WO3/TiO2 composite films,and utilizes hydrothermal method to prepare ZnFe2O4/TiO2 and ZnWO4/TiO2 composite films on TiO2 nanotubes with zinc semiconductor ZnFe2O4 and ZnWO4.The morphology,composition,performance of the samples are characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),X ray photoelectron spectroscopy(XPS),UV-vis diffuse reflectance spectrophotometry(UV-vis-DRS)and photoelectrochemical performance tests including open circuit potential(OCP),photocurrent response,polarization,Mott-Schottky.TiO2 nanotubes prepared by different anodized oxidation conditions were tested by SEM.The morphology of the two-step anodized oxidation sample at 20 V voltage is more regular.The SEM of WO3/TiO2 composite films show that WO3 nanomaterials adhered to the surface of TiO2,but did not affect the formation of nanotubes.Then the photochemical properties of the WO3/TiO2 composite films with different loads were investigated under simulated solar light.The results show that under the simulated solar light,the optimal sample photocurrent density of WO3 attached to the surface of TiO2 nanotubes can reach 1200 μA/cm2 and has a certain energy storage effectThe prepared ZnFe2O4/TiO2 composite films are composed of ZnFe2O4 nanoparticles and TiO2 nanotubes.With the increase of the load,some nanoparticles are gradually loaded into the internal TiO2 nanotubes,and the loaded materials are spinel structure.The DRS test show that ZnFe2O4 broadened the absorbance of TiO2 and reduced the band-gap of TiO2 nanotubes to 3.08 eV.The photocathodic protection performance of pure TiO2 nanotubes and ZnFe2O4/TiO2 composite films on 304 stainless steel was measured by a potentiostat under visible light.The photocurrent test results show that the photocurrent density of the composite film is 58 μA/cm2,about 3 times of the pure TiO2 nanotubes.OCP results show that the potential of 304 stainless steel of the coupled composite film is reduced to-780 mV,obviously lower than the pure TiO2 nanotubes.The results show that ZnFe2O4/TiO2 composite films can provide a certain photocathode protection effect for 304 stainless steel.The prepared ZnWO4/TiO2 composite films show regular nanorods ZnWO4 on the TiO2 nanotubes by SEM.The composition and valence state of the load are determined by EDS,XRD and XPS,which is sanmartinite ZnWO4.DRS has been used to explore the absorbability of ZnWO4/TiO2 composite film.The results show that ZnWO4 broadens the absorption property of TiO2 in the visible and UV light regions,and reduces the band-gap to 2.75 eV.Under visible light,the electrochemical test results show that the photocurrent density of ZnWO4/TiO2 composite film reaches 54 μA/cm2,OCP reaches-780 mV,and the potential is still lower than TiO2 nanotubes when the light was cut off.The result suggests that the photocathodic protection effect of ZnWO4/TiO2 composite films on 304 stainless steel is better than that of pure TiO2 nanotubes,and it can still store electrons for 304 stainless steel under dark. |
PDF Full Text Request