TiO2 nanotube layers can be formed with titanium in the electrolytes containing fluoride by electrochemical method.The role of fluoride ion,the crystallinity of the anodic oxide,and the chemical state were investigate...TiO2 nanotube layers can be formed with titanium in the electrolytes containing fluoride by electrochemical method.The role of fluoride ion,the crystallinity of the anodic oxide,and the chemical state were investigated.The results show the anodic film is composed of oxide and a little amount of hydroxide.The presence of F- ions leads to chemical dissolution of Ti oxide layer and prevents hydroxide precipitation.Consequently,chemical dissolution rate increases with increasing the fluoride content in the range of 0-2%(in mass fraction) because F- ions in electrolyte attack the interface and allow the ions of the electrolyte to easily penetrate into the interface.The as-anodized TiO2 nanotubes exhibit an amorphous structure.Thermally treated nanotubes are composed of mixtures of the anatase and rutile phases.展开更多
Mesoporous titanium dioxide films were fabricated on titanium plates by micro-arc oxidation method.To increase the photocatalytic activity of the films,NH4NO3 was added to the H2SO4 solution,and anodizing was carried ...Mesoporous titanium dioxide films were fabricated on titanium plates by micro-arc oxidation method.To increase the photocatalytic activity of the films,NH4NO3 was added to the H2SO4 solution,and anodizing was carried out at high voltages using a DC power supply.The crystal structure,chemical composition,surface morphology and the optical property of the films were investigated by XPS,XRD,UV-VIS spectroscopy and SEM.The photocatalytic activity of the films was evaluated by the decomposition of aniline blue,and the activity of the films for the degradation turned out to be improved by the additives to the electrolyte solution.The enhanced photocatalytic activity might result from the increased porosity and nitrate ion incorporation into the anodic films by micro arcing,and thereby the TiO2 layer might exhibit an improved absorption property for the visible light.展开更多
The effects of microstructure of aluminum substrate on regular nanopore arrangement in anodic alumina layer were investigated. The dissimilar microstructure and texture on aluminum sheets were prepared by various cold...The effects of microstructure of aluminum substrate on regular nanopore arrangement in anodic alumina layer were investigated. The dissimilar microstructure and texture on aluminum sheets were prepared by various cold rollings and heat treatments, and anodic alumina nanoporous layers were fabricated by two step anodizing method at 40 V in oxalic acid solution. For the aluminum sheets with similar surface texture and annealing condition except purity, the regularity of the nanopore arrangement on the anodic alumina layer increased with purity of aluminum substrate. The difference of surface texture on AI sheets is not critical parameter for formation of ordered nanopore array compared with purity and heat treatment of substrate aluminum. The investigation suggested that the purity and reasonable annealing temperature of aluminum substrate are very important process to obtain the highly-ordered nanopore array on anodic alumina layer.展开更多
文摘TiO2 nanotube layers can be formed with titanium in the electrolytes containing fluoride by electrochemical method.The role of fluoride ion,the crystallinity of the anodic oxide,and the chemical state were investigated.The results show the anodic film is composed of oxide and a little amount of hydroxide.The presence of F- ions leads to chemical dissolution of Ti oxide layer and prevents hydroxide precipitation.Consequently,chemical dissolution rate increases with increasing the fluoride content in the range of 0-2%(in mass fraction) because F- ions in electrolyte attack the interface and allow the ions of the electrolyte to easily penetrate into the interface.The as-anodized TiO2 nanotubes exhibit an amorphous structure.Thermally treated nanotubes are composed of mixtures of the anatase and rutile phases.
基金supported by the research program of the Kookmin University in Korea
文摘Mesoporous titanium dioxide films were fabricated on titanium plates by micro-arc oxidation method.To increase the photocatalytic activity of the films,NH4NO3 was added to the H2SO4 solution,and anodizing was carried out at high voltages using a DC power supply.The crystal structure,chemical composition,surface morphology and the optical property of the films were investigated by XPS,XRD,UV-VIS spectroscopy and SEM.The photocatalytic activity of the films was evaluated by the decomposition of aniline blue,and the activity of the films for the degradation turned out to be improved by the additives to the electrolyte solution.The enhanced photocatalytic activity might result from the increased porosity and nitrate ion incorporation into the anodic films by micro arcing,and thereby the TiO2 layer might exhibit an improved absorption property for the visible light.
基金supported by the research program of Kookmin University in Korea
文摘The effects of microstructure of aluminum substrate on regular nanopore arrangement in anodic alumina layer were investigated. The dissimilar microstructure and texture on aluminum sheets were prepared by various cold rollings and heat treatments, and anodic alumina nanoporous layers were fabricated by two step anodizing method at 40 V in oxalic acid solution. For the aluminum sheets with similar surface texture and annealing condition except purity, the regularity of the nanopore arrangement on the anodic alumina layer increased with purity of aluminum substrate. The difference of surface texture on AI sheets is not critical parameter for formation of ordered nanopore array compared with purity and heat treatment of substrate aluminum. The investigation suggested that the purity and reasonable annealing temperature of aluminum substrate are very important process to obtain the highly-ordered nanopore array on anodic alumina layer.
