RESUMO
ZnWO4/TiO2 composite films were fabricated on TiO2 substrate by hydrothermal method. The ZnWO4 nanorods-sensitized TiO2 coupled with 304 stainless steel was served as photoelectrode to study its anticorrosion effect for metal. Under visible light, the photocathodic protection ability of TiO2 and ZnWO4/TiO2 composite film was measured by photoelectrochemical program on potentiostat. Open circuit potential variation result showed that sanmartinite ZnWO4 nanorods could enhance the photoelectrochemical activity of TiO2, and the ZnWO4/TiO2 composite films could absorb energy and store electrons to play a role in corrosion protection for metal.
RESUMO
Titanium dioxide (TiO2) nanotube arrays coupled with a narrow gap semiconductor-bismuth selenide (Bi2Se3)-exhibited remarkable enhancement in the photocathodic protection property for 304 stainless steel under visible light. Bi2Se3/TiO2 nanocomposites were successfully synthesized using a simple two-step method, including an electrochemical anodization method for preparing pure TiO2 and a chemical bath deposition method for synthesizing Bi2Se3 nanoflowers. The morphology and structure of the composite films were studied by scanning electron microscopy, energy dispersion spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. In addition, the influence of the Bi2Se3 content on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. The photocurrent density of the Bi2Se3/TiO2 nanocomposites was significantly higher than that of pure TiO2 under visible light. The sensitizer Bi2Se3 enhanced the efficient separation of the photogenerated electron-hole pairs and the photocathodic protection properties of TiO2. Under visible light illumination, Bi2Se3/TiO2 nanocomposites synthesized by the chemical bath deposition method with Bi3+ (0.5 mmol/L) exhibited the optimal photogenerated cathodic protection performance for 304 stainless steel.
RESUMO
A series of ZnFeAl-layered double hydroxides/TiO2 (ZnFeAl-LDHs/TiO2) composites are synthesized by a combined anodization and hydrothermal method. The structure, surface morphology, photo absorption and photocathodic protection properties of these samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) and electrochemical tests. The unique structure of the ZnFeAl-LDHs reduces the charge carriers recombination, and the visible photoresponse property increase the light harvesting. The XPS study reveals that the electrons in the ZnFeAl-LDHs travel to TiO2, and the ZnFeAl-LDHs/TiO2 composites generate and transfer more electrons to 304 stainless steel (304SS), and exhibits a better photocathodic protection performance than pure TiO2. In addition, after intermittent visible-light illumination for four days, the photoanode still exhibits good stability and durability.
