Hong Yun

Sonoelectrochemical synthesis of highly photoelectrochemically active TiO2 nanotubes by incorporating CdS nanoparticles

Self-organized anodic TiO2 nanotube arrays (TiO2NTs) are functionalized with CdS nanoparticle based perfusion and deposition through a single-step sonoelectrodeposition method. Even controlled at 50 degrees C, CdS nanoparticles with smaller size and more homogeneous distribution are successfully synthesized in dimethyl sulfoxide (DMSO) under ultrasonic irradiation. Moreover, TiO(2) nanotubes can be filled with nanoparticles because of the ultrasonic effect. The CdS incorporated TiO2NTs (CdS-TiO2NTs) effectively harvest solar light in the UV as well as the visible light (up to 480 nm) region. Compared with pure TiO2NTs, a more than ninefold enhancement in photocurrent response is observed using the CdS-TiO2NTs. Maximum incident photon to charge carrier efficiency (IPCE) values of 99.95% and 9.85% are observed respectively for CdS-TiO2 nanotubes and pure TiO2NTs. The high value of IPCE observed with the CdS-TiO2NTs is attributed to the increased efficiency of charge separation and transport of electrons. A schematic diagram is proposed to illustrate the possible process of CdS formation in nanotubes under sonochemical and electrochemical conditions.

A Photoelectrochemical Study of n-Doped TiO2 Nanotube Arrays as the Photoanodes for Cathodic Protection of SS

In order to improve the characteristics of TiO 2 -based cathodic protection coatings, including the visible light response and the protection performance in the dark conditions, the n-doped TiO 2 nanotube layers with a highly ordered structure on titanium were prepared by a self-organized electrochemical anodization in fluorinated electrolyte. The structure and composition of the as-prepared nanotubes were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The n-doped TiO 2 nanotubes show a stronger absorption in the 400-550 nm range. The performances of photogenerated cathodic protection and the photoelectrochemical response for the n-doped TiO 2 nanotube layers coupled with 316L stainless steel (SS) under illumination and dark conditions were evaluated through the electrochemical measurements. It is found that the open-circuit potentials of 316L SS coupled with the n-doped TiO 2 nanotube layers shift negatively under visible light irradiation (λ > 400 nm). It is indicated that the n-doped TiO 2 nanotube layers are able to function effectively to provide a photogenerated cathodic protection for metals under regular sunlight conditions.

Synthesis Mechanism and Microstructure Characterization of BaIn2O4

The synthesis mechanism and microstructures of BaIn2O4 particles were analyzed by simultaneous thermogravimetry - differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM). Firstly, In(OH)3 and BaCO3 precursors were prepared by the co-precipitation method. Next, during the sintering process In(OH)3 initially decomposed into In2O3 and water, and then BaCO3 reacted with In2O3 to synthesize Ba4In6O13. Finally, Ba4In6O13 and In2O3 further reacted to form BaIn2O4. The obtained BaIn2O4 particles were in monoclinic structure and exhibited high crystal quality. The grains were tightly bound together and their boundaries became blurry. The grain sizes increased with increasing the sintering temperature.

Anatase TiO2 Films via a Sol-Gel and Hydrothermal Crystallization for Enhanced Corrosion Resistance

Anatase of TiO2films were supplied on the surface of 316L stainless steel by a sol–gel process followed by hydrothermal treatment in water. The as-prepared samples were characterized with filed emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. The corrosion performances of the films in 3.5 wt% NaCl solution were evaluated by electrochemical impedance spectroscopy (EIS) and polarization measurements. The results revealed that the corrosion resistance of the TiO2 films via the hydrothermal treatment at 170°C for 4h exceeded that of the counterparts treated by conventional calcination at 450°C. This could be attributed that the surface of such a sample was more compact and uniform, relatively well-crystallized, able to act as an optimal barrier layer to metallic substrates.

Fabrication of Hydrophobic Surfaces and its Electrochemical Research on Copronickel B30

A novel hydrophobic film was prepared by Stearic acid (SA) chemically adsorbed onto the cupronickel B30 surface. The film properties were characterized by means of water contact angle measurement and electrochemical techniques. The results indicate that the structure of the adsorbed film is hydrophobic, and the contact angle is 113.82° for water. AC impedance and polarization curve measurements show that the corrosion resistance of cupronickel B30 modified by stearic acid is improved remarkably, and the inhibition efficiency reached 66.85%. After hydrophobic modified by stearic acid, the inhibition efficiency could reach 88.85% in 3% NaCl solution with the concentration of 0.1 g/L Na2WO4.

Enhanced Anticorrosion Properties of SnO2 Coatings in Simulated PEMFC Environments by Hydrothermal Treatment

SnO2 coatings were supplied on the surface of 304 stainless steel (304SS) by a sol-gel process followed by hydrothermal treatments at different reaction temperature and time, respectively. The effects of hydrothermal temperature and time in pure water on the anticorrosion performances of the SnO2 films in simulated proton exchange membrane fuel cells (PEMFC) environments were investigated by potentiodynamic polarization curves, open circuit potential-time curves and electrochemical impedance spectroscopy (EIS). It was found that the SnO2 coated 304SS via the hydrothermal treatment showed a better corrosion resistance than the sample without hydrothermal treatment and bare 304SS. The SnO2 coated 304SS hydrothermally treated at 160°C for 3h showed the highest corrosion resistance among the samples. The results have been discussed in terms of surface structure of SnO2 film and its anticorrosion performance in simulated PEMFC environments.

The Effect of Hydrothermal Post Treatments on Corrosion Properties of SnO2 Films in Simulated PEMFC Environments

SnO2 films were supplied on the surface of 304 stainless steel (304SS) by a sol–gel process followed by a hydrothermal post treatment. The measurements of XRD, SEM and water contact angles were carried out to characterize the as-prepared samples. The effect of hydrothermal post treatments in different media such as deionized (DI) water, HF solution and NaOH solution on the corrosion performances of the SnO2 films in simulated proton exchange membrane fuel cells (PEMFC) environments was investigated by electrochemical impedance spectroscopy (EIS) and polarization measurements. The results suggested that the SnO2 films via the hydrothermal post treatment in 0.3 M NaOH solution showed a highest corrosion resistance and could act as an optimal barrier layer to metallic bipolar plates in simulated PEMFC environments. It could be attributed that the hydrothermal post treatment in NaOH solution was beneficial to improve the compact structure and enhance the hydrophobic property of the SnO2 films.

Inhibition Action and Adsorption Behavior of PESA on Copper

The inhibition action and adsorption behavior of an environment-friendly inhibitor polyepoxysuccinic acid (PESA) on copper in aqueous NaCl (0.02%) solution was investigated by means of electrochemical techniques. The results indicated that the best inhibition efficiency of PESA was 69.5% with the concentration of 12 mg/L at 20 . The adsorption of PASP prevented Cu from being corroded. The adsorption behavior of PASP followed Langmuir isotherm, it was spontaneous, and belonged to chemical adsorption.

Inhibition Action and Adsorption Behavior of 3-Amino-1,2,4-Triazole on Copper in 3% NaCl Solution

The corrosion inhibition of copper in 3% NaCl solution by 3-amino-1, 2, 4-triazole (ATA) has been studied in relation to the concentration of the inhibitor using electrochemical (AC impedance and dc polarization) techniques. The results indicate that ATA has good corrosion inhibition for copper in 3% NaCl solution. The inhibition efficiency attains the maximum value of 97.65% when the concentration of ATA is 20 mg•L-1.Polarisation curves show that ATA behaves as a type of cathodal inhibition in 3% NaCl solution. Adsorption of the ATA is found to follow the Langmuir’s adsorption isotherm, and the adsorption mechanism is typical of chemisorption.