Xiani Huang

Controllable synthesis of well-ordered TiO 2 nanotubes in a mixed organic electrolyte for high-efficiency photocatalysis

Well-ordered TiO2 nanotube arrays (TNAs) were fabricated by electrochemical anodization in a mixed organic electrolyte consisting of ethylene glycol and glycerol. The morphology, structure, crystalline phase, and photocatalytic properties of TNAs were characterized by using TEM, SEM, XRD and photodegradation of methylene blue. It was found that the morphology and structure of TNAs could be significantly influenced by the anodization time and applied voltage. The obtained tube length was found to be proportional to anodization time, and the calculated growth rate of nanotubes was 0.6 μm/h. The microstructure analysis demonstrated that the diameter and thickness of the nanotubes increased with the increase of anodization voltage. The growth mechanism of TNAs was also proposed according to the observed relationship between current density and time during anodization. As expected, the obtained TNAs showed a higher photocatalytic activity than the commercial TiO2 P25 nanoparticles.

Hydrogen Generation by Hydrolysis of the Ball Milled Al-C-KCl Composite Powder in Distilled Water

In the present investigation, the Al-C-KCl composite powders were prepared by a ball milling processing in an attempt to improve the hydrogen evolution capacity of aluminum in water. The results showed that the hydrogen generation reaction is affected by KCl amount, preparation processing, initial aluminum particle size and reaction temperature. Increasing KCl amount led to an increased hydrogen generation volume. The use of aluminum powder with a fine particle size could promote the aluminum hydrolysis reaction and get an increased hydrogen generation rate. The reaction temperature played an important role in hydrogen generation rate and the maximum hydrogen generation rate of 44.8 cm3 min-1g-1of Al was obtained at 75oC. The XRD results identified that the hydrolysis byproducts are bayerite (Al(OH)3) and boehmite (AlOOH).

Preparation of Well-Ordered TiO2 Nanotube Arrays by Electrochemical Anodization of Titanium Foil in Neutral Electrolytes

To obtain high performance TiO2 nanotube arrays (TNAs)-based material is interesting because of its wide applications in photocatalysis field such as solar energy conversion, photocatalysis and sensors. In the present work, the well-ordered TNAs were prepared by electrochemical anodization of titanium foil in the SO42−/F− based electrolyte under 20 V for 2 h during which the Ti foil and Pt wire were used as anode and cathode, respectively. The FESEM results showed that the as-obtained TNAs were well-aligned on Ti substrate with ~ 1.5 μm in length and ~ 100 nm pore in diameter. The XRD results indicated that the as-formed TNAs was in the form of amorphous and could be transformed into crystalline anatase phase under the heat treatment at 450 °C. Meanwhile, the UV-vis diffuse reflectance spectra demonstrated that the band-gap of the obtained TNAs was narrower than the commercial TiO2 nanoparticles, indicating a better photocatalytic activity of the as-prepared TNAs over the commercial TiO2 nanoparticles.

On-Demand Hydrogen Generator Based on the Reaction between Aluminum Slurry and Alkaline Solution

In the present work, the aqueous slurry containing 30 wt% solid aluminum particles was prepared, using paraffin oil and oleic acid dispersant and surface active agent respectively. The results showed that no obvious aluminum particle sediment was observed even after being kept it at room temperature in air up to 15 days. The hydrogen generator based on the reaction of the aluminum slurry and sodium hydroxide aqueous solution was manufactured and could supply a maximum hydrogen flow rate of 20 NL/min. The dew point of the hydrogen from the generator was lower than -40oC, indicating the high purity of the as-obtained hydrogen. As expected the X-ray diffraction patterns revealed that the byproduct was bayerite.