Q2. What is the effect of the TNT films on photocatalytic activity?
It is generally believed that both the absorption of the incident photons and adsorption of 2,3-DCP by the TNT films should increase with the increasing of tube length, which are beneficial to achieve a greater photocatalytic degradation rate.
Q3. What is the effect of the thin nanotubes on the photocatalytic activity?
In other words, the thinner wall is easier for the excited electrons migrate from bulk to surface and provides more accessible carriers trapped on catalyst surface for the photocatalysis thus, enhancing the photocatalytic efficiency.
Q4. What is the role of the XRD in the photocatalytic activity of TNT?
Since the interaction between two reactions could significantly affect the morphology and structure of TNT films, it would be a key factor to influence the photocatalytic activity of catalysts.
Q5. What is the effect of anodizing time on the structure of the TNT nanotube?
Although the formation of TiO2 nanotubes is a result of the competition between the electrochemical etching of Ti and the chemical dissolution of TiO2 occurring in the electrolyte solution during anodization [16], the chemical dissolution would be a limiting factor for the growth of nanotube length and wall, depending on the solution temperature.
Q6. What is the reason why the photoactivity declined with the longer nanotubes?
The fact that the photoactivity declined with the longer nanotubes may be attributed to the limited depth of incident photon penetration through the nanotubes and the diffusion of reactant inside nanotubes [27].
Q7. At what temperature did the rutile peak of anatase disappear?
At 800 °C (pattern 5), the diffraction peak of anatase (101) disappeared completely and the rutile peak (110) became very strong.
Q8. What is the effect of the nanotubes on the photocatalytic activity?
7]The photocatalytic activity of the TiO2 nanotubes after calcination at different temperatures was evaluated in terms of 2,3-DCP photodegradation in aqueous solutions.
Q9. What are the main techniques for synthesizing titania?
In recent years, considerable efforts have been focused on new techniques for synthesizing titania with a unique nanoarchitecture consisting of vertically-oriented, immobilized, highly-ordered and high-aspect ratio nanotubes such as hydrothermal treatment [8,9], template synthesis [10], and anodic oxidation [11].
Q10. What is the effect of the length of the nanotubes on the photoactivity of TNT?
If the length of nanotubes is longer than the effective depth of light penetration, the lower part of nanotubes has a difficulty to well absorb UV light.
Q11. At what temperature did the rutile diffraction peak occur?
It can be seen that at 300 °C (pattern 3), only a small diffraction peak of anatase at 25.35o (101) but no any the rutile diffraction peaks occurred.
Q12. What is the common method used to synthesize titania?
Kasuga et al. [8] used a hydrothermal process for treatment of titania particles in NaOH solution at 110 °C and then washed with water and hydrochloric acid to form titania nanotubes.
Q13. Where did the NH4F, H2SO4 and 2,3-DCP be?
Titanium foils (140 μm thickness, 99.6% purity) were purchased from Goodfellow Cambridge Ltd. Ammonium fluoride (NH4F), H2SO4, and 2,3-DCP were purchased from Aldrich Chemical Company.
Q14. What is the effect of the nanotube wall thickness on the photocatalytic activity?
Comparing the affecting factors of nanotube wall thickness and length, it seems that the wall thickness is a more important parameter influencing the overall photocatalytic efficiency of the 2,3-DCP decomposition reaction than the tube length.[Fig.