| In contrast to randomly oriented titanium oxide(Ti O2) nanoparticle as well as Ti O2 nanotube, Ti O2 nanotube array(TONTAs) possesses better photocatalytic efficiency because of its unique structure. However, the band gap of TONTAs is large, so its absorption spectrum is in the ultraviolet(UV) region(about 4% of sunlight). Zinc ferrite(ZFO) has a relative small band gap, it can absorb more sunlight than that TONTAs, but its recombination rate of photoelectrons and holes is high, so the phtocatalytic efficiency of ZFO is low. Therefore, for further improving the photocatalytic efficiency of TONATAs and ZFO, electrochemical anodic oxidation method and hydrothermal method were accordingly used to prepare TONTAs and ZFO nanoparticles, respectively. Afterwards ZFO/TONTAs nanocomposites were obtained by perfusing ZFO nanoparticles into TONTAs under the bias voltage, and its photocatalytic performace was stuied in detail, the results were listed as below:(1) By varying the reaction parameters such as oxidation voltage, oxidation time and water content, the TONTAs with different diameters were prepared via the electrochemical anodic oxidation method. In presence of 9 vol% of water, the TONTAs, which were prepared after the anodic oxidation under 60 V for 2 h, possessed the largest diameter, and its average diameter was 180 nm(TONTAs-180). After TONTAs-180 was calcined at different temperatures, the phase transformations from amorphous to anatase, rutile were carried out with the increase of calcination temperature. In this study, the phase tranformation temperature between anatase and rutile was 800?. The photocatalytic degradation of Methyl orange(MO) was used as a probe reaction. After TONTAs-180 was calcined at 600?, it exhibted optimal photocatalytic activity. By adding 0.5 wt% of the above TONTAs-180 into the MO solution(20 mg/L), they could completely photodegrade the MO molecules after the irradiation under UV light for 70 min.(2) By mediating the p H value and the amount of lactoferrin(LF), the ZFO nanoparticles with different hydraulic diameters were prepared via the hydrothermal method. In the absence of LF, the smallest ZFO nanoparticles were synthesized when p H=8, and its hydraulic diameter was 45 nm. However, the ZFO nanoparticles with the largest saturation magnetization(Hs) were obtained when p H=10, its Hs was XX. LF had less effects on constraining ZFO grain size, but it could accelerate the nucleation of ZFO and significantly improve the crystallinity of ZFO. Hereinto, the Hs of the ZFO nanocrystals which were syntheiszed in presence of 50 mg(ZFO-50LF) was 19.9 emu/g. The photocatalytic degradation of MO was used as a probe reaction, and 0.5 wt% of ZFO-0LF and ZFO-50 LF were separately added into the MO solutions(20 mg/L). After being irradiated under UV light, it was found that ZFO-50 LF had better photocatalytic performance than ZFO-0LF, which suggested LF could remarkablely enhance the photocatalytic efficiency of ZFO. ZFO-0LF needed 6 h to completely photodegrade the MO molecules, whereas ZFO-50 LF only needed 4 h.(3) By altering the concentration of ZFO nanoparticle suspensions, the bias voltage value and the perfusion time, different ZFO/TONTAs nanocomposites were prepared via the perfusion method under the bias voltage. It indicated that the thickness of Ti O2 tube wall increased with the augmentation of the concentration of ZFO nanoparticle suspensions, but the bias voltage value as well as the perfusion time had less effects on the thickness of Ti O2 tube wall. No blocking phenomenon could be observed when 0.025 mg/L of ZFO nanoparticles were perfused into TONTAs under 60 V for 1 h. The photocatalytic degradation of Methylene Blue(MB) was used as a probe reaction under the simulated sunlight irradiation, and the effect of the calcination temperature on photocatalytic performance of ZFO/TONTAs nanocomposites were studied. Meanwhile, the photocatalysis synergy enhancement mechanism of ZFO/TONTAs nanocomposites was discussed in detail. Under the simualted sunlight irradiation, all the ZFO/TONTAs samples had the photocatalytic activity, and the ZFO/TONTAs after the calcination at 750?(ZFO/TONTAs-750?) exhibied optimal photocatalytic activity. After being irradiated under the simulated sunlight for 50 min, ZFO/TONTAs-750°C could completely make the degradation of MB molecules. In contrast to the individual TONTAs as well as ZFO nanoparticles, ZFO/TONTAs nanocomposites possessed better photocatalytic efficiency because of the formation of nano heterojuction structure in the interface of ZFO and Ti O2. |
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