Selective growth of ZnO nanorods on SiO2/Si substrates using a graphene buffer layer

A promising strategy for the selective growth of ZnO nanorods on SiO₂/Si substrates using a graphene buffer layer in a low temperature solution process is described. High densities of ZnO nanorods were grown over a large area and most ZnO nanorods were vertically well-aligned on graphene. Furthermore, selective growth of ZnO nanorods on graphene was realized by applying a simple mechanical treatment, since ZnO nanorods formed on graphene are mechanically stable on an atomic level. These results were confirmed by first principles calculations which showed that the ZnO-graphene binding has a low destabilization energy. In addition, it was found that ZnO nanorods grown on SiO₂/Si with a graphene buffer layer have better optical properties than ZnO nanorods grown on bare SiO₂/Si. The nanostructured ZnO-graphene materials have promising applications in future flexible electronic and optical devices.     

原位水解低温制备ZnO-TiO2复合半导体光催化剂

以乙二醇作反应物和溶剂，通过原位水解低温晶化法在较温和的条件下制备出纳米复合ZnO-TiO2光催化剂．通过TEM、XR-D、UV-Vis、BET、粒度分析等技术手段对光催化剂进行了表征，发现ZnO-TiO2是由纳米级的ZnO和TiO2粒子组成，该光催化剂分散性好，并且可以吸收部分可见光，扩大了光吸收范围。光催化降解甲基橙实验表明，ZnO-TiO2纳米复合氧化物的光催化活性明显高于自制的TiO2和ZnO单一氧化物和商业P25TiO2．     

Studies on TiO(2)/ZnO photocatalysed degradation of lignin

The photocatalytic degradation of lignin obtained from wheat straw kraft digestion has been investigated by using TiO(2) and ZnO semiconductors. ZnO has been found to be a better photocatalyst than TiO(2). The different variables studied, include catalyst dose, solution pH, oxidant concentration and initial concentration of the substrate. The degradation of lignin was favorable at pH 11. Optimum values of catalyst dose and oxidant concentration were found to be 1g/l and 12.2 x 10(-6) M, respectively. The degradation of the organic compound was also evaluated as COD removal and increase in the COD removal was observed with increase in degradation rate. An attempt has also been made to explore the applicability of ZnO in immobilized mode for the degradation of lignin under solar light for industrial scale application. Further the comparative evaluation of ZnO in slurry/immobilized mode has been carried out.     

Photocatalytic degradation of phosphamidon on semiconductor oxides

The photocatalytic degradation of a small concentration of an organo-phosphorous (OP) insecticide phosphamidon, in water, on ZnO and TiO(2) is investigated. Of the two semiconductor oxides, TiO(2) is found to be more effective as a photocatalyst for this reaction. Several factors such as concentration of phosphamidon, pH of the system, catalyst loading and presence of anions are found to influence the degradation rate. The reaction follows apparent first-order kinetics, though at higher concentrations, there is a reduction in the order of the reaction. There is a simultaneous formation and decomposition of H(2)O(2) in the system, resulting in a periodic increase and decrease in its concentration. The catalyst TiO(2) is effective for the degradation of phosphamidon in direct sunlight and thus opens the possibility of solar decontamination of wastewater containing small amounts of OP pesticides.     

A new submerged membrane photocatalysis reactor (SMPR) for fulvic acid removal using a nano-structured photocatalyst

The study focuses on the degradation of fulvic acid by nano-structured TiO2 in a submerged membrane photocatalysis reactor (SMPR). It has been demonstrated that the composite TiO2 photocatalyst could be automatically settled due to its gravity and then be easily separated by MF membrane. In addition, it was more efficient to maintain high flux of membranes than that of commercial TiO2 P25. The paper describes the effects of operational parameters on the photocatalytic degradation of fulvic acid in SMPR. It was found that the photocatalyst at 0.5 g/L and airflow at 0.06 m3/h were the optimal condition for the removal of fulvic acid (FA) and the FA degradation rate was higher at acidic condition than that at alkalinous media. In order to compare the effects of different filtration duration on permeate flux rate of MF, P25 powder and nano-structured TiO2 were employed. According to the experiments, the permeate flux rate of MF is improved and thus the membrane fouling phenomenon is reduced with the addition of nano-structured TiO2 catalyst. Therefore, the submerged membrane photocatalysis reactor can be potentially applied in photocatalytic oxidation process during drinking water treatment.     

氧化锌/氧化镁纳米复合材料的制备及其光催化性能研究

采用微波辅助共沉淀法制备了纳米氧化锌/氧化镁(ZnO/MgO)光催化剂,并对催化剂样品进行了X射线衍射、透射电镜、红外光谱以及紫外-可见吸收光谱等表征。以亚甲基蓝(MB)为目标降解物对不同锌镁比的ZnO/MgO催化剂样品及相同方法下合成的ZnO及MgO进行光催化降解实验。结果表明:合成的纳米ZnO/MgO光催化剂由立方相的ZnO和非晶相的MgO组成,其尺寸均匀,在40nm左右,并在紫外区域吸收性能良好。光催化降解MB实验表明,锌镁比为2∶1时ZnO/MgO催化剂的光催化性能最佳。     

Efficient visible light driven photocatalytic removal of NO with aerosol flow synthesized B, N-codoped TiO2 hollow spheres

In this study, we demonstrate that aerosol assisted flow synthesized B, N-codoped TiO(2) photocatalyst possesses superior photocatalytic activity to pure and single element doped counterparts on the degradation of NO in a flow system under both simulated solar light and visible light irradiation. Characterization results revealed that B, N-codoped TiO(2) photocatalyst was composed of hollow microspheres. Boron and nitrogen were in the form of Ti-O-B and N-Ti-O structures, respectively. The introduction of B and N into the TiO(2) lattice could effectively tune the band gap of TiO(2) and extend its optical response to the visible-light region. The synergistic effect of B and N codoping on visible light driven photocatalytic activity enhancement of TiO(2) was discussed on the basis of experimental results.     

活性炭负载TiO2光催化材料的研究

活性炭(AC)及活性炭纤维(ACF)作为光催化剂载体具有较高的比表面积和较强的吸附性能,可以有效提高负载型光催化剂TiO2/AC和TiO2/ACF对有机污染物的光催化降解效率.首先介绍了TiO2光催化剂的结构特性以及各种掺杂改性方法,对负载型TiO2/AC及TiO2/ACF光催化剂的各种制备方法进行了详细评述.在此基础上,讨论了影响有机污染物光催化降解性能的重要因素,指出了负载型TiO2光催化材料研究中有待解决的问题和发展方向.     

纳米TiO2光催化降解双酚A的研究

采用溶胶-凝胶法制备了纳米TiO2.以纳米TiO2为光催化剂,研究了在氧气存在条件下对典型内分泌干扰物质双酚A的光催化降解反应.分别讨论了分子氧、不同晶型、不同晶粒尺寸的纳米TiO2以及光照时间对双酚A降解反应的影响.结果表明,以0.2L/min的通氧速度进行光化学反应5h,锐钛矿型TiO2晶粒尺寸在10～20nm时对双酚A的光催化降解效率最好.     

Utilization of ZnO nanocones for the photocatalytic degradation of acridine orange

A facile aqueous solution process was used to synthesize well-crystalline ZnO nanocones at 60 degrees C by using zinc nitrate hexahydrate and sodium hydroxide. The morphological, structural and optical properties of the synthesized ZnO nanocones were investigated by using field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) equipped with high-resolution (HRTEM), X-ray diffraction (XRD) pattern, Fourier transform infrared (FTIR) spectroscopy and UV-Vis. spectroscopy measurements. The structural and optical properties of the as-synthesized nanocones confirmed a pure and well crystalline product possessing wurtzite hexagonal phase. The as-synthesized ZnO nanocones were used as photocatalyst for the efficient photocatalytic degradation of acridine orange. The acridine orange was almost completely degraded within 105 minutes. This research demonstrates that the simply synthesized ZnO nanostructures could be efficient photocatalyst for the photocatalytic degradation of various organic dyes and chemicals.     

多孔Ag/TiO2的制备及其光催化性研究

以工业TiOSO4溶液水解得到的多孔偏钛酸为载体,通过光催化还原法制备了多孔Ag/TiO2光催化剂.用XRD、SEM、EDS及低温氮吸附脱附法对样品进行了表征.以光催化氧化降解亚甲基蓝为目标反应,考察了不同制备条件对样品光催化活性的影响.结果表明,制备的Ag/TiO2为负载有非晶态纳米银粒的锐钛矿型TiO2光催化剂,比表面积高达197m2/g,其光催化活性远优于未载银的TiO2.     

Comparison of zinc oxide nanoparticles and its nano-crystalline particles on the photocatalytic degradation of methylene blue

Comparison of ZnO nanoparticles and its nano-crystalline particles on the photocatalytic degradation of methylene blue was investigated. ZnO nanoparticles and its nano-crystalline particles were synthesized from sprayed droplets of an aqueous zinc nitrate solution by flame spray pyrolysis and spray pyrolysis assisted with an electrical furnace, respectively. ZnO nanoparticles of 20 nm in average diameter and ZnO nano-crystalline particles of 20 nm in the grain size were prepared to compare the photocatalytic activity. The photocatalytic activity of those ZnO particles was evaluated by measuring the degradation of methylene blue in water under the illumination of ultraviolet rays. Effect of the particle morphology, initial concentration of methylene blue, and photocatalyst loading on the degradation of the methylene blue was investigated under the illumination of ultraviolet rays. The photocatalytic degradation capacity of the ZnO nanoparticles was higher than that of the ZnO nano-crystalline particles. The efficiency of photocatalytic degradation of methylene blue increased with increase in photocatalyst loading and decrease in initial concentration regardless of particle morphology.     

Photocatalytic activity of heterostructures based on TiO2 and halloysite nanotubes

A one-step solvothermal method was used to prepare TiO(2)/halloysite composites. TiO(2) nanoparticles were deposited on the platform of the halloysite nanotubes (HNTs). XRD, FT-IR, FE-SEM, and TEM were applied to investigate the structures and morphologies of the resultant samples. The as-prepared TiO(2)/HNTs photocatalyst exhibits pH sensibility on the degradation of methanol and a higher photocatalytic activity on the degradation of acetic acid. The combination of the photocatalytic property of TiO(2) and the unique structure of halloysite endowed this material with a bright perspective in degradation of organic pollutant.     

Preparation and photocatalytic activity of nanoglued Sn-doped TiO2

In this paper, Sn-doped TiO(2) photocatalyst was prepared and immobilized on a glass substrate using an about-to-gel SiO(2) sol as a nanoglue. The characterization of the Sn-doped TiO(2) by XRD showed that 5% Sn content is formed by anatase and rutile crystallites. Characterization of the nanoglued photocatalyst by the BET measurement, TEM, and SEM showed that the photocatalyst was a nanoporous material with a high-surface area. The Sn-doped TiO(2) was uniformly dispersed within the three-dimensional network of the silica in the form of nanoparticles. The nanoglued photocatalyst showed high photocatalytic activity during the degradation of penicillin under UV light. The effect of different Sn content on the amount of hydroxyl radical was discussed by using salicylic acid as probe molecules. The results show that an appropriate amount of Sn dopant can greatly increase the amount of hydroxyl radicals generated by TiO(2) nanoparticles, which are responsible for the obvious increase of photocatalytic activity.     

纳米四针状氧化锌晶须光催化降解甲基橙

以纳米四针状氧化锌晶须(T-ZnOw)为光催化剂,以甲基橙为染料模型化合物,研究了T-ZnOw的光催化氧化降解性能.考察了甲基橙溶液的初始浓度、催化剂用量和粒径等因素对光催化氧化降解反应的影响.研究结果表明,纳米T-ZnOw光催化氧化降解甲基橙的反应遵循一级反应动力学规律;光催化剂纳米T-ZnOw的最佳用量为2g/L,此时经60min光催化降解后,甲基橙溶液的色度剩余率仅为8%;T-ZnOw粒子直径越小,光催化活性越高,效果越好.对比实验和重复实验结果表明,纳米T-ZnOw的光催化氧化降解效果比纳米TiO2和普通球形纳米ZnO粉体更好,是一种高效、长寿的光催化剂材料.     

Different methods in TiO2 photodegradation mechanism studies: gaseous and TiO2-adsorbed phases

The development of photocatalysis processes offers a significant number of perspectives especially in gaseous phase depollution. It is proved that the photo-oxidizing properties of photocatalyst (TiO(2)) activated by UV plays an important role in the degradation of volatile organic compounds (VOC). Heterogeneous photocatalysis is based on the absorption of UV radiations by TiO(2). This phenomenon leads to the degradation and the oxidation of the compounds, according to a mechanism that associates the pollutant's adsorption on the photocatalyst and radical degradation reactions. The main objective of the study is the understanding of the TiO(2)-photocatalysis phenomenon including gaseous and adsorbed phase mechanisms. Results obtained with three different apparatus are compared; gaseous phases are analysed and mechanisms at the gaseous phase/photocatalyst interface are identified. This study leads to improve understanding of various mechanisms during pollutant photodegradation: adsorption of pollutants on TiO(2) first takes place, then desorption and/or photodegradation, and finally, desorption of degradation products on TiO(2). The association of analytical methods and different processes makes the determination of all parameters that affect the photocatalytic process possible. Mastering these parameters is fundamental for the design and construction of industrial size reactors that aim to purify the atmosphere.     

Preparation and characterization of visible-light-driven TiO2 photocatalyst Co-doped with nitrogen and erbium

A series of nitrogen and erbium co-doped TiO2 photocatalyst was prepared by sol-hydrothermal method. The structure and properties of the photocatalyst were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (DRS). The XRD and BET results showed that co-doping inhibited the increase of crystallite size and enlarged specific surface areas. XPS spectroscopy indicated nitrogen atoms were incorporated into TiO2 lattice, and erbium atoms mostly existed in the forms of Er2O3. A shift of the absorption edge to the lower energy and four absorption bands located at 654, 544, 524 and 489 nm attributed to the 4f transitions of 4I15/2 --> 4F2/9, 4I15/2 --> 4S3/2, 4I15/2 --> 2H11/2, 4I15/2 --> 4F7/2 of Er3+ were observed using DRS spectroscopy. The catalytic efficency was evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the photocatalytic performance of the co-doped TiO2 was related with the hydrothermal temperature and the molar ratio of N/Ti, and they showed higher acitivites than pure TiO2. Results determined by fluorescence technique revealed that irradiation (lambda > 400 nm) of TiO2 photocatalyst dispersed in MO solution induces the generation of the highly active hydroxyl radicals (OH). It indicated the photocatalytic activities of TiO2 photocatalyst were correlation with the formation rate of hydroxyl radicals (OH) and other active oxygen species.     

聚氨酯TiO2纳米管复合材料的制备与光催化特性研究

为了解决水体中光催化剂的分离和回收问题,对纳米TiO2的改性和固载化及其光催化特性进行了研究。首先以纳米TiO2为原料,采用水热合成法制备TiO2纳米管;再对TiO2纳米管硅烷化,改善其表面性质;然后以聚氨酯(PU)膜片为载体负载TiO2纳米管,制成了负载型PU/TiO2薄膜的光催化材料。采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、衰减全反射傅里叶变换红外光谱(ATR-FTIR)和扫描电子显微镜(SEM)等手段对催化剂进行了表征,结果表明硅烷化后的TiO2纳米管能很好地接枝在PU薄膜表面。以300 W高压汞灯为光源,萘普生为目标降解物,研究了负载PU/TiO2薄膜的光催化活性和稳定性,结果表明其对目标物的降解具有较高活性,用乙醇冲洗即可多次重复使用,其催化活性能较长时间保持稳定。     

纳米TiO2光催化降解水中有机污染物的研究与发展

光催化降解水中有机污染物是一项新兴的颇有发展前任的废水处理技术,纳米Ｔｉｏ２因其活性高,稳定性好而在该领域广泛被用作光催化剂。本文系统介绍了纳米ＴｉＯ２的制备,光催化降解水中有机污染物的机理,动力学规律及其研究现状和发展方向。     

Ce掺杂ZnO/膨润土复合光催化材料的制备及其性能

以膨润土为载体,硝酸锌、硝酸铈和氢氧化钠为原料,采用沉淀法制备了Ce掺杂ZnO/膨润土复合光催化材料.利用X射线衍射(XRD)、红外光谱仪(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、氮气吸附仪等对其进行表征,并通过对亚甲基蓝(MB)溶液脱色反应,考察紫外光照射下复合材料的光催化性能.结果表明,复合光催化材料中由于Ce掺杂ZnO的光催化作用与膨润土的吸附性相互协同,显示出优良的光催化活性和稳定性.当Ce的掺杂量为3.0%,同时复合光催化材料的加入量为20 mg/L,MB溶液的pH值为6时,复合光催化材料的性能最优,在紫外灯下照射2 h后,MB溶液的脱色率达到98.6%.