Hydrothermal synthesis and photocatalytic activity of CdO2 nanocrystals

CdO(2) nanocrystals with different sizes were synthesized via the hydrothermal reaction of 3CdSO(4).8H(2)O and H(2)O(2) in 1.25-6.25 vol.% ammonia solutions at 100-140 degrees C for 12h. The resultant products were characterized by powder X-ray diffraction, transmission electron microscope, thermal gravimetric and differential scanning calorimetry, and UV-vis absorption spectra. It was concluded that the resultant products were pure cubic phase CdO(2) nanocrystals, and they would decompose at temperatures higher than 180 degrees C. In addition, degradation of methyl orange in aqueous solution (20.0mg/l) was carried out with the CdO(2) nanocrystals as photocatalyst under ultraviolet light irradiation. The experimental results showed that even a little amount (0.2g) of as-prepared CdO(2) nanocrystals could catalyze degradation of 500 ml methyl orange solution above 99% after 5h of illumination, and smaller size made for higher photocatalytic activity of CdO(2) nanocrystals.     

TiO2纳米棒光催化降解甲基橙的研究

本文以甲基橙为目标降解物考察了催化剂的添加量、甲基橙溶液的pH值、晶化时间、热处理温度等因素对用"软模板"制备的TiO2纳米棒光催化活性的影响.研究表明:当催化剂添加量为0.08g、甲基橙溶液的pH=4、晶化时间为24h、热处理温度为500℃时,TiO2光催化剂的催化效果最佳,达到了85.96%.     

Synthesis and characterization of Ce2S3-ZnS-CuS nanoparticles and their photocatalytic activity

ZnS-CuS nanoparticles were prepared by a controlled coprecipitation method and ZnS-CuS-Ce2S3 nanoparticles were prepared by ball milling. The photocatalysts were characterized by scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, and terephthalic acid photoluminescence probing technique. The photocatalytic activity of the photocatalysts was evaluated by photocatalytic reduction of Cr2O7(2-), nitrobenzene and photocatalytic oxidation of methyl orange. The results showed that the optimal preparation condition of ZnS-CuS is 200 degrees C for 7 h. The optimal doped amount of Ce2S3 for Ce2S3-ZnS-CuS photocatalyst is 1.0 wt%, and the optimal ball milling time is 16 h. For the ZnS-CuS photocatalyst, the photooxidation efficiency of methyl orange and the photoreduction efficiency of Cr2O7(2-) were 27.4% and 60.7%, respectively; and for Ce2S3-ZnS-CuS photocatalysts, they were 73.6% and 83.1%, respectively. The production efficiency of aniline for ZnS-CuS and Ce2S3-ZnS-CuS were 25.4% and 31.3%, respectively. The mechanisms of influence on the photocatalytic activity were also discussed.     

不同合成过程对溶胶-凝胶法制备的ZnO/Ag纳米复合材料光催化性能的影响

以乙酸锌、硝酸银为前驱体,二乙醇胺作为稳定剂,利用溶胶-凝胶法分别采用一步法和两步法制备得到ZnO以及ZnO/Ag纳米复合粉体。所有ZnO/Ag复合物中Ag的含量均为3%(摩尔分数)。对所制备样品的结构和光学性质通过XRD、SEM、TEM、XPS、PL、UV-vis进行了表征,进而以甲基橙为模拟污染物进行了光催化测试。结果表明,不同方法制备得到的ZnO/Ag纳米粉体晶粒均匀,无明显团聚现象,面心立方结构的金属Ag吸附在纤锌矿结构的ZnO表面形成异质结。与纯ZnO相比,掺Ag极大地改善了样品在紫外光下的光催化活性。对不同合成工艺的比较表明,用溶胶-凝胶一步法制备的ZnO/Ag复合物的光催化活性最高,经紫外光照射70min可完全降解甲基橙。     

WO_3-TiO_2纳米材料的制备及其光催化性能

采用溶胶-凝胶法制备WO3-TiO2纳米复合材料,并用透射电镜和X射线衍射对所制备材料进行表征和分析。以WO3-TiO2纳米材料为光催化剂对甲基橙进行光催化降解处理,研究WO3的掺杂量、煅烧温度、光照时间等因素对甲基橙降解率的影响。结果表明:在紫外灯照射下,使用w(WO3)=3%、550℃下煅烧得到的WO3-TiO2纳米复合粉体0.02 g,甲基橙溶液20 mL(ρ=5 mg/L,pH=4),光催化3 h后,甲基橙降解率达到94.93%。     

Synthesis and performance of novel magnetically separable nanospheres of titanium dioxide photocatalyst with egg-like structure

A magnetically separable photocatalyst TiO(2)/SiO(2)/NiFe(2)O(4) (TSN) nanosphere with egg-like structure was prepared by a unique process that combined a liquid catalytic phase transformation method, reverse micelle technique and chemical precipitation means. The prepared photocatalyst shows high photocatalytic activity for the degradation of methyl orange in water. The magnetic property measurements indicate that the photocatalyst possesses a superparamagnetic nature. It can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for wastewater treatment. A transmission electron microscope (TEM) and an x-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that nickel ferrite core nanoparticles were completely encapsulated into monodisperse silica nanospheres as carrier, and titania nanoparticle aggregates were coated onto the surface of SN nanospheres, forming an imperfect TiO(2) shell for photocatalysis. The SiO(2) layer between the NiFe(2)O(4) core and the TiO(2) shell effectively prevents the injection of charges from TiO(2) particles to NiFe(2)O(4), which gives rise to an increase in photocatalytic activity. Moreover, the recycled TSN exhibits good repeatability of the photocatalytic activity.     

磁性La3+掺杂TiO2的制备及性能

利用溶胶-凝胶法,在室温条件下,以钛酸四丁酯、硝酸镧为主要原料,无水乙醇为溶剂,冰醋酸为抑制剂,浓硝酸为催化剂制得稳定的掺La3+TiO2溶胶,陈化后的凝胶经不同温度煅烧3h后制得不同掺La3+量的TiO2。通过XRD对不同煅烧温度及不同掺La3+量的TiO2进行了表征;以紫外光为光源,研究了掺La3+-TiO2对甲基橙溶液的光降解效果。用化学共沉淀法制备了具有强磁性的Fe3O4水基磁流体,再与La3+掺杂TiO2进行复合,制备了Fe3O4负载量不同的磁性La3+掺杂TiO2,研究了Fe3O4负载量不同的La3+掺杂TiO2对甲基橙的光催化降解效果、磁分离回收率的影响。结果表明,掺La3+量及煅烧温度对TiO2的晶型、各晶型TiO2的相对含量及对甲基橙的光降解效果均有影响。La3+掺杂TiO2比纯TiO2显示出更强的光催化性能,掺La3+量2%,热处理温度450℃的La3+掺杂TiO2光催化活性最高。Fe3O4负载量为10%的Fe3O4/La3+-TiO2对甲基橙的降解率8h时为99.4%;磁分离回收率达97.39%。     

溶胶一凝胶法制备钒酸铋及其光催化性能研究

采用溶胶一凝胶法制备钒酸铋颗粒光催化剂,研究银掺杂、煅烧温度、煅烧时间对BiVO4晶型组成和催化活性的影响,用X射线衍射（XRD）、透射电镜进行表征,研究了BiVO4粉体在焙烧过程中的相转变,确定了煅烧温度、煅烧时间及掺杂比例;以甲基橙（MO）的可见光催化降解反应为探针,研究了催化剂的可见光催化性能,研究发现,当煅烧时间为4h,煅烧温度为500℃时,BiV04对甲基橙光催化效率可达约20％。银掺杂的BiVO4对基橙光催化效率可达约40％。     

磁性纳米TiO2/SiO2/Fe3O4光催化剂的制备及表征

以纳米Fe3O4磁粉为核心，采用溶胶一凝胶法制备了TiO2／SiO2／Fe3O4复合光催化剂．用XRD、TEM及元素分析对其结构和表面形貌进行了表征．以具有偶氮染料结构的甲基橙水溶液为目标反应物，评价其光催化活性．结果表明，所制TiO2／SiO2／FeaO4样品为双层包覆型结构，SiO2为中间层，最外层是锐钛矿型的TiO2,该复合光催化剂对甲基橙溶液有较高的光催化活性，并具有可利用其磁性回收重用的特点，应用前景广泛。     

Preparation,characterisation and activity evaluation of CaCO3/ZnO photocatalyst

The photocatalyst CaCO₃/ZnO with high activity was prepared by coprecipitation method using (NH₄)₂CO₃, Zn(NO₃)₂ and Ca(NO₃)₂ as raw materials. The photocatalyst was characterised by X-ray powder diffraction, terephthalic acid photoluminescence probing technique (TA-PL), UV–vis diffuse reflectance spectroscopy and the fluorescence emission spectra. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic oxidation of methyl orange and rhodamine B. The results showed that the photocatalytic activity of the photocatalyst was much higher than that of pure ZnO. The best mole ratio of Ca/Zn in the sample was 1?:?2, and its intensity of TA-PL was the strongest. The effect of heat treatment condition on the photocatalytic activity of the photocatalyst was investigated. The best preparation condition was about 650°C for 7?h. Compared with pure ZnO, the photoabsorption wavelength range of the CaCO₃/ZnO extends towards visible light and improves the utilisation of the total spectrum. The possible mechanisms of influence of CaCO₃ on the photocatalytic activity of CaCO₃/ZnO were also discussed.     

One-pot synthesis of visible-light-driven plasmonic photocatalyst Ag/AgCl in ionic liquid

Plasmonic photocatalyst Ag/AgCl was prepared by in situ hydrothermal method with the contribution of 1-octyl-3-methylimidazolium chloride ([Omim]Cl), in which the [Omim]Cl ionic liquid acted not only as a precursor but also as a reducing reagent in the process of formation of Ag?. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric and differential scanning calorimetry (TG-DSC). The photocatalytic activity of the composites were evaluated by degradation of methyl orange (MO) under visible light irradiation. The experimental results showed that the high activity and stability of Ag/AgCl photocatalysts under visible-light irradiation were due to their localized surface plasmon resonance (LSPR). Based on the characterization of the structure and photocatalytic performance, the LSPR was determined by synergetic effect of many factors, such as particle size of metallic Ag, contents of the Ag? nanoparticles, and the extent of metallic Ag dispersing. A photocatalytic mechanism of the Ag/AgCl photocatalyst was also proposed.     

溶胶-凝胶法制备TiO_2-Al_2O_3复合光催化剂及其表征

以钛酸四正丁酯为钛源,异丙醇铝为铝源,采用溶胶-凝胶法制备了TiO2-Al2O3复合光催化剂,考察其对甲基橙的吸附性能和在紫外光照射下的光催化活性。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、傅里叶变换红外光谱(FT-IR)、N2吸附-脱附等对催化剂的晶相结构、化学组成及BET比表面积和孔径分布等进行了表征。结果表明TiO2-Al2O3复合光催化剂由TiO2和Al2O3组成,其中TiO2为单一的锐钛矿晶相,Al2O3为非晶态,Al2O3的存在可抑制TiO2晶粒的生长。在n(Ti)/n(Al)=12,500℃煅烧3h制得的TiO2-Al2O3复合光催化剂比表面积达99.21m2/g,平均孔径为22.39nm,累计孔容积为0.4493cm3/g。在500℃煅烧制得的复合光催化剂具有最佳的光催化活性和吸附性能。与纯TiO2相比,相同条件下TiO2-Al2O3复合光催化剂的光催化活性和吸附性能都有较大提高。     

石墨/TiO2复合光催化剂的制备和性能

以石墨和纯的TiO₂为原料,采用球磨工艺制备了石墨/TiO₂复合光催化剂。使用XRD、SEM、TEM、XPS和DRS等手段对其性能进行了表征。以甲基橙为模拟污染物,研究了石墨掺入量、球磨时间对复合光催化剂光催化活性的影响。结果表明,石墨/TiO₂复合光催化剂具有锐钛矿结构,球磨后TiO₂(101)面的衍射峰宽化并右移,TiO₂成为200 nm左右的不规则球状颗粒,在其表面均匀分布着石墨。TiO₂晶粒的Ti-O键的结合能变高,且表面有缺陷产生,使其在可见光区具有显著的吸收。石墨掺入量为5%、球磨时间为12 h的石墨/TiO₂样品对甲基橙具有优异的光催化降解效果,在70 min的降解时间内甲基橙的降解去除率可达95.08%。石墨/TiO₂复合光催化剂的光催化反应速率常数k为0.043035 min^-1,是纯TiO₂的2.64倍。     

Facile procedure to synthesize highly crystalline Ag/NiO nanocomposite microspheres and their photocatalytic activity

The β-Ni(OH)₂ microspheres have been fabricated by a facile hydrothermal method in the assistance of biomolecule (l-arginine). The NiO microspheres were obtained with further calcination of β-Ni(OH)₂ precursor at 500 °C for 2 h. Subsequently, Ag/NiO nanocomposite microspheres were also prepared by the reduction of AgNO₃ solution. The as-synthesized products were characterized by X-ray power diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis et al. The photocatalytic activity of Ag/NiO composite microspheres was also investigated by UV–Vis spectrophotometer and the results display enhanced photocatalytic activity in degradation of methyl orange.     

Preparation of Ag nanoparticles coated tetrapod-like ZnO whisker photocatalysts using photoreduction

Ag/tetrapod-like ZnO whisker (T-ZnOw) photocatalysts with different Ag loadings were synthesized by photoreduction of Ag⁺ on the surface of T-ZnOw. The chemical composition, morphology and photocatalytic properties of Ag/T-ZnOw photocatalysts were characterized and studied in detail. It is found that metal Ag can exist either as nanoparticles or as agglomerates through varying the Ag/ZnO molar ratio (MR). In photodegradation of methyl orange, enhanced degradation rates are achieved by all Ag/T-ZnOw photocatalysts due to increased separation efficiency of photogenerated electron and hole pairs. Specifically, the photocatalytic activities of Ag/T-ZnOw photocatalysts increase with increasing Ag/ZnO MR from 2.4 to 12%. However, further increasing the Ag/ZnO MR to 14.4% induces the formation of more agglomerates, which can act as recombination centers of photogenerated electron and hole pairs, leading to decreased photocatalytic activity of the photocatalyst.     

Cd/CdS光催化降解甲基橙的研究

采用胶体化学法制备表面富镉的Cd／CdS纳米粒子为催化剂对水溶液中甲基橙的光催化降解进行了研究。探讨了光催化反应机理,讨论了光催化剂用量,双氧水的用量,试液的pH值,光照时间与甲基橙脱色率的关系。实验结果表明,当甲基橙起始浓度为20mg／L,Cd／CdS用量为0．500g,双氧水用量为5．88mmol／L,pH值为7．0时,光照6h,甲基橙的脱色率可达到95．5％。     

均匀沉淀法制备ZnO、Fe/ZnO光催化剂

以六水合硝酸锌、九水合硝酸铁和CO(NH2)2为原料,采用均匀沉淀法并且改变实验条件制备了纯纳米ZnO和纳米Fe/ZnO光催化剂。通过X射线衍射(XRD)和扫描电子显微镜(SEM)对所有样品进行表征,并对部分样品进行了X射线能谱分析仪(EDS)测试。结果显示所有样品均为六方纤锌矿结构。此外,所有样品均由小颗粒聚集在一起而形成了形状、大小各不相同的团聚物或颗粒膜。而且随煅烧温度和Fe掺杂浓度的改变,Fe/ZnO样品的晶粒尺寸和表面形貌也随之变化。以甲基橙溶液作为污染物,在高压汞灯的照射下进行了光降解实验,实验结果表明:Fe掺杂Fe/ZnO样品的光催化性能相较纯纳米ZnO样品得到了改善。当Fe掺杂量为1.5%时Fe/ZnO样品的光催化性能最好;另外,适当煅烧温度也使Fe/ZnO样品的光催化活性得到了提升,其中最适煅烧温度为500℃。无论是Fe的掺杂浓度还是煅烧温度,适当的Fe的掺杂浓度和煅烧温度都有利于改善Fe/ZnO样品光催化剂的性能。     

静电溶液喷射Fe2O3/Al2O3超细纤维负载型光催化剂的制备及催化性能研究

利用静电溶液喷射法,结合浸渍焙烧工艺成功制备了Fe2O3/Al2O3超细纤维负载型光催化剂.采用SEM、EDS、XRD等技术对其进行表征,以酸性大红(RR 195)的光催化降解为目标反应,评价其光催化活性.结果表明,通过静电溶液喷射方法制备的氧化铝超细纤维毡柔性较好,纤维平均直径为3.78 μm.光催化实验表明,当煅烧温度为500℃、铁负载量为195.5mg/g时,催化剂的性能最佳.在紫外光照及H2O2存在的条件下,反应120 min后,该催化剂对RR 195的脱色率达到95％,3次循环反应后,120min内染料的脱色率可达70％.反应后该催化剂仍然保持良好的纤维形态,易于分离,避免了二次污染.     

Ag~+掺杂FeVO_4光催化剂的制备及光催化性能

采用液相沉淀法制备了银(Ag+)掺杂钒酸铁(FeVO4)光催化剂。采用XRD、SEM、EDS、BET和XPS等手段对样品的性能进行了表征分析,并以甲基橙为目标降解物,考察了催化剂在节能灯照射下的光催化活性。结果表明,Ag的掺杂没有改变FeVO4晶型,但引起了晶格畸变和膨胀。适量Ag的掺杂可提高FeVO4的光催化性能,在所进行实验的条件下,钒酸银最佳掺杂量为1%(质量分数)时,掺杂后的Fe-VO4对甲基橙溶液的脱色率较未掺杂前提高21%左右。     

酞菁钴/MCM-41的制备及其可见光催化性能

以MCM-41分子筛为载体,采用浸渍法将酞菁钴负载到分子筛上以氙灯为光源降解甲基橙溶液。对负载型酞菁钴催化剂进行FT-IR、XRD、SEM表征,结果表明所制催化剂负载效果良好,且分子筛结构未发生改变。以甲基橙溶液为模拟处理对象,研究催化剂的催化性能,考察了光照、酞菁钴负载、催化剂用量等因素对催化效果的影响。结果表明,氧气充足时,在光照条件下、0.04g负载型酞菁钴催化剂处理200mL的0.05g/L甲基橙溶液能够有很好的处理效果,2h降解率能够达到98.3%,且重复利用4次后降解率仍能达到90%。