Ag负载WO3/TiO2光催化剂的合成及其催化性能

以钛酸丁酯、无水乙醇、钨酸铵为原料,采用溶胶-凝胶法合成了WO3/TiO2复合光催化剂;采用光还原技术制备了Ag负载WO3/TiO2光催化剂,借助X射线粉末衍射(XRD)和UV-Vis光谱等技术对样品的组成和光吸收性能进行了表征,并以罗丹明B为模型污染物考察样品的光催化活性。XRD分析表明,所得粉体均为锐钛矿型纳米TiO2,且与WO3复合后,纳米TiO2特征衍射峰宽化,强度降低;UV-Vis光谱分析表明,载银使得催化剂在400—700nm的可见光区域对光响应,且在紫外光区吸收显著增强,对光具有更高的利用率;以罗丹明B为降解物的光催化实验表明,WO3复合对纳米TiO2光催化活性有显著的影响,而载Ag后其光催化活性进一步提高,将该光催化剂用于炼油厂废水的处理,效果较好。     

A twice liquid arc discharge approach for synthesis of visible-light-active nanocrystalline Ag:ZnO photocatalyst

Ag:ZnO hybrid nanostructures were successfully prepared by a twice arc discharge method in liquid. The visible light photocatalytic activities were successfully demonstrated for the degradation of Rhodamine B (Rh. B), Methyl orange (MO), and Methylene blue (MB) as standard organic compounds under the irradiation of 90 W halogen light for 2 h. The Ag:ZnO nanostructures were characterized by X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible absorption spectroscopy (UV-Vis). The results revealed that the Ag:ZnO nanostructures extended the light absorption spectrum toward the visible region and significantly enhanced the Rh. B photodegradation under visible light irradiation. 3 mM Ag:ZnO nanostructures exhibited highest photocatalytic efficiency. It has been confirmed that the Ag:ZnO nanostructures could be excited by visible light (E<3.3 eV). The significant enhancement in the Ag:ZnO nanostructures photocatalytic activity under visible light irradiation can be ascribed to the effect of physisorbed noble metal Ag by acting as electron traps in ZnO band gap. A mechanism for photocatalytic degradation of organic pollutant over Ag:ZnO photocatalyst was proposed based on our observations.     

碳量子点负载TiO_2纳米棒阵列的光电化学性能

研究了碳量子点负载的Ti O2纳米棒阵列光阳极的光电化学过程和光催化行为。实验发现碳量子点的引入使Ti O2纳米棒阵列在可见光区域的吸收强度增强,对可见光的响应电流提高3倍,光照下的开路电位增加了2.5%,光生载流子的转移和传输能力得到相应提高。光阳极对亚甲基蓝的降解特性显示,碳量子点的引入使Ti O2纳米棒在可见光照射下的催化效率由25%提高到33%。利用电化学交流阻抗谱(EIS)、MottSchottky曲线讨论了光影响下的电荷运动过程,表明Ti O2纳米棒阵列负载碳量子点后的电荷转移电阻减小,电子寿命增加;碳量子点的负载使Ti O2纳米棒的平带电位负移,导带位置提高,电子的还原能力增强。     

Efficient one-pot synthesis of Ag nanoparticles loaded on N-doped multiphase TiO2 hollow nanorod arrays with enhanced photocatalytic activity

The simultaneous Ag loaded and N-doped TiO₂ hollow nanorod arrays with various contents of silver (Ag/N-THNAs) were successfully synthesized on glass substrates by one-pot liquid phase deposition (LPD) method using ZnO nanorod arrays as template. The catalysts were characterized by Raman spectrum, field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscope (HRTEM), ultraviolet-vis (UV-vis) absorption spectrum and X-ray photoelectron spectroscopy (XPS). The results suggest that AgNO₃ additive in the precursor solutions not only can promote the anatase-to-rutile phase transition, but also influence the amount of N doping in the samples. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The sample exhibited the highest photocatalytic activity under UV light illumination when the AgNO₃ concentration in the precursor solution was 0.03 M, due to Ag nanoparticles acting as electron sinks; When the AgNO₃ concentration was 0.07 M, the sample performed best under visible light illumination, attributed to the synergetic effects of Ag loading, N doping, and the multiphase structure (anatase/rutile).     

PbMoO4微晶的水热合成及光催化性能

以钼酸铵、硝酸铅为原料,采用水热法合成了纳米PbMoO₄光催化剂,并采用光还原处理对其进行表面载Ag修饰。借助X-射线粉末衍射（XRD）、扫描电镜（FE-SEM）和紫外-可见吸收光谱（UV-Vis）等测试手段对样品进行表征,并以罗丹明B为模型污染物,考察了纳米PbMoO₄光催化剂的催化活性,研究了样品的制备条件和表面载银对催化剂活性的影响。XRD分析结果表明,所得样品为四方晶系结构,且产物纯度高;样品的形貌分析和光催化活性实验结果表明,水热体系的pH值对产物的形貌和活性影响显著,且表面载银可显著提高催化剂的可见光催化活性。     

Cu2O/Ag复合物的合成及SERS原位分析其可见光催化降解活性

A multifunctional Cu₂O/Ag micro-nanocomposite, which has the characteristics of high catalytic activities under the visible light and high surface-enhanced Raman scattering (SERS) activity, was fabricated via a facile method and employed for the in situ SERS monitoring of the photocatalytic degradation reaction of crystal violet. Through the variation of the AgNO₃ concentration, Ag content on the Cu₂O template can be controllably tuned, which has great influence on the SERS effect. The results indicate that Ag nanoparticles form on the Cu₂O nanoframes to obtain the Cu₂O/Ag nanocomposite, which can act as an excellent bifunctional platform for in situ monitoring of photocatalytic degradation of organic pollutions by SERS.     

Microwave-assisted synthesis of silver nanocrystals in benzyl alcohol and their subsequent in situ chemical transformation into Ag–AgCl nanohybrids for plasmonic photocatalysis

In heterostructured metal–semiconductor system, plasmonic metal nanostructures can cooperate with semiconductors to enhance the solar light harness and energy conversion. In this study, we report on the plasmonically photocatalytic system constructed by in situ growth of semiconductor on metal nanostructures with high performance and stability. A facile and rapid microwave-assisted route was first explored to synthesize Ag nanocrystals, and subsequently converting them to Ag–AgCl nanohybrids was realized by in situ chemical transformation strategy at room temperature. These Ag–AgCl nanohybrids were characterized by X-ray diffraction, scanning electronic microscopy, and UV–vis absorption spectroscopy. The resulting Ag–AgCl nanohybrids showed remarkable photocatalytic activity and excellent durability for the degradation of organic pollutants under visible light irradiation. This finding provides a new way to improve photocatalytic efficiency through controllable chemical transformation.     

Effects of NiTiO3 nanoparticles supported by mesoporous MCM-41 on photoreduction of methylene blue under UV and visible light irradiation

In this work, we report the synthesis of nickel titanate nanoparticles loaded on nanomesoporous MCM-41 nanoparticles to determine the effect of MCM-41 nanoparticles on the photocatalytic activities of nickel titanate (NiTiO₃) nanoparticles by using simple solid-state dispersion (SSD) method. Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and UV–Vis diffuse reflectance spectra (DRS) analysis were used to characterize the size and morphology of the obtained nanocomposite. The photocatalytic activity (PA) of the as-prepared NiTiO₃ loaded on MCM-41 was evaluated by degradation of the methylene blue under irradiation of UV and visible light. The results showed that NiTiO₃ loaded on nanosize MCM-41 has higher photocatalytic activity than that of NiTiO₃ nanoparticles.     

Photocatalytic properties of porous C-doped TiO2 and Ag/C-doped TiO2 nanomaterials by eggshell membrane templating

Porous organic carbon-doped titania (C-TiO₂) nanomaterials and their composites with Ag nanoparticles (Ag/C-TiO₂) were synthesized by an eggshell membrane templating method, and their structural and photocatalytic properties were systematically characterized. These nanomaterials, exhibiting a macroscopic morphology of a thin film, are composed of interwoven tubes, and the tube wall consists of nanocrystals. The doped organic carbon was composed of the active carbon and carbonate species, which could form a layer around the surface of TiO₂ nanoparticles, while the silver was incorporated into Ag/C-TiO₂ composites as separated Ag nanoparticles. The degradation of methylene blue under visible light irradiation was employed to evaluate the photocatalytic activity of these as-prepared TiO₂-based materials. Both C-TiO₂ and Ag/C-TiO₂ nanomaterials showed higher photocatalytic activity than pure TiO₂ material–commercial Degussa P25. These results can be accounted for the coupling effect of the incorporation of carbon species and Ag nanoparticles.     

Ag/K_4Nb_6O_(17)异质结催化剂的制备、光谱分析及光催化性能研究

采用低温水热法成功制备了层状的K4Nb6O17半导体光催化材料。考虑到水热合成的K4Nb6O17表面多羟基(Nb—OH)和端氧(Nb O,Nb—O-)的特点,采用Ag(en)2+配合物前驱体法制备了高度均匀分散的Ag/K4Nb6O17异质结光催化剂,光催化性能评价结果表明,半导体K4Nb6O17表面负载极少量的Ag,其光催化降解甲基橙活性便得到大幅度提高,Ag的最佳负载量为0.5 at%。综合XRD,FTIR,UV-VisDRS,XRF和TEM表征结果,对Ag/K4Nb6O17异质结光催化剂的作用机制进行了较详细地阐述并获得如下结论:(1)K4Nb6O17提供了降解有机染料分子的电子和空穴;(2)K4Nb6O17纳米晶上Ag粒子作为光生电子接受器,促进了金属-半导体界面上电荷的转移,有效地分离了光生电子-空穴对,提高了光催化活性。     

Carbon quantum dots supported ZnO sphere based photocatalyst for dye degradation application

A Carbon quantum dots supported ZnO hollow Sphere (ZnO/C-dots) were synthesized through a solvothermal method using polyethylene glycol 400 (PEG 400) as a solvent. The phase and crystal structure of as-prepared ZnO/C-dots photocatalyst were characterized by powder X-ray diffraction (XRD). The surface morphology and size of the composite were analyzed using field emission scanning microscopy (FE-SEM). The optical properties of the as-prepared nanocomposites were examined using UV–visible (UV–Vis) spectrometer. The photocatalytic activity of pure ZnO and ZnO/C-dots nanocomposites were evaluated by the degradation of methylene blue (MB) under UV–Visible light irradiation. The ZnO/C-dots nanocomposites exhibited maximum photocatalytic MB dye degradation efficiency of 96% which is much higher that the pure ZnO (63%). The enhanced photocatalytic activity of ZnO/C-dots is due to the extended light absorption in the visible region and suppressed photoexcited electron-hole pair recombination rate. Moreover, the activity of photocatalyst after five cycles exhibits high stability, which is vital for the sustainable photocatalytic procedures. It is concluded that the prepared ZnO/C-dots composite have low cost, good stability and has a great potential application for Photocatalytic dye degradation.     

The enhanced photocatalytic activity of CdS/TiO2 nanocomposites by controlling CdS dispersion on TiO2 nanotubes

CdS/TiO₂ nanocomposites were prepared via a simple wet chemical method, and characterized through X-ray diffraction (XRD) and transmission electron microscopy (TEM). Their ability to degrade Acid Rhodamine B was investigated under visible light irradiation. The results indicate that CdS/TiO₂ nanocomposite with a mass ratio of 4:1(TiO₂:CdS) showed high photocatalytic activity and the CdS loaded on TiO₂ nanotube surface exhibited a hexagonal phase. The dispersion of CdS on TiO₂ nanotube surface had an important effect on the degradation efficiency of pollutant, which provides a strategy for practical industry application.     

Synthesis and characterization of the efficient visible-light-induced photocatalyst AgBr and its photodegradation activity

AgBr photocatalysts were prepared with the 1-hexadecyl-3-methylimidazolium bromide ([C₁₆mim]Br) reactable ionic liquid at different temperatures by one-step hydrothermal method, in which the ionic liquid acted as a precursor and a template to control the size of AgBr crystal. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), the Brunauer–Emmett–Teller (BET) surface area and diffuse reflectance spectroscopy (DRS). Methyl orange (MO) dye was chosen as a model pollutant to investigate the photocatalytic activity and the stability of the samples under visible light irradiation. The results indicated that the AgBr photocatalysts showed high efficiency in the degradation of MO under visible light irradiation. The kinetic property of the reaction followed the first-order reaction model. During the photocatalytic degradation reaction, AgBr was transformed to the Ag⁰/AgBr composite. However, the photocatalytic efficiency was still high and the photocatalytic activity was stable. The possible photocatalytic mechanism of the photocatalysts was also eventually proposed.     

SnO2量子点/石墨烯复合结构的合成及其光催化性能研究

本文以SnCl₄·5H₂O和氧化石墨烯为先驱物, 乙醇水溶液为溶剂, 采用一种简单的水热法一步合成了具有可见光催化活性的SnO₂量子点(约3–5 nm)与石墨烯复合结构, 利用透射电子显微镜(TEM), 高分辨透射电子显微镜(HRTEM), X射线衍射仪(XRD), 傅里叶变换红外光谱(FT-IR)等技术对其结构进行了表征, 利用紫外可见吸收光谱(UV-vis)分析了其光学性能, 罗丹明-B染料为目标降解物研究了SnO₂量子点/石墨烯复合结构可见光催化性能. 结果表明: 与纯SnO₂、纯石墨烯相比, 复合结构显示出了很高的可见光催化活性. 通过对其结构进行分析, 我们提出了SnO₂量子点/石墨烯复合结构的形成机制及其可见光催化活性机理.     

分光光度法研究膨润土负载型 光催化剂降解亚甲基蓝

以Zn(NO3)2、SnCl4和膨润土为原料,采用沉淀法制备膨润土负载ZnO/SnO2光降解催化剂,用XRD对其结构进行了表征.在可见光下对亚甲基蓝染料废水进行降解实验,讨论了影响亚甲基蓝降解的主要因素.结果表明,光降解催化剂具有优良的光催化活性,在可见光下对浓度为10mg/L亚甲基蓝,30min降解率达到99.5%.     

Ag3PO4/rectorite nanocomposites: Ultrasound-assisted preparation,characterization and enhancement of stability and visible-light photocatalytic activity

To overcome the drawback of low stable brought by the transformation of Ag⁺ into Ag, a highly efficient and stable photocatalyst Ag₃PO₄/rectorite composite was successfully synthesized by ultrasound-assisted precipitation method. The as-prepared samples were characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N₂ adsorption-desorption, room-temperature photoluminescence spectra, Fourier transform infrared spectrum measurements and UV–vis diffuse reflectance spectra. The absorption edges of the Ag₃PO₄/rectorite display a noticeable shift to the visible light region as compared to that of the Ag₃PO₄. Compared with bare Ag₃PO₄, the Ag₃PO₄/rectorite composite by ultrasound-assisted precipitation process exhibits significantly enhanced photocatalytic activity and stable for methyl orange (MO) degradation under visible light irradiation. The improved activity of the Ag₃PO₄/rectorite photocatalyst could be attributed to the expanded visible light absorption, the enhanced interfacial charge transfer and the inhibited recombination of electron-hole pairs. Therefore, the facile ultrasound-assisted preparation process provides some insight into the application of Ag₃PO₄/rectorite nanocomposites in photocatalytic degradation of organic pollutants.     

Ultrasonic-assistant fabrication of cocoon-like Ag/AgFeO2 nanocatalyst with excellent plasmon enhanced visible-light photocatalytic activity

The AgFeO₂ delafossite was reported as a potential photocatalyst as well as its intense recombination rate of photogeneration charge carriers. In this work, we utilized plasmon modification method to enhance the photocatalytic activity of AgFeO₂. Silkworm cocoon like Ag/AgFeO₂ nanocatalyst was synthesized by an ultrasonic enhanced reduction method. XRD, HRTEM and XPS results demonstrated the well dispersed Ag⁰ on the surface of AgFeO₂. Under visible light irradiation, 20 mg/L of ARG solution was completely degraded by 0.25 g/L of Ag/AgFeO₂ photocatalyst with pseudo-first-order rate of 0.040 min⁻¹. The inducement of the prominently enhanced photocatalytic activity of Ag/AgFeO₂ was deeply analyzed. Significant decreased intensity of photoluminescence (PL) spectra suggested the superior separation of photo-induced electrons and holes of Ag/AgFeO₂ as compared to that of AgFeO₂. The free h⁺ was confirmed as the dominant active species for the pollutant degradation. Ultimately, the photodegradation mechanism was proposed and discussed.     

Continuous one-step synthesis of N-doped titania under supercritical and subcritical water conditions for photocatalytic reaction under visible light

N-doped titania was prepared continuously by one-step synthetic method under supercritical and subcritical water conditions using titanium(IV)tetraisopropoxide (TTIP) and nitric acid as a titania precursor and nitrogen source, respectively. The synthesized N-doped titania particles were characterized by XRD, N₂-adsorption, TEM, XPS, UV-vis diffuse reflectance spectroscopy. N-doped titania was successfully synthesized and its crystalline structure was homogenous anatase phase with high surface area. The absorption edge of synthesized N-doped titania shifted into the visible light region compared with commercial titania P25. All synthesized N-doped titania have higher photocatalytic activity than P25 under visible light irradiation. The photocatalytic activity of N-doped titania synthesized under supercritical water condition was the highest for the degradation of methyl orange under visible light due to the larger crystallite size compared with the N-doped titania synthesized under subcritical water condition.     

Visible-light-driven titania photocatalyst co-doped with nitrogen and ferrum

Nitrogen and ferrum co-doped titania photocatalyst was prepared by the sol-gel route. The prepared photocatalyst was characterized by various techniques including X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption-desorption isotherm. The photocatalytic activity of the co-doped titania photocatalyst was evaluated by the degradation of methyl orange (MO) from aqueous solution under visible light irradiation and was compared with that of the commercial TiO₂ photocatalyst (Degussa P25). The results revealed that the nitrogen doping could lead to the response to visible light and that the ferrum doping could improve the photocatalytic performance. The effects of the component and the annealing temperature of the co-doped titania photocatalyst on the photocatalytic activity were investigated.     

Synthesis and characterization of Ag/BiVO4 composite photocatalyst

Ag/BiVO₄ composite photocatalysts were hydrothermal synthesized and characterized by XRD, SEM, XPS and DRS techniques. Their photocatalytic activities were determined by oxidative decomposition of methyl orange in aqueous solution under visible light irradiation. It revealed that the doped Ag species greatly improved the visible light absorption abilities and morphologies of the composites, and thus lead to enhanced photocatalytic activities compared with that of the pure BiVO₄.