Preparation and photocatalytic activity of carbon dot/Ag/AgCl

CD (carbon dot)/Ag/AgCl compound photocatalysts with different compounding degrees were prepared via a precipitation method, and their physiochemical properties were characterized by X‐ray diffraction, FE‐SEM, UV–vis and the like. Through the degradation experiment of methyl orange (MO), the effects of different compounding amount and methyl orange concentration on photocatalytic degradation were investigated to find the best ratio. It was found the photocatalytic activity of CD/Ag/AgCl was significantly higher than Ag/AgCl, and the best compounding dosage was 6 mg/l carbon dot. The degradation rate of CD/Ag/AgCl was lower when the initial MO concentration was higher. Five repeated experiments were conducted to test the stability of the catalysts, and showed the MO degradation rates were all above 85%, indicating the CD/Ag/AgCl compound photocatalysts all showed high stability and repeatability. The reaction mechanism of CD/Ag/AgCl photocatalyst was studied by electrochemical experiments and ESR experiments. The results show that the doping of CD effectively improves the photocatalytic degradation ability of MO.     

MoSe2/Ag3PO4复合材料的制备及其可见光降解罗丹明B的光催化性能

通过原位沉积法合成了一种光催化活性强、稳定性高的MoSe2/Ag3PO4复合材料。MoSe2/Ag3PO4形成的异质结构能有效分离光生电子-空穴对,从而提高光催化活性。光生电子从Ag3PO4表面向MoSe2的转移降低了Ag+向金属Ag的可能性。当MoSe2和Ag3PO4的质量分数为1∶5(最优组合)时,MoSe2/Ag3PO4在可见光照射下30 min内降解RhB效率达98%,并且经过4次重复试验,其可见光照射下RhB降解效率仍可达到89%。通过液相色谱/质谱(LC/MS)技术测定光催化过程中产物的变化,提出了MoSe2/Ag3PO4光催化降解RhB的途径。     

Synthesis and photocatalytic performance of Ag/AgCl/ZnO tetrapod composites

Ag/AgCl is a visible-light plasmonic photocatalyst that has attracted considerable attention because of its high visible-light absorption and activity owing to the surface plasmon resonance of noble-metal nanoparticles. In this study, Ag/AgCl/ZnO tetrapod composite was prepared by introducing ZnO tetrapods into Ag/AgCl prepared by a polydopamine reduction route. Ag/AgCl was densely deposited on the three-dimensional support framework provided by the ZnO tetrapods. The framework possessed a certain degree of porosity, thereby improving the specific surface area of the Ag/AgCl/ZnO composite. The interaction of ZnO with Ag/AgCl further increased the separation and transfer of electron–hole pairs. The Ag/AgCl/ZnO composite showed excellent photocatalytic activity and good stability. Under xenon lamp irradiation for 20 min, degradation of rhodamine B reached 90%. After four recycling tests, degradation remained stable without any sign of reduction. Ag/AgCl/ZnO tetrapod composite is shown to be a kind of green photocatalyst offering high activity, good stability, and recyclability.

     

Photochemical Synthesis and Spectral-Optical Characteristics of ZnO/Cu and ZnO/Ag/Cu Nanoheterostructures

The photoreduction of Cu²⁺ at the surface of ZnO nanoparticles and ZnO/Ag nanostructures was investigated. The spectral characteristics of the obtained ZnO/Cu and ZnO/Ag/Cu composites were studied in relation to the reaction conditions. It was shown that the ZnO/Ag nanoparticles have higher photocatalytic activity in the reduction of Cu²⁺ ions than the individual ZnO particles.     

Ag/ZnO/ZnSe三元异质结的合成及其可见光光催化性能

以Ag纳米线为模板,通过两步水浴法合成了Ag/Zn O/Zn Se三元异质结光催化材料。利用场发射扫描电子显微镜(FESEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)以及透射电子显微镜(FETEM)对样品的形貌和结构进行了表征。结果显示,Ag/Zn O/Zn Se三元异质结为蠕虫状的Ag/Zn O二元异质结外镶嵌着Zn Se小颗粒。在可见光下,对比纯Ag纳米线、纯Zn O纳米球、Ag/Zn O异质结对罗丹明B的可见光降解效率,结果发现Ag/Zn O/Zn Se异质结表现出了更高的光催化效率。其光催化性能的提高主要是由于Ag/Zn O/Zn Se异质结的作用促使电子空穴对的分离,降低了电子空穴对的复合机率,从而提高了材料的光催化效率。     

Ag/ZnO/ZnSe三元异质结的合成及其可见光光催化性能

以Ag纳米线为模板,通过两步水浴法合成了Ag/ZnO/ZnSe三元异质结光催化材料。利用场发射扫描电子显微镜(FESEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)以及透射电子显微镜(FETEM)对样品的形貌和结构进行了表征。结果显示,Ag/ZnO/ZnSe三元异质结为蠕虫状的Ag/ZnO二元异质结外镶嵌着ZnSe小颗粒。在可见光下,对比纯Ag纳米线、纯ZnO纳米球、Ag/ZnO异质结对罗丹明B的可见光降解效率,结果发现Ag/ZnO/ZnSe异质结表现出了更高的光催化效率。其光催化性能的提高主要是由于Ag/ZnO/ZnSe异质结的作用促使电子空穴对的分离,降低了电子空穴对的复合机率,从而提高了材料的光催化效率。     

g-C3N4/Ag/TiO2复合材料的构筑及其光催化性能（英文）

以合成的g-C3N4纳米片和Ag/TiO2空心微球为原料,采用机械搅拌的方法构筑了g-C3N4/Ag/TiO2三元复合光催化剂。采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、X射线光电子能谱(XPS)、紫外-可见光漫反射(UV-Vis DRS)和光致发光光谱(PL)对g-C3N4/Ag/TiO2进行了表征。研究表明,g-C3N4/Ag/TiO2是由Ag/TiO2微球和g-C3N4纳米片复合而成的。与TiO2相比,其可见光响应范围延长,光生载流子的分离速率加快。在室温下,用降解罗丹明B的反应考察了g-C3N4/Ag/TiO2的可见光催化活性。研究表明,光照180 min时,g-C3N4(0.5%)/Ag/TiO2显示了最高的光催化活性(91.9%),分别是TiO2和Ag/TiO2的7.5和1.8倍。光催化活性的提高与合理的异质结构建和Ag的导电性能有关。     

Z型Ag3PO4/Ag2MoO4异质结光催化剂构建和光催化降解有机污染物

作为一种绿色技术,半导体光催化氧化广泛应用于环境污染物治理和太阳能转化领域.高效、稳定、可回收利用催化剂的开发是光催化技术发展的一个重要方向.Ag系半导体光催化剂因在可见光分解水制氢及降解有机污染物等方面表现出优异的催化性能而广受关注.然而,该催化剂失活快,制约了其应用.因此,提高Ag系半导体材料的光催化稳定性成为近年研究热点.在各种Ag基光催化剂中,Ag3PO4光催化剂因其在可见光下光氧化水产生O2以及有机染料的光催化分解中有着高的量子效率,引起了人们广泛关注.如何进一步提升Ag3PO4光催化剂性能及在光催化过程中的稳定性成为研究焦点,包括Ag3PO4光催化剂的特殊形貌和晶体结构控制生长以及复合材料控制制备.但是Z型Ag3PO4基可见光催化剂的构筑仍然是一个挑战.本文利用Ag2MoO4和Ag3PO4的溶液相反应法合成了Z型Ag3PO4/Ag2MoO4复合光催化剂,通过Ag3PO4/Ag2MoO4异质结光催化剂在可见光下降解罗丹明B(RhB)、亚甲基橙(MO)、亚甲基蓝(MB)和苯酚研究了其光催化性能,采用X射线衍射(XRD)、能谱、傅立叶变换红外光谱(FT-IR)、拉曼光谱、场发射扫描电子显微镜(FE-SEM)以及紫外可见漫反射光谱(UV-vis)等手段表征了该催化剂.XRD,FTIR和拉曼光谱结果表明,复合材料由Ag3PO4,Ag2MoO4和单质银组成,表面成功合成了Z构型Ag3PO4/Ag/Ag2MoO4复合材料.SEM结果发现纯Ag3PO4是规则的球状,纯Ag2MoO4则是多面体状块的颗粒,在Ag3PO4/Ag2MoO4复合材料中可以看到规则的球状体Ag3PO4和Ag2MoO4纳米颗粒,并且随着Ag2MoO4含量的增加,Ag3PO4颗粒的尺寸逐渐减小.UV-vis结果发现Ag2MoO4的加入拓展了复合材料对可见光的吸收范围.光催化性能测试结果表明,8%Ag2MoO4/Ag3PO4在可见光下具有优异的光催化性能:可见光照射5 min,RhB,MO和MB的降解效率分别可达95%,97%和90%.复合材料样品经过4个循环实验后,其降解RhB的效率仍然保持在84%,证明了其具有较高的稳定性.为了进一步研究Ag3PO4/Ag2MoO4的光催化机理,我们用对苯醌、乙二胺四乙酸二钠和丁醇进行了捕捉剂实验.结果表明,超氧自由基和光生空穴在降解有机染料过程中起主要作用.通过光电流测试、复合材料价带导带位置计算以及循环过程样品XRD分析并结合文献结果认为,Z构型Ag3PO4/Ag/Ag2MoO4异质结光催化体系以及可见光照射初期金属Ag纳米颗粒的生成是其具有高光催化活性和稳定性的原因.     

ZnO/Ag复合膜的制备及其润湿性转换研究

利用溶胶-凝胶技术制备了ZnO/Ag复合膜. 采用X射线粉末衍射和扫描电子显微镜对其物相组成、 晶型结构以及表面形貌进行了表征, 采用接触角测试仪对其润湿性进行了表征, 并研究了紫外光照射下Ag的掺杂量对ZnO薄膜润湿性的影响. 结果表明, 当Ag掺杂量(摩尔分数)为5%时, 所得膜的润湿性转换速率最快, 紫外光照3 h后, 其润湿性由超疏水性转换为亲水性, 黑暗中放置5 d后, 亲水性再次转换为超疏水, 实现了润湿性的可逆转换.     

Environmentally benign chitosan as precursor and reductant for synthesis of Ag/AgCl/N-doped carbon composite photocatalysts and their photocatalytic degradation performance

In this study, we reported a novel Ag/AgCl loaded N-doped carbon composite photocatalyst (Ag/AgCl/NC) which was fabricated by a facile and green method. The composite was prepared only by two simple steps. Firstly, the Ag/N-doped carbon (Ag/NC) was prepared by one-step hydrothermal treatment; during this progress the environmentally benign and renewable natural chitosan was used as not only reducer and stabilizer, but also as a nitrogen source and carbon source. Secondly, Ag/AgCl/NC composite was synthesized via in situ oxidation reaction by adding FeCl₃. The Ag/AgCl/NC composite was characterized using X-ray diffraction, transmission electronic microscopy, energy dispersive X-ray spectra, UV-visible diffused reflectance spectra, X-ray photoelectron spectroscopy and nitrogen adsorption-desorption measurements, respectively. The obtained Ag/AgCl/NC composite exhibited a superior photocatalytic activity and stability for the degradation of rhodamine B (RhB) under visible light irradiation.     

Effect of ZnO on the performance of Ag/SiO2 catalyst for the vapor-phase synthesis of 3-methylindole

The vapor-phase synthesis of 3-methylindole over Ag/SiO2 doped with ZnO was investigated. The catalysts were characterized by XRD, H2- TPR, NH3-TPD and TG techniques. The results indicated that ZnO promoter greatly enhanced the initial activity of the catalyst but disfavored its stability. H2-TPR and XRD results showed that the reduction peak of Ag2O shifted to higher temperature and the intensity of silver diffraction peaks was much weaker after the addition of ZnO promoter to Ag/SiO2. This indicated that there existed the interaction between Ag2O and SiO2-ZnO which promoted the silver particles dispersing on the support and inhibited the sintering of silver during the reaction. NH3-TPD and TG results revealed that the acid amounts of the catalyst and coking increased after adding ZnO to Ag/SiO2, which resulted in the deactivation of Ag/SiO2-ZnO catalyst rapidly.     

Ag/AgBr/TiO2 visible light photocatalyst for destruction of azodyes and bacteria

Ag/AgBr/TiO2 was prepared by the deposition-precipitation method and was found to be a novel visible light driven photocatalyst. The catalyst showed high efficiency for the degradation of nonbiodegradable azodyes and the killing of Escherichia coli under visible light irradiation (lambda>420 nm). The catalyst activity was maintained effectively after successive cyclic experiments under UV or visible light irradiation without the destruction of AgBr. On the basis of the characterization of X-ray diffraction, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, the surface Ag species mainly exist as Ag0 in the structure of all samples before and after reaction, and Ag0 species scavenged hVB+ and then trapped eCB- in the process of photocatalytic reaction, inhibiting the decomposition of AgBr. The studies of ESR and H2O2 formation revealed that *OH and O2*- were formed in visible light irradiated aqueous Ag/AgBr/TiO2 suspension, while there was no reactive oxygen species in the visible light irradiated Ag0/TiO2 system. The results indicate that AgBr is the main photoactive species for the destruction of azodyes and bacteria under visible light. In addition, the bactericidal efficiency and killing mechanism of Ag/AgBr/TiO2 under visible light irradiation are illustrated and discussed.     

Plasmonic enhancements of photocatalytic activity of Pt/n-Si/Ag photodiodes using Au/Ag core/shell nanorods

We report the plasmonic enhancement of the photocatalytic properties of Pt/n-Si/Ag photodiode photocatalysts using Au/Ag core/shell nanorods. We show that Au/Ag core/shell nanorods can be synthesized with tunable plasmon resonance frequencies and then conjugated onto Pt/n-Si/Ag photodiodes using well-defined chemistry. Photocatalytic studies showed that the conjugation with Au/Ag core/shell nanorods can significantly enhance the photocatalytic activity by more than a factor of 3. Spectral dependence studies further revealed that the photocatalytic enhancement is strongly correlated with the plasmonic absorption spectra of the Au/Ag core/shell nanorods, unambiguously demonstrating the plasmonic enhancement effect.     

Preparation and Characterization of Polysulfone/Nanosilver-Doped Activated Carbon Nanocomposite

In this study, nano silver-doped activated carbon (Ag/C) acted as an inorganic additive and was blended with a polysulfone (PSF) matrix in a tetrahydrofuran (THF) solution, thereby forming nano silver- doped activated carbon/polysulfone (Ag/C/PSF) composites. Subsequently, the silver content and characterization of the Ag/C were identified using energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The FTIR, XRD, EDS and SEM were used to characterize the structure and morphology of the Ag/C/PSF composites. The FTIR spectra analysis revealed that adding a small volume of Ag/C in a PSF matrix did not substantially affect the functional groups of the matrix. The XRD results showed that the characteristic crystallization peaks of Ag/C/PSF (2θ = 26°) increased as the Ag/C content increased. The EDS results revealed that silver elements were inlaid into Ag/C/PSF composites, and the SEM results demonstrated strong interfacial interaction between the Ag/C particles and PSF matrix. The results of thermogravimetric analysis and differential scanning calorimetry appeared that adding Ag/C particles increased the thermal decomposition temperature and glass transition temperature of the Ag/C/PSF composites. From a stress–strain analysis, the added Ag/C particles enhanced the tensile strength of the PSF matrix. The results of contact-angle and atomic-force microscopy measuring showed that the hydrophobicity and surface roughness increased when Ag/C content increased. The antibacterial test results revealed that the Ag/C/PSF composites exhibited excellent antibacterial activity against both Staphylococcus aureus and Escherichia coli. In addition, the electrical conductivity measurements showed that volume resistivity of the Ag/C/PSF composites decreased with the amount of Ag/C increase.     

纳米复合材料Ag/MxOy-TiO2(MxOy=ZnO、Al2O3和Fe2O3)的制备及其微波辅助光催化降解甲基橙

采用溶胶-凝胶-程序升温溶剂热一步法,利用表面活性剂EO₂₀PO₇₀EO₂₀(P123)作为模板剂,分别制备了三元纳米复合材料Ag/ZnO-TiO₂、Ag/Al₂O₃-TiO₂和Ag/Fe₂O₃-TiO₂。通过XRD、氮气吸附-脱附测定、TEM以及扫描电子显微镜配合X-射线能量色散谱仪(SEM-EDS)等对合成的3种催化剂进行了对比表征分析。结果表明,复合材料Ag/M_xO_y-TiO₂中Ag以单质形式存在并较好地分布在M_xO_y-TiO₂表面上。所合成产物颗粒尺寸较小(约10 nm左右),形貌较好。其中,Ag/ZnO-TiO₂的比表面积与Ag/Al₂O₃-TiO₂十分相近,略大于Ag/Fe₂O₃-TiO₂。光催化活性研究中,以甲基橙为模型分子且辅以微波场作用。结果显示,上述三元复合材料的活性均明显高于未掺杂银的二元复合材料,其中Ag/ZnO-TiO₂的光催化活性最好,在90 min内对甲基橙的降解率高达86%。     

A study on the solvent extraction of Ag/I/ with 1,2,3-benzotriazole in chloroform

A rapid and selective method has been developed for the substoichiometric extraction of Ag/I/with 1,2,3-benzotriazole /1,2,3-BT/ in chloroform in the presence of versenate. The effect of various parameters such as pH, time of equilibration, solvent, anions, cations, etc., on the extraction coefficient value has been studied. The stoichiometry of the extracted species of 11 /Ag:1,2, 3-BT/ was obtained by the slope ratio method and substoichiometric extraction. Decontamination factors for most elements in the substoichiometric extraction of Ag/I/ were found to be higher than 10⁴.     

Ag/TCNQ薄膜中的传质行为研究

采用真空蒸发的方法在玻璃基板上交替蒸发Ag和TCNQ(四氰基对醌二甲烷), 形成不同厚度的双层膜, 经Ag的固体化学扩散与TCNQ反应, 形成金属有机络合物. 利用透射光谱作为表征, 研究了Ag的传质规律, 给出了60~110 ℃温度下的恒温传质系数k和对应的激活能, 并对传质机制进行了探讨.     

Ag/Ag_3PO_4/g-C_3N_4复合光催化剂的合成与再生及其可见光下的光催化性能(英文)

研究了用离子交换沉淀法制备的Ag/Ag3PO4/g-C3N4的可见光光催化性能及再生方法.通过X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、紫外-可见(UV-Vis)吸收光谱及X射线光电子能谱(XPS)对其进行了结构特性分析.XRD结果显示再生后催化剂的结构未发生改变.FESEM及UV-Vis分析结果说明催化剂由Ag3PO4与g-C3N4复合而成.XPS分析结果表明催化剂表面出现少量的银单质.利用可见光(λ420nm)照射下的苯酚降解实验评价了样品的光催化活性,并通过活性物种及能带结构的分析对催化剂的光催化机理进行了推测.研究表明,Ag/Ag3PO4/g-C3N4的光催化活性明显高于纯Ag3PO4及纯g-C3N4,主要原因归结为单质银、Ag3PO4及g-C3N4的协同效应.经过氧化氢和磷酸氢铵钠(NaNH4HPO4)的再生可完全恢复催化剂的活性,这表明该绿色环保的再生方法可实现Ag/Ag3PO4/g-C3N4催化剂在环境中的实际应用.     

水热法合成多孔Ag_2S敏化二氧化钛催化剂及其可见光催化活性(英文)

Porous Ag2S sensitized TiO2 catalysts were synthesized by the hydrothermal process.The crystallization and porous structure of the Ag2S/TiO2 composite photocatalysts were investigated by X-ray diffraction,scanning electron microscopy with energy dispersive X-ray analysis,UV-Vis diffuse reflectance spectroscopy,and N2 adsorption.The Ag2S/TiO2 composites were mainly composed of anatase TiO2 and acanthite Ag2S.The absorption edge wavelengths of TiO2 and the Ag2S/TiO2 composite prepared with 3 mmol Na2S.5H2O were 400 and 800 nm,respectively,that is,the absorption edge of the composite had a pronounced red shift.The photocatalytic activity under visible light was investigated by the degradation of methylene blue with a UV-Vis spectrophotometer.The photocatalytic activities under visible light of the Ag2S/TiO2 photocatalysts were much higher than that of TiO2.     

Dependence of the catalytic activity of Ag/Al2O3 on the silver concentration in the selective reduction of NOx with n-hexane in the presence of H2

The activity of 0.25–5% Ag/Al₂O₃ catalysts in the selective catalytic reduction of nitrogen oxides with n-hexane under the conditions of promotion with a small amount of H₂ was studied. It was found that, upon the introduction of ∼1000 ppm of H₂ into the reaction mixture, the Ag/Al₂O₃ samples containing 1–2% Ag exhibited optimum activity and selectivity. It was established that, in the presence of 1000 ppm of H₂, the rate of the selective catalytic reduction of NO _x was higher by a factor of 10–13, and the onset temperature of the reaction was lower by approximately 100°C. It was found by X-ray photoelectron spectroscopy, temperature-programmed reduction, and UV spectroscopy that the high activity of 1–2% Ag/Al₂O₃ catalysts was due to the presence of small Ag _n ^δ+ and Ag _m ⁰ clusters on their surface. A decrease in the concentration of Ag below the optimum value resulted in the predominance of an inactive ionic form on the catalyst surfaces. As the concentration of Ag was increased (>2%), large particles of Ag₂O and Ag⁰, which facilitate the oxidation of n-C₆H₁₄, were formed to lead to a decrease in selectivity and in the degree of reduction of nitrogen oxides.