Ag改性TiO2／SnO2纳米薄膜及光催化降解甲基橙的性能

以光还原沉积法对TiO2/SnO2薄膜进行Ag改性,制备Ag-TiO2/SnO2纳米薄膜,讨论紫外光照时间、光照强度、AgNjO3浓度等工艺条件埘光催化活性的影响.用XRD和SEM对薄膜的结构、表面形貌和化学组成进行表征,以甲基橙为模拟污染物对光催化性能进行测定.结果表明:在最佳条件下制备的Ag-TiO2/SnO2薄膜,Ag担载量为0.51%(摩尔分数),Ag簇直径在30～90 nm之间:薄膜具有较高的光催化活性,对甲基橙的降解率是修饰前TiO2/SnO2薄膜的2.02倍,是相同质量TiO2/ITO薄膜的3.30倍;催化活性的提高,源于反应机理的改变:薄膜中Ag-TiO2异质结的引入,一方面进一步促使光生电荷的分离,另一方面加速了氧气与激发电子的还原反应.     

纳米WO_3/DWCNTs材料的制备及其光催化性能

通过液相法制备出钨酸/DWCNTs和纯钨酸2种前驱体,然后在氮气气氛下焙烧至700℃,保温2 h,分别生成了WO_3/DWCNTs和WO_3粉末。采用扫描电子显微镜和X射线衍射仪对产物的形貌和结构进行表征。在11 W可见光的照射下,分别利用WO_3/DWCNTs和WO_3粉末对有机染料亚甲基蓝进行光催化降解反应;利用紫外-可见分光光度计测定出样品的紫外可见吸收光谱,通过朗伯比尔定律计算出光催化降解率。当光照时间为30 min时,WO_3/DWCNTs降解率达到87.50%,纯WO_3降解率仅为25.39%。结果表明,DWCNTs的加入可以有效抑制颗粒的团聚,减小颗粒尺寸,增大WO3的比表面积,增强WO_3的吸附能力,显著提高WO_3对亚甲基蓝的光催化降解效率。     

Micro-arc oxidation of TC4 substrates to fabricate TiO2/YAG:Ce compound films with enhanced photocatalytic activity

This paper introduces a process for “in situ” preparing TiO₂ photocatalytic film compounded with YAG:Ce³⁺ semiconductor upon titanium alloy by using micro-arc oxidation (MAO). The surface morphology, chemical compositions, phase structures and photocatalytic properties of the films were characterized and measured by field emission gun scanning electron microscope (FEG-SEM), energy-dispersive X-ray spectrometer (EDS), X-ray diffractometer (XRD), electro-chemical workstation and UV-vis spectrophotometer. The results show that the YAG:Ce³⁺ semiconductor particles which were added in the electrolyte had been homogenously compounded within the TiO₂ film during MAO. Compared with the pure TiO₂ film, the compounded film exhibited much larger specific surface area, stronger absorption in the visible light and higher photo-generated current density, which improves the photocatalytic property markedly. It is expected that MAO will provide a simple, economic and promising approach for preparing a superior photocatalytic TiO₂ film.     

High photocatalytic activity of Cu_2O/TiO_2/Pt composite films prepared by magnetron sputtering

Cu_2O/TiO_2/Pt three-layer films were deposited on glass substrates using magnetron sputtering method.The surface morphology and the optical properties of the composite film were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), ultravioletvisible spectroscopy(UV-Vis) and photoluminescence spectroscopy(PL). The photocatalytic activity of the samples was evaluated by the photocatalytic degradation of methyl orange(MO) aqueous solution under visible light irradiation. The results indicate that the Cu_2O/TiO_2/Pt composite films are made up of three layers which are Pt layer,anatase-TiO_2 layer and Cu_2O layer from bottom to top. The surface of the films is even and composed of regular-shaped spherical particles. The photocatalytic activity of the Cu_2O/TiO_2/Pt three-layer film is much higher than that of the Cu_2O/TiO_2 double-layer film. Such enhancement is ascribed to the presence of Pt layer, which further inhibits the photogenerated electron-hole recombination, prolongs the lifetime of the photogenerated carriers, increases the quantum efficiency and hence improves the photocatalytic activity of the film effectively.     

PVP辅助水热合成Bi2WO6纳米花及其光催化活性探究

本文成功利用PVP(聚乙烯吡咯烷酮)辅助水热技术合成了Bi₂WO₆空心纳米花,并对其结构和形貌进行了X射线衍射、扫描电子显微镜、透射电子显微镜、荧光光谱和紫外可见漫反射谱表征。结果表明：PVP对Bi₂WO₆空心纳米花的形成起到关键作用。在未添加PVP时,钨酸铋呈现出实心的纳米片状堆叠的结构,仅在纳米片的表面垂直生长少量小片。而随着PVP的量增多,表面的钨酸铋纳米片发生劈裂,垂直生长的纳米片数量增多,以至最终形成了空心的纳米花状结构。同时,钨酸铋的晶粒尺寸随着PVP含量的增加呈现出先减小再增大的趋势。基于PVP对其比表面积和吸附能力的改善,这种空心的钨酸铋纳米花展现出良好的光催化性能。在35W金卤灯模拟的可见光照射下,3小时内对罗丹明B的降解率达到了47%。荧光光谱分析表明PVP辅助水热的钨酸铋纳米花也具有更高的载流子迁移率。     

The influence of CuAlO2 on the strength of eutectically bonded Cu/Al2O3 interfaces

This work investigates the effect of continuous CuAlO₂ interfacial reaction product layers on the strength of eutectic bonded copper–alumina interfaces. The fracture resistance was characterized for interfaces produced by eutectic bonding with and without continuous CuAlO₂ interlayers. Results show that continuous CuAlO₂ layers can weaken the overall Cu/Al₂O₃ bond.     

不同前驱体制备的锡锑中间层对Ti／SnO2＋Sb2O3／PbO2电极性能的影响

研究了以乙二醇与柠檬酸反应制得的乙二醇柠檬酸酯溶液、乙二醇、乙醇、正丁醇为前驱体溶剂制备的锡锑中间层对Ti/SnO2 Sb2O3/PbO2电极性能的影响,用XRD、ESEM对不同前驱体制备的锡锑中间层和对应的二氧化铅活性层进行了表征,并用极化曲线法和阳极寿命快速检测法比较了不同前驱体对Ti/SnO2 Sb2O3/PbO2电极的阳极寿命和在1．0mol/L硫酸溶液中的电催化活性的影响。结果表明,不同前驱体溶剂对锡锑中间层的结构和形貌有着显著的影响;以乙二醇与柠檬酸反应制得的聚合前驱体为溶剂制备的锡锑中间层表面致密,锡锑含量相对较高,该中间层的均匀度和平整度明显好于其它3种前驱体。由聚合前驱体中间层制得的Ti/SnO2 Sb2O3/PbO2电极的使用寿命明显提高,但不同中间层前驱体对电极的电催化活性影响不大。     

杂化Cu2O/Cu纳米粒子的水相合成及强化光降解甲基橙的催化活性研究

为了优化Cu2O纳米粒子的光催化性能,论文以抗坏血酸作为还原剂、聚乙烯吡咯烷酮为表面活性剂采用水相合成的方法通过调控反应温度制备出杂化Cu2O/Cu纳米粒子。利用SEM、XRD和N2吸附技术对Cu2O/Cu纳米粒子的形貌特征和结构性能进行表征。同时,也研究Cu2O/Cu纳米粒子催化降解甲基橙(MO)的效果和降解反应动力学。实验结果表明,制备的杂化Cu2O/Cu纳米粒子为“鹅卵石”形状,粒径尺寸范围在20至40nm之间,与纯Cu2O粒子相比相比,杂化Cu2O/Cu粒子具有尺寸小、比表面积大的特点。由于杂化材料中引入了Cu纳米粒子,促进了Cu和Cu2O和之间的界面电荷转移,使得Cu2O/Cu纳米粒子展现更优异的催化性能。Cu2O/Cu催化降解MO的反应符合一级动力学反应模型。经过四次循环使用后,杂化Cu2O/Cu仍然能表现出良好的催化活性。     

(CuO, Fe2O3)掺杂Ag/SnO2电接触材料的物理性能

以CuO、Fe_2O_3为掺杂剂,采用机械合金化方法结合冷压-烧结-热压工艺制备(CuO, Fe_2O_3)掺杂Ag/SnO2电接触材料。利用X射线衍射(XRD)仪、扫描电镜(SEM)、透射电镜(TEM)、金属电阻率仪、热导率仪和霍尔效应测量仪等分析了不同掺杂比例Ag/SnO_2电接触材料的微观结构和物理性能。结果表明:热压可显著改善电接触材料中SnO_2颗粒与Ag基体的界面结合;CuO和Fe_2O_3单一掺杂可分别提高Ag/SnO_2电接触材料的导电性能和导热性能,而复合掺杂的Ag-11.5SnO_2-0.3CuO-0.2Fe_2O_3电接触材料的导电导热性能最佳,其电阻率为2.25μΩ·cm,硬度(HV_(0.5))为748MPa,在室温下的热扩散系数和热导率分别为111.4 mm~2/s和338.6 W/(m·K)。复合掺杂的SnO_2增强相对Ag基体的平均润湿角为62.7°,界面润湿效果好;SnO_2与Ag晶粒之间界面结合良好,SnO_2(200)晶面与Ag(111)晶面的界面晶格错配度为14.25%。     

The connection between ab initio calculations and interface adhesion measurements on metal/oxide systems: Ni/Al2O3 and Cu/Al2O3

The Ni/Al₂O₃ and Cu/Al₂O₃ interfaces have been examined by atomistic, first-principles computations. Relationships have been established with such metallurgical variables as the activity of aluminum and the partial pressure of oxygen. The calculations reveal that the interfaces could be either stoichiometric, or Al-rich, or O-rich, depending on the Al activity. The results are amenable to comparison with available sessile drop and fracture measurements. For conditions applicable to sessile drop experiments performed with Ni(Al) or Cu(Al), the calculations reveal that, as the Al activity increases, initially the work of adhesion increases, reaches a maximum, and finally decreases to that for pure Al. This trend is consistent with the known measurements. Interfaces generated by diffusion-bonding with ‘pure’ Ni or Cu are predicted to be O-rich, with a large work of separation, W_sep. The implication is that the separation process induces substantial plastic dissipation in the metal, consistent with the high interface toughness. For interfaces formed through Al₂O₃ growth on Ni(Al) alloys, the interface is predicted to be Al terminated, with W_sep several times smaller than for either bulk Ni or Al₂O₃. This reduction is in accordance with observations that these interfaces fail in a brittle manner with no noticeable plasticity.     

Microstructure characterization and photocatalytic activity of mesoporous TiO2 films with ultrafine anatase nanocrystallites

A series of mesoporous TiO₂ films on borosilicate glass with ultrafine anatase nanocrystallites were successfully synthesized using a non-acidic sol gel preparation route, which involves the use of nonionic surfactant Tween 20 as template through a self assembly pathway. The microstructure of these TiO₂ films was characterized by XRD, SEM, HR-TEM, UV-Vis spectroscopy, and N₂ adsorption-desorption isotherm analysis. Their photocatalytic activities were investigated by using creatinine as a model organic contaminate in water. It was found that all mesoporous TiO₂ films prepared with Tween 20 exhibited a partially ordered mesoporous structure. The photocatalytic activity of the TiO₂ films could be remarkably improved by increasing Tween 20 loading in the sol at the range of 50% (v/v), which yielded large amount of catalyst (anatase) on the glass support and enhanced specific surface area. The optimum Tween 20 loading was 50% (v/v) in the sol, above which good adhesion between TiO₂ films and borosilicate glass could not be maintained. The final TiO₂ film (Tween 20: final sol = 50%,v/v) exhibits high BET surface area (∼ 120 m²/g) and pore volume (0.1554 cm³/g), ultrafine anatase nanocrystallinity (7 nm), uniform and crack free surface morphology, and improved photocatalytic activity.     

Fe3O4/SiO2/Bi2WO6磁性复合光催化剂的制备及其光催化性能

钨酸铋(Bi₂WO₆),结构最简单的Aurivillius相化合物,是近期受到研究者关注的新型光催化材料。然而,光催化剂粉末在反应介质中难被回收,工业化应用成本较高。本文用三步方法合成了可回收的Fe₃O₄/SiO₂/Bi₂WO₆磁性复合光催化剂,通过溶剂热法合成具有磁性的Fe₃O₄,用溶胶凝胶法在Fe₃O₄表面覆盖SiO₂层,后将磁性颗粒与Bi₂WO₆纳米片相结合。光催化剂的形貌结构及性能通过XRD、SEM、PL、UV-vis进行表征测试。结果表明,直径约500 nm的Fe₃O₄微球附着在边长约500 nm的Bi₂WO₆纳米片的表面,SiO₂在两者之间起到了粘连作用。光催化剂Fe₃O₄/SiO₂/Bi₂WO₆对于罗丹明B的光降解活性较好,且有一定磁性,可以通过外加磁场将其从溶液中分离,有较大的应用潜力。     

二氧化钛负载磷钨钼杂多酸催化合成缩醛(酮)

首次采用回流法制备了二氧化钛负载磷钨钼杂多酸催化剂H3PW6Mo6O40/TiO2,该催化剂的适宜制备条件为原料质量比m(TiO2)∶m(H3PW6Mo6O40)=1∶2.0,水的用量30 mL,回流反应时间2.0 h,活化温度150℃.以H3PW6Mo6O40/TiO2为催化剂,对以环己酮、丁酮、正丁醛、苯甲醛与二元醇(乙二醇、1,2-丙二醇)为原料合成的8种缩醛(酮)反应条件进行对比,较系统研究了醛(酮)与二元醇摩尔比、催化剂用量、反应时间对收率的影响.结果表明,在n(醛(酮∶n(乙二醇(1,2-丙二醇))=1.0∶1.4、催化剂用量占反应物料总质量的0.8%、反应时间1.0 h的条件下,8种缩醛(酮)的收率在53.0%～86.9%之间.     

Ag-decorated 3D flower-like Bi_2MoO_6/rGO with boosted photocatalytic performance for removal of organic pollutants

A series of unique 3 D flower-like Bi_2 MoO_6(BMO)/reduced graphene oxide(rGO) heterostructured composites decorated with varying amounts of Ag nanoparticles(NPs) were fabricated.Their morphological characteristics,structural features,energy band structures and photoelectrochemical properties were systematically studied.All the Ag/BMO/rGO ternary composites(AgBGy;y=1%,2% and 3%) demonstrated greater photocatalytic activity towards efficient removal of our selected organic models [methyl orange(MO),rhodamine B(RhB)and phenol],as compared with the BMO/rGO binary composites(BG-x;x=0.25,2,4 and 5).Particularly,AgBG-2%,which was synthesized with the addition of 2 wt% rGO and 2 wt% Ag in BMO,possessed superior photocatalytic activity.The fitted rate constants(k) for the photocatalytic degradation of RhB,MO and phenol using AgBG-2% were estimated to be 0.0286,0.0301 and 0.0165 min~(-1),respectively,which were over one order of magnitude greater than those obtained using pure BMO.Several factors may contribute to the observed enhancement,including greater specific surface area,enhanced light absorption,promoted spatial separation of electronhole(e~--h~+) pairs and their suppressed recombination,especially benefiting from the synergistic effects among BMO,rGO and Ag NPs.Our work suggests that the rational design of BMO/rGO/Ag ternary composite was an effective strategy to boost the photocatalytic activity of the resulting catalyst towards the highly efficient removal of organic pollutants from water.     

The effects of thermal spray technique and post-deposition treatment on the photocatalytic activity of TiO2 coatings

Titanium dioxide coatings were deposited by two thermal spray methods: high velocity oxygen fuel and atmospheric plasma spray. The coatings were characterized by XRD, SEM, Raman and UV-vis spectroscopy. The photocatalytic activities of the samples towards decomposition of methylene blue were also determined. As-prepared samples showed a very limited photocatalytic activity. In contrast, post-deposition oxidation of the samples in air resulted in significantly improved catalytic performance of the coatings. It appears that the oxidation state of titania played a critical role in photocatalytic activity given that partially reduced coatings resulted a very low activity. This conclusion was consistent with the observation of the Ti₈O₁₅ phase in the as-prepared samples. However, when oxidized, parameters such as the anatase content became a dominant factor in catalytic performance of the samples. The coating sprayed by high velocity oxygen fuel resulted in much higher activity than the atmospheric plasma sprayed coating, which can be attributed to higher anatase content of the former.     

Fast fabrication of Co3O4 and CuO/BiVO4 composite photocatalysts with high crystallinity and enhanced photocatalytic activity via ultrasound irradiation

A facile and efficient approach for the fabrication of Co₃O₄ and CuO/BiVO₄ composite photocatalysts was developed by intense ultrasound irradiation at room temperature. The as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, UV-vis diffuse reflectance spectra (UV-vis DRS), and Brunauer-Emmett-Teller (BET) surface areas. The photocatalytic activity of the composite catalysts was evaluated by photocatalytic degradation of acid orange II under visible light (λ > 420 nm) irradiation. Results showed that under intense ultrasonic irradiation, the precursors of copper acetate and cobaltous acetate could transform into CuO and Co₃O₄, respectively and the amorphous BiVO₄ can easily crystallize to highly crystalline BiVO₄. The composite photocatalysts exhibited much higher photocatalytic activity than that of pure BiVO₄. The enhanced photocatalytic performance could be attributed to the high crystallinity of BiVO₄ and the formed p-n heterojunction of Co₃O₄/BiVO₄ or CuO/BiVO₄. These two factors can effectively suppress the recombination of photogenerated hole-electron pairs.     

Identification and evolution of interfacial structure of SiO2 glass ceramic/Ti-6Al-4V alloy joint bonded with AgCu/Ni interlayer

AgCu/Ni composite interlayer was utilized to join SiO2 glass ceramic （74. 52% SiO2-23. 40% Al2 03 -2. 08 % K2 O, wt. % ） and Ti-6Al-4V alloy by eutectic reaction. Interface structures of the joints were identified by means of TEM analysis. This joining method contains three characteristic processes, which are the melting of AgCu eutectic alloy, eutectic reaction between interlayer and Ti-6Al-4V base material and active reaction of element Ti to SiO2 glass ceramic. It is different from traditional active brazing because active element Ti totally dissolves from Ti-6Al-4 V and reacts with SiO2 glass ceramic. SiO2 glass ceramic can be joined suecessfuUy to Ti-6Al-4 V alloy by this novel bonding method and the joint exhibits high shear strength, up to 110 MPa.     

Effects of Dy on the adherence of Al2O3/NiAl interface: A combined first-principles and experimental studies

The effects of dysprosium (Dy) on the adherence of Al₂O₃/NiAl interface were investigated by using first-principles theory calculations as well as experimental methods. The results showed that Dy could improve the adherence of the oxide/metal interface by two mechanisms: the first one was that Dy had a strong affinity for sulfur impurity in NiAl by the formation of Dy–S bonds, and thus can suppress the negative effects of sulfur; the second one was that Dy directly improved the Al₂O₃/NiAl interface adhesion by participating in bonding across the interface.     

NiCoCrAlY coatings with and without an Al2O3/Al interlayer on an orthorhombic Ti2AlNb-based alloy: Oxidation and interdiffusion behaviors

The mechanism of oxidation protection of NiCoCrAlY overlay coatings on the orthorhombic Ti₂AlNb-based alloy (O alloy) Ti–22Al–26Nb (at.%) is described. While the bare alloy exhibited poor oxidation resistance at 800 °C, adding NiCoCrAlY coatings significantly improved the oxidation resistance. However, serious interdiffusion between the coatings and the substrate resulted in rapid degradation of the coating system. Several reaction layers were formed at the coating/substrate interface by interdiffusion, and non-protective scales mainly of Cr₂O₃ and TiO₂ were formed due to the degradation of the coating. In order to solve this problem, an Al₂O₃/Al interlayer was sandwiched into the coating system as a diffusion barrier. The isothermal and cyclic oxidation protection of the multilayer coating system on the Ti–22Al–26Nb substrate was evaluated at 800 and 900 °C. The results indicated that the interdiffusion was much suppressed, and the duplex coating system demonstrated improved oxidation resistance on the Ti–22Al–26Nb substrate, with a thin and adherent protective α-Al₂O₃ scale forming on the surface.