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.     

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.     

Synthesis and characterization of TiO2/MoO3/carbon clusters composite material

Nano-sized TiO₂/MoO₃/carbon clusters composite material has been successfully obtained by the calcinations of a TiO(acac)₂/MoO₂(acac)₂/epoxy resin complex under an oxygen atmosphere. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis and surface characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The ultraviolet–visible (UV–Vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. ESR spectra of the composite materials suggest that they have visible light-responsive catalytic ability with an electron transfer process of carbon clusters → MoO₃ → carbon clusters → TiO₂.     

Synthesis of a magnetically separable composite photocatalyst with high photocatalytic activity under sunlight

A novel magnetically separable composite photocatalyst (N-doped titania-coated γ-Fe₂O₃ magnetic activated carbon) was prepared. It consists of N-doped titania, activated carbon and γ-Fe₂O₃. The whole processes were carried out under low temperature. The prepared sample was characterized by XRD, DRS, SEM, BET and vibrating sample magnetometer (VSM). The photocatalytic activity was determined by degradation of Reactive Brilliant Red X-3B in an aqueous solution under solar irradiation. Results showed that this as-prepared composite photocatalyst exhibited much higher photocatalytic activity than Degussa P25. Furthermore, the photocatalyst can be separated easily by an external magnetic field. Thus, the photocatalyst can be recycled without mass losing, and the degradation percent of X-3B decreased less than 2% after six cycles.     

Characterization and photocatalytic activity of Zn–TiO2/AC composite photocatalyst

Activated carbon (AC) supported Zn²⁺–TiO₂ photocatalyst was prepared by sol–gel method. The prepared samples were characterized by X-ray diffraction, scanning electron micrograph, nitrogen absorption, diffuse reflectance UV/VIS and X-ray photoelectron spectroscopy. Using toluene as a pollution target, the photocatalytic activity of photocatalyst was evaluated. The results showed that prepared photocatalyst was obviously helpful for the removal of toluene in air. The photocatalytic degradation of toluene by Zn²⁺–TiO₂/AC reached 100% for 40 min and remained 75% after 160 min, while degradation by TiO₂ was only 30%. It indicated that the photocatalytic activity of prepared photocatalyst was enhanced. It is due to Zn²⁺-doping increased the oxidation and reduction of hole–electron pairs, which was the important factor in heterogeneous photocatalysis.     

Fabrication and efficient visible light-induced photocatalytic activity of Bi2MoO6/BiPO4 composite

Novel Bi₂MoO₆/BiPO₄ composites with heterojunction structure were fabricated by a one-step hydrothermal method. The photocatalytic properties of Bi₂MoO₆/BiPO₄ composites were evaluated by photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation (λ>420 nm). The results showed that Bi₂MoO₆/BiPO₄ photocatalysts showed much higher photocatalytic activity for the Rh B degradation than the pure BiPO₄ and Bi₂MoO₆ under visible light. The best photocatalytic performance of Bi₂MoO₆/BiPO₄ with about 98.0% Rh B degradation located at molar ratio of 2:1 under visible light illumination for 30 min. The enhanced photocatalytic activity could be mainly ascribed to the formation of heterojunction interface in Bi₂MoO₆/BiPO₄ composites, which is beneficial to the transfer and separation of photogenerated electron–hole pairs, as well as the strong visible light absorption resulting from the sensitization role of Bi₂MoO₆ to BiPO₄. It was also observed that the photodegradation of Rh B is chiefly attributed to the oxidation action of the generated O₂⁻ radicals and the action of h_vb⁺ through direct hole oxidation process.     

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.     

Preparation, characterization and photocatalytic activity of polycrystalline Bi2O3/SrTiO3 composite powders

Bi₂O₃/SrTiO₃ composite powders have been prepared and their photocatalytic activities were investigated by photooxidation of methanol. These powders were characterized by UV-Visible diffuse reflectance spectra, SEM and X-ray diffraction (XRD). The results revealed that all the Bi₂O₃/SrTiO₃ composite powders exhibited higher photocatalytic activity than pure SrTiO₃, Bi₂O₃ and TiO₂ (P25) under visible light irradiation (λ>440 nm). The effects of the Bi₂O₃ contents on the photocatalytic activities of the composite powders were examined, the photocatalytic activities increased with the content of Bi₂O₃ increasing to a maximum of 83% and then decreased under visible light irradiation. The effects of the calcination temperatures on the photocatalytic activities of the composite powders were also investigated.     

Preparation, characterization and photocatalytic activity of metal-loaded NaNbO3

Fe-, Ni-, Co- and Ag- loaded NaNbO₃ catalysts were prepared and their activities have been investigated in the reaction of photocatalytic hydrogen generation. Me/NaNbO₃ were synthesized by impregnation of NaNbO₃ in an aqueous solution of metal nitrates and then by calcination at the temperature of 400 °C. The crystallographic phases and optical and vibronic properties were examined by X-ray diffraction (XRD) and diffuse reflectance (DR) UV-vis and resonance Raman spectroscopic methods, respectively. Morphology and chemical composition of the produced samples were studied using a high-resolution transmission electron microscope (HR-TEM) and an energy dispersive X-Ray spectrometer (EDX) as its mode. The detailed analysis has revealed that all the investigated catalysts exhibit high crystallinity and the presence of Fe₂O₃, NiO, Co₃O₄ and Ag₂O oxides on Me/NaNbO₃ was confirmed. Finally, the influence of different metal loadings (Fe, Ni, Co and Ag) on the photocatalytic activity of NaNbO₃ for photocatalytic hydrogen generation has been investigated. Here we report that among all the Me/NaNbO₃ photocatalysts Ag-loaded NaNbO₃ exhibited higher photocatalytic efficiency for photocatalytic hydrogen generation than NaNbO₃.     

MoO3/Ag/MoO3 top anode structure for semitransparent inverted organic solar cells

In this study, we fabricated semitransparent polymeric solar cells with an inverted structure, with the structure being indium tin oxide (ITO)/cesium carbonate (Cs₂CO₃)/poly(3-hexylthiophene) (P3HT):1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61(PCBM)/transparent multilayer. The structure of the transparent multilayer (DMD multilayer), which acted as the anode, was MoO₃ (1–40 nm)/Ag (10 nm)/MoO₃ (0–80 nm). The inner MoO₃ layer showed a great performance changes depending on the variation of thickness, while the outer MoO₃ layer showed relatively slight changes. The best performance was observed with the of anode DMD multilayer thickness of 6/10/40 nm and with the illumination from the ITO side in organic solar cell devices. High performance result was observed in high reflectance and low transmittance of the DMD layer.     

基于MoO3/Ag/MoO3透明阳极的顶发射OLED的模拟计算与制备

运用传输矩阵法和正交分析法模拟计算出MoO₃/Ag/MoO₃透明电极的最佳厚度,采用镀膜实验验证模拟计算的准确性,制备了一系列不同MoO₃膜厚度和Ag膜厚度的透明电极。然后,制备了一系列顶发射有机电致发光器件:铝/氟化锂(LiF)/三(8-羟基喹啉)铝(Alq₃)/N,N'-二苯基-N,N'-(1-萘基)-1,1'-联苯-4,4'-二胺/三氧化钼(MoO₃)/银(Ag)/三氧化钼(MoO₃),来进一步验证模拟计算运用在器件制备中的准确性。MoO₃(10 nm)/Ag(10 nm)/MoO₃(25 nm)在532 nm处的透射率达到最大值88.256%,以该透明电极制备的器件与参考器件相比,性能有了明显提高,最大亮度和最大效率分别为20 076 cd/m²和4.03 cd/A,提高了18.5%和56%。器件性能的提高归因于顶发射OLED器件透射率的提高和MoO₃对空穴注入能力的提升。     

新型无铟透明导电-电致变色双功能MoO_3/Ag/MoO_3薄膜的制备及性能研究

研制了集电致变色和透明导电功能为一体的MoO_3/Ag/MoO_3(MAM)双功能薄膜。MAM薄膜采用电子束热蒸发技术在室温下制备。作为透明电极,MAM薄膜显示出良好的光电性能,可见光平均透过率为59.4%,方块电阻为12.2Ω/□。作为电致变色材料,MAM薄膜具有较快的响应时间(着色时间4.3 s,褪色时间11.1s),25%的光学对比度(528 nm),良好的稳定性(100次循环),以及较高的着色效率(40.5 cm~2·C~(-1)),在已报道的MoO_3着色效率中处于较高的水平。     

Graphene-CdS composite, synthesis and enhanced photocatalytic activity

Graphene-CdS (G-CdS) composites were synthesized through a simple solvothermal method. The formed CdS nanospheres were homogeneously scattered on the surface of graphene sheets. Fluorescence quenching effect of the G-CdS composites indicated effective transfer of photo-excited electrons from CdS to graphene, suppressed the recombination of photo-generated electron-hole pairs, so that the enhanced visible light induced photodegradation activity for Rhodamine B (RhB) was achieved. Based on the high photocatalytic activity and well stability, the G-CdS composite containing 70% CdS can be expected to be a practical visible light photocatalyst.     

Unprecedented photocatalytic activity of carbon coated/MoO3 core–shell nanoheterostructurs under visible light irradiation

We reveal that nano-scale carbon layer deposited by hydrothermal process on molybdenum oxide (MoO₃) nanowires surface significantly improve the light absorption range. Furthermore, the graphene-carbon coated MoO₃ nanocopmosite (rGO/C-MoO₃ nanocomposite) exhibits excellent chemical stability and enhanced photocatalytic activity for methylene blue in aqueous solution under visible light irradiation compared to the bare MoO₃ nanowires and carbon coated MoO₃ nanowires (C-MoO₃ nanowires). The enhanced photocatalytic activity of rGO/C-MoO₃ nanocomposite could be attributed to the extended light absorption range, better adsorptivity of dye molecules and efficient separation of photogenerated electrons and holes. Overall, this work provides new insights that the as synthesized rGO/C-MoO₃ nanocomposite can be efficiently used as high performance photocatalysts to improve the environmental protection issues under visible light irradiation.     

Synthesis and characterization of Ag/PPy composite films via enhanced redox reaction of metal ions

A facile approach to the formation of Ag/PPy composite film, through the reaction of Ag⁺ and pyrrole monomer, was developed with the help of synergistic effect of NH₃·H₂O on this reaction. Black or gray Ag/PPy film precipitated on the insert wall of the vessel within 0.5 h with this new method. The Ag/PPy composite film has good conductivity (sheet resistance: 0.28 Ω/square) and superhydrophility (contact angle of water, CAW 0°). Mechanism involved in the reaction rate acceleration was briefly discussed.     

Flowerlike PtCl4/Bi2WO6 composite photocatalyst with enhanced visible-light-induced photocatalytic activity

Flowerlike PtCl₄/Bi₂WO₆ composite photocatalyst was successfully synthesized through a simple two-step method involving a template-free hydrothermal process and the following impregnation treatment. The samples were fully characterized by the study of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis absorption spectra. The results indicated that the doping of Pt species did not affect the crystal structure and the morphology of Bi₂WO₆ photocatalyst, but it had great influences on the photocatalytic activity of Bi₂WO₆ towards rhodamine-B (RhB) degradation. Besides, the Pt species was found to be present as PtCl₄ in the composite samples, and also an optimal Pt species content on the surface of Bi₂WO₆ photocatalyst was discovered with the highest photocatalytic ability. The improved photocatalytic performance could be ascribed to the enhanced interfacial charge transfer and the inhibited recombination of electron-hole pairs. Meanwhile, a possible mechanism for RhB photocatalytic degradation over PtCl₄/Bi₂WO₆ catalyst was also proposed.     

Hierarchical nanostructured 3D flowerlike BiOX particles with excellent visible-light photocatalytic activity

BiOX (X = Cl, Br, and I) semiconductors were firstly prepared by a facile mixed solvent solvothermal route. Several characterization tools were employed to study the phase structures, morphologies, and optical properties of the samples. The in situ chemically mixed prepared BiOX particles with diameters 3.0–5.0 μm, fabricated by nanoplates in the thickness range of 5–18 nm, exhibited the highest visible-light photocatalytic activity among the as-prepared samples and Degussa P₂₅ for the degradation of Rhodamine B (RhB). This result can be due to the narrow bandgap, broad sunlight range, high electronic negativity, and efficient separation of photoinduced electron–hole pairs. Finally, a possible photocatalytic mechanism has been proposed.     

镉掺杂氧化锌纳米花的制备及其光催化活性

以氯化锌、氯化镉、氢氧化钠为原料,采用水热法合成Cd掺杂纳米花状ZnO光催化剂,并通过该样品对罗丹明B水溶液的降解来研究其光催化活性。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线能量色散谱（EDS）、光致发光谱（PL）及紫外-可见分光光度计（UV-Vis）等测试手段对材料物性进行表征。实验结果表明：当掺杂Cd²⁺时,样品形貌发生变化、粒径减小;掺杂Cd²⁺后的ZnO的吸收边和紫外峰对比于纯ZnO均发生红移,禁带宽度由3.24 eV 减小到3.16 eV。通过光催化实验分析可知,掺杂后纳米ZnO光催化剂对罗丹明B 水溶液的降解率有所提高,光照3 h其降解率高达98%,说明与纯ZnO相比,Cd掺杂ZnO纳米花具有更高的光催化活性。