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The flower-like Ag/AgCl/BiOCl composite was prepared by a one-step chemical bath method at low te... more The flower-like Ag/AgCl/BiOCl composite was prepared by a one-step chemical bath method at low temperature for the first time. The morphology, crystallinity, composition, and optical property were well characterized by scanning electron microscope, X-ray diffraction, energy dispersive X-ray analysis, UV-vis diffuse reflectance spectrophotometer and nitrogen adsorption-desorption. The Ag/AgCl/BiOCl composite displayed enhanced visible-light photocatalytic activity against rhodamine B, which was much higher than Ag/AgCl or BiOCl. The mechanism for the degradation of rhodamine B over the Ag/AgCl/BiOCl was discussed. The superoxide radical and chlorine radical or the hole played critical roles instead of hydroxyl radicals.

A membrane based photocatalyst consisting of Ag/AgCl coated PAN nanofibers was synthesized in lar... more A membrane based photocatalyst consisting of Ag/AgCl coated PAN nanofibers was synthesized in large quantities by electrospinning technique combining electroless plating method and subsequent in situ oxidation strategy. Electrospinning was firstly used to fabricate PAN/AgNO 3 composite nanofibers. After reduction, Ag nanoparticles dispersed along the nanofibers act as seeds in the following metal electroless plating step for the growth of continuous Ag shell. Then an in situ oxidation reaction between Ag shells and FeCl 3 solution was carried on to prepare Ag/AgCl coated PAN nanofiber membranes. The as-prepared materials exhibited excellent photocatalytic activity under visible-light, long-term stability, flexibility, as well as easy separation from the liquid. The present work can open a new and effective route for preparing high-performance membrane based photocatalysts for practical application.

Usually, it is difficult to get small AgCl nanoparticles by a conventional aqueous solution route... more Usually, it is difficult to get small AgCl nanoparticles by a conventional aqueous solution route owing to their high nucleation and growth rate. In this study, AgCl nanoparticles with a diameter of less than 30 nm were uniformly coated on the surface of Ag 8 W 4 O 16 nanorods to form Ag 8 W 4 O 16 /AgCl-nanoparticle core-shell heterostructures by a simple in situ anion-exchange route. It was found that the ion exchange reaction between Cl − and WO 4 2− ions was preferable to occur on the surface of Ag 8 W 4 O 16 nanorods rather than in the bulk solution, resulting in the formation of core-shell nanorods. The AgCl shell layer could be easily controlled by adjusting the concentration of NaCl solution. With increasing NaCl concentration, more Ag 8 W 4 O 16 phase in the core transferred into AgCl-nanoparticle shell layer while the total size of the core-shell nanorods almost remained unchanged. The photocatalytic activity experiments of methyl orange aqueous solution under fluorescence light irradiation indicated that the AgCl nanoparticles coated on the surface of Ag 8 W 4 O 16 nanorods, which could be readily separated from a slurry system after photocatalytic reaction, exhibited a much higher photocatalytic activity than the bulk AgCl photocatalyst.

The Ag/AgCl/TiO 2 nanocomposite thin films are prepared on the pre-coated SiO 2 soda-lime glass s... more The Ag/AgCl/TiO 2 nanocomposite thin films are prepared on the pre-coated SiO 2 soda-lime glass substrates by a sol-gel method for depositing TiO 2 films, and then loaded with Ag/AgCl nanoparticles (NPs) by an impregnating precipitation photoreduction method. The as-prepared composite thin film exhibits a highly visible-light photocatalytic activity for degradation of 4-chlorophenol (4-CP) in water. The photocatalytic mechanism is proposed on the basis of the fact that the Ag NPs are photoexcited due to plasmon resonance, and then charge separation is accomplished by the transfer of photoexcited electrons from the Ag NPs to the TiO 2 conduction band and the simultaneous formation of OH • radical and Cl 0 , which cause the photocatalytic degradation of organic pollutants. The proposed mechanism is further confirmed by the detection of hydroxyl radicals. On the other hand, 4-CP can also be oxidized directly by plasmoninduced h + (or Ag + ) on Ag NPs, thereby accelerating the photooxidized Ag NPs back to their initial state. Therefore, the Ag NPs can be rapidly regenerated and the Ag/AgCl/TiO 2 system remains self-stability.

Ag/ZnO nanocomposites have been synthesized by facile hydrothermal and photodeposition method. Th... more Ag/ZnO nanocomposites have been synthesized by facile hydrothermal and photodeposition method. The effect of different concentration of Ag on the luminous intensity of ZnO was studied. The morphology, structure and optical properties of Ag/ZnO were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL), respectively. The XRD patterns show that intensities of diffraction peaks of Ag/ZnO were enhanced. The weak diffraction peak at 38.28°can be assigned to Ag 2 O when the concentration of Ag increased to 0.09 M. PL results demonstrate that the UV luminous intensity of ZnO was significantly influenced by the concentration of Ag. The UV luminous intensity of Ag/ZnO nanocomposites increased by 11 times as compared with undoped ZnO when the concentration of Ag was 0.03 M due to the local surface plasma resonance effect of Ag nanoparticles.

The combination of TiO 2 nanotubes and a surface plasmon resonance (SPR) photocatalyst used their... more The combination of TiO 2 nanotubes and a surface plasmon resonance (SPR) photocatalyst used their large adsorption capacity and wide visible light response, respectively, and a synergistic effect to enhance photocatalytic activity under visible light irradiation. Anatase TiO 2 nanotubes were prepared by hydrothermal synthesis, a hydrogen peroxide treatment, and calcination at 400 o C. AgCl nanoparticles were then loaded onto the TiO 2 nanotubes by a precipitation reaction, and some of the AgCl particles were reduced to Ag particles under halogen tungsten lamp irradiation. This gave a visible light SPR photocatalyst of Ag@AgCl/TiO 2 nanotubes that exhibited high photocatalytic activity, which was due to its large adsorption capacity, wide visible light response due to the SPR effect, fast separation of photogenerated electron-hole pairs, and strong oxidizing ability of Cl 0 generated by combining Cl ions with photoexcited holes. Methylene blue dye was thoroughly decolorized within 1 h in the presence of this photocatalyst under visible light irradiation. In addition, the photocatalyst was stable after recycling the photocatalytic reaction five times.

Zinc oxide (ZnO) and silver doped zinc oxide (ZnO:Ag) nanoparticles were prepared using nitrates ... more Zinc oxide (ZnO) and silver doped zinc oxide (ZnO:Ag) nanoparticles were prepared using nitrates of zinc and silver as oxidizers and ethylene diaminetetraacetic acid (EDTA) as a fuel via low-temperature combustion synthesis (LCS) at 500 1C. X-ray diffraction (XRD) pattern indicates the presence of silver in the hexagonal wurtzite structure of ZnO. Fourier transform infrared (FTIR) spectrum indicates the presence of Ag-Zn-O stretching vibration at 510 cm À 1 . Transmission electron microscopy (TEM) images shows that the average particle size of ZnO and ZnO:Ag nanoparticles were found to be 58 nm and 52 nm, respectively. X-ray photoelectron spectroscopy (XPS) data clearly indicates the presence of Ag in ZnO crystal lattice. The above characterization techniques indicate that the incorporation of silver affects the structural and optical properties of ZnO nanoparticles. ZnO:Ag nanoparticles exhibited 3% higher photocatalytic efficiency than pure ZnO nanoparticles. ZnO:Ag nanoparticles show better photocatalytic activity for the degradation of trypan blue (TrB) compared to undoped ZnO nanoparticles.

This paper presents a systematic study on two different preparation methods for titanium dioxide ... more This paper presents a systematic study on two different preparation methods for titanium dioxide with silver. The silver can be incorporated by irradiating the reaction mixture during preparation to reduce silver ion to silver metal or by direct calcination of the sol-gel material to decompose silver nitrate to silver. Of the two methods, we found the latter produces a more effective photocatalytic material (6-50% improvement in catalytic efficiency), which is attributed to the fact that the silver is homogeneously dispersed throughout the material. The efficiency of the materials were examined using a Q-Sun solar simulator (visible light) and in Dublin summer sunlight (latitude 54 • N). In both cases, the addition of increasing amounts of silver, for both batches of samples, significantly increases the rate of degradation of a model dye, rhodamine 6G (R6G), increasing the rate of degradation from 0.06 min −1 for TiO 2 to 0.34 min −1 for 5 mol% Ag-TiO 2 . This is attributed to the increasing visible absorption capacity due to the presence of silver nanoparticles.

Silver ions doping made enhancement of the photocatalytic activity of TiO 2 , which was determine... more Silver ions doping made enhancement of the photocatalytic activity of TiO 2 , which was determined by degradation of methyl orange (MO), a probe molecule, in an aqueous solution. X-ray diffraction (XRD) investigation demonstrated that the silver doping changed lattice parameters of TiO 2 , which should attribute to the O vacancies produced by the substitutional silver ion at lattice site. On above results, a doping mechanism of silver ions in TiO 2 was also discussed. #

Nanocrystals of undoped and silver doped zinc oxide (Zn 1-x Ag x O (where x = 0.00 to 0.05) were ... more Nanocrystals of undoped and silver doped zinc oxide (Zn 1-x Ag x O (where x = 0.00 to 0.05) were synthesized by coprecipitation method. Crystalline phases and optical absorption of prepared samples were determined by X-ray diffraction and UV-visible spectrophotometer. The average particles size was determined from X-ray line broadening. X-ray analyses reveals that Ag doped ZnO crystallizes in hexagonal wurtzite structure. The incorporation of Ag + in the place of Zn 2+ provoked an increase in the size of nanocrystals as compared to undoped or pure ZnO. Optical absorption measurement indicates red shift in the absorption band edge upon Ag doping. The band gap values of as prepared undoped and doped with silver samples are found to decrease with increase in temperature from 300 to 800 o C.

Synthesis of silver-doped zinc oxide (ZnO:Ag) nanoparticles through precipitation method has been... more Synthesis of silver-doped zinc oxide (ZnO:Ag) nanoparticles through precipitation method has been reported. The synthesis was conducted at room temperature and no subsequent thermal treatment was applied. ZnO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fourier transmission infrared spectroscopy (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. Detailed crystallographic investigation was accomplished through Rietveld refinement. The effect of silver content on structural and optical properties of resultant ZnO nanoparticles has been reported. It was found that silver doping results in positional shifts for the XRD peaks and the absorption band edge of ZnO. These were attributed to the substitutional incorporation of Ag + ions into Zn 2+ sites within the ZnO crystal. In addition, higher silver incorporation resulted in smaller size for ZnO nanoparticles. The photocatalytic activity of the ZnO:Ag nanoparticles was also determined by methylene orange (MO) degradation studies and compared to that of undoped ZnO. Improved photocatalytic activity was obtained for ZnO:Ag nanoparticles. It has been shown that an optimum amount of silver dopant is required to obtain maximum photocatalytic activity.

ZnO and Pd-doped ZnO photocatalysts with different molar ratio of Pd/Zn (1/100, 2/100, 3/100 and ... more ZnO and Pd-doped ZnO photocatalysts with different molar ratio of Pd/Zn (1/100, 2/100, 3/100 and 4/ 100) were prepared by a solegel method. The photocatalysts prepared were characterized by BET surface area, X-ray diffraction (XRD), UV/vis diffuse reflectance (DRS) and surface photovoltage spectroscopy (SPS), respectively. The results show that doping Pd into ZnO decreases the BET surface area. The XRD spectra of the Pd-doped ZnO catalysts calcined at 773 K show only the characteristic peaks of wurtzite-type. Doping Pd into ZnO increases the absorbance of ZnO in visible region and enhances the photoinduced charge separation rate. The photocatalytic activity of Pd-doped ZnO photocatalysts for decolorization of methyl orange (MO) solution was evaluated, of all the photocatalysts prepared, the Pddoped ZnO with 3/100 possesses the best photocatalytic activity. The results of further experiments show that increased adsorption ability of light and high separation rate of photoinduced charge carriers all play an important role in promotion of photocatalytic activity of Pd-doped ZnO nanostructure.

Cu-doped ZnO nanorods with different Cu concentrations were synthesized through the vapor transpo... more Cu-doped ZnO nanorods with different Cu concentrations were synthesized through the vapor transport method. The synthesized nanorods were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectroscopy. The XRD results revealed that Cu was successfully doped into ZnO lattice. The FE-SEM images showed that the undoped ZnO has needle like morphology whereas Cu-doped ZnO samples have rod like morphology with an average diameter and length of 60-90 nm and 1.5-3 µm respectively. The red shift in band edge absorption peak in UVvis absorbance spectrum with increasing Cu content also confirm the doping of Cu in ZnO nanorods. The photocatalytic activity of pure and Cu-doped ZnO samples was studied by the photodegradation of resazurin (Rz) dye. Both pure ZnO and the Cu-doped ZnO nanorods effectively removed the Rz in a short time. This photodegradation of Rz followed the pseudo-first-order reaction kinetics. ZnO nanorods with increasing Cu doping exhibit enhanced photocatalytic activity. The pseudo-first-order reaction rate constant for 15 % Cu-doped ZnO is equal to 10.17 × 10 −2 min −1 about double of that with pure ZnO. The increased photocatalytic activity of Cu-doped ZnO is attributed to intrinsic oxygen vacancies due to high surface to volume ratio in nanorods and extrinsic defect due to Cu doping.

Objectives: The present study has been undertaken to synthesize silver doped zinc oxide nanoparti... more Objectives: The present study has been undertaken to synthesize silver doped zinc oxide nanoparticles, with pharmaceutical importance. The synthesized particles have been evaluated to study the effect of silver doping on grain size and further on antibacterial activities against the microorganisms Bacillus subtilis and Staphylococcus aureus.