ZnO/CdS/Ag复合光催化剂的制备及其催化和抗菌性能

先用水热反应合成六方晶相CdS多层级花状微球并在其表面生长ZnO纳米棒形成均匀的ZnO/CdS复合结构,然后用光还原法将Ag纳米颗粒负载于ZnO纳米棒制备出ZnO/CdS/Ag三元半导体光催化剂,对其进行扫描电镜和透射电镜观察、光电性能测试、活性基团捕获实验以及光催化降解和抗菌性能测试,研究其对亚甲基蓝(MB)的降解和抗菌性能。结果表明：ZnO纳米棒均匀生长在CdS微球表面,CdS晶体没有明显裸露,Ag纳米粒子负载在ZnO纳米棒的表面;ZnO/CdS/Ag三元复合光催化剂有良好的可见光响应、较低的阻抗和较高的光电流密度;ZnO/CdS/Ag复合光催化剂能同时产生羟基和超氧自由基等活性氧基团;ZnO/CdS/Ag三元复合光催化剂对亚甲基蓝(MB)的30 min降解率高于90%;0.25 mg/mL的ZnO/CdS/Ag对革兰氏阴性菌(大肠杆菌)的灭菌率高于96%,对革兰氏阳性菌(金黄色葡萄球菌)能完全灭除。     

Facile preparation of Ag/ZnO nanoparticles via photoreduction

Ag/ZnO nanoparticles can be obtained via photocatalytic reduction of silver nitrate at ZnO nanorods when a solution of AgNO₃ and nanorods ZnO suspended in ethyleneglycol is exposed to daylight. The mean size of the deposited sphere like Ag particles is about 5 nm. However, some of the particles can be as large as 20 nm. The ZnO nanorods were pre-prepared by basic precipitation from zinc acetate di-hydrate in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide. They are about 50–300 nm in length and 10–50 nm in width. Transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDS), X-ray powder diffraction (XRD), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) were used to characterize the resulting Ag/ZnO nanocomposites.     

Tyrosine-assisted preparation of Ag/ZnO nanocomposites with enhanced photocatalytic performance and synergistic antibacterial activities

In this paper, Ag/ZnO metal-semiconductor nanocomposites were prepared through a facile one-pot hydrothermal method with the assistance of tyrosine. The synthesized samples were structurally characterized by x-ray diffraction, scanning electron microscope, transmission electron microscope and x-ray photoelectron spectroscopy. It was shown that the added tyrosine served both as a shape conductor for the formation of ZnO faceted nanorods and as a reducing agent of Ag(+) ions. In the reaction process, the complexation of Ag(+) with NH(3) and OH(-) decreased the redox potential of Ag(+)/Ag, which prevented the formation of isolated Ag nanoparticles in solution. The prepared Ag/ZnO nanocomposites showed potential applications in photodegradation of organic dye pollutants and destruction of bacteria.     

Reduced graphene oxide-based photocatalysts containing Ag nanoparticles on a TiO2 nanotube array

A simple one-step electrochemical deposition method was demonstrated to fabricate reduced graphene oxide/Ag nanoparticle co-decorated TiO₂ nanotube arrays (RGO/Ag–TiO₂NTs) photocatalyst in this study. The structures and properties of these photocatalysts were characterized using scanning electron microscope, X-ray diffraction, UV–Vis diffuse reflection spectra, and photoluminescence. By taking the advantages of TiO₂, graphene, and Ag nanoparticles (AgNPs), RGO/Ag–TiO₂NTs showed a greatly improved photocatalytic activity compared with the bare TiO₂NTs, Ag–TiO₂NTs or RGO–TiO₂NTs. The deposited RGO and AgNPs not only reduce the recombination of photogenerated electrons and holes, but also increase the surface area of the catalyst. Both photocatalytic performance and adsorptivity of the catalyst have been improved. The ternary photocatalyst exhibited over 93 % removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) under simulated solar light irradiation with good stability and easy recovery, which justifies the photocatalytic system, a promising application for herbicide or other organic pollutant removal from water.     

RGO/ZnO纳米棒复合材料的合成及光催化性能

采用水热合成法制备ZnO纳米棒及RGO/ZnO纳米棒复合材料。研究不同含量的RGO对RGO/ZnO纳米棒复合材料光催化活性的影响。采用X射线衍射仪(XRD)、场发射电子显微镜(FESEM)、光电子能谱仪(XPS)及漫反射紫外-可见吸收光谱(UV-Vis)检测手段对RGO/ZnO进行表征。结果显示:RGO与ZnO纳米棒成功复合。加入GO的含量不同,获得的RGO/ZnO样品在可见光区域的吸光度值不同。以甲基橙作为模拟污染物的光催化结果表明,RGO/ZnO复合材料具有高的紫外-可见光光降解效率,加入GO与ZnO的质量比为3%时,样品紫外-可见光光催化性能最佳,120min内甲基橙基本可以完全降解;且在波长大于400nm可见光照射下,RGO/ZnO具有一定的可见光活性,180min内其降解甲基橙效率最大可达26.2%。同时,RGO/ZnO具有较好的光稳定性。     

Synthesis and enhanced light absorption of alumina matrix nanocomposites containing multilayer oxide nanorods and silver nanoparticles

In this paper, multilayer oxide nanorods were deposited in the nanopores of anodic aluminum oxide (AAO) via solution infiltration followed by heat treatment. The nanorods have a core–shell structure. First, the shell (nanotube) with the thickness of about 40 nm was made of TiO₂ through the hydrolysis of (NH₄)₂TiF₆. Second, silver nanoparticles with the diameter of about 3 nm were added into the TiO₂ layer through thermal decomposition of AgNO₃ at elevated temperatures. Then, cylindrical cores (nanorods) of CoO and ZnO with 200 nm diameter were prepared, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and composition of the nanorods. UV–vis light absorption measurements in the wavelength range from 350 to 1000 nm were performed to study the effect of nanorod and nanoparticle addition on the light absorption property of the alumina nanocomposites. It is found that CoO nanorods increase the light absorption of the alumina matrix composite in the wavelength range from 500 nm to 800 nm, but the TiO₂ shell does not increase the light absorption much. The ZnO nanorods do not change the light absorption either. However, the addition of silver nanoparticles significantly enhances light absorption of both AAO/TiO₂/Ag/CoO and AAO/TiO₂/Ag/ZnO nanocomposites. This increase in the visible light absorption reveals that there exists surface plasmon around the fine silver nanoparticles in the nanorods.     

Synthesis of 1-D ZnO nanorods and polypyrrole/1-D ZnO nanocomposites for photocatalysis and gas sensor applications

1-D ZnO nanorods and PPy/1-D ZnO nanocomposites were prepared by the surfactant-assisted precipitation and in situ polymerization method, respectively. The synthesized nanorods and nanocomposites were characterized by UV–Vis spectrophotometer, Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM), which gave the evidence of 1-D ZnO nanorods, polymerization of pyrrole monomer and strong interaction between PPy and 1-D ZnO nanorods, respectively. Photocatalytic activity of 1-D ZnO nanorods was conducted by 3³ level full-factorial design to evaluate the effect of three independent process variables viz., dye concentration (crystal violet), catalyst concentration (1-D ZnO nanorods) and the reaction time on the preferred response: photodegradation efficiency (%). The PPy/1-D ZnO nanocomposites were used for the sensing of NH₃, LPG, CO₂ and H₂S gases, respectively, at room temperature. It was observed that PPy/1-D ZnO nanocomposites with different 1-D ZnO nanorod weight ratios (15 and 25%) had better selectivity and sensitivity towards NH₃ at room temperature.     

Photo-electrochemical and enhanced photocatalytic activity of CdS/rGO nanocomposites prepared by hydrothermal method

CdS/rGO nanocomposites with different mass ratio of rGO were fabricated via a facile one-pot hydrothermal method. The influences of different ratios on the microstructure, photo-electrochemical, and photocatalytic properties of the as-prepared samples were investigated. The experimental results show that CdS/rGO nanocomposites are hexagonal structure, one-dimensional CdS nanorods decorated on the surface of graphene. CdS/rGO nanocomposites show excellent visible light absorption and the band gap smaller than that of pure CdS and occur red shift. The photoluminescence spectra, transient photocurrent response and electrochemical impedance spectra indicate this nanostructure can accelerate the separation and migration efficiency of photogenerated electron–hole pairs, inhibit the recombination of photogenerated carries and and enhance electron transportation in the photocatalytic reactions. CdS/rGO nanocomposites display enhanced photocatalytic activity in degradation of MO under the simulated sunlight irradiation than that of pure CdS. In addition, in the photocatalytic degradation process ·O₂^? and ·OH play the key role.

     

Enhanced ferromagnetic and photocatalytic properties in Mn or Fe doped p-CuO/n-ZnO nanocomposites

Mn doped CuO/ZnO heterostructure exhibited significant room temperature ferromagnetism and visible light photocatalytic properties. Phase analysis for the pure, Mn and Fe doped CuO/ZnO nanocomposites evidently confirmed the formation of CuO and ZnO phases in each composite without any impurities. Based on Rietveld refinement analysis, the inclusion of Mn ions into CuO/ZnO nanocomposite decreased the unit cell volume of both oxides while Fe ions lead to lattice expansion. Mn ions induced the formation of ZnO hexagonal nanorods in CuO/ZnO nanocomposite. Nano-flakes and spherical nanoparticles shapes were seen for Fe doped CuO/ZnO nanocomposites. The characteristics IR absorption bands of CuO and ZnO overlapped together in their nanocomposites structure. From Kubelka-Munk plots, the incorporation of Mn ions enabled the ZnO band gap to absorb in the visible light region. Pure CuO/ZnO nanocomposite exhibited room temperature ferromagnetism with saturation magnetization (M_s) of 0.042 emu/g and coercivity (H_c) of 547 Oe. The ferromagnetic properties of the pure CuO/ZnO nanocomposite were greatly improved by Mn and Fe doping and the saturation magnetization extremely jumped to 0.86 and 0.85 emu/g, respectively. High photocatalytic activity, 98%, with good reusability for methyl orange (MO) degradation under visible light irradiation was achieved by 4 wt% Mn doped CuO/ZnO nanocomposite. A relation between the crystallinity, band gap and photocatalytic activity with dopant type (Mn or Fe) incorporated into CuO/ZnO nanocomposites was noticed. In contrary to Fe dopant, Mn as dopant played successful roles in improving the crystallinity, band gap and photocatalytic properties of CuO/ZnO nanocomposite. Multifunctional properties can be realized by combining different oxides in heterostructure form and using doping technique.     

Promoting Photocatalytic Performance of ZnO Particles by Photochemically Reducing Ag+ on the Particle Surfaces

Dispersive Ag nanoparticles were formed on the surface of crystalline ZnO particles, using a photochemical reduction technique, to produce the Ag/ZnO with high photocatalytic performance. The prepared Ag/ZnO particles, as well as the ZnO particles without Ag attachments, were characterized using x-ray diffractometer, transmission electron microscope, and surface area analyzer. The abilities of the ZnO and the Ag/ZnO particles to photocatalytically decompose methylene blue under 365-nm ultraviolet light irradiation were evaluated by determining the corresponding specific reaction rate constant, k′_MB,m (based on the mass of the photocatalyst used). While the ZnO crystalline particles (k′_MB,m > 0.43 m³/(kg min)) already possessed better photocatalytic performance than the commercial photocatalyst P25 (k′_MB,m = 0.39 m³/(kg min)), the Ag/ZnO particles exhibited much better photocatalytic performance than the ZnO particles. The highest k′_MB,m for the Ag/ZnO particles was 1.93 m³/(kg min), which was about five times that of the P25.     

Growth and characterization of flower-like Ag/ZnO heterostructure composites with enhanced photocatalytic performance

Flower-like Ag/ZnO heterostructure composites were prepared through a solvothermal method without surfactants or templates. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence (PL) spectroscopy. Results demonstrate that flower-like Ag/ZnO heterostructure composites were composed of wurtzite ZnO flowers coated by face-center-cubic Ag nanoparticles. The growth process of flower-like ZnO crystals was investigated, and a possible growth mechanism was proposed. The photocatalytic activity of the as-prepared flower-like Ag/ZnO samples, pure ZnO samples, and commercial TiO₂ (Degussa, P-25) was tested with the photocatalytic degradation of methylene blue. Results show that the Ag/ZnO heterostructures were superior in photocatalytic activity to the pure ZnO samples and the commercial TiO₂ (Degussa, P-25), but the mixture of Ag (0.1 wt%) particles and ZnO flowers did not, which implies that the heterostructure promoted the separation of photogenerated electron–hole pairs, enhancing the photocatalytic activity. That was primarily verified by the PL results.     

Synthesis and characterization of plasmonic visible active Ag/ZnO photocatalyst

Ag deposited ZnO nanoparticles (NPs) have been synthesized by simple sol–gel method for visible light active photocatalytic application. X-ray diffraction (XRD), TEM, UV–DRS and PL studies have been used to characterize the photocatalyst. The results show that Ag/ZnO NPs are wurtzite phase (WZ) of ZnO with Ag NPs in the surface region forming a hetero-interface of Ag–WZ (ZnO). Visible light activity of the material has been studied using photocatalytic degradation kinetics of methylene blue as a probe pollutant. Ag/ZnO NPs exhibit five times higher visible-light driven photocatalytic activity than pristine ZnO and four times than the reference Degussa P-25, under identical conditions. The high visible activity of Ag/ZnO may be attributed to the surface plasmon effect complemented sensitization in the presence of metallic Ag and effective charge separation through Ag–WZ hetero-interfaces.     

Green synthesis of nanosilver‐decorated graphene oxide sheets

A green facile method has been successfully used for the synthesis of graphene oxide sheets decorated with silver nanoparticles (rGO/AgNPs), employing graphite oxide as a precursor of graphene oxide (GO), AgNO₃ as a precursor of Ag nanoparticles (AgNPs), and geranium (Pelargonium graveolens) extract as reducing agent. Synthesis was accomplished using the weight ratios 1:1 and 1:3 GO/Ag, respectively. The synthesised nanocomposites were characterised by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, UV‐visible spectroscopy, Raman spectroscopy, energy dispersive X‐ray spectroscopy and thermogravimetric analysis. The results show a more uniform and homogeneous distribution of AgNPs on the surface of the GO sheets with the weight ratio 1:1 in comparison with the ratio 1:3. This eco‐friendly method provides a rGO/AgNPs nanocomposite with promising applications, such as surface enhanced Raman scattering, catalysis, biomedical material and antibacterial agent.Inspec keywords: silver, nanoparticles, graphene, nanocomposites, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X‐ray diffraction, ultraviolet spectra, visible spectra, X‐ray chemical analysis, surface enhanced Raman scattering, catalysis, nanofabricationOther keywords: antibacterial agent, biomedical material, catalysis, surface enhanced Raman scattering, rGO‐AgNP nanocomposite, eco‐friendly method, homogeneous distribution, thermogravimetric analysis, energy dispersive X‐ray spectroscopy, Raman spectroscopy, UV‐visible spectroscopy, X‐ray diffraction, atomic force microscopy, transmission electron microscopy, scanning electron microscopy, nanocomposites, reducing agent, geranium, graphene oxide sheets, graphite oxide, silver nanoparticles, green facile method     

Eco-friendly synthesis of Ag-ZrO2 nanocomposites for degradation of methylene blue

In this work, we have successfully synthesized ZrO₂ nanoparticles (NPs) using Ficus benghalensis (FB) leaf extract via simple microwave-assisted method. Silver NPs were deposited on the surface of ZrO₂ through photocatalytic reduction. The synthesized ZrO₂ and Ag-ZrO₂ photocatalysts were characterized through X-ray Diffraction (XRD), UV–Vis Diffuse Reflectance Spectroscopy (DRS), Fourier Transform-Infrared Spectroscopy (FT-IR), High-Resolution Transmission Electron Microscopy (HR-TEM), Photoluminescence (PL), and Brunauer–Emmett–Teller (BET) surface area. From the aforesaid characterization of the materials, it is revealed that synthesized Ag NPs are crystalline in nature with the face-centered cubic structure (FCC), while ZrO₂ NPs have both monoclinic and tetragonal phases. TEM images indicate that both ZrO₂ and Ag-ZrO₂ nanocomposite have spherical shape with the particle size of 20 and 15 nm, respectively. The optical properties were obtained using UV–Vis DRS which showed a decrease in the band gap energy of ZrO₂ due to surface plasmon resonance (SPR) effect of Ag NPs. A lower in PL intensity of Ag-ZrO₂ compared to that of ZrO₂ NPs confirms the suppression of recombination rate of excited electron–hole pairs ultimately resulted into high photocatalytic activity. BET analysis shows that all the nanocomposites have higher surface area than pure ZrO₂. The pure ZrO₂ and Ag-ZrO₂ show the efficient photocatalytic activity towards the methylene blue (MB) and methyl orange (MO). Ag-ZrO₂ (1.0 wt.%) shows 21% increment in photocatalytic activity as compared to pure ZrO₂ within 160 min under UV–Vis light.

     

ZnO:Cd纳米棒的制备及其光催化降解性能研究

采用水热法制备了ZnO和不同Cd掺杂浓度的ZnO:Cd纳米棒。通过x射线衍射仪、扫描电子显微镜、紫外-可见-近红外分光光度计和拉曼光谱对ZnO:Cd纳米棒的结构和光学特性进行了系统研究。结果显示,样品为一维纳米棒结构,Cd的掺杂可以减小ZnO纳米棒的晶粒尺寸和光学带隙。利用分光光度计检测ZnO:Cd纳米棒对偶氮结构染料(甲基橙溶液)的光催化降解效率,结果表明Cd掺杂可以改善ZnO的光催化性能,掺杂浓度为16%时ZnO:Cd纳米棒对甲基橙溶液的光催化降解效率最高。     

Enhanced wound healing activity of Ag–ZnO composite NPs in Wistar Albino rats

In the present study, silver (Ag) and Ag–zinc oxide (ZnO) composite nanoparticles (NPs) were synthesised and studied their wound‐healing efficacy on rat model. Ultraviolet–visible spectroscopy of AgNPs displayed an intense surface plasmon (SP) resonance absorption at 450 nm. After the addition of aqueous Zn acetate solution, SP resonance band has shown at 413.2 nm indicating a distinct blue shift of about 37 nm. X‐ray diffraction analysis Ag–ZnO composite NPs displayed existence of two mixed sets of diffraction peaks, i.e. both Ag and ZnO, whereas AgNPs exhibited face‐centred cubic structures of metallic Ag. Scanning electron microscope (EM) and transmission EM analyses of Ag–ZnO composite NPs revealed the morphology to be monodispersed hexagonal and quasi‐hexagonal NPs with distribution of particle size of 20–40 nm. Furthermore, the authors investigated the wound‐healing properties of Ag–ZnO composite NPs in an animal model and found that rapid healing within 10 days when compared with pure AgNPs and standard drug dermazin.Inspec keywords: wounds, tissue engineering, biomedical materials, nanocomposites, nanofabrication, nanomedicine, silver, zinc compounds, II‐VI semiconductors, wide band gap semiconductors, ultraviolet spectra, visible spectra, nanoparticles, particle size, surface plasmon resonance, spectral line shift, X‐ray diffraction, scanning electron microscopy, transmission electron microscopyOther keywords: enhanced wound healing activity, Ag‐ZnO composite nanoparticles, Wistar Albino rats, wound‐healing efficacy, ultraviolet‐visible spectroscopy, intense surface plasmon resonance absorption, aqueous Zn acetate solution, SP resonance band, blue shift, X‐ray diffraction analysis, diffraction peaks, face‐centred cubic structures, scanning electron microscope, SEM, transmission electron microscope, TEM, monodispersed hexagonal nanoparticles, quasihexagonal nanoparticles, particle size, animal model, time 10 d, size 20 nm to 40 nm, Ag‐ZnO     

Structural analysis of graphene oxide/silver nanocomposites: optical properties,electrochemical sensing and photocatalytic activity

In the present study, graphene oxide/silver (GO/Ag) nanocomposites were synthesized via a facile simple one pot chemical reduction method using ethylene glycol/sodium borohydrate (EG/NaBH₄) as solvent and reducing agent. GO was selected as a substrate and stabilizer to prepare GO/Ag nanocomposites. The synthesized GO/Ag nanocomposites were characterized by a series of techniques. Highly monodispersed stable crystalline silver nanoparticles having a face-centered cubic (fcc) phase were confirmed by X-ray powder diffraction (XRD) on GO signature. Scanning electron microscopy images showed that Ag nanoparticles are deposited on the GO sheet with a narrow size distribution. Transmission electron microscopy observations revealed that large numbers of Ag nanoparticles were uniformly distributed on GO sheet and well separated with an average size of 18 nm. Ultraviolet–visible (UV–Vis) spectroscopic results showed the peak of GO and surface plasmon resonance (SPR) of Ag nanoparticles. The SPR property of GO/Ag nanocomposites showed that there was an interaction between Ag nanoparticles and GO sheet. The intensities of the Raman signal of GO/Ag nanocomposites are gradually increased with attachment of Ag nanoparticles i.e. there is surface-enhanced Raman scattering activity. Electrochemical investigations indicated that the nanocomposites possessed an excellent performance for detecting towards 4-nitrophenol. An application of the obtained GO/Ag nanocomposites as a catalyst in the reduction of 4-nitrophenol to 4-aminophenol by NaBH₄ was demonstrated. The GO/Ag nanocomposites exhibited high activity and stability for the catalytic reduction of 4-nitrophenol. The prepared GO/Ag nanocomposites act as photo-catalysts.     

One-step microwave synthesis of Ag/ZnO nanocomposites with enhanced photocatalytic performance

Ag/ZnO nanocomposites have been successfully prepared via a facile microwave method without any post-synthesis treatment. This is a facile and rapid process requiring only low power of microwave irradiation (120 W). The formation mechanism of Ag/ZnO nanocomposites was clearly discussed. The photocatalytic performance of the Ag/ZnO nanocomposites with different Ag contents for degradation of methylene blue was systematically evaluated. The Ag/ZnO nanocomposites showed enhanced photocatalytic activities compared with pure ZnO. Specifically, the photocatalytic activities of Ag/ZnO nanocomposites increased with increasing Ag content from 0.5 to 1.5 %. However, further increasing Ag content to 2.0 % induced the formation of more agglomerates, which could act as recombination centers of photoexcited electron–hole pairs, leading to decreased photocatalytic activity. It is believed that this facile, rapid microwave-assisted strategy is scalable and can be applied to synthesize other noble metal/semiconductor oxide nanocomposites for different applications.     

Plasmonic effect and bandgap tailoring of Ag/Ag2S doped on ZnO nanocomposites for enhanced visible-light photocatalysis

Ag/Ag₂S-ZnO nanocomposites were prepared via a simple hydrothermal process followed by a plasmonic Ag⁺ reduction through a photo-deposition method. Ag₂S was introduced to narrow the overall composite bandgap and activate the surface plasmon resonance (SPR) effect of the Ag⁺ cation present. The physicochemical properties of the as-synthesised catalysts were characterised by X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM and TEM), Brunauer-Emmett-Teller (BET) analysis. Fourier-transform infrared spectroscopy (FTIR), Ultraviolet diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence emission spectra (PL) and X-ray photoelectron spectroscopy (XPS) was conducted to investigate the photo-absorption and emission spectra of the nanocomposites. The degradation efficiency of all the synthesised catalysts (ZnO, Ag₂S, Ag/ZnO and Ag₂S/ZnO) prior to the final product, Ag/Ag₂S/ZnO was tested and compared. Results showed that the ternary Ag/Ag2S/ZnO achieved a 98 % phenol removal compared to 50 %, 11 %, 64 % and 93 % for ZnO, Ag2S, Ag/ZnO and binary Ag2S/ZnO, respectively. The degradation kinetics followed the Langmuir-Hinshelwood model, which typically describes heterogeneous photocatalytic surface reactions. The linear fits had R² values higher than 0.97, which confirms the degree of accuracy or statistical fitness to the kinetic model. Degradation scavenger test confirmed the holes (h⁺) as the main inhibitor and identified the superoxide O₂?¯ radical as the main active specie responsible for the degradation. Total organic carbon analysis using the ternary Ag/Ag₂S-ZnO catalyst only achieved a 74% phenol mineralization after 24 h of photocatalysis. Recyclability tests showed good phenol removal stability of Ag/Ag₂S-ZnO at 41 % after five recycle runs. Hence, a synergistic degradation mechanism responsible for the efficient photo-degradation performance was proposed.     

Optical properties of Ag doped ZnO nanocrystals prepared by hydrothermal and photodeposition method

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 Ag₂O 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.