WO3 Quantum Dots Decorated GO/Mg‐doped ZnO Composites for Enhanced Photocatalytic Activity under Nature Sunlight

Graphene oxide/Mg‐doped ZnO/tungsten oxide quantum dots composites (WQGOMZ) were prepared through co‐precipitation method, and were studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Fluorescence spectra (FL), and UV–vis diffuse reflection spectra. Furthermore, the photocatalytic activity of resultant WQGOMZ was evaluated under nature sunlight. Experimental results showed that WO₃QDs can remarkably heighten the photocatalytic activity of GOMZ composite, in which is nearly 6.58 times higher than that of GOMZ composite. Simultaneously, WQGOMZ composites possess optical memory ability and maintain high photocatalytic stability for more than 40 days. The enhanced photocatalytic activity and optical memory ability are attributed to the effective synergistic effect between ZnO and WO₃QDs.     

Synthesis of the Dy: SrMoO4 with High Photocatalytic Activity under Visible Light Irradiation

Dysprosium (Dy)‐doping SrMoO₄ (with different molar ratio of Dy/Sr = 0/100, 10/100, 15/100 and 20/100) have been synthesized by high temperature thermal decomposition of metal–organic salt in organic solvent with a high boiling point. Their structures, morphology, and optical properties were characterized by X‐ray diffraction (XRD), high‐resolution tuning electron microscopy ((HR)TEM), X‐ray photo‐electron spectroscopy (XPS), and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Using this method, the pure phase, nano‐size, and low band gap of SrMoO₄ sample are obtained. The results shows that the size of as‐synthesized SrMoO₄ nanoparticles was about 200 nm. The band gap of Dy‐doped SrMoO₄ ranges from 3.76–3.90 eV, and decreases with increasing Dy concentration. The photocatalytic performance of as‐syntheszied products were determined from the degradation of methylene blue (MB) by UV–vis light irradiation. The 15 mol%Dy‐doped SrMoO₄ sample shows the best performance for photocatalytic degradation of methyl blue of nearly 100% in 120 min under visible irradiation, which is higher than most of those reported before. The present work is meaningful for revealing the underlying mechanism in photocatalyst and improving the photocatalytic performance.     

Facile fabrication of ZnO/N‐doped helical carbon nanotubes composites with enhanced photocatalytic activity toward organic pollutant degradation

Novel ZnO/N‐doped helical carbon nanotubes (ZnO/N‐HCNTs) composites were successfully synthesized via a facile chemical precipitation approach at room temperature. The sample was well characterized by X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic activity was evaluated in the degradation of methylene blue (MB) aqueous solution under UV light irradiation. It is found that ZnO nanoparticles were highly and uniformly anchored on the surface and inner tubes of the N‐HCNTs with size of about 5 nm, and significantly enhanced the photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity of ZnO/N‐HCNTs composites can be ascribed to the integrative synergistic effect of effective interfacial hybridization between N‐HCNTs and ZnO nanoparticles and the prolonged lifetime of photogenerated electron–hole pairs. Moreover, the ZnO/N‐HCNTs could be easily recycled without any obvious decrease in photocatalytic activity and could be promote their application in the area of environmental remediation.     

Synthesis,Characterization, and Photocatalytic Activity of N‐Doped TiO2 Nanotubes

N‐doped TiO₂ nanotubes with high photocatalytic activity were prepared by the combination of sol‐gel process with hydrothermal treatment. The prepared materials are characterized with transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), x‐ray diffraction (XRD), x‐ray photoelectron spectra (XPS), and UV‐vis spectra. Photocatalytic performance of the N‐doped TiO₂ nanotubes is studied by testing the degradation rate of methyl orange under UV irradiation. Obtained results indicate that N‐doped TiO₂ nanotubes have high catalytic activity for photocatalytic oxidation.     

Li‐doped nanosized TiO2 powder with enhanced photocalatylic acivity under sunlight irradiation

This work reports on the synthesis of Li‐doped TiO₂ nanoparticles using the sol–gel process and solid‐state sintering, and investigates their potential use as a photocatalyst for degradation under sunlight excitation of different organic model compounds in aqueous solution. The structure of the nanocrystals was examined by X‐ray diffraction, UV‐vis ground state diffuse reflectance absorption spectra and X‐ray photoelectron emission spectroscopy. Results showed that samples prepared by sol–gel process and calcined at 400 °C are composed of a mixture of anatase and rutile phases, in contrast to the one prepared by solid‐state sintering, which exhibits an anatase phase with Li being involved in a spinel phase. The photocatalytic degradation of aqueous solutions of different aromatic compounds was successfully achieved under sunlight excitation in presence of Li‐doped TiO₂ prepared via sol–gel process. It was shown that the calcination temperature and the preparation mode greatly affect the photocatalytic efficiency. Copyright © 2010 John Wiley & Sons, Ltd.     

光稳定二氧化钛纳米管负载钯催化剂光降解甲基橙过程中的活性物种(英文)

采用光沉积法制备了光稳定二氧化钛纳米管负载钯催化剂.通过X射线衍射、紫外-可见漫反射光谱、透射电子显微镜(TEM)、氮气吸附-脱附、X射线光电子能谱(XPS)、光致发光光谱和光电流等表征手段研究了催化剂的结构和性质.TEM表明二氧化钛纳米管经光照后仍然保持良好的管状结构;XPS结果表明大部分Pd以零价形式存在.以甲基橙溶液作为模拟废液研究了催化剂在紫外光及模拟日光条件下的光催化活性.当Pd的负载量为0.3 wt%时,催化剂的光催化活性最高并且优于P25的光催化活性.另外,通过在光降解过程中加入不同的捕获剂研究了不同氧化活性组分的作用.结果表明,光生空穴(hrb+)在光催化降解过程中起主要作用.     

?-Bi2O3/BiOI异质结的制备及其有效去除有机染料的光催化作用

窄带半导体氧化铋(Bi2O3,带宽介于2.1-2.8 eV)因其强的可见光吸收和无毒性等特性而一直被认为是潜在的可见光催化材料.通常, Bi2O3具有a,b,g,d,e和w等六种晶型,其中,a,b和d-Bi2O3具有催化可见光降解有机物的活性.可是,由于其光生电子-空穴复合较快, Bi2O3的光催化活性还很低,远不够实际应用.将半导体与另一种物质如贵金属或其他半导体复合形成异质结是一种有效控制光生电子-空穴复合,提高光催化活性的方法.目前已成功开发了许多Bi2O3基的异质结光催化材料.尤其是通过用卤化氢酸与a-Bi2O3直接作用原位形成的a-Bi2O3与铋的卤氧化合物BiOX (X = Cl, Br或I)的异质结在提高光催化活性和制备方面显示了优越性.然而,具有更强可见光吸收的b-Bi2O3(带宽约2.3 eV)与卤氧化合物的异质结光催化性能却鲜有报道.本文通过用HI原位处理b-Bi2O3形成b-Bi2O3/BiOI异质结.该异质结表现较纯b-Bi2O3和BiOI更高的降解甲基橙(MO)可见光催化活性.通过多晶X射线衍射(XRD)、紫外漫散射(UV-DRS)、扫描电镜、透射电镜(TEM)、X光电子能谱(XPS)和荧光(PL)等手段研究了b-Bi2O3/BiOI异质结,并提出其高催化活性的机理. XRD结果显示,用HI原位处理b-Bi2O3可形成BiOI相,并且随着HI使用量增加,混合物中的BiOI相逐渐增多. HRTEM结果进一步表明,在混合物中的b-Bi2O3和BiOI都是高度结晶态,且两相之间有很好的接触,从而有利于两相之间的电荷移动.根据UV-DRS和ahv =A(hv –Eg)n/2等公式,计算出了b-Bi2O3和BiOI带隙分别为2.28和1.77 eV,以及两种半导体的导带和价带位置. b-Bi2O3的导带和价带位置分别为0.31和2.59 eV,而BiOI的导带和价带位置分别为0.56和2.33 eV.这样两种半导体能带结构呈蜂窝状,显然不适合光生电子-空穴的分离.然而, XPS测定结果显示,b-Bi2O3和BiOI相互接触形成异质结后,b-Bi2O3相的电子向BiOI相发生了明显的移动.根据文献报道,当两种费米能级不同的半导体接触时,电子会从费米能级高的半导体移向费米能级低的半导体,直至建立新的费米能级.b-Bi2O3被报道是典型的n型半导体,其费米能级在上靠近其导带位置;而BiOI是典型的p型半导体,其费米能级在下靠近其价带位置.基于此,我们提出了b-Bi2O3/BiOI异质结高催化活性的机理.当b-Bi2O3与BiOI形成异质结时,由于b-Bi2O3的费米能级较BiOI的高,因而电子从b-Bi2O3转向BiOI,直至新的费米能级形成.因此电子在两相之间移动导致了b-Bi2O3能带结构整体下移,以及BiOI能带结构整体上移,使得新形成的BiOI导带和价带位置高于b-Bi2O3的.当该异质结在可见光的照射下,光生电子将移至b-Bi2O3的导带,而空穴会移至BiOI的价带,最终达到了光生电子-空穴分离的效果,产生高的光催化活性. PL测试也证实了b-Bi2O3/BiOI异质结具有更长的光生电子-空穴寿命.     

Photodegradation of Rhodamine B on Sulfur Doped ZnO/TiO2 Nanocomposite Photocatalyst under Visible-light Irradiation

Sulfur doped ZnO/TiO₂ nanocomposite photocatalysts were synthesized by a facile sol‐gel method. The structure and properties of catalysts were characterized by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), UV‐vis diffusive reflectance spectroscopy (DRS) and N₂ desorption‐adsorption isotherm. The XRD study showed that TiO₂ was anatase phase and there was no obvious difference in crystal composition of various S‐ZnO/TiO₂. The XPS study showed that the Zn element exists as ZnO and S atoms form SO^2?₄. The prepared samples had mesoporosity revealed by N₂ desorption‐adsorption isotherm result. The degradation of Rhodamine B dye under visible light irradiation was chosen as probe reaction to evaluate the photocatalytic activity of the ZnO/TiO₂ nanocomposite. The commercial TiO₂ photocatalyst (Degussa P25) was taken as standard photocatalyst to contrast the prepared different photocatalyst in current work. The improvement of the photocatalytic activity of S‐ZnO/TiO₂ composite photocatalyst can be attributed to the suitable energetic positions between ZnO and TiO₂, the acidity site caused by sulfur doping and the enlargement of the specific area. S‐3.0ZnO/TiO₂ exhibited the highest photocatalytic activity under visible light irradiation after Zn amount was optimized, which was 2.6 times higher than P25.     

Template‐free Fabrication of Hierarchical Macro‐/mesoporous N‐doped TiO2/graphene Oxide Composites with Enhanced Visible‐light Photocatalytic Activity

Hierarchical macro‐/mesoporous N‐doped TiO₂/graphene oxide (N‐TiO₂/GO) composites were prepared without using templates by the simple dropwise addition mixed solution of tetrabutyl titanate and ethanol containg graphene oxide (GO) to the ammonia solution, and then calcined at 350 °C. The as‐prepared samples were characterized by scanning electron microscopy (SEM), Brunauer‐Emmett‐Teller (BET) surface area, X‐ray diffraction (XRD), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐Vis absorption spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under visible‐light irradiation. The results show that N‐TiO₂/GO composites exhibited enhanced photocatalytic activity. GO content exhibited an obvious influence on photocatalytic performance, and the optimal GO addition content was 1 wt%. The enhanced photocatalytic activity could be attributed to the synergetic effects of three factors including the improved visible light absorption, the hierarchical macro‐mesoporous structure, and the efficient charge separation by GO.     

Enhanced visible‐light‐driven photocatalytic activity of F doped reduced graphene oxide ‐ Bi2WO6 photocatalyst

The reduced graphene oxide‐Bi₂WO₆ (rGO‐BWO) photocatalysts with the different R_F/O values (molar ratio of the F molar mass and the O's molar mass of Bi₂WO₆) had been successfully synthesized via one‐step hydrothermal method. The F‐doped rGO‐BWO samples were characterized by X‐ray diffraction patterns (XRD), field‐emission scanning electron microscopy (FE‐ESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X‐ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS). The results indicate that F^? ions had been successfully doped into rGO‐BWO samples. With the increasing of the R_F/O values from 0 to 2%, the evident change of the morphology and the absorption edges of F‐doped rGO‐BWO samples and the photocatalytic activities had been enhanced. Moreover, the photocatalytic activity of F‐doped rGO‐BWO with R_F/O = 0.05 were better than rGO‐BWO and the other F‐doped rGO‐BWO under 500 W Xe lamp light irradiation. The enhanced photocatalytic activity can be attributed to the morphology of the intact microsphere that signify the bigger specific surface area for providing more possible reaction sites for the adsorption–desorption equilibrium of photocatalytic reaction, the introduction of F^? ions that may cause the enhancement of surface acidity and creation of oxygen vacancies under visible light irradiation, the narrower band gap which means needing less energy for the electron hole pair transition.     

Synthesis of iron‐based metal organic framework and its visible light‐driven photocatalytic degradation of dye pollutants

A novel metal–organic compound [Fe (ox)(phen)]_n (phen = 1,10‐Phennannthroline, ox = oxalate acid) has been hydrothermally synthesized and structurally characterized by X‐ray single‐crystal diffraction, X‐ray diffraction, IR, UV–vis diffuse reflectance spectroscopy and X‐ray photoelectron spectroscopy. The compound crystallized in monoclinic,space group P2₁ with a = 0.92289 (3) nm, b = 1.35719 (3) nm, c = 1.02012 (4) nm,β = 94.372 (2)°,V = 1.27402(8)nm³,Z = 2,and exhibited a 2D layer structure. The photocatalytic activities of the compound were evaluated by decomposing Rhodamine B (RhB) and methyl orange (MO) under the visible light irradiation. In addition, the mechanism of the photocatalytic properties were proposed during this process.     

Preparation of Ce‐doped TiO2 Hollow Fibers and Their Photocatalytic Degradation Properties for Dye Compound

Cerium‐doped titanium dioxide (TiO₂) with a hollow fiber structure was successfully prepared using ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fiber as the template. The effects of cerium (Ce)‐doping on the crystallite sizes, crystal pattern, and optical property of the prepared catalysts were investigated by means of techniques such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), BET surface area, and UV‐vis diffuse absorption spectroscopy. SEM observation showed that the prepared TiO₂ fibers possessed fibrous shape inherited from the cotton fiber and had a hollow structure. As confirmed by XRD and UV‐vis diffuse absorption spectroscopy examinations, Ce‐doping restrained the growth of grain size and extended the photoabsorption edge of TiO₂ hollow fiber into the visible light region. The present photocatalyst showed higher photocatalytic reactivity in photodegradation of highly concentrated methylene blue (MB) solutions than pure TiO₂ under UV and visible light, and the amount of Ce‐doped significantly affected the catalytic property. In the experiment condition, the photocatalytic activity of 0.5 mol% Ce‐doped TiO₂ fiber was optimal of all the prepared samples. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed. The material was easily removed by centrifugal separation. Therefore, using the template method and by doping with cerium, TiO₂ may hopefully become a low‐energy consuming, high activity and green environmentally friendly catalytic material.     

Ultrasonic assisted synthesis of nanocrystalline cellulose as support and reducing agent for Ag nanoparticles: green synthesis and novel effective nanocatalyst for degradation of organic dyes

In this study, nanocrystalline cellulose (NCC) prepared from microcrystalline cellulose using high‐intensity ultrasonication as mechanical method without any chemical treatment. The obtained NCC with around 30–50 nm diameters, utilized as support, reducing and stabilizing agent for in‐situ green and eco‐friendly synthesis of silver nanoparticles (Ag NPs). The catalytic activity of composite was examined for degradation of environmental pollutants. The structure of as‐synthesized composite (Ag@NCC) was characterized by ultraviolet–visible spectroscopy (UV–vis), field emission scanning electron microscopy (FE‐SEM); Transmission electron microscopy (TEM); Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA). The results of the catalytic reaction experiments showed that spherically shaped silver nanoparticles of around 20 nm distributed on the surface of nanocellulose demonstrated high catalytic efficiency towards the removal of methyl orange (MO) and 4‐nitrophenol (4‐NP).     

Hydrothermal oxidation synthesis of rod‐like ZnO and the influence of oxygen vacancy on photocatalysis

Rod‐like ZnO nanoparticles (NPs ) were synthesized from zinc powder by a simple hydrothermal oxidation method. The presence of acetylacetone could promote the oxidation reaction of Zn and the formation of hexagonal nanorods. Then, the as‐prepared samples were annealed in N₂ , O₂ , and air atmosphere at 550°C for 2 h to control the number of oxygen vacancies in the samples. The samples were characterized by X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy, and UV –vis spectroscopy. The correlation between the oxygen vacancies and the photocatalytic activity was investigated. The results reveal that the annealing process alters the samples’ bandgap and number of the oxygen vacancies, thereby improving the photocatalytic activity. The enhancement of photodegradation efficiency arising from the appropriate content of oxygen vacancies is discussed.     

V2O5 based quadruple nano‐perovskite as a new catalyst for the synthesis of bis and tetrakis heterocyclic compounds

In this article, we presented a novel, efficient and facile approach for using strontium titanate supported catalyst in organic synthesis. Bis and tetrakis of coumarin, indole and xanthene derivatives can effortlessly have prepared using V₂O₅/perovskite nanoparticles (NPs) under solvent‐free condition. V₂O₅/perovskite in (NPs) was prepared and identified using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) and scanning electron microscope supported with energy dispersive X‐ray (SEM/EDAX). Calculated crystal size was from the intense XRD peaks was found to range between 50–60 nm in agreement with that obtained from the transmission electron microscopic investigation. EDAX analysis and mapping images reveal a homogenous distribution of all constituents with their calculated ratios in the synthesized catalyst.     

Preparation of upconversion Yb3+ doped microspherical BiOI with promoted photocatalytic performance

Bismuth oxychloride (BiOI) has a good visible light responsive property due to their relatively narrow band gap, and its photocatalytic performance was further improved by doping ytterbium ions (Yb³⁺). This may be due to strong optical absorption in UV–visible light, effective separation of the photoinduced electron-hole pairs, and the capacity to up-convert Near-IR light into visible-light of Yb³⁺ ions. In this study, a facile solvothermal method was adopted to synthesize Yb³⁺ ions doped BiOI photocatalysts. The doped photocatalysts with molar ratios of 0, 0.5, 1, 1.5, 2 and 2.5% Yb³⁺ ions were prepared. The 2% Yb³⁺ ions doped BiOI exhibited the highest photocatalytic degradation efficiency on degrading Rhodamine B, which was two times higher than that of pure BiOI. Also Yb³⁺ ions doped BiOI showed high photocatalytic degradation on herbicide isoproturon. The prepared photocatalysts were characterized by SEM, XRD, UV–vis DRS. It indicated that the doping ions entered the lattice of BiOI crystals and improved the photocatalytic performance. The photocatalytic mechanism was also studied. This work provided the potential application of Yb³⁺ doped BiOI for the degradation of organic contaminants.     

Synthesis,characterization and photocatalytic application of TiO2/magnetic graphene for efficient photodegradation of crystal violet

A magnetized nano‐photocatalyst based on TiO₂/magnetic graphene was developed for efficient photodegradation of crystal violet (CV). Scanning electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and elemental mapping were used to characterize the prepared magnetic nano‐photocatalyst. The photocatalytic activity of the synthesized magnetic nano‐photocatalyst was evaluated using the decomposition of CV as a model organic pollutant under UV light irradiation. The obtained results showed that TiO₂/magnetic graphene exhibited much higher photocatalytic performance than bare TiO₂. Incorporation of graphene enhanced the activity of the prepared magnetic nano‐photocatalyst. TiO₂/magnetic graphene can be easily separated from an aqueous solution by applying an external magnetic field. Effects of pH, magnetized nano‐photocatalyst dosage, UV light irradiation time, H₂O₂ amount and initial concentration of dye on the photodegradation efficiency were evaluated and optimized. Efficient photodegradation (>98%) of the selected dye under optimized conditions using the synthesized nano‐photocatalyst under UV light irradiation was achieved in 25 min. The prepared magnetic nano‐photocatalyst can be used in a wide pH range (4–10) for degradation of CV. The effects of scavengers, namely methanol (OH^? scavenger), p‐benzoquinone (O₂^?? scavenger) and disodium ethylenediaminetetraacetate (hole scavenger), on CV photodegradation were investigated.     

La掺杂 BiFeO3对苯酚光催化降解性能的影响

苯酚是一种稳定、毒性大且难降解的有机物,对人类和生态环境产生很大威胁,因此急需研发出能有效移除工业废水中苯酚污染物的方法.其中,绿色、高效的光催化氧化技术得到研究人员青睐.在半导体光催化剂中, BiFeO3具有带隙窄(2.2–2.5 eV)、化学稳定性好及成本低等优点,被看作是最有潜力的光催化剂.但是, BiFeO3存在光生电子空穴对复合率高,制备过程中易形成杂质相的缺点,使得其光催化活性很差,限制了 BiFeO3在光催化领域的应用.异种离子的引入能产生杂质能级或裁剪半导体带隙,同时促进光生载流子分离,故可考虑采用离子掺杂改性 BiFeO3的手段来抑制杂质相生成,提高载流子分离,从而提高 BiFeO3的光催化性能.本文以柠檬酸为络合剂,通过一步溶胶凝胶法合成了系列样品 Bi1-xLaxFeO3(摩尔分数x =0,0.10,0.15,0.20).通过 X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外可见漫反射(UV-Vis DRS)及荧光光谱(PL)等手段对不同样品的物相、形貌、表面价态和光学性能进行了表征.并通过活性物种捕获实验和羟基自由基(?OH)产生实验分析了 Bi0.85La0.15FeO3样品在苯酚降解过程中的主要活性物种和降解机理.相对于单相 BiFeO3, La改性 BiFeO3催化剂的光降解苯酚性能均有提高,其中 La最佳掺杂量为0.15.在模拟太阳光下照射180 min后, Bi0.85La0.15FeO3的光催化活性达到96%,同时 COD去除率达到81.53%,并表现出好的循环使用活性和稳定性.研究发现,该光催化过程中主要的活性物种为?OH. XRD, SEM, TEM和 EDS结果表明, La元素掺杂进 BiFeO3结构中,且各元素分布均匀,同时,适量 La元素掺杂能有效抑制杂质相 Bi25FeO40的形成,而且 La掺杂 BiFeO3样品的颗粒尺寸略有减小,有利于电子空穴转移. XPS显示, La改性 BiFeO3样品的表面有氧空位形成,将有利于有机物的吸附和降解;另外,羟基氧和吸附氧含量增大,有利于活性氧物种形成. UV-Vis DRS和 PL测试证明, La改性后的样品对可见光的响应增强,样品带隙变窄,产生杂质能级,抑制了光生载流子复合,有利于产生更多载流子来促进活性物种形成,从而提高光催化活性.氧物种捕获实验说明,在 Bi0.85La0.15FeO3参与的苯酚降解过程中的主要活性物种是?OH,同时?OH的产生实验也证明了在光照下?OH在 Bi0.85La0.15FeO3光催化剂表面持续产生,并提出了光催化降解机理.     

Improved Photocatalytic Activity and Stability of Nano‐sized Ag/Ag2CO3 Plasmonic Photocatalyst by Surface Modification of Fe(III) Nanocluster

The surface modification of Ag/Ag₂CO₃ with Fe(III) ions has been achieved through simply photoreduction‐impregnation method. The obtained products were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and UV‐vis absorption spectroscopy. Under visible‐light irradiation (γ>420 nm), the Fe(III)/Ag/Ag₂CO₃ sample displays a higher photocatalytic activity and stability than pure Ag₂CO₃ and Ag/Ag₂CO₃ samples for the degradation of methyl orange (MO). The improved photocatalytic activity and stability of this ternary system could be ascribed to the synergetic effect between Ag nanoparticles and Fe(III) nanocluster. The metallic Ag nanoparticles cause an obviously enhanced visible‐light absorption to produce more photogenerated charges, while the Fe(III) works as an active site for the following oxygen reduction to reduce the recombination rate of photogenerated electrons and holes.     

Zinc Oxide Nanoparticle‐modified Glassy Carbon Electrode as a Highly Sensitive Electrochemical Sensor for the Detection of Caffeine

Zinc oxide nanoparticles (ZnO NPs ) were prepared by a simple, convenient, and cost‐effective wet chemical method using the biopolymer starch. The prepared ZnO NPs were characterized by X‐ray diffraction (XRD ), scanning electron microscopy (SEM ), energy‐dispersive X‐ray (EDX ), Fourier transform infrared (FT‐IR ), and UV ‐visible spectroscopic techniques. The average crystallite size calculated from XRD data using the Debye–Scherer equation was found to be 15 nm. The electrochemical behavior of caffeine (CAF ) was studied using a glassy carbon electrode (GCE ) modified with zinc oxide nanoparticles by cyclic voltammetry (CV ) and differential pulse voltammetry (DPV ). Compared to unmodified GCE , ZnO NPs‐ modified GCE (ZnO NPs MGCE ) exhibited excellent electrocatalytic activity towards CAF oxidation, which was evident from the increase in the peak current and decrease in the peak potential. Electrochemical impedance study suggested that the charge‐transfer capacity of GCE was significantly enhanced by ZnO NPs . The linear response of the peak current on the concentrations of CAF was in the range 2–100 μM . The detection limit was found to be 0.038 μM. The proposed sensor was successfully employed for the determination of CAF in commercial beverage samples.