氮掺杂石墨烯负载的硫化镉空心球纳米复合材料的光催化性能

通过无模板法一步合成了一种新型N掺杂石墨烯负载的CdS空心球复合材料. 采用X射线衍射、透射电镜、红外光谱、紫外-可见光谱、N₂吸附-脱附、荧光光谱和X射线光电子能谱等技术对该材料进行了表征, 并在可见光照射下测试了其在降解亚甲基蓝和水杨酸中的光催化性能. 结果表明, 相对于氧化石墨烯负载硫化镉空心球和单独的硫化镉空心球, 氮掺杂石墨烯负载的硫化镉空心球具有更高的光催化活性和稳定性. 这是由于氮掺杂的石墨烯能充当优异的电子受体和传输体, 从而抑制了载流子的复合. 另外发现, 羟基自由基是可见光下降解亚甲基蓝的主要活性物种.     

Hierarchical Ag/ZnO micro/nanostructure: Green synthesis and enhanced photocatalytic performance

Ag/ZnO metal-semiconductor nanocomposites with hierarchical micro/nanostructure have been prepared by the hydrothermal synthesis in the presence of bovine serum albumin (BSA). The results suggest that this biomolecule-assisted hydrothermal method is an efficient route for the fabrication of Ag/ZnO nanocomposites by using BSA both a shape controller and a reducing agent of Ag⁺ ions. Moreover, Ag nanoparticles on the ZnO act as electron sinks, improving the separation of photogenerated electrons and holes, increasing the surface hydroxyl contents of ZnO, facilitating trapping the photoinduced electrons and holes to form more active hydroxyl radicals, and thus, enhancing the photocatalytic efficiency of ZnO. This is a good example for the organic combination of green chemistry and functional materials.     

纳米复合材料Ag/ZnO的制备与微波增强光催化二甲酚橙

采用溶胶凝胶再结合程序升温溶剂热法制备了纳米复合材料Ag/ZnO,通过X射线衍射(XRD)、N2吸附-脱附、透射电子显微镜(TEM)以及扫描电子显微镜配合X射线能量色散谱仪(SEM-EDS)等测试手段对其结构、形貌等进行了表征.结果表明,复合材料中Ag以单质形式存在且掺杂于ZnO表面,产物具有六方晶系纤锌矿结构,其颗粒...     

Core-shell structure CdS/TiO2 for enhanced visible-light-driven photocatalytic organic pollutants degradation

CdS modified mesoporous titania core-shell spheres (CdS/CS-TiO₂) with enhanced visible-light activity were synthesized by an in situ method. This method included two steps: planting CdO into the framework of anatase TiO₂ core-shell spheres and then converting it to CdS by ion-exchange. The physicochemical properties of the obtained samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electronic micrograph, UV–vis diffuse reflectance spectra and nitrogen sorption. The in situ strategy resulted in CdS quantum dots highly dispersed in CS-TiO₂ without destroying the mesoporous core-shell structure. Compared with CS-TiO₂, the as-synthesized samples exhibited stronger visible-light absorption capability and greatly enhanced photocatalytic activity toward the degradation of Rhodamine B and 4-chlorophenol aqueous solution under visible light irradiation (λ > 420 nm).     

ZnO纳米柱状阵列表面AgX等离子基元修饰及其可见光光催化活性

采用浸渍法制备了表面AgX（X=I,Br）等离子基元修饰的ZnO纳米柱状阵列,研究了浸渍浓度和时间以及紫外光光照预处理对ZnO纳米柱状阵列可见光光催化活性的影响.采用场发射扫描电子显微镜、X射线衍射仪、紫外可见漫反射吸收光谱以及X射线光电子能谱仪等手段对ZnO纳米柱状阵列的形貌、相组成、禁带宽度及其表面特性进行了表征.结果显示,AgBr颗粒分布于ZnO纳米柱状阵列的顶端及顶端侧面,同时AgBr颗粒之间相互接触而形成网状结构.通过紫外光光照预处理,AgBr表面出现细小颗粒,形成Ag/AgBr/ZnO纳米复合结构.可见光光催化降解甲基橙结果表明,在相同工艺条件下所制AgBr/ZnO的可见光光催化活性明显优于AgI/ZnO,且与浸渍浓度及时间有关.由于ZnO纳米柱状阵列的比表面积大,AgBr的可见光响应特性以及Ag/AgBr纳米结构的表面等离子效应,经过紫外光光照预处理形成的Ag/AgBr/ZnO纳米复合结构表现出最好的可见光光催化活性.     

Transparent flexible ZnO/MWCNTs/pbma ternary nanocomposite film with enhanced mechanical properties

Functional organic-inorganic nanocomposites with high transparency show significant potential application in many fields. However, it is still a great challenge to prepare flexible transparent nanocomposites due to the intrinsic stiffness of the nanoparticles and the poor interaction between nanoparticles and organic matrices. In this work, a transparent ternary nanocomposite film with enhanced mechanical performance is fabricated by two-steps. First, the transparent ternary ZnO/MWCNTs/n-butyl methacrylate (BMA) nanodispersion is prepared by mixing the ZnO/BMA and MWCNTs/BMA dispersions directly. Then, the ternary nanocoposites film is fabricated via in-situ bulk polymerization of the above nanodispersions. As a result, the tensile strength of the ZnO/MWCNTs/poly-n-butyl methacrylate (PBMA) ternary film is enhanced by 42% and the elongation at break is three times that of ZnO/PBMA nanocomposite. The hardness of the film increases from 5B to 1H with 40 wt% ZnO. These results indicate that ZnO and MWCNTs can improve the mechanical properties of the composite significantly. Importantly, the ternary nanocomposite film still remains high transparency and exhibit excellent UV-shielding performance. The as-prepared transparent multifunctional nanocomposite films have promising applications in optical materials and devices, such as optical filters, contact lenses and protection packing.     

Sonochemical synthesis of Ag/AgCl nanocubes and their efficient visible-light-driven photocatalytic performance

A novel one-step sonochemical approach to synthesize a plasmonic photocatalyst of AgCl nanocubes (ca. 115 nm in edge length) with a small amount of Ag metal species is presented. The nanoscale Ag/AgCl hybrid photocatalysts with cubic morphology are readily formed under ambient ultrasonic conditions and neither external heat treatment nor reducing agents are required. The size of the Ag/AgCl photocatalysts could be controlled by changing the concentrations of Ag(+) ions and polyvinylpyrrolidone molecules in precursor solutions. The compositions, microstructures, influencing factors, and possible growth mechanism of the Ag/AgCl hybrid nanocubes were systematically investigated. The Ag/AgCl photocatalysts show excellent photocatalytic performance for degradation of various dye molecules under visible light.     

Preparation, characterization, and photocatalytic activity of polyaniline/ZnO nanocomposite

Polyaniline (PANI)/zinc oxide (ZnO) nanocomposite was synthesized by in-situ polymerization. X-ray diffraction patterns, UV?Cvisible spectroscopy, SEM, and TEM were used to characterize the composition and structure of the nanocomposite. Nanostructured PANI/ZnO composite was used as photocatalyst in the photodegradation of methylene blue dye molecules in aqueous solution. The photocatalytic activity of PANI/ZnO nanocomposite under UV and visible light irradiation was evaluated and was compared with that of ZnO nanoparticles. ZnO/PANI core?Cshell nanocomposite had greater photocatalytic activity than ZnO nanoparticles and pristine PANI under visible light irradiation. According to these results, application of PANI as a shell on the surface of ZnO nanoparticles causes the enhanced photocatalytic activity of the PANI/ZnO nanocomposite. Also UV?Cvisible spectroscopy studies showed that the absorption peak for PANI/ZnO nanocomposite has a red shift toward visible wavelengths compared with the ZnO nanoparticles and pristine PANI. The effect of different operating conditions on the photocatalytic performance of PANI/ZnO nanocomposite in the photodegradation of methylene blue dye molecules was investigated in a bath experimental setup.     

晶相组成可调的高活性可见光应答型二氧化钛纳米复合光催化材料的制备

采用新的化学溶液法,通过不同体积的钛酸四异丙酯的2-乙二醇单乙醚溶液与一定浓度的H₂O₂水溶液直接反应并对生成的钛过氧化配合物进行焙烧,制备了一系列TiO₂光催化剂. 表征发现,所得TiO₂样品为金红石和锐钛矿的纳米复合晶体,改变2-乙二醇单乙醚的体积可实现金红石相比例在0~96%广范围的调变.与商业二氧化钛P-25相比,所得的TiO₂紫外-可见光吸收谱出现明显红移,间隙能降低, 在可见光照射下,该样品对亚甲基蓝有良好的降解活性. 当2-乙二醇单乙醚的添加量为5 ml时,所得样品体相中金红石相比例接近50%,其光催化活性和吸附性能最好,可分别是P-25的3倍和5倍. 拉曼光谱结合X射线衍射等表征结果表明,该样品的表面仅含少量的金红石相. TiO₂纳米复合晶表面晶相的组成和分布对其光催化降解亚甲基蓝的活性及其吸附能力有直接的影响. 另外,TiO₂纳米复合晶的缺陷浓度也是增强其光吸收能力,提高其可见光光催化活性的原因之一.     

Surface-treated TiO2 nanoparticles for dye-sensitized solar cells with remarkably enhanced performance

Dye-sensitized solar cells (DSSCs) were prepared by capitalizing on mesoporous P-25 TiO(2) nanoparticle film sensitized with N719 dyes. Subjecting TiO(2) nanoparticle films to TiCl(4) treatment, the device performance was improved. More importantly, O(2) plasma processing of TiO(2) film that was not previously TiCl(4)-treated resulted in a lower efficiency; by contrast, subsequent O(2) plasma exposure after TiCl(4) treatment markedly enhanced the power conversion efficiency, PCE, of DSSCs. Remarkably, with TiCl(4) and O(2) plasma treatments dye-sensitized TiO(2) nanoparticle solar cells produced with 21 μm thick TiO(2) film illuminated under 100 mW/cm(2) exhibited a PCE as high as 8.35%, twice of untreated cells of 3.86%.     

Facile hydrothermal growth graphene/ZnO nanocomposite for development of enhanced biosensor

Graphene/zinc oxide nanocomposite was synthesised via a facile, green and efficient approach consisted of novel liquid phase exfoliation and solvothermal growth for sensing application. Highly pristine graphene was synthesised through mild sonication treatment of graphite in a mixture of ethanol and water at an optimum ratio. The X-ray diffractometry (XRD) affirmed the hydrothermal growth of pure zinc oxide nanoparticles from zinc nitrate hexahydrate precursor. The as-prepared graphene/zinc oxide (G/ZnO) nanocomposite was characterised comprehensively to evaluate its morphology, crystallinity, composition and purity. All results clearly indicate that zinc oxide particles were homogenously distributed on graphene sheets, without any severe aggregation. The electrochemical performance of graphene/zinc oxide nanocomposite-modified screen-printed carbon electrode (SPCE) was evaluated using cyclic voltammetry (CV) and amperometry analysis. The resulting electrode exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H₂O₂) in a linear range of 1–15 mM with a correlation coefficient of 0.9977. The sensitivity of the graphene/zinc oxide nanocomposite-modified hydrogen peroxide sensor was 3.2580 μAmM⁻¹ with a limit of detection of 7.4357 μM. An electrochemical DNA sensor platform was then fabricated for the detection of Avian Influenza H5 gene based on graphene/zinc oxide nanocomposite. The results obtained from amperometry study indicate that the graphene/zinc oxide nanocomposite-enhanced electrochemical DNA biosensor is significantly more sensitive (P < 0.05) and efficient than the conventional agarose gel electrophoresis.     

Fabrication of niobium doped titanate nanoflakes with enhanced visible-light-driven photocatalytic activity for efficient ibuprofen degradation

Niobium doping increases the visible light adsorption of titanate nanoflakes, which greatly enhances the photocatalytic activity for ibuprofen elimination.     

Fabrication of niobium doped titanate nanoflakes with enhanced visible-light-driven photocatalytic activity for efficient ibuprofen degradation

In this study, a novel class of niobium (Nb) doped titanate nanoflakes (TNFs) are fabricated through a one-step hydrothermal method. Nb doping affects the curving of titanate nanosheet, leading to the formation of nanoflake structure. In addition, Nb⁵⁺ filled in the interlayers of [TiO₆] alters the light adsorption property of pristine titanate. The band gap of Nb-TNFs is narrowed to 2.85 eV, while neat titanate nanotubes (TNTs) is 3.4 eV. The enhanced visible light adsorption significantly enhances the visible-light-driven activity of Nb-TNFs for ibuprofen (IBP) degradation. The pseudo-first order kinetics constant for Nb-TNFs is calculated to be 1.04 h^?1, while no obvious removal is observed for TNTs. Photo-generated holes (h⁺) and hydroxyl radicals (OH) are responsible for IBP degradation. The photocatalytic activity of Nb-TNFs depends on pH condition, and the optimal pH value is found to be 5. In addition, Nb-TNFs exhibited superior photo-stability during the reuse cycles. The results demonstrated Nb-TNFs are very promising in photocatalytic water purification.     

Thickness-dependent photocatalytic performance of ZnO nanoplatelets

In this paper, we report the large-scale synthesis of ZnO nanoplatelets as thin as 10 nm. The nanoplatelets show higher efficiency in photodegrading organic dyes than ZnO nanorods do, and for the nanoplatelets, the thinner they are, the higher the performance. The photocatalytic decomposition of organic dyes (eosin B) by ZnO nanoplatelets compares favorably to the performances of ZnS porous nanoparticles and commercial Degussa P25 titania particles. This finding may have significant implications in the environment remediation and the fabrication of functional nanodevices.     

Band structure tuning of ZnO/CuO composites for enhanced photocatalytic activity

The toxic dye pigments, even in small quantities, can damage ecosystems. Removing organic, inorganic, and microbiological contaminants from wastewater via heterogeneous photocatalysis is a promising method. Herein, we report the band structure tuning of ZnO/CuO nanocomposites to enhance photocatalytic activity. The nanocomposites were synthesized by a chemical approach using step-wise implantation of p-type semiconductor CuO to n-type semiconductor ZnO. Various characterization techniques such as X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) and UV spectroscopy were used to investigate the crystal structure, surface morphology, elemental composition and optical properties of the synthesized samples. As the CuO content increased from 10% to 50% in ZnO/CuO nanocomposites, the optical bandgap decreased from 3.36 to 2.14 eV. The photocatalytic activity of the samples was evaluated against the degradation of methylene blue (MB) under visible irradiation. Our study demonstrates a novel p–n junction oxide photocatalyst based on wt. 10% CuO/ZnO with superior photocatalytic activity. Effectively 66.6% increase in degradation rate was achieved for wt. 10% CuO/ZnO nanocomposite compared to pure ZnO nanoparticles.     

Synthesis and characterization of g-C3N4/BiVO4 composite photocatalysts with improved visible-light-driven photocatalytic performance

Novel visible-light-driven g-C₃N₄/BiVO₄ composite photocatalysts were fabricated via sol–gel and simple mixing and heating methods. The photocatalysts were characterized by X-ray diffraction, thermogravimetric, Fourier transform infrared, transmission electron microscope, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, and photoluminescence spectra. The results indicated that BiVO₄ was well dispersed on g-C₃N₄ sheet and an interaction between g-C₃N₄ and BiVO₄ was confirmed, which were facile to the electron transfer from g-C₃N₄ to BiVO₄ species. The mechanism was further induced to the heterojunction effect to improve the photocatalytic efficiency. The g-C₃N₄/BiVO₄ heterojunction at a weight ratio of 80 % calcined at 500 °C exhibited the most excellent photocatalytic ability for RhB decolorization under visible-light irradiation (λ > 420 nm) which was extraordinary more active than that of pure components.     

Synthesis and photocatalytic performance of Ag/AgCl/ZnO tetrapod composites

Ag/AgCl is a visible-light plasmonic photocatalyst that has attracted considerable attention because of its high visible-light absorption and activity owing to the surface plasmon resonance of noble-metal nanoparticles. In this study, Ag/AgCl/ZnO tetrapod composite was prepared by introducing ZnO tetrapods into Ag/AgCl prepared by a polydopamine reduction route. Ag/AgCl was densely deposited on the three-dimensional support framework provided by the ZnO tetrapods. The framework possessed a certain degree of porosity, thereby improving the specific surface area of the Ag/AgCl/ZnO composite. The interaction of ZnO with Ag/AgCl further increased the separation and transfer of electron–hole pairs. The Ag/AgCl/ZnO composite showed excellent photocatalytic activity and good stability. Under xenon lamp irradiation for 20 min, degradation of rhodamine B reached 90%. After four recycling tests, degradation remained stable without any sign of reduction. Ag/AgCl/ZnO tetrapod composite is shown to be a kind of green photocatalyst offering high activity, good stability, and recyclability.

     

CeO2/NaNbO3复合物的水热合成及其光催化性能的提高

钙钛矿型NaNbO3由于其非线性光学、铁电、离子导电性、高声速、光催化性能和光折变等优良性能而备受关注. 在光催化反应中, 宽禁带宽度(≈ 3.24 eV)使NaNbO3具有较高的导带底(CBM)和较低的价带顶(VBM). 因此, 它表现出强烈的光氧化和光还原能力. 众所周知, 钙钛矿型光催化剂光电子激发和传输能力的增强归因于其较高的对称性. 因此, 具有高对称性的立方NaNbO3有利于电子激发和转移. 但是, 一些固有的缺点, 包括电荷分离效率低、量子产率差和光催化活性差等, 限制了其在光催化领域的实际应用. 为了解决这些问题, 一种有效的方法是与其他半导体结合, 形成具有改善光催化活性的异质结复合物. CeO2作为传统的催化剂在光催化领域得到了广泛研究. CeO2具有稳定、无毒的特点, 是一种n型半导体. 目前, 研究人员已经发现CeO2与不同半导体的耦合可以提高CeO2的光催化活性. 这归因于能级水平的适当匹配.本文通过简易水热法制备了高活性的CeO2/NaNbO3异质结复合物, 并采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM, HRTEM)和紫外-可见漫反射光谱(DRS)等表征技术研究了所制光催化剂的物相结构、样品形貌和光学性能. 所制样品的光催化活性通过光催化降解无色抗菌环丙沙星(CIP)和染料罗丹明B(RhB)证实. 结果表明,在紫外和可见光照射, CeO2/NaNbO3复合物比纯NaNbO3具有更高的光催化活性. 此外, CeO2/NaNbO3复合物中CeO2的最佳质量比为2.0 wt%. 紫外光照射下光催化性能的显著提高是由于CeO2/NaNbO3异质结的形成不仅提高了光生电荷在界面范围内的迁移速率, 而且降低了光激发产生的电子和空穴的复合率. 可见光照射下内置电场的存在促进了电子和空穴的分离, 提高了光催化性能. 此外, 利用光致发光(PL)光谱、光电流、电化学阻抗谱和捕获实验证明了样品的光催化反应机理.捕获实验结果表明, ·OH自由基、·O2-自由基和空穴都参与了RhB的光催化降解过程. 最后, 探讨了提高光催化活性的可能机理.     

Facile synthesis and characterization of Chrysotile/SnO2 nanocomposite for enhanced photocatalytic properties

SnO₂ nanocrystals grown on chrysotile surfaces could be facilely synthesized in large quantities through a direct precipitation process coupled with a calcination treatment. The as-synthesized chrysotile/SnO₂ nanocomposites showed a smaller band gap energy (2.88 ev) and relatively strong light absorption than the individually dispersed SnO₂ nanocrystals. Due to the narrow gap and chemical passivation aroused by inherently negative charges on the surface of chrysotile, chrysotile/SnO₂ nanocomposite was endowed with superior performance to chrysotile nanotube and SnO₂ nanocrystals.