Immobilization of metalloporphyrins on CeO_2@SiO_2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

Ce O2@Si O2 core-shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the Ce O2@Si O2 core-shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption-desorption isotherm(BET), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), ultraviolet and visible spectroscopy(UV-Vis), and Fourier transform infrared spectroscopy(FT-IR). The results show that the morphology of Ce O2@Si O2 nanoparticles is core-shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the Ce O2@Si O2 core-shell nanoparticles via amide bond. Especially, the core-shell structure contains multi Ce O2 core and thin Si O2 shell, which may benefit the synergistic effect between the Ce O2 core and the porphyrin anchored on the very thin Si O2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80% for acetophenone even after six-times reuse of the catalyst.     

Core-Shell Structure of NaYF_4@SiO_2@Au Nanocomposite of Synthesis and Characterization with Mechanisms Research

A facile method for preparing monodisperse NaYF_4@SiO_2@Au core-shell nanocomposite was developed. Transmission electron microscopy(TEM) as well as EDX(energy dispersive X-ray) was used to characterize the samples. The TEM showed the composite was a core-shell structure, spherical,with the uniform size of about 100 nm. TEM and EDX revealed that the NPs were coated with a layer of SiO_2 and Au shell. The core shell structure of NaYF_4@SiO_2@Au nanocomposite could dispersed in water easily. More importantly,after being coated with SiO_2 and Au, it was feasible for function by-SH and-NH2 groups, respectively. The forming process of the Au shell was monitored with TEM. The mechanism of coating Au shell was discussed in detail. It is expected that the core shell nanoparticle will act as multifunctional molecular imaging probes, such as positron emission tomography(PET), magnetic resonance imaging(MRI), optical imaging(OI), or contrast agent for sensing and detection.     

Synthesis and characterization of core-shell hydroxyapatite/chitosan biocomposite nanospheres

Novel core-shell hydroxyapatite/chitosan biocomposite nanospheres were synthesized in a multiple emulsion. The multiple emulsion was a w/o/w emulsion, made of diammonium phosphate solution as an inner aqueous phase, cyclohexane as an oil phase, and calcium nitrate solution and chitosan solution as an outer aqueous. The forming mechanism of core-shell spheres and the influence of temperature on the morphology of the nanospheres were investigated. The diameter of the resulting core-shell nanospheres was 100–200 nm and the thickness of the chitosan shell was about 10 nm. And it concluded that at different reaction temperature the morphologies of the products would be changed. The core-shell nanospheres have potential applications for the development of new biomedical materials.     

Stepwise synthesis of cuprous oxide nanoparticles with adjustable structures and growth model

By stepwise adding of reducer N2H4·H2O,cuprous oxide(Cu2O)nanoparticles(NPs)with adjustable structures were synthesized.The features of Cu2O NPs were characterized by XRD,TEM and UV-Vis absorption spectra.When the reducer was added into the reactant system at one time,the sizes of the Cu2O NPs are in the range of 120–140 nm.Most Cu2O NPs are solid spheres.As the reducer was divided into two equal parts and stepwisely added,almost all the NPs are hollow spheres with good size(150–170 nm)distribution and dispersity.But when the reducer was divided into three or four equal parts and stepwisely added,the NPs are hollow spheres,core-shell structures or solid spheres,and the sizes distribution of the products is deteriorated.The effect of sodium hydrate(NaOH)was also probed.Addition of NaOH speeded up the nucleation and growth processes of Cu2O NPs.With the alkalinity increase,the shells of the hollow spheres become compact and the thicknesses of the shells increase,but the size distribution of the NPs is deteriorated.The absorption spectra of the Cu2O NPs are tunable.With the shell thicknesses increase,the absorption peaks have red shifts.An inside-outside growth model of Cu2O NPs was proposed to explain the results.The Cu2O single crystalline grains grow not only in the reactant solution,but also inside of the hollow nanospheres.The new Cu2O nanocrystallines can not only aggregate onto the shells of the nano hollow spheres,but also inside and outside of the hollow spheres,which leads to increasing the shell thicknesses of the hollow spheres,forming core-shell structures or small solid spheres of Cu2O NPs,respectively.     

聚乙烯吡咯烷酮与柠檬酸钠的加入量对葡萄糖还原法制备Cu_2O颗粒形貌的影响

利用葡萄糖与本尼迪特试剂反应制备Cu2O颗粒,以X射线衍射、扫描电镜为表征手段,研究了聚乙烯吡咯烷酮(PVP)与柠檬酸钠的加入量对Cu2O颗粒形貌的影响。结果表明,通过改变PVP量可调控Cu2O的形貌与大小,即随着PVP量的增加,Cu2O颗粒由边长约为500nm的立方体变为大小约为1μm的切角八面体再演变为大小约为2μm的八面体。研究结果还表明,在没有柠檬酸钠存在的情况下,产物是由Cu2O小纳米晶自组装而成的、大小不均的球形颗粒;柠檬酸钠的加入有助于Cu2O晶体的生长,随着柠檬酸钠加入量的增加,球形Cu2O颗粒逐渐变为大小均一的晶体。     

Cu_2O空心微球光催化降解生活污水

以硫酸铜为铜源,聚乙烯吡咯烷酮(PVP)为表面修饰剂,水合肼为还原剂,在水溶液中制备纳米氧化亚铜颗粒构成的空心微球。通过扫描电子显微镜、透射电子显微镜、X射线衍射、紫外-可见光漫反射光谱等手段对样品进行表征,并研究了氧化亚铜空心微球对生活污水的光催化降解性能。研究结果表明,氧化亚铜空心微球壳厚20～30nm,直径170～220nm,在400～700nm波长范围有较强吸收,对生活污水有明显的光催化降解效果。     

Gap-plasmon of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@Ag core-shell nanostructures for highly enhanced fluorescence detection of Rhodamine B

A novel gap-plasmon of Fe₃O₄@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B (RB) was developed. Fe₃O₄@Ag core-shell nanostructures with Ag shell and Fe₃O₄ core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane (MPTS). To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe₃O₄@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe₃O₄@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance (SPR) band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon (LSP) and the gap plasmon near-field coupling with the Fe₃O₄@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^-7 mol/L, and the Fe₃O₄@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe₃O₄@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.     

液相合成不同形貌的Cu_2O微晶

以乙酸铜为铜源,L-抗坏血酸为还原剂,采用简单的液相反应制备不同形貌的Cu2O微晶,并进行了表征。考察了温度、反应物浓度、表面活性剂种类等条件对Cu2O微晶粒径及形貌的影响,初步探讨了Cu2O微晶的生长机理。实验结果表明:通过改变表面活性剂的种类,可以选择性地制备出不同形貌的Cu2O微晶。以PVP为表面活性剂时制备的是直径约为1μm的Cu2O微球,以PEG为表面活性剂时制备的是边长约为700 nm的Cu2O立方体。     

碘介导金包银核壳纳米粒子的合成及SERS应用

金包银核壳纳米粒子有望在保持纳米银优良表面增强拉曼（SERS）增强性能的同时,提高银纳米粒子的抗氧化能力;但是目前制备完整纳米金壳包裹的纳米银粒子仍较困难. 以AuI₄^-代替传统使用的AuCl₄^-,利用碘与金、银原子的相互作用,避免了金与纳米银核的电化学置换反应而导致的结构缺陷,制备得到了完整均匀包裹的金包银核壳粒子（Ag@Au NPs）. 该粒子不仅具有与银类似的SERS增强效果,同时具有可以与纳米金相比拟的抗氧化性能. 将上述方法得到的金包银核壳粒子成功地应用于玫瑰红B、亮蓝等合成色素以及农药百草枯的测定.     

固相配位反应法制备Cu0．30Ni0.66Mn2．04O4超细粉体

以乙酸盐和草酸为原料,采用室温固相配位反应制得Cu0.30Ni0.66Mn2.04（C2O4）·nH2O复合草酸盐,将该草酸盐在800℃煅烧2h,得到尖晶石相Cu0.30Ni0．66Mn2.04O4复合氧化物粉体。该氧化物粉体粒径均匀细小,一次粒径为-150nm;烧结活性较高,在1050℃烧结5h制得的热敏陶瓷相对密度高达-97％。     

TiO_2/PBA/PMMA核壳粒子的制备与表征

纳米粒子是热力学不稳定体系,容易发生颗粒团聚。为了更好地改善纳米粒子的分散性,本文报道利用乳液聚合的方法制备以表面处理过的纳米二氧化钛为核丙烯酸丁酯和甲基丙烯酸甲酯为壳的TiO2/PBA/PMMA复合粒子。分析二氧化钛、乳化剂、引发剂、反应温度和超声震荡时间等因素对聚合反应单体转化率的影响,并表征核壳复合粒子。结果表明,利用乳液聚合方法制备的二氧化钛粒子为核壳结构,平均粒径为251 nm,其粒径分布较未改性纳米TiO2明显变窄,改善了纳米粒子的分散性。     

TiO2／PBA／PMMA核壳粒子的制备与表征

纳米粒子是热力学不稳定体系，容易发生颗粒团聚。为了更好地改善纳米粒子的分散性,本文报道利用乳液聚合的方法制备以表面处理过的纳米二氧化钛为核丙烯酸丁酯和甲基丙烯酸甲酯为壳的TiO2／PBA／PMMA复合粒子。分析二氧化钛、乳化剂、引发剂、反应温度和超声震荡时间等因素对聚合反应单体转化率的影响，并表征核壳复合粒子。结果表明，利用乳液聚合方法制备的二氧化钛粒子为核壳结构。平均粒径为251nm。其粒径分布较未改性纳米TiO2明显变窄,改善了纳米粒子的分散性。     

纳米级Cu2O的制备与其光催化性能

以抗坏血酸为还原剂,通过均相化学还原法合成纳米Cu2O半导体光催化剂,采用XRD,SEM对它进行表征。结果表明:在简单温和制备条件下,可得到形貌规整、分散较好、边长为70～140 nm的Cu2O立方体;在模拟太阳光谱氙灯照射下,合成的Cu2O对罗丹明B染料具有较好的光催化降解性能,少量1%双氧水能够显著增强罗丹明B的降解效果,40 min内降解率达90.32%。     

分散剂PVP对液相还原法制备纳米铜粉的影响

采用KBH4在液相中化学还原CuSO4,并加入KOH、络合剂EDTA和分散剂PVP,制得了纳米级的纯净的铜粉,通过调整反应物的浓度,可以消除Cu2O等杂质.研究了分散剂PVP对铜粉粒度的影响,结果表明分散剂PVP有助于粉末的分散.     

核壳型叔碳氟碳共聚乳液的制备

以叔碳单体-丙烯酸酯类单体共聚物为核,有机氟单体-丙烯酸酯类单体共聚物为壳．采用种子乳液聚合方法制得了核壳型叔碳氟碳共聚乳液。讨论了乳化剂量、引发剂量、反应温度、恒温时间等对乳液聚合的影响,并对乳液进行了接触角、透射电镜表征。结果表明：反应温度为85℃,恒温时间为2h,w（乳化剂）=3.5％,w（引发剂）=0.3％,制备的核壳型乳液性能较佳。     

Fabrication and Magnetic Properties of Composite Ni_(0.5)Zn_(0.5)Fe_2O_4/Pb(Zr_(0.52)Ti_(0.48))O_3 Nanofibers by Electrospinning

One-dimensional and quasi-one-dimensional nanostructure materials are promising building blocks for electromagnetic devices and nanosystems.In this work,the composite Ni0.5Zn0.5Fe2O4(NZFO)/ Pb(Zr0.52Ti0.48)O3(PZT) nanofibers with average diameters about 65 nm are prepared by electrospinning from poly(vinyl pyrrolidone) (PVP) and metal salts.The precursor composite NZFO/PZT/PVP nanofibers and the subsequent calcined NZFO/PZT nanofibers are investigated by Fourier transform infrared spectroscopy (FT- IR) ,X-ray diffraction (XRD),scanning electron microscopy (SEM).The magnetic properties for nanofibers are measured by vibrating sample magnetometer(VSM).The NZFO/PZT nanofibers obtained at calcination temperature of 900 °C for 2 h consist of the ferromagnetic spinel NZFO and ferroelectric perovskite PZT phases,which are constructed from about 37 nm NZFO and 17 nm PZT grains.The saturation magnetization of these NZFO/PZT nanofibers increases with increasing calcination temperature and contents of NZFO in the composite.     

纳米铜对自养脱氮亚硝化工艺的短期及长期影响

为考察纳米铜对自养脱氮亚硝化工艺的影响,在SBR反应器内分别进行短期影响实验(8 h)及长期影响实验(20 d),研究氨氮氧化速率、氮素转化规律及污泥性能的变化规律.短期实验结果表明,低质量浓度的纳米铜(≤1 mg/L)对亚硝化有促进作用,纳米铜质量浓度在3~30 mg/L内严重抑制自养脱氮亚硝化,氨氮氧化速率降低率为21.9%~44.9%.纳米铜为50 mg/L时,由于质量浓度过高导致纳米颗粒团簇,降低了真正作用于细胞的量,亚硝化活性得到强化.长期实验结果表明,长期暴露在低质量浓度(1 mg/L)的纳米铜环境中,氨氮氧化速率受到严重抑制,氨氮去除率从90%降低为44.8%,氨氧化细菌比亚硝酸盐氧化细菌对纳米铜更加敏感.在长期作用后,污泥中的铜含量增加,胞外聚合物含量增加,解除纳米铜抑制后,两者均降低.纳米铜对自养脱氮亚硝化工艺的微生物活性、脱氮能力、污泥性能均具有较大的影响.     

核壳型阳离子丙烯酸酯乳液的合成

采用核壳乳液聚合法,制得可用于木器底漆的核壳型阳离子丙烯酸酯乳液。考察了反应型乳化剂DADMAC、种子引发剂AIBA、功能单体GMA用量及乳化剂配比、软硬单体配比对乳液性能的影响。研究表明,反应型乳化剂DADMAC质量分数为单体总量的0.45%,种子引发剂质量分数为引发剂总量的0.4%,乳化剂配比m(核)∶m(壳)=1∶1,功能单体GMA质量分数为1.2%,软硬单体配比为m(MMA)∶m(St)∶m(BA)=18∶13∶10时可制得性能较佳的核壳型阳离子丙烯酸酯乳液。     

聚甲基丙烯酸甲酯包覆氢氧化镁壳-核粒子的制备

以烷基化氢氧化镁为核，以甲基丙烯酸甲酯为壳层单体，制备聚甲基丙烯酸甲酯包覆氢氧化镁的壳一核粒子。系统研究了烷基化氢氧化镁、引发剂、单体、分散剂、反应温度等因素对无皂乳液聚合反应的单体转化率、产物粒子平均粒径及分散系数的影响。通过重量法测得聚合反应体系的单体转化率．用激光粒度仪测定了产物粒子的平均粒径和多分散系数，运用红外光谱分析，透射电镜等手段对产物进行了表征，证实了壳一核粒子的存在。     

聚甲基丙烯酸甲酯包覆氢氧化镁壳-核粒子的制备

以烷基化氢氧化镁为核,以甲基丙烯酸甲酯为壳层单体,制备聚甲基丙烯酸甲酯包覆氢氧化镁的壳-核粒子。系统研究了烷基化氢氧化镁、引发剂、单体、分散剂、反应温度等因素对无皂乳液聚合反应的单体转化率、产物粒子平均粒径及分散系数的影响。通过重量法测得聚合反应体系的单体转化率,用激光粒度仪测定了产物粒子的平均粒径和多分散系数,运用红外光谱分析,透射电镜等手段对产物进行了表征,证实了壳-核粒子的存在。