模板法合成金银核壳纳米线及电化学表征

采用氧化铝模板由交流电沉积制备纯银纳米线.然后借助化学还原法,在已制备好的银线表面包裹不同厚度的金壳层,得到具有核壳结构的AgcoreAushell复合纳米线.电子显微镜(SEM,TEM)显示该复合结构纳米线表面形貌与加入的金盐量有关,而且包裹层较薄的复合纳米线表面存在大量的孔洞.循环伏安测试表明,具有孔洞效应的复合纳米线经多次循环扫描后即可过渡到无孔洞效应的表面.以对巯基苯胺(PATP)作为探针分子的表面增强拉曼光谱,可用于表征纳米材料的表面结构.     

聚吡咯/硫化镉核壳纳米线的制备及整流特性

以无机多孔氧化铝膜为模板,利用气相沉积和原位电化学沉积方法成功地制备了有机-无机杂化聚吡咯/硫化镉核壳纳米线;采用扫描电子显微镜和透射电子显微镜分析了聚吡咯/硫化镉核壳纳米线的表面形貌和微结构.结果表明,内部的聚吡咯纳米线紧紧依附在外部的硫化镉纳米管中,并且硫化镉纳米管被聚吡咯全部填充.与此同时,在聚吡咯/硫化镉核壳纳米线中,外部硫化镉壳与内部聚吡咯核之间存在电荷转移;聚吡咯和硫化镉之间形成有机-无机杂化的P-N界面,从而导致单根聚吡咯/硫化镉核壳纳米线显示出不同于外部壳和内部核的整流特性.     

取向碳纳米管/硅纳米线复合阵列的制备

在阳极氧化铝模板(AAO)的取向微孔内, 利用化学气相沉积(CVD) 技术首先制备了两端开口高度取向的碳纳米管阵列, 再在碳纳米管中间的孔洞内沉积硅纳米线, 成功制备了碳纳米管/硅纳米线(CNTs/SiNWs)核鞘复合阵列结构. 用SEM, TEM, XRD等仪器分析了CNTs/SiNWs核鞘复合阵列和沉积在碳纳米管孔洞内的硅纳米线的生长特性和晶体结构, 利用I-V关系和Fowler-Nordheim方程研究了其场发射(FE)特性, 用荧光光谱分析仪分析了复合阵列的荧光(PL)特性. 证明了模板法制备的CNTs/SiNWs核鞘复合阵列结构可用来制作具有金属/半导体(M/S)特性的纳米PN结, 该复合阵列结构也使SiNWs包覆在CNTs惰性鞘内, 可防止SiNWs在空气中的进一步氧化. 制备出的CNTs/SiNWs核鞘复合阵列结构生长方向高度有序, 直径和长度易于控制, 极少产生其他制备方法中出现的纳米结构弯曲和相互缠绕现象.     

核壳结构CdS/ZnS微米球表面处理与光催化制氢性能的关系

具有高活性和稳定性的半导体光催化材料是太阳能光催化制氢领域的研究热点,其中CdS胶体颗粒催化剂因其合适的禁带宽度和带边位置以及较低的原料价格而广受关注.但它在水溶液中不稳定,易受光腐蚀,因而限制了其应用.目前人们致力于用各种方法提高其稳定性,包括各种纳米结构的应用、复合其他催化剂材料以及不同晶相结构复合.ZnS是一种宽禁宽半导体,禁带宽度为3.6 eV,常被用来与CdS形成固溶体调控其能带结构,从而提高其性能和稳定性.其中核壳结构CdS/ZnS异质结具有骑跨型(I型)能带结构,具有特殊的光学和电学性质,在量子点LED和量子点生物荧光显示剂方面获得关注和应用,同时也显示了良好的光催化性能.研究人员对核壳结构CdS/ZnS异质结材料中ZnS壳层厚度对其光学性能包括荧光效率等的影响进行了研究,然而ZnS壳层厚度、颗粒尺寸及其表面处理对光催化性能影响方面的报道很少.本文发展了一种简易的两步法,制备了核壳结构CdS/ZnS微米球光催化剂.首先采用超声喷雾热分解法制备CdS微米球,然后以水浴法在CdS微米球上生长ZnS壳层.采用扫描电镜(SEM)、X射线衍射(XRD)、紫外-可见吸收光谱(UV-vis)和透射电镜(TEM)对所得样品进行了表征.SEM和TEM结果显示,所得微米球为完整包裹的球形核壳结构;XRD表征证实CdS核与ZnS壳层皆为六角相晶型;光催化性能表征结果显示,该样品的光催化制氢性能远高于单独的CdS微米球以及同法所制的ZnS微米球.通过改变前驱液浓度(Zn源浓度分别为0.2,0.3和0.5 mol/L)获得了三种不同厚度的核壳结构CdS/ZnS微米球,X射线荧光光谱结果证实了其壳层厚度成功调控.UV-vis结果发现,其吸收边由内核CdS决定,受壳层厚度的影响不大.光致荧光发射光谱分析发现,随着壳层厚度的增加,其540 nm处的CdS带边发射峰强度逐渐增大.这可能是由于ZnS壳层对CdS表面缺陷的钝化作用降低了其非辐射复合过程,从而提高了荧光发光效率.光催化制氢性能结果表明,前驱液浓度为0.3 mol/L时合成的核壳结构CdS/ZnS微米球的产氢效率最高.为了进一步提高其光催化效率,采用氮气中高温热处理、水热二次硫化法以及两者共用三种方式对性能最优的微米球进行改性,获得了三种核壳结构CdS/ZnS样品.结果发现,这些改性方法未影响其吸收边,但水热二次硫化法处理以及两者共用处理的样品在540 nm处的光致荧光发射峰强度明显高于未处理的和高温热处理的样品,证实水热二次硫化法处理可以有效地消除其表面缺陷,减少非辐射复合.XRD结果表明其晶型没有发生变化.TEM表征发现,经高温热处理后其壳层发生重结晶,形成颗粒包裹形貌,而经水热二次硫化法处理后其壳层同样发生重结晶,但包裹颗粒的尺寸明显更小.光催化性能测试表明,处理后样品的光催化性能皆优于未处理样品,其中两者共用法处理的样品产氢性能和稳定性最高.     

含氟/硅丙烯酸酯核壳型乳液的合成及性能

采用半连续种子乳液聚合法, 在十二烷基硫酸钠(SDS)/辛基苯基聚氧乙烯醚(TX-10)复合乳化剂的作用下, 合成了以丙烯酸丁酯(BA)为核, 以甲基丙烯酸甲酯(MMA)、甲基丙烯酸十二氟庚酯(DFHMA)、3-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPTMS)和甲基三甲氧基硅烷(MTMS)为壳的核壳型含氟/硅丙烯酸酯聚合物乳液. 利用FTIR, TEM, SEM-EDX和DSC等手段对乳液组成、乳胶粒子结构、膜表面及断面形态等进行了表征, 讨论了氟/硅含量对聚合物膜性能的影响. 结果表明, 核-壳粒子尺寸为20~30 nm, 乳液膜的性能与膜表面氟和硅的含量及相容性有较大的相关性, 当m(氟)∶m(硅单体)=3∶1时, 形成的膜均匀透明, 吸水率较低, 尺寸稳定性较好.     

P3HT修饰一维有序壳核式CdS/ZnO纳米棒阵列复合膜的光电化学性能

采用电化学方法在铟锡氧化物(ITO)导电玻璃上制备了高度有序的ZnO纳米棒阵列, 在ZnO纳米棒阵列上先后电化学沉积CdS纳米晶膜及聚3-己基噻吩(P3HT)薄膜得到P3HT修饰的一维有序壳核式CdS/ZnO纳米阵列结构, 并通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、能量散射X射线(EDX)等表征手段证实了该结构的形成. 以此纳米结构薄膜为光阳极组装新型半导体敏化太阳电池, 研究了CdS纳米晶膜的厚度和P3HT薄膜的沉积对电池光伏性能的影响, 初步探讨了电荷在电池结构中的传输机理, 结果表明, CdS纳米晶膜和P3HT薄膜的沉积有效地拓宽了光阳极的光吸收范围, 实验中电池的光电转换效率最高达到1.08%.     

Ag核Au壳双金属复合纳米线的制备及其表面增强拉曼光谱研究

采用氧化铝模板结合交流电沉积技术制备纯银纳米线, 然后通过化学还原方法, 并控制加入的金盐的量, 在已制备好的银线表面包裹不同厚度的金壳层, 得到具有核壳结构的Ag_核Au_壳复合纳米线. 采用电子显微镜(SEM, TEM)和表面增强拉曼光谱对该复合结构纳米线进行相关表征, 纳米线的表面形貌与加入的金盐的量有关. 以苯硫酚(TP)和对巯基苯胺(PATP)为探针分子, 研究了此类复合纳米线的表面增强拉曼散射效应. 并以PATP在金银纳米线表面吸附的表面增强拉曼光谱的差别为探针, 表征了复合纳米线表面金的包裹程度, 结果表明一定厚度的包裹程度可制备无针孔效应的核壳结构金银复合纳米线.     

电化学沉积法制备金（核）-铜（壳）纳米粒子阵列

以组装在有机分子自组装膜/金基底电极上的Au纳米粒子阵列为电化学沉积模板,制备了金(核)-铜 (壳)纳米粒子阵列.选用巯基十一胺（AUDT）和巯基癸烷（DT）混合自组装膜作为基底电极与Au纳米粒子的耦联层,可以在一定的电位下实现金属Cu在Au纳米粒子上的选择性沉积.将沉积电位控制在－0.03 V（vs SCE）时,沉积初期（t ≤ 15 s,沉积粒子粒径 ≤ 20 nm ）金(核)-铜 (壳)粒子具有良好的单分散性和近似球形,而且粒径实验值同计算值非常吻合.     

一维CdTe@C@TiO2-Au异质结纳米线的制备及其光催化性能

先利用一步水热法制备了具有核壳结构的CdTe@C纳米线,然后以钛酸异丙酯（TIP）作为钛源对CdTe@C纳米线进行二氧化钛包覆,最后通过原位还原HAuCl4的方法将Au纳米粒子组装到CdTe@C@TiO₂表面形成CdTe@C@TiO₂-Au一维异质结纳米复合材料。用扫描电镜（SEM）,X射线能谱（EDX）,透射电镜（TEM）,X射线衍射（XRD）,X射线光电子能谱（XPS）和紫外-可见漫反射光谱（UV-Vis DRS）等对材料进行表征。探究了CdTe@C@TiO₂-Au催化剂在模拟可见光下降解罗丹明B（RhB）的光催化性能。实验结果表明：不同催化剂对RhB的光降解率不一样,其效果依次为CdTe@C@TiO₂-Au > CdTe@C@TiO₂ > pure TiO₂,其中CdTe@C@TiO₂-Au能在270 min的模拟太阳光下对RhB的光降解率达95.3%,这主要得益于CdTe、碳层、TiO₂和具有表面等离子效应的纳米Au的共同作用。     

n-型多孔Si/TiO2纳米线异质结构的制备及光电化学性能

采用光辅助电化学腐蚀法制备了n-型多孔硅衬底, 再采用水热法在其表面生长TiO₂纳米线制得了三维n-型多孔Si/TiO₂纳米线异质结构. 通过X射线衍射、 扫描电子显微镜和X射线能量散射等表征证实了n-型多孔Si/TiO₂纳米线异质结构的形成. 紫外-可见漫反射光谱测试结果表明, n-型多孔硅与TiO₂纳米线的复合提高了紫外-可见波段的光吸收. 光电性能测试结果表明, 3个样品中n-型多孔Si/TiO₂纳米线异质结作为光电极的光电流最高, 这说明n-型多孔Si/TiO₂纳米线作为光电极具有更高的光电化学分解水性能.     

Nanoengineering core/shell structured brucite@polyphosphate@amine hybrid system for enhanced flame retardant properties

A novel organic-inorganic hybrid flame retardant consisting of a brucite core and a dodecylamine polyphosphate shell was synthesized by a facile nanoengineering route. The flammability characterization and synergistic flame retardant mechanism of the core/shell flame retardant (CFR) in ethylene-vinyl acetate (EVA) blends had been compared with EVA/physical mixture (PM, with the given proportion of brucite and dodecylamine polyphosphate as well as CFR) and EVA/brucite blends. With the same loading amount (40 wt%) of fillers in EVA, the peak heat release rate and smoke production rate of EVA/CFR blends were significantly reduced to 49% and 48% of that of EVA/PM blends, respectively. Meanwhile, the limiting oxygen index (LOI) was increased up to 32 (14.3% higher than that of EVA/PM blends) and the UL-94 test could achieve the V-0 rating. These remarkable properties were obtained just by nanoengineeing the core/shell structured brucite@polyphosphate@amine hybrid system, facilitating the formation of intact and compact residue with fence structure in process of polymer composite burning.     

TiC/C core/shell nanowires arrays as advanced anode of sodium ion batteries

High-perfo rmance anodes of sodium ion batteries(SIBs)largely depends on rational architecture design and binder-free smart hybridization.Herein,we report TiC/C core/shell nanowires arrays prepared by a one-step chemical vapor deposition(CVD)method and apply it as the anode of SIBs for the first time.The conductive TiC core is intimately decorated with carbon shell.The as-obtained TiC/C nanowires are homogeneously grown on the substrate and show core/shell heterostructure and porous architecture with high electronic conductivity and reinforced stability.Owing to these merits,the TiC/C electrode displays good rate performance and outstanding cycling performance with a capacity of 135.3 mAh/g at 0.1 A/g and superior capacity retention of 90.14%after 1000 cycles at 2 A/g.The reported strategy would provide a promising way to construct binder-free arrays electrodes for sodium ion storage.     

Bifunctional o-CoSe2/c-CoSe2/MoSe2 heterostructures for enhanced electrocatalytic and photoelectrochemical hydrogen evolution reaction

The bottleneck of alkaline hydrogen evolution reaction lies in the kinetically sluggish brought from multistep reaction processes involving water adsorption and dissociation, as well as hydrogen adsorption. In this work, we successfully synthesized o-CoSe₂/c-CoSe₂ heterostructures anchored on MoSe₂ nanosheets to powerfully promote reaction processes. As an electrocatalyst, it exhibits a low overpotential of 112 mV at 10 mA/cm² and a Tafel slope of 96.9 mV/dec for an alkaline hydrogen evolution reaction. Moreover, the as-prepared catalyst can behave as both cathode and anode for overall water splitting, which only requires 1.61 V cell voltage at 10 mA/cm². Significantly, the cell voltage can be further reduced to 1.53 V at 10 mA/cm² for water electrolysis under the simulated solar irradiation owing to such a semiconductor-based heterostructure that facilitates the separation of photogenerated charges. Here, the improving overall performance of this ternary electrocatalyst is attributed to the multifunctionality and synergistic interaction of different components in this heterogeneous material. The work provides a novel strategy to design active catalysts simultaneously using electric energy and solar energy for effective water splitting.     

Highly ordered MnO2 nanowire array thin films on Ti/Si substrate as an electrode for electrochemical capacitor

AAO/Ti/Si substrate was successfully synthesized by a two-step electrochemical anodization of the aluminum film on the Ti/Si substrate and then used as template to grow nanowire arrays. The ordered MnO₂ nanowire arrays with about 40 nm diameters had been directly fabricated on AAO/Ti/Si substrate by direct current (DC) electrodeposition. The microstructure of the nanowire arrays was investigated by field-emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Their electrochemical characterization was performed using cyclic voltammetry in 0.5 M Na₂SO₄ aqueous solution. The synthesized MnO₂ nanowires had amorphous nature until 400 °C. The deal capacitive behavior was obtained when the as-prepared sample was heat-treated at 200 °C. The specific capacitance of the electrode was about 254 F/g.     

Anchored Ni-dimethylglyoxime complex on Fe3O4@SiO2 core/shell nanoparticles for the clean catalytical synthesis of dicoumarols

Ni-Dimethylglyoxime complex immobilized on functionalized Fe₃O₄ was synthesized by a post-grafting way and utilized as a novel, thermally stable, recoverable, and efficient for green synthesis of dicoumarols through reaction of 4-hydroxycoumarin with various aldehydes in excellent yields and higher rate. Fe₃O₄@SiO₂-silylcyclopropyl-dimethylglyoxime-Ni superparamagnetic nanoparticles (MNP_s) were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer–Emmett–Teller technique. This nanocatalyst could be conveniently recovered via the use of an external magnetic field and reused for subsequent reactions for at least 7 times without any remarkable change and decrease in catalytic activity.     

Stimuli-sensitive core/shell template particles for immobilizing inorganic nanoparticles in the core

We synthesize and characterize stimuli-sensitive core/shell particles with functional group (or material) localized in the core. We previously reported two types of hybrid particles prepared by using the template particles which were synthesized by soap-free emulsion copolymerization with N-isopropylacrylamide and glycidyl methacrylate (GMA) as monomers but by different preparation methods. GMA has advantages in immobilizing materials having several functional groups such as thiol ones. In this study, to obtain the suitable template particles for immobilizing any inorganic nanoparticles in the core, we investigated the effect of feed ratio of the two monomers. Obtained template particles were modified by thiol compounds to introduce ionic groups. They were characterized by dynamic light scattering and scanning electron microscopy. After in situ synthesis of magnetic nanoparticles in the templates, the hybrid particles were characterized directly by transmission electron microscopy. Consequently, we could obtain the hybrid core/shell particles which contained a large amount of magnetic nanoparticles (∼33 wt%) in the core.     

Synthesis and properties of organo-fly ash/polyaniline with core/shell structure based on emulsion polymerization

Organo-fly ash(OFA) was prepared with pretreated fly ash(FA) and hexadecyltrimethyl ammonium bromide (HDTMAB),and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios(2.0 wt%,5.0 wt%,10.0 wt%,15.0 wt%and 20.0 wt%) in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier.A polymerization procedure was supposed.The electrical conductivities of the composites were tested by the four-probe technique.The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction,respectively.Morphologies of FA,OFA and the composites were observed by SEM.The element analysis was performed by energy dispersive spectrometry.The thermal stability of the composites was analyzed by TGA.The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA,and the lowest value was 0.62 S/cm.HDTMAB and PAn were just adsorbed on the surface of FA and OFA,respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA.The surface became smoother after organification of FA by using HDTMAB,and its content on FA surfaces was about 26.9 wt%.The core/shell structure of the composite was observed by SEM analysis.The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system,the heat stability of PAn was increased by decreasing 31.8 wt%of weight loss after introducing 20 wt%of OFA.     

Preparation of Pt deposited nanotubular TiO2 as cathodes for enhanced photoelectrochemical hydrogen production using seawater electrolytes

The purpose of this study was to develop effective cathodes to increase the production of hydrogen and use the seawater, an abundant resource in the earth as the electrolyte in photoelectrochemical systems. In order to fabricate the Pt/TiO₂ cathodes, various contents of the Pt precursor (0–0.4 wt%) deposited by the electrodeposition method were used. On the basis of the hydrogen evolution rate, 0.2 wt% Pt/TiO₂ was observed to exhibit the best performance among the various Pt/TiO₂ cathodes with the natural seawater and two concentrated seawater electrolytes obtained from single (nanofiltration) and combined membrane (nanofiltration and reverse osmosis) processes.The surface characterizations exhibited that crystal structures and morphological properties of Pt and TiO₂ found the results of XRD pattern and SEM/TEM images, respectively.     

Synthesis of Co/MFe2O4 (M=Fe, Mn) core/shell nanocomposite particles

Monodispersed cobalt nanoparticles (NPs) with controllable size (8–14 nm) have been synthesized using thermal decomposition of dicobaltoctacarbonyl in organic solvent. The as-synthesized high magnetic moment (125 emu/g) Co NPs are dispersible in various organic solvents, and can be easily transferred into aqueous phase by surface modification using phospholipids. However, the modified hydrophilic Co NPs are not stable as they are quickly oxidized, agglomerated in buffer. Co NPs are stabilized by coating the MFe₂O₄ (M=Fe, Mn) ferrite shell. Core/shell structured bimagnetic Co/MFe₂O₄ nanocomposites are prepared with tunable shell thickness (1–5 nm). The Co/MFe₂O₄ nanocomposites retain the high magnetic moment density from the Co core, while gaining chemical and magnetic stability from the ferrite shell. Compared to Co NPs, the nanocomposites show much enhanced stability in buffer solution at elevated temperatures, making them promising for biomedical applications.     

Hydrogen activation on organometallic complexes and H2 production, utilization, and storage for future energy

This perspective article serves to highlight the contributions to this special volume of Journal of Organometallic Chemistry entitled “Organometallics for Energy Conversion”. The key features of dihydrogen coordination to transition metal complexes are discussed in the context of the challenge of producing and utilizing hydrogen as the energy carrier of the future. Ultimately, production of H₂ fuel from water will be needed rather than its current production principally from natural gas. Schemes involving use of solar energy to split water are currently of high interest, and a massive research effort is underway worldwide to accomplish this goal. This is primarily a chemistry problem (rather than engineering or materials), and it can then be assumed that organometallic chemistry will play an important role for both hydrogen production and storage.