高电压氟化碳纳米球材料的制备及性能

从结构设计上提升氟化碳(CF_(x))材料的导电性。通过简单水热法设计合成CF_(x)前驱体材料,再经高温氟化,制备高电压CF_(x)纳米球材料。用SEM和热重分析(TG)对CF_(x)纳米球材料的形貌和热稳定性进行分析,并用恒流放电、功率放电和电化学阻抗等对电化学性能进行测试。与商用CF_(x)材料相比,CF_(x)纳米球材料热稳定性提高了12.22%,且结合了金属氧化物的倍率性能和CF_(x)材料的容量特性,在功率输出测试时未出现明显的电压滞后现象,且放电时间延长了12.66%。随着导电性的提升,高电压CF_(x)纳米球电极具有更高的离子扩散系数(2.18×10^(-13)cm^(2)/s)。

无机材料纳米空心球的制备方法研究进展

探索新的纳米结构已成为近年来物理、化学、材料等领域的研究热点之一。纳米空心球作为一种新的纳米结构,其特有的核-壳空心结构及纳米厚度的壳层使它具有许多优异的物理化学性能,从而在医学、制药学、材料学、染料工业等领域具有很好的应用前景。本文综述了模板法和由模板法发展而来的L-b-L自组装法制备无机材料纳米空心球的一般过程及原理,最后展望了纳米空心球材料的发展前景,并探讨了目前在无机材料纳米空心球研究领域中存在的问题。

金胶/碳球复合纳米材料的制备及表征

通过微波水热法,以葡萄糖水溶液为原料,制备了单分散的溶胶碳球,用自组装方法把金胶纳米粒子修饰在碳球表面合成了金胶/碳球纳米复合材料。通过扫描电镜、透射电镜、红外光谱及循环伏安等技术对最终产物的形貌、组成和光学性质进行了表征。由于所得到的金胶/碳球复合材料具有很好的化学稳定性与无毒性,同时金胶纳米粒子具有生物相容性,该复合材料可作为载体材料应用于生物分析。

空心球纳米材料的制备及其在环境保护中的应用现状

空心球作为一种具有特殊结构及性质的纳米材料,其制备研究得到了极大的发展,性质和应用研究相对较少。本文对国内外空心球的制备及其在环境保护和污染治理方面的应用研究现状进行了总结和分析。

纳米组装体系及其研究进展

评述了近年来纳米组装体系,如纳米微球材料、纳米团簇、纳米介孔复合、纳米有序阵列等体系的研究进展,总结了这几类物质的先进合成方法,展望了其应用前景。

聚丙烯原位碳化合成石墨烯负载碳球纳米杂化材料研究

本研究以氧化石墨烯（GO）为模板负载氢氧化镍（Ni（OH）2）和氢氧化钴（Co（OH）2）纳米粒子,并分别熔融共混到聚丙烯（PP）中,利用PP原位碳化方法成功制备出GO负载碳球纳米杂化材料。利用X射线衍射（XRD）和拉曼波谱分析（Raman）对合成的Ni（OH）2、Co（OH）2、GO负载Ni（OH）2和GO负载Co（OH）2进行表征。采用透射电子显微镜（TEM）、XRD和Raman等对合成的石墨烯负载碳球纳米杂化材料的形貌结构和物理性质进行表征。结果表明：利用PP原位碳化可成功制备两种不同类型的石墨烯负载碳球纳米杂化材料。

Effect of mechanical alloying time and rotation speed on evolution of CNTs/Al-2024 composite powders

Carbon nanotubes （CNTs） reinforced aluminum matrix composites were fabricated by mechanical milling followed by hot extrusion. The commercial Al-2024 alloy with 1% CNTs was milled under various ball milling conditions. Microstructure evolution and mechanical properties of the milled powder and consolidated bulk materials were examined by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and mechanical test. The effect of CNTs concentration and milling time on the microstructure of the CNTs/Al-2024 composites was studied. Based on the structural observation, the formation behavior of nanostructure in ball milled powder was discussed. The results show that the increment in the milling time and ration speed, for a fixed amount of CNTs, causes a reduction of the particle size of powders resulting from MM. The finest particle size was obtained after 15 h of milling. Moreover, the composite had an increase in tensile strength due to the small amount of CNTs addition.

Effect of SiC content on dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites

The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.

Specific Heat of Hollow Nanosphere Coupled to Substrate： Quantum Size Effects

With the help of the elastic wave theory in the perturbed approximation the density-of-states for vibrational modes and the specific heat are studied for different hollow Si nanospheres, coupled with a semi-infinite substrate. We find that the modes of such coupled hollow spheres are significantly broadened and shifted toward low frequencies. The specific heat of the coupled hollow nanosphere is bigger than an isolated one due to the coupling interaction and quantum size effects. The predicted coupling and size enhancements on specific heat are probed in thermal experiments.

In-situ growth of ultrathin MoS_2 nanosheets on sponge-like carbon nanospheres for lithium-ion batteries

Developing novel electrode materials for li-thium-ion batteries （LIBs） with rapid charge/discharge cap- ability and high cycling stability remains a big challenge to date. Herein, we demonstrate the design and synthesis of ul- trathin MoS2 nanosheets in-situ grown on sponge-like carbon nanospheres by a simple diffusion-controiled process. The unique sponge-like carbon nanosphere core can be used as ＂reservoir＂ of electrolyte by adsorbing to shorten the ion- diffusion path, and meanwhile as ＂elastomer＂ to alleviate the structural change of the MoS2 nanosheets during the charge/ discharge processes. Furthermore, the vertical ultrathin MoS2 nanosheets with broadened interlayer space greatly enrich the electrochemical active sites. Consequently, the as-obtained MoS2/C nanospheres exhibit increased specific capacities at various rates with superior cycling stability compared to the MoS2/C floccules. It is reckoned that the present concept can be extended to other electrode materials for achieving high- rate and stable LIBs.

Bimetallic phosphides embedded in hierarchical Pdoped carbon for sodium ion battery and hydrogen evolution reaction applications

Transition metal phosphides have been explored as promising active materials for sodium-ion batteries(SIBs)and hydrogen evolution reaction(HER) applications owing to their unique physical and chemical characteristics. However,they suffer from the drawbacks such as severe agglomeration,and sluggish reaction kinetics. Herein, bimetallic phosphides(Ni2 P/Zn P4) embedded in P-doped carbon hierarchical microspheres are demonstrated with robust structural integrity,fast charge transfer, and abundant active sites. As expected,the optimally structured Ni2 P/Zn P4 composite exhibits good electrochemical performance as an anode material in SIBs,including high specific capacity, good cycling stability and rate capability. Meanwhile, the Ni2 P/Zn P4 composite also exhibits excellent electrocatalytic performance for HER with a small overpotential of 62 m V, a Tafel slope of 53 m V dec^-1, as well as excellent stability.

Controlled synthesis of core-mesoporous shell from biomass sustainable N-doped hollow carbonaceous nanospheres

Encompassing ecological and economic concerns, the utilization of biomass to produce carbonaceous materials has attracted intensive research and industrial interest. Using nitrogen containing precursors could realize an in situ and homogeneous incorporation of nitrogen into the carbonaceous materials with a controlled process. Herein, N-doped hollow core-disordered mesoporous shell carbonaceous nanospheres （HCDMSs） were synthesized from glucosamine hydrochloride （GAH）, an applicable carbohydrate-based derivative. The obtained HCDMSs possessed controlled size （-450-50 nm） and shell thickness （-70-10 nm）, suitable nitrogen contents （-6.7-4.4 wt.%）, and Brunauer-Emmett-Teller （BET） surface areas up to 770 m^2.g^-1. These materials show excellent electrocatalytic activity as a metal-free catalyst for the oxygen reduction reaction （ORR） in both alkaline and acidic media. Specifically, the prepared HCDMS-1 exhibits a high diffusion-limited current, and superior durability and better immunity towards methanol crossover and CO poisoning for ORR in alkaline solution than a commercial 20 wt.% Pt/C catalyst.

A single Au nanoparticle anchored inside the porous shell of periodic mesoporous organosilica hollow spheres

An ideal metal catalyst requires easy contact with reaction reagents, a large number of exposed active sites, and high stability against leaching or particle agglomeration. Anchoring a metal core inside a porous shell, though scarcely reported, may combine these advantages owing to the integration of the conventional supported metal arrangement into a core@void@shell architecture. However, achieving this is extremely difficult owing to the weak core-shell affinity. Herein, we report, for the first time, an approach to overcome this challenge by increasing the core-shell interaction. In this regard, we synthesized a novel Au@void@periodic mesoporous organosilica （PMO） architecture in which a single Au core is firmly anchored inside the porous shell of the hollow PMO sphere. The non-covalent interactions between the poly（vinylpyrrolidone） （PVP） groups of functionalized Au and ethane moieties of PMO facilitate the movement of the Au core towards the porous shell during the selective alkaline etching of Au@SiO2@PMO. Shell-anchored Au cores are superior to the suspended cores in the conventional Au@void@PMO in terms of contact with reagents and exposure of active sites, and hence show higher catalytic efficiency for 4-nitrophenol reduction. The methodology demonstrated here provides a new insight for the fabrication of versatile multifunctional nanostructures with cores anchored inside hollow shells.

High-efficiency laser-irradiation spheroidizing of NiCo_2O_4 nanomaterials

We realized the desired spheroidizing of NiCo_2O_4 nanomaterials by laser irradiating NiCo_2O_4 suspensions with different concentrations. The results reveal that the as-prepared samples are desired spheres with the maximal average size of 568 nm and the superior dispersity, which were obtained at the energy density of 0.30 J·pulse^(-1)·cm^(-2) and NiCo_2O_4 suspension concentration of 0.2 mg·mL^(-1). However, the phase segregation, which was induced by large amounts of solid redox of Co^(3+)/Co^(2+) and Ni^(3+)/Ni^(2+), also appears in the laser-irradiation process.

Green photochemical synthesis of fluorescent carbon spheres in-situ enwrapped around Ag nanoparticles

Biocompatible carbon-spheres-based nanocomposites exhibit great potential in biomedical and clinical applications. In this contribution we report the first green photochemical synthesis of carbon spheres through in-situ enwrapping around silver nanoparticles(CS–Ag NPs). Since mesoporous carbon spheres can provide the location for combining Ag NPs and other agents, one-step synthesis of glutathione-stabilized CS–Ag NPs could be readily realized by photoreduction. TEM characterization of CS–Ag NPs nanocomposites illustrates that Ag NPs were superbly wrapped inside the carbon spheres and also adhered to the surfaces of the carbon spheres. These porous CS–Ag NPs show excellent fluorescence and effective antibacterial efficiency, exhibiting ideal lengthened activities against Escherichia coli and Staphylococcus aureus compared with bare Ag NPs. The relevant rationale behind it could be attributed to the fact that CS–Ag NPs nanocomposites can provide some excellent niches for the durable and slow release of silver ions. This raises the possibility of promising applications of CS–Ag NPs nanocomposites as excellent antibacterial agents for the efficient monitoring of some disease-related bacteria.