A novel nonaqueous route to V2O3 and Nb2O5 nanocrystals

The reaction between transition metal alkoxides and benzyl alcohol provides a novel soft chemistry route to metal oxide nanoparticles. The method allows the preparation of nanocrystals of two important transition metal oxides, namely V₂O₃ and Nb₂O₅. Although the reaction temperatures of 200–220 °C are comparably low, the obtained particles are highly crystalline. According to TEM investigations, the V₂O₃ crystals exhibit particle sizes between 20 and 50 nm, and the Nb₂O₅ crystals display platelet-like particle shapes with sizes of 50–80 nm, without any indications of amorphous character.     

Photothermal performance of MFe2O4 nanoparticles

In this paper, we synthesized three kinds of ferrites and investigated their photothermal property. The result indicated that the photothermal effect of Fe₃O₄ and MnFe₂O₄ nanoparticles declined while that of ZnFe₂O₄ nanoparticles maintained relatively stable after preservation for 70 days, and then ZnFe₂O₄ nanoparticles could effectively kill cancer cells under NIR laser.     

MoS_2负载量对MoS_2/TiO_2光催化降解苯酚效率的影响及其作用机理研究

通过水解法制备TiO_2纳米颗粒,与经过超声处理后的MoS_2片层纳米材料复合制备MoS_2/TiO_2纳米催化剂,考察不同MoS_2负载量对其光催化降解苯酚效率及路径的影响。XRD、SEM、EDS、FT-IR和UV-vis DRS等表征结果表明,复合催化剂主要由锐钛矿型TiO_2和MoS_2组成;剥离后的MoS_2呈现薄片层状结构,均匀地分散在TiO_2纳米颗粒当中。光催化降解苯酚性能测试结果显示,对于MoS_2/TiO_2催化剂,MoS_2负载量的提高有利于光催化降解苯酚效率的提高;当MoS_2负载量为27%时,复合M o S2/TiO_2纳米颗粒的光催化性能最佳,反应80 min后可将苯酚完全降解。通过对苯酚降解过程中生成中间产物跟踪发现,MoS_2负载量的提高有利于促进中间产物苯醌、对苯二酚以及邻苯二酚的生成,进而提升了MoS_2/TiO_2复合材料的光催化性能。     

Shape-controlled synthesis and photocatalytic activity of In2O3 nanostructures derived from coordination polymer precursors

In（BTC）（phen）（H₂O）nanocrystals with controllable morphology and size were successfully obtained by solvothermal method.Hierarchical straw-sheaf-like architectures,nanorods and elongated hexagons have been synthesized by varying the volume ratio of DMF:H₂O:C₂H₅OH.Phase-pure In₂O₃nanocrystals were obtained by the calcination of the precursors without significant alteration of the morphology.The products were characterized by PXRD,SEM,TEM,TGA,IR and gas adsorption measurements.The photocatalytic effect was investigated for the In₂O₃ nanocrystals with different morphology on the degradation of rhodamine B（Rh B）and it was found that the nanorods exhibited the best photocatalytic activity,which shows the degradation efficiency of 94%for 8 h.The results showed that the photocatalytic activity increased with the increase of BET surface area and pore volume.     

CuInS2/CdS基掺杂纳米晶的晶体结构、光谱性质及性能调控研究

多功能纳米晶的制备、性能及其应用是材料、化学、能源、生物医学等领域十分关注的课题之一。基于掺杂调控纳米晶生长和性能的思想,发展了纳米晶修饰和复合的概念和技术,使用绿色安全的化学溶液法结合外延生长技术合成了巯基丙酸(MPA)包覆的掺杂CuInS₂/CdS基纳米晶材料。通过适当调整掺杂异价离子的种类,实现了对CuInS₂/CdS基纳米晶显微结构和性能的调控,获得了具有特定相结构、组分、尺度和光学性能(吸收性质、光学带隙、发光强度)的纳米晶。存在于基质晶体中不同金属掺杂离子,会造成半导体的禁带中间产生掺杂能级,导致二次跃迁,进而产物体现出不同的禁带宽度。掺杂Co ²⁺、Fe ²⁺、Er ³⁺离子的CuInS₂/CdS纳米晶光致发光(PL)峰强度降低明显,这是由于Co ²⁺、Fe ²⁺、Er ³⁺离子掺杂有效地抑制了空穴-电子对的复合,降低了纳米晶的光生电子-空穴复合几率,使得其光催化活性得到增强。这些半导体纳米材料在光催化、能量转换与储存方面具有良好的应用潜力。     

SiO2-Al2O3玻纤载体负载CuO-CeO2对挥发性有机化合物催化燃烧性能研究

采用等体积共浸渍法制备了CuO-CeO₂整体式催化剂,评价了催化剂对乙酸乙酯、异丙醇及甲苯的催化燃烧性能。采用N₂吸附-脱附、X射线衍射（XRD）、氢气程序升温还原（H₂-TPR）、氨气程序升温脱附（NH₃-TPD）以及挥发性有机化合物脱附等手段对催化剂进行了表征。表征数据显示,氧化铜以高分散态均匀分散存在于载体表面,氧化铈则是小的纳米颗粒,氧化铈颗粒粒径随着Cu/Ce物质的量比的减小而增大。添加铈氧化物会显著增加总酸量,特别是路易斯酸酸位的量,同时增强了乙酸乙酯和异丙醇的吸附量,吸附量的增加提高了催化剂对乙酸乙酯和异丙醇的催化燃烧性能。从甲苯的催化燃烧实验可以看出,大量添加CeO₂稍微增加了甲苯的吸附容量,减弱了催化剂的还原性、降低了活性氧的含量,最终导致甲苯的低转化率。催化行为由氧化铜、氧化铈以及载体三者之间的共同作用决定,这三者的协同作用不仅影响着表面氧的活性同时影响着催化剂对甲苯的吸附能力。     

Synthesis and study of Bi2Ti2O7/TiO2 composites as efficient visible-light-active photocatalysts in the reduction of aqueous Cr(VI)

In this work, Bi_2Ti_2O_7/TiO_2 composites were synthesized and studied as potential visible-light-activated photocatalysts in the reduction of aqueous Cr(VI). Bi_2Ti_2O_7/TiO_2 composites with tunable compositions were synthesized via a solvothermal-calcination two-step method, simply by changing the molar ratios of Bi(NO_3)_3·5H_2O to tetrabutyl titanate in the reactants. The compositions, structures and optical properties of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and UV–vis diffuse reflectance spectra. The photocatalytic activity of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites was tested in the reduction of aqueous Cr(VI)under visible-light(λ420 nm) irradiation, and compared with that of TiO_2 nanoparticles. It was observed that the as-synthesized Bi_2Ti_2O_7/TiO_2 composites exhibited much higher photocatalytic activity than TiO_2 nanoparticles, and the most efficient composite(300 mg) can achieve the complete reduction of Cr(VI) in 300 mL of 50 mg/L K_2Cr_2O_7 aqueous solution under visible-light(λ420 nm)irradiation in 90 min.     

SnS2/graphene nanocomposite: A high rate anode material for lithium ion battery

In this work,via a facile solvothermal route,we synthesized an anode material for lithium ion batteries(LIBs)—SnS_2 nanoparticle/graphene(SnS_2 NP/GNs) nanocomposite.The nanocomposite consists of SnS_2nanoparticles with an average diameter of 4 nm and graphene nanosheets without restacking.The SnS_2 nanoparticles are firmly anchored on the graphene nanosheets.As an anode material for LIBs,the nanocomposite exhibits good Li storage performance especially high rate performance.At the high current rate of 5,10,and 20 A/g,the nanocomposite delivered high capacities of 525,443,and 378 mAh/g,respectively.The good conductivity of the graphene nanosheets and the small particle size of SnS_2contribute to the electrochemical performance of SnS_2 NP/GNs.     

Fast synthesis of dopamine-coated Fe3O4 nanoparticles through ligand-exchange method

A fast approach was described for the synthesis of water-dispersible monodisperse dopamine-coated Fe₃O₄ nanoparticles（DA-Fe₃O₄） with uniform size and shape via ligand-exchange of oleic acid on Fe₃O₄ using only 2 min.The prepared DA-Fe₃O₄ nanoparticles were characterized by transmission electron microscopy,Fourier transform infrared spectrometry,and vibrating sample magnetometer.The results indicated that the resulting DA-Fe₃O₄ nanoparticles had an average diameter of about 19.2 nm. The magnetic saturation value of the prepared DA-Fe₃O₄ nanoparticles was determined to be 72.87 emu/g,which indicating a well-established superparamagnetic property.     

氧化锆催化合成气直接转化制芳烃

采用共沉淀法和水热法制备了三种不同粒径、不同结构的纳米氧化锆催化剂,借助XRD、TEM、Raman光谱、N_2物理吸附、XPS、NH_3-TPD表征了催化剂的物理化学性质,并研究了其合成气催化转化性能。在400℃、3 M Pa、空速500 m L/(gcat·h)、进料组成H_2/CO/Ar(体积比)为5∶5∶1时,氧化锆能够一步催化合成气转化为高辛烷值烃类产物,主要是异构烯烃、环状烯烃及芳烃。在烃类产物中,C_(5+)选择性高达48%,C_(5+)中芳烃含量为30%-53%。结果表明,单斜相氧化锆比四方相更有利于CO转化,其中,比表面积较大、酸量较大的小粒径氧化锆表现出最高的CO转化率及产物收率;而大晶粒单斜相氧化锆表现出最高的芳烃选择性,这与其较高的酸性位密度相对应。因此,CO转化在Zr O_2催化剂上是酸催化反应,酸量影响催化剂的活性,而酸性位密度是影响芳烃等较大分子量产物生成的主要因素。     

Combined investigation of experimental characterization and theoretic calculation on the structure of dextran-Fe3O4 clusters

Dextran-Fe₃O₄ hybrid clusters were fabricated by coprecipitating ferric and ferrous ions in the presence of dextran, and after characterization of these clusters combined with calculation based on classical nucleation theory, a structure model of these hybrid clusters was proposed. The hybrid cluster was believed including small Fe₃O₄ nanoparticles and dextran which acted as both nucleating agent and stabilizer, so that exist in both the inside of magnetite nanoparticles and the periphery of the hybrid clusters. Besides, the effects of W_CD (weight_{iron cation}:weight_dextran) and molecular weight of dextran on the size, morphology and magnetic property of clusters were also investigated in this paper. It was found that the variation of W_CD and molecular weight of dextran have great effect on the size of the hybrid clusters, but have almost no effect on the size of the Fe₃O₄ nanoparticles. The characterization of magnetic property demonstrated that the Fe₃O₄ nanoparticles are of a single domain and the saturation magnetization was affected by the size of dextran-Fe₃O₄ hybrid clusters.     

2D Bi2WO6/MoS2 as a new photo-activated carrier for boosting electrocatalytic methanol oxidation with visible light illumination

A kind of new 2D heterojunction of Bi₂WO₆/MoS₂ was constructed and used as visible-light activated carrier for depositing Pt electrocatalyst. With assistance of visible light irradiation, Pt-Bi₂WO₆/MoS₂ composite shows enhanced electrocatalytic activity and stability towards methanol oxidation than traditional electrocatalytic process and commercial Pt/C.     

磁性荧光双功能复合纳米粒子Fe3O4@SiO2@ZrO2:Tb3+的合成和表征

通过原位反应合成法成功合成了一种新型水溶性的磁性荧光复合纳米粒子Fe₃O₄@SiO₂@ZrO₂:Tb³⁺,并通过扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)、红外光谱仪(FT-IR)、磁性测试仪和荧光(PL)光谱对其形貌、尺寸、相组成、磁性和荧光性能进行了表征。 结果表明,核(Fe₃O₄@SiO₂)壳(ZrO₂:Tb³⁺)结构组成的磁性荧光复合纳米粒子具有超顺磁性,其饱和磁化强度达到36 emu/g,并且在494 nm(⁵D₄→⁷F₆)、549 nm(⁵D₄→⁷F₅)、587 nm(⁵D₄→⁷F₄)和625 nm(⁵D₄→⁷F₃)处具有4个Tb³⁺特有的荧光发射光谱带峰值。 磁性荧光双功能的复合纳米粒子在生物医学领域具有潜在的应用价值。     

Thermal behavior of nitrided TiO2/In2O3 by TG–DSC–MS combined with PulseTA

TiO₂/InN (In/(Ti + In) = 6.5:100 mol) was prepared by nitridation of TiO₂/In₂O₃ by NH₃ at 580 °C for 8 h. Only the anatase TiO₂ phase was detected in the XRD measurements. The highly dispersed InN clusters on the surface of anatase TiO₂ nanocrystals were beyond the detection limit of XRD. In order to confirm the existence of InN in the products of nitridation, thermogravimetry–differential scanning calorimetry–mass spectrometry (TG–DSC–MS) coupling techniques were used for a simultaneous characterizing study of the changes of mass, enthalpy and determination of the evolved gases during the thermal decomposition of the InN and the nitrided TiO₂/In₂O₃ samples. Moreover, pulse thermal analysis (PulseTA) was combined with TG–DSC–MS for the quantitative calibration of the evolved nitrogen formed during the thermal decomposition of the InN and the nitrided TiO₂/In₂O₃. The applied technique enabled identification and quantification of the InN in the products of the nitridation of TiO₂/In₂O_3.     

CO2/NIR light dual-controlled nanoparticles for dsDNA unzipping

Both of carbon dioxide(CO2)and near-infrared(NIR)light as triggers for non-invasive remotely control are attracting wide attentions due to their good biocompatibility and easy operation.Here,CO2/NIR light dual controlled nanoparticles are proposed to remotely regulate the unzipping of dsDNA by using imidazole functionalized conjugated polymer nanoparticles(imidazole-CPNs).The dsDNA successfully coats on the shell of imidazole-CPNs to form imidazole-CPNs/dsDNA assembly due to intensively electrostatic interaction triggered by CO2.Furthermore,the unzipping process of dsDNA is remotely controlled by NIR light based on the photothermal effect,and it can be readily monitored by the fluorescence intensity of ethidium bromide(EB)and CD spectra of dsDNA.Thus,dual stimulation responsive imidazole-CPNs effectively control dsDNA unzipping under CO2 stimulus and NIR light,promising a new direction in the biological applications of DNA,such as the treatments of diseases caused by gene duplication abnormality.     

Synthesis of nano-TiO2 assisted by diethylene glycol for use in high efficiency dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSSCs) consisting of anatase TiO_2 nanoparticles that were synthesized via a hydrothermal method was studied.The synthesized TiO_2 nanoparticles were characterized by X-ray diffraction(XRD),nitrogen sorption analysis,scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),and UV-vis spectroscopy.Then the J-Vcurve,electrochemical impedance spectroscopy(EIS),and open-circuit voltage decay(OCVD) measurement were applied to evaluate the photovoltaic performance of DSSCs.Compared with the commercial TiO_2nanoparticles(P25),the synthesized-TiO_2 nanoparticles showed better performance.By adding diethylene glycol(DEG) before the hydrothermal process,the synthesized TiO_2 nanoparticles(hereafter referred to as TiO_2-DEG particles) shows narrower size distribution,larger specific surface area,higher crystallinity,and less surface defects than TiO_2(DEG free) particles.The analysis of photovoltaic properties of DSSCs based on TiO_2-DEG particles showed that the recombination of electron-hole pairs was decreased and the trapping of carries in grain boundaries restrained.It was believed that the photoelectrode fabricated with the as-prepared TiO_2 nanoparticles improved the loading amount of dye sensitizers(N719).and enhanced the photocurrent of the DSSCs.As a result,the TiO_2-DEG particle based cells achieved a photo-to-electricity conversion efficiency(η) of 7.90%,which is higher than 7.53%for the cell based on TiO2(DEG free) and 6.59%for the one fabricated with P25.     

Schiff碱改性法制备Ag/TiO2纳米粒子催化剂及其催化性能

通过引入水杨醛衍生的Schiff 碱功能单体与钛酸正丁酯发生水解共缩聚反应,制备了二氧化钛负载的银纳米粒子催化剂。采用红外光谱分析仪(FTIR)、广角X射线衍射仪(Wide Angle XRD)、高分辨透射电子显微镜(HRTEM)和紫外-可见分光光度计(UV-Vis) 等技术手段对制得的样品进行了表征,并考察了样品催化CO氧化反应的活性。结果表明,通过改变Schiff碱功能单体的用量和样品焙烧温度可以调控Ag纳米粒子的粒径和TiO₂载体的结构,从而可以调控Ag/TiO₂纳米催化剂的活性。当Schiff碱功能单体用量为20%,焙烧温度为873 K时,Ag/TiO₂纳米催化剂活性最好,CO转化率达到99.9%。     

The geometry, vibrational frequencies, thermochemistry, quadrupole moments and electronic structure of C2Na2: Comparison with C2Li2, C2H2, C2F2 and C2Cl2

The electronic structure of Na₂C₂ is studied using ab initio electronic structure methods and is compared to the companion molecule Li₂C₂. Both the linear D_∞h and planar structures are minima on the ground state potential surface with the planar D_2h conformation being the lowest energy form, similar to Li₂C₂. At the CCSD(t) level the planar form is more stable that the linear by 11.2 kcal/mol as compared with 7.34 kcal/mol for Li₂C₂. Both molecules are significantly ionic. The vibrational frequencies, atomization energy at 0 K, D₀, and the standard enthalpy of formation, are calculated and compared to those of Li₂C₂ as well as HCCH, FCCF and ClCCCl. We find D₀ and to be 331.1 and 84.92 kcal/mol for Li₂C₂ and 298.3 and 93.25 kcal/mol for Na₂C₂. We calibrate these by calculating the same quantities for HCCH, FCCF and ClCCCl.     

碱性介质中制备纳米四氧化三锰及其超级电容特性

比较了不同碱溶液中纳米Mn₃O₄的制备及其超级电容性能。用X射线粉末衍射仪、扫描电子显微镜和原子力显微镜等技术手段分别测试了晶体结构和表面形貌。用循环伏安、恒流充放电和交流阻抗测试了材料的电化学性能。结果表明,在氢氧化钠、氨水中Mn²⁺沉淀氧化可以直接制备纳米Mn₃O₄;碳酸钠中先生成MnCO₃,加氢氧化钠可转化为纳米Mn₃O₄。NaOH、NH₃和Na₂CO₃ 3种介质中制备的Mn₃O₄晶粒尺寸分别为29.5、20.2和36.3 nm。纳米Mn₃O₄经连续充放电循环后可活化为Birnessite-type MnO₂。氨水中制备的Mn₃O₄活化后比容量最大,达到239 F/g,是一种具有应用前景的超级电容器材料。     

Preparation of crack-free ZrO2 membrane on Al2O3 support with ZrO2–Al2O3 composite intermediate layers

To develop porous alumina supported MF ZrO₂ membranes, ZrO₂–Al₂O₃ composite intermediate layers are considered in order to decrease stress creation during the processing and avoid cracks formation. The relation between distortion stress and sintering shrinkage was experimentally studied. And the cracks formation mechanism was qualitatively evaluated and discussed. Finally, crack-free YSZ membrane with pore size of 0.16 μm on the two ZrO₂–Al₂O₃ intermediate layers possessing a gradient composition was successfully prepared and characterized.