Highly photoreactive TiO_2 hollow microspheres with super thermal stability for acetone oxidation

TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.

Hollow Carbon Microspheres/MnO_2 Nanosheets Composites:Hydrothermal Synthesis and Electrochemical Behaviors

This article reported the electrochemical behaviors of a novel hollow carbon microspheres/manganese dioxide nanosheets(micro-HC/nano-MnO2) composite prepared by an in situ self-limiting deposition method under hydrothermal condition. The results of scanning electron microscopy reveal that MnO2 nanosheets homogeneously grow onto the surface of micro-HC to form a loose-packed microstructure. The quantity of MnO2 required in the electrode layer has thereby been reduced significantly, and higher specific capacitances have been achieved. The micro-HC/nano-MnO2 electrode presents a high capacitance of 239.0 F g-1 at a current density of 5 m A cm-2, which is a strong promise for high-rate electrochemical capacitive energy storage applications.

Controllable preparation of hierarchical NiO hollow microspheres with high pseudo-capacitance

Nickel oxide(NiO)hollow microspheres with hierarchical structure were fabricated through a process consisting of a self-assembling,hydrothermal reaction and calcination.The prepared NiO hollow microspheres composed of many nanoflakes,are about 2-3μm in diameter.The length of the NiO flakes,having clear edges,is about 500-700 nm,while the thickness is only about 40-50 nm.This indicates that the NiO microspheres possess a hierarchical structure that can provide porous channels to facilitate the transmission of both electrons and electrolyte ions.NiO microspheres exhibit a high specific capacitance of about 1340 F/g at a current density of 1 A/g and high capacitance retention about 96.5%after 1000 cycles.What’s more,the conductive mechanism of nickel oxide for electrochemical capacitor electrodes was also studied.

Multi-shelled TiO2/Fe2TiO5 heterostructured hollow microspheres for enhanced solar water oxidation

There remains a pressing challenge in the fabrication of superior photocatalysts for light-driven water oxidation.Here,we designed and fabricated heterostructured TiO2/Fe2TiO5 hollow microspheres with single-,double-,closed-double-,triple-,and core-shell structures and different Fe/Ti molar ratios using a facile sequential templating approach.The closed-double-shelled TiO2/Fe2TiO5 hollow microspheres with 35% Fe exhibited the highest oxygen evolution reaction rate up to 375 μmol＆#183;g-1＆#183;h-1 and good stability for 5 h.The high performance can be attributed to the closed-double shell,which had more reactive sites and greater light-harvesting ability,self-supported thin shells with short charge-transfer paths,and a favorable staggered band alignment between the TiO2 and Fe2TiOs.

HGM@GO聚氨酯复合材料的制备和导热性能研究

首先通过氧化石墨烯(GO)包覆对空心玻璃微珠(HGM)进行表面改性,再经过物理混合制备改性空心玻璃微珠/聚氨酯复合材料,使用X射线衍射仪、扫描电子显微镜、热重分析仪对经过氧化石墨烯包覆改性的空心玻璃微珠进行形貌和结构分析,对改性空心玻璃微珠/聚氨酯复合材料进行力学性能、导热性能、热膨胀性能等测试。结果表明:使用氧化石墨烯包覆空心玻璃微球对复合材料的硬度、拉伸强度、压缩强度和弯曲强度均有一定提升。在空心玻璃微球添加量高于5%后,复合材料的导热性能开始优于纯聚氨酯材料,表明空心玻璃微珠表面的石墨烯层使材料内部形成了高导热通道,整体提高了复合材料的导热系数,使复合材料密度降低的同时具备更加优良的导热性能。对复合材料的热稳定性进行测试分析发现,在添加了空心玻璃微珠填料之后,复合材料的热膨胀系数随温度增加的趋势得到了很好的抑制,在180℃下仍能保持较好的尺寸稳定性。

Synthesis of Hollow Three-Dimensional Channels LiNi_(0.5)Mn_(1.5)O_4 Microsphere by PEO Soft Template Assisted with Solvothermal Method

A appropriate size with three-dimension(3 D) channels for lithium diffusion plays an important role in constructing highperforming LiNi_(0.5)Mn_(1.5)O_4(LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li~+ intercalation/deintercalation. In this work, an e fficient method for designing the hollow LNMO microsphere with 3 D channels structure by using polyethylene oxide(PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3 D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g~(-1) at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3 D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion.

Novel synthesis of V_2O_5 hollow microspheres for lithium ion batteries

In this work,hollow structured V_2O_5 microspheres were fabricated from solid vanadium precursor microspheres which were prepared by microwave-assisted,solvothermal approach.In the annealing process,the spherical precursor microspheres can be converted into hollow microspheres,serving as a sacrificial template.The synthesis approach is quite different from the previously reported approaches for the preparation of hollow structured V_2O_5microspheres.As cathode materials for lithium ion batteries,the hollow-structured V_2O_5 microspheres exhibit high capacity and good rate capability.The electrodes deliver specific discharge capacities of 132 and 113 mA h g^(-1) at the current densities of 1 C and 8 C,respectively.

Rational Fabrication of Size Tunable SnO2 Hollow Microspheres

A designed solution route was developed to fabricate size tunable SnO2 hollow microspheres based on the sol-gel theory. The hydrolysis of SnSO4 released protons to form SnO2 particulates and induced the decrease of pH value. To minimize the high surface energy, the SnO2 particulates tended to assemble into large particles, the size of which was affected by the electrolyte concentration or pH value. Elevating SnSO4 content aroused the decrease of the pH value that directed to the shrinkage of the aggregated particle size of SnO2. Size tunable SnO2 hollow micro- spheres were then rationally fabricated under solvothermal conditions via Ostwald ripening by simply adjusting the SnSO4 concentration. The in situ pH decrease directed to the shrinkage of the particle size from 270 nm to 112 nm. The formation mechanism was confirmed and rationally elucidated by the time dependant morphology evolution. Charge-discharge tests revealed that the reduced particle size aroused an improved lithium ion battery performance.

酵母模板合成CuO空心微球及其催化性能研究

以酵母作为生物模板合成了氧化铜空心微球。X-射线粉末衍射、电子扫描电镜、氮气吸附-脱附、紫外-可见光漫反射光谱对产品的物化结构和性能进行了表征。电子扫描电镜分析表明氧化铜产物具有空心结构,粒径为2.2-2.9μm。X射线粉末衍射表明CuO空心微球具有很好的单斜晶型结构。氮气吸附-脱附表明CuO空心微球的比表面积是8.15 m2/g,壳体表面具有多孔性,中孔尺寸分布在2.0-35.4 nm。紫外-可见光漫反射光谱证实产物的能隙是1.38 ev。傅里叶红外、热重-差热以及X射线能谱分析监控了合成过程中组分及化学键的变化,据此提出了空心氧化铜的合成机理。进一步利用差热分析,研究了空心氧化铜催化热分解高氯酸铵的反应,证实了该空心氧化铜产品具有很高的催化活性。

炭微球的结构演变:从实心到中空(英文)

采用简单的空气氧化法由实心炭微球制备中空结构的炭微球。通过场发射扫描电子显微镜、高分辨透射电子显微镜、X-射线衍射仪、拉曼光谱和热重分析仪对产物的形貌和结构进行表征。结果表明:中空炭微球的石墨化程度较低。在炭微球的空气热氧化过程中,反应温度对炭微球从实心到中空的结构演变起着关键性的作用,温度越高,中空炭微球的内径越大、壁越薄。其形成机理可认为是炭微球的曲率和结晶度协同作用的结果。亦即,实心炭微球进行热氧化时,其内部的大曲率和低结晶度更易氧化,以致形成中空炭微球。

多孔氧化铜空心微球的一步法制备及其光催化性能(英文)

采用一步法成功制备出多孔氧化铜空心微球,用SEM、XRD和FTIR对制得的样品进行了表征。研究发现,碳源、反应温度、反应时间、CuSO4浓度等实验条件在多孔微球的制备过程中起着重要作用。在实验结果的基础上,提出了多孔氧化铜空心微球的形成机理。制备的多孔氧化铜空心微球的比表面积为409 m2.g-1,平均孔径为3.15 nm,总孔体积为0.256 cm3.g-1,这种空心微球具有量子尺寸效应并对罗丹明B有较高的光催化性能。

SnO_2中空微球的制备与气敏性能

在不加任何表面活性剂情况下,采用磺化的聚苯乙烯(PS)微球为模板,二水结晶二氯化锡(SnCl_2·2H_2O)为锡源,成功制得SnO_2中空微球。利用X射线衍射仪(XRD)、扫描电镜(SEM)、高分辨透射电镜(HRTEM)和氮气吸附脱附仪(BET)对材料的结构和形貌进行了表征,研究并讨论了温度、乙醇浓度等因素对SnO_2纳米颗粒及SnO_2中空微球气敏性能的影响。结果显示,SnO_2中空微球的比表面积为48.49m^2/g,比SnO_2纳米颗粒的比表面积(21.94m^2/g)提升了1.21倍。比表面积增加有助于SnO_2材料表面吸附更多被测气体以提升表面化学反应,进而提升气敏性能。在260℃下,SnO_2中空微球对200μL/L乙醇的灵敏度为66.26,与SnO_2纳米颗粒相比(51.34),气敏性能提高了0.29倍。

基于中空氧化镍纳米微球和离子液体复合膜固定血红蛋白的NaNO_2生物传感器

采用微波水热法合成了一种中空氧化镍纳米微球(NiO),然后将其与1-丁基-3-甲基-咪唑四氟硼酸盐(BMIMBF4)的复合膜用于血红蛋白(Hb)在碳糊电极上的固定,制备了NaNO2生物传感器.通过扫描电子显微镜、傅里叶变换红外光谱及紫外-可见光谱等分析表明,Hb已固定于NiO和BMIMBF4的复合膜中并能保持其生物活性;进一步通过电化学阻抗法研究了修饰电极中混合物各组分的作用.结果表明,在NiO和BMIMBF4的复合膜中,Hb能实现有效的直接电子转移,且修饰后的电极对NaNO2有良好响应,响应时间小于5 s,检出限为4.57μmol/L(S/N=3),灵敏度为46.2μA.L.mmol-1,线性范围为10～170μmol/L,表观米氏常数KM为2.4 mmol/L,该方法的重现性和电极的稳定性良好.

氧化锌空心微球的制备及其催化性能

以乙二醇为溶剂,聚乙二醇-10000为表面活性剂,硝酸锌和醋酸钠为原料,利用溶剂热法,合成了氧化锌空心微球。并用X射线衍射、扫描电子显微镜、热重、比表面和孔径分布等对其进行了表征。考察了硝酸锌用量、聚乙二醇-10000用量、反应时间和反应温度等对氧化锌空心微球形貌和大小的影响。考察了氧化锌空心微球催化分解高氯酸铵的性能,结果表明,由于氧化锌空心微球的加入,高氯酸铵的分解温度由442℃降低至280℃左右。

水热法制备高相变温度的二氧化钛纳米结构空心球

实验采用无模板水热法合成了高相变温度的TiO2纳米结构的空心微球,对其结构和光催化性能进行了表征。X射线衍射分析表明,160℃水热条件下即可得到结晶良好的锐钛矿型TiO2,经过900℃热处理后仍为锐钛矿型,直到1 100℃热处理后完全转变为金红石型。场发射扫描电子显微镜和透射电子显微镜照片表明,所得锐钛矿型TiO2颗粒为空心微球,直径约为1μm,由尺寸20～30 nm的TiO2纳米粒子组装而成。光催化测试表明,该空心球有较高的光催化氧化性能,25 min后二氧化钛空心微球对罗丹明B的降解率可达100%。

铁氧化物纳米晶自组装空心微球的制备、表征及其应用

铁氧化物纳米材料和纳米结构空心微球分别代表了材料研究中组分和结构的研究热点.而由铁氧化物纳米晶自组装形成的空心微球的研究则是二者相结合,具有重要的科学意义和良好的应用前景.虽然已发展了多种方法制备各种单质及化合物的空心微球,但铁氧化物纳米晶自组装空心微球的制备方法报道较少.本文简要介绍了近几年发展起来的多种铁氧化物纳米晶自组装空心微球的一些制备方法,利用上述方法,制备出了多种不同组成单元、不同尺寸、不同空心程度的铁氧化物纳米晶自组装空心微球,对所制备的铁氧化物纳米晶自组装空心微球进行了表征,并初步介绍了所制备的铁氧化物纳米晶自组装空心微球在药物缓释和环境领域中的应用.

氧化石墨烯包覆空心玻璃微珠的制备及其协效APP阻燃TPU的研究

用氧化石墨烯(GO)对空心玻璃微珠(HGM)进行包覆制得了一种新型阻燃剂HGM@GO。并分别采用同等含量的聚磷酸铵(APP)、HGM协效APP、HGM@GO协效APP制得了阻燃热塑性聚氨酯弹性体(TPU)复合材料。通过锥形量热仪(CCT)、烟密度仪(SDT)及热重(TG)手段研究了其生热、生烟及热降解性能。CCT结果显示:HGM@GO协效APP阻燃TPU时能够显著降低复合材料的热释放速率(HRR)、总热释放(THR)等热参数及生烟速率(SPR)、总生烟量(TSR)等烟参数,显著提高材料的抑热及抑烟性能。SDT结果表明:无焰或有焰条件下,HGM@GO协效APP均能够显著提高复合材料的光通量,抑烟效果更明显。TG实验结果显示:同等含量阻燃剂条件下,HGM@GO协效APP阻燃TPU对提高材料的热稳定性能更有效。总之,从测试结果来看,HGM@GO协效APP阻燃TPU时,在提高材料的火灾安全性方面更突出,将有更好的应用前景。

正辛胺模板法制备Si/Al复合空心微球及其结构表征

以正辛胺为模板、正硅酸乙酯（TEOS）为硅源、异丙醇铝为铝源，在盐酸的催化作用下通过溶胶一凝胶方法制备出圆形度和分散性好、结构完整的Si／Al复合空心微球。分析了不同反应时间和反应温度下Si／Al复合空心微球的形貌、粒径、成分和结构。结果表明：Si／Al复合空心微球的平均粒径随反应温度和反应时间的增加而缓慢增大，但明显小于同样条件SiO2空心微球的粒径。Si／Al复合空心微球的平均粒径为8～16μm、壳层厚度为2．18～3．61μm。Si／Al复合空心微球中的铝主要以氧化物的形式存在；壳层表面具有微孔结构，比表面积为431～912m3／g；可几孔径为1．2～2．0nm。

纳米SiO_2/环氧树脂/空心微珠反应动力学研究

研究了纳米SiO2/环氧树脂/空心微珠体系的粘度特性,说明填料的加入对体系有一定的增粘作用。同时,采用示差扫描量热法(DSC)研究了纳米SiO2/环氧树脂/空心微珠体系的固化过程,利用不同升温速率下的DSC曲线求出三元体系的表观活化能、反应级数和频率因子等参数,得出了固化体系的反应动力学方程。

升温速率对氧化锌空心微球形貌及性能的影响

以乙酸锌为锌源,采用溶剂热技术,在2.92、1.46、0.97、0.73、0.49℃/min 5组不同升温速率下制备了氧化锌空心微球。分别采用XRD和SEM对样品的物相结构和形貌特点进行了表征,用荧光分光光度计测试了样品的室温光致发光性能,研究了升温速率对产物形貌的影响。结果表明:随着升温速率下降,氧化锌空心微球断面的小晶粒逐渐溶解,所形成的较大晶粒延空心微球的径向连接在一起,形成光滑的纳米棒,纳米棒的末端逐渐显现出比较清晰的六棱锥状结构。微球的结晶度逐渐提高,晶粒的平均粒径呈现先减小后增大的规律,紫外发射峰发生了红移。