以锯齿状碳纳米管为模板原位合成微/纳米球状氧化钨（英文）

以锯齿状CNTs管束作为模板担载H_2WO_4前驱体。在液相沉积过程中H_2WO_4被锯齿状CNTs包裹,所得H_2WO_4/CNTs团簇的平均尺寸为500 nm,由直径10～20 nm的H_2WO_4组成,比表面积和孔容分别为85.24 m~2·g~(-1)和0.2933 m~3·g~(-1)。将H_2WO_4/CNTs置于氧气气氛中进行热处理,除去CNTs后,得到了由纳米颗粒组成的WO_3微米球,比表面积和孔容分别为18.7 m~2·g~(-1)和0.2055 m~3·g~(-1)。结果表明,锯齿状CNTs对有效调节分层结构WO_3发挥重要作用,对制备微纳米结构材料具有广阔的应用前景。     

微波法合成介孔WO_3 ·NiO ·0.33H_2O及光催化降解气相甲醛

以复合表面活性剂为模板,采用微波辐射、二甲苯萃取脱除模板剂法制备了介孔材料WO_3·0.33H_2O、WO_3·NiO·0.33H_2O,利用XRD、TGA、TEM、BET等手段表征了材料的结构、形貌、比表面积、孔径分布.结果表明,微波辐射比传统加热法制备的材料晶粒小,结晶度高,孔径分布更均匀,比表面积更大;制备的材料WO_3·NiO·0.33H_2O介孔呈现蠕虫状,掺杂Ni~(2+)能稳定介孔结构,抑制晶粒长大,其比表面积达66.37m~2·g~(-1).分别以WO_3·NiO·0.33H_2O催化剂考察在紫外光(UV)、黑光灯、可见光3种光源下对气相甲醛光催化降解反应动力学规律及紫外光下的催化稳定性,其光催化降解气相甲醛降解率为传统加热法样品的3倍,在可见光下达76.8%.     

化学溶液沉积法制备WO3•2H2O薄膜及其电致变色性能

目的研究具有不同微观结构的WO_3·2H_2O薄膜的电致变色性能。方法采用化学溶液沉积法在FTO玻璃上制备WO_3·2H_2O薄膜,通过加入不同的形貌控制剂(柠檬酸或草酸铵),制备不同纳米结构的WO_3·2H_2O薄膜。采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分析薄膜的成分结构和微观形貌,利用紫外可见光分光光度计对薄膜在波长为200～1000nm范围内的透光性进行研究,并通过电化学工作站对薄膜进行电化学性能分析。结果采用柠檬酸作为形貌控制剂制备的WO_3·2H_2O薄膜的透光性高达82%左右,其在着色和褪色状态的透过率差值为36.2%。通过添加柠檬酸或草酸铵作为形貌控制剂制备的WO_3·2H_2O薄膜均呈现出纳米片状结构,纳米片的厚度分别为5～15 nm和50～60 nm,但是采用柠檬酸制备的WO_3·2H_2O具有较多的间隙和裂缝,使其表现出了较好的电致变色性能。结论具有间隙和裂缝的纳米WO_3·2H_2O薄膜增加了薄膜与电解质的接触面积,减少了离子扩散的路径距离,更小的纳米结构可以提供更多的化学活性位点,从而表现出较好的电致变色性能。     

热处理条件对介孔Al_2O_3结构性质的影响

以氯化铝和氨水反应制得拟薄姆石为前驱体,研究了拟薄姆石前驱体热处理性质,考察了焙烧温度对介孔Al_2O_3微观结构的影响,通过焙烧升温速率调控了γ-Al_2O_3表面酸碱性,借助XRD、SEM、BET及NH3/CO2-TPD等手段对焙烧产物晶相组成、微观形貌、孔结构及表面酸碱性进行分析表征。结果表明,焙烧温度对介孔Al_2O_3晶相组成、微观形貌、孔结构影响较大。随焙烧温度升高,Al_2O_3结晶度逐渐增大,且焙烧温度不同,Al_2O_3晶型不同,焙烧温度为600℃时制得了比表面积240.23 m~2·g~(-1),介孔孔容0.602 cm3·g~(-1),平均孔径10.71 nm的纳米球形介孔γ-Al_2O_3。升温速率对600℃焙烧制得γ-Al_2O_3表面酸碱性质具有较大影响,焙烧升温速率越快,表面酸碱强度越强。升温速率为5℃·min~(-1)时,表面具有最大弱酸(0.342 mmol·g~(-1))和弱碱量(0.322 mmol·g~(-1))。     

碳包覆铜纳米颗粒的比表面积和孔结构

采用直流电弧放电等离子体技术制备碳包覆铜纳米颗粒,并对样品的形貌、晶体结构、粒度、比表面积和孔结构采用高分辨透射电子显微镜(HRTEM)、X射线衍射仪(XRD)和N_2吸-脱附等测试手段进行分析。结果表明:直流电弧等离子体技术制备的碳包覆铜纳米颗粒具有典型的核壳型结构,内核为面心立方的金属铜,外壳为石墨碳层。颗粒主要呈球形或椭球形,粒度相对比较均匀,分散性良好,粒径分布在20~100 nm范围内,平均粒径为50 nm,外壳碳层的厚度为10 nm。碳包覆铜纳米颗粒的等温吸附曲线属Ⅳ型,晶粒之间的孔隙以介孔为主,样品的BET比表面积为33 m~2/g,当量粒径为45 nm,与TEM和XRD测得的结果基本一致。BJH吸附累积总孔孔容与BJH吸附平均孔径分别为0.112 cm~3/g和13 nm。     

Improved performance of Li-Se battery based on a novel dual functional CNTs@graphene/CNTs cathode construction

A dual functional CNTs@graphene/CNTs cathode for Li–Se battery was constructed by a CNTs@graphene network and a CNTs interlayer. CNTs were first integrated with graphene to form a three-dimensional(3D) framework and work together as a conductive matrix for Se confinement. The optimized composite cathode delivers a high initial capacity of 575 mAh·g~(-1) at 0.5 A·g~(-1) and good rate capacity with a retained capacity of 479 mAh·g~(-1) at 2.0 A·g~(-1)(73% of the capacity at 0.2 A·g~(-1)). CNTs were further served as an interlayer to confine the diffusion of polyselenides by constructing a thin CNTs layer outside the CNTs@graphene network. An improved initial capacity of 616 mAh·g~(-1) at 0.5 A·g~(-1) is achieved with a retained capacity of 538 mAh·g~(-1) after 80 cycles, indicating the effective dual function of CNTs in this novel cathode construction and great application potential for Li–Se battery.     

纳米Co3O4/CNTs复合粒子的制备及其对AP和AP/HTPB推进剂热分解催化性能的研究

以碳纳米管为载体,采用化学沉淀法制备了Co3O4/CNTs复合粒子,使用透射电子显微镜(TEM)、X衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDS)、比表面积分析仪(BET)等手段对产物的结构、形貌、粒度和比表面积进行表征,并用差示扫描量热仪(DSC)研究了纳米Co3O4、纯CNTs及Co3O4/CNTs复合粒子对高氯酸铵(AP)及AP/HTPB推进剂热分解的催化效果.结果表明Co3O4/CNTs复合粒子结晶好、包复均匀、比表面积大;此复合粒子可使AP和AP/HTPB推进剂的高温分解峰分别降低153.06℃和60.0℃,使总表观分解热分别增加了1063 J/g和920 J/g,表现出显著的催化性能,其催化性能明显优于纯纳米Co3O4和纯CNTs.     

烧结工艺对木材陶瓷孔隙结构的影响

以松木粉、液化木材和ZnCl_2为原料制备木材陶瓷,采用低温氮吸附法和扫描电镜(SEM)检测与评价烧结工艺对木材陶瓷孔隙结构的影响。SEM观测显示:木材陶瓷中多种孔隙结构并存,且木材的天然结构得以部分保存。低温氮吸附法检测表明:孔隙结构为H3型,以孔径为2.3~4.5 nm左右的介孔为主。烧结温度、升温速度和保温烧结时间等因素对孔隙结构有较大的影响。其比表面积随着烧结温度的升高而增加,但在高温区减小,而平均孔径则随烧结温度的升高表现为先减小后增加的趋势。1300℃、保温烧结30 min木材陶瓷的比表面积和平均孔径分别为364.2 m~2·g~(-1)和2.473 nm。     

原位聚合物限制法合成核-壳结构的LiFePO_4/C纳米复合材料及其热分析动力学研究（英文）

以FeCl_36H_2O、NH_4H_2PO_4、CH_3COOLi等为原料,通过原位聚合物限制法制备出了具有核-壳结构的LiFePO4/C纳水材料,利用XRD、HRTEM和TG-DSC等分析测试手段对材料的组成、形貌和热稳定进行表征。结果表明,LiFePO_4/C纳米材料是由20~40 nm的LiFePO4核和1~2 nm的炭壳组成。LiFePO_4/C纳米材料的热分解机理为1维随机成核,热分解动力学公式为da/dT=(A/β)exp(-E_a/RT)(1-a),动力学参数为lgA=10.386 min~(-1),E_a=1 38.849 kJ·mol~(-1)     

Neurons-system-like structured SnS_2/CNTs composite for high-performance sodium-ion battery anode

Sodium-ion batteries(SIBs) have attracted significant attention with respect to renewable energy power generation systems because of the abundant reserves of sodium on earth.However,anode materials are presently limited by low energy density,poor rate performance and inferior cycling stability.In recent years,tin disulfide(SnS2) with a particular layered structure has been considered as a promising anode material for SIBs due to its high theoretical capacity and low cost.Herein,a nervoussystem-like structured SnS2/CNTs composite was successfully synthesized via a hydrothermal method.The SnS2 sheets were strung with carbon nanotubes(CNTs) to form a hierarchical porous structure,which is effective for electrolyte diffusion and electronic transmission.The large distance of the(001) plane(0.5899 nm) of SnS_2 favors Na+insertion-extraction dynamics.Benefitting from these structural characteristics,SnS_2/CNTs electrodes exhibit high specific capacity,excellent rate performance and superior cycling stability.A high charge capacity of 642 mAh·g~(-1) was released at 0.2 A·g~(-1),and then,a high reversible capacity of 427 mAh·g~(-1) was retained after 100 cycles.Even charged at 2 A·g~(-1),the SnS_2/CNTS electrode maintained a capacity of 282 mAh·g~(-1).The nervous-system-like structure of the SnS_2/CNTs composite provides a novel strategy for the development of SIBs with high electrochemical performance.     

Preparation of nanosized sodium-aluminum tungstate, NaAl(WO4)2

Investigations are carried out for preparing nanosized pure phase of NaAl(WO₄)₂ by means of solid state synthesis with mechanical activation, applying the sol-gel method (Pechini) and by co-precipitation. It is shown that it is not possible to obtain pure phase when the initial substances are in stoichiometric amounts due to the simultaneous formation of a number of accompanying tungstate phases. The reasons for their origin are discussed. A method is demonstrated for obtaining a pure phase of NaAl(WO₄)₂ by co-precipitation of aqueous Na₂WO₄ and Al(NO₃)₃ solutions with considerable excess of Na₂WO₄. It is proved that NaAl(WO₄)₂ with particle size 40-80 nm is obtained with final synthesis of the powders at temperature 600-650 °C and duration of thermal treatment of 1-2 h.     

Fabrication of High Thermal Conductivity Carbon Nanotube Arrays by Self Assembled Fe3O4 particles

The outstanding properties of carbon nanotubes (CNTs) have induced widespread interest in researches and applications. A new approach of fabricating vertically aligned CNT arrays with good CNT size and distribution control, and enhanced substrate attachment is under development. This technique includes fabrication and size tuning of Fe₃O₄ nanoparticles, buffer layer preparation on Si substrates, self assembly of Fe₃O₄ nanoparticles on substrates, CNT synthesis by thermal CVD with optimized operation parameters. One application of the synthesized CNT arrays is serving as thermal interface material to meet the thermal management challenge in high power microelectronic packages. The thermal performance of the synthesized CNT arrays was evaluated.     

Synthesis and electrochemical properties of porous LiV3O8 as cathode materials for lithium-ion batteries

In this paper, we report on the synthesis of porous LiV₃O₈ by using a tartaric acid-assisted sol-gel process and their enhanced electrochemical properties for reversible lithium storage. The crystal structure, morphology and pore texture of the as-synthesized samples are characterized by means of XRD, SEM, TEM/HRTEM and N₂ adsorption/desorption measurements. The results show that the tartaric acid plays a pore-making function and the calcination temperature is an important influential factor to the pore texture. In particular, the porous LiV₃O₈ calcined at 300 °C (LiV₃O₈-300) exhibits hierarchical porous structure with high surface area of 152.4 m² g⁻¹. The electrochemical performance of the as-prepared porous LiV₃O₈ as cathode materials for lithium ion batteries is investigated by galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy. The porous LiV₃O₈-300 displays a maximum discharge capacity of 320 mAh g⁻¹ and remains 96.3% of its initial discharge capacity after 50 charge/discharge cycles at the current density of 40 mA g⁻¹ due to the enhanced charge transfer kinetics with a low apparent activity energy of 35.2 kJ mol⁻¹, suggesting its promising application as the cathode material of Li-ion batteries.     

Synthesis of WO3 nanoparticles for photocatalytic O2 evolution by thermal decomposition of ammonium tungstate loading on g-C3N4

Tungsten trioxide (WO₃) nanoparticles have been successfully synthesized by thermal decomposition of ammonium tungstate loading on g-C₃N₄. The as prepared nanoparticles were characterized by XRD, UV-vis, photoluminescence spectra (PL) and TEM. The XRD results indicate that the g-C₃N₄ decomposed completely with WO₃ remaining at calcination temperature higher than 550 °C. The WO₃ prepared at temperature below 750 °C exhibits orthorhombic phase, and monoclinic phase at temperature higher than 850 °C. The UV-vis absorption onset wavelength of the obtained samples is approximately 470 nm, and the absorption intensity increases with calcination temperature, and reaches a maximum at 750 °C. The as prepared WO₃ powders, loaded with 0.5 wt% Pt as cocatalyst, were used as photocatalysts for O₂ evolution from an aqueous KIO₃ solution. The WO₃ nanoparticles prepared from ammonium tungstate loading on g-C₃N₄ showed photocatalytic activity in O₂ evolution up to 77 times higher than that of WO₃ samples prepared from ammonium tungstate without loading on g-C₃N₄.     

Mn3O4 doped with nano-NaBiO3: A high capacity cathode material for alkaline secondary batteries

In this paper we report a novel Mn₃O₄ electrode doped with nano-NaBiO₃. It is demonstrated that doping with nano-NaBiO₃ alters the electrochemical inertia of Mn₃O₄, converting it into a rechargeable secondary alkaline cathode material that exhibits highly efficient charge/discharge properties. While a pure Mn₃O₄ electrode can barely maintain a single charge and discharge cycle, the cycling capacity of the Mn₃O₄ electrode doped with nano-NaBiO₃ can reach and become stable at 372 mAh g⁻¹ under 60 mA g⁻¹. The doped cathode can also maintain a cycling capacity of 261 mAh g⁻¹ while holding a 95.3% reversible capacity after 60 cycles at a high rate of 500 mA g⁻¹. Moreover, the experimental results indicate that charging time for an alkaline battery using doped Mn₃O₄ cathode could possibly shorten to as little as 30 min.     

Preparation and characteristic of spherical Li3V2(PO4)3

Spherical Li₃V₂(PO₄)₃ was synthesized by using N₂H₄ as reducer. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that single-phase, spherical and well-dispersed Li₃V₂(PO₄)₃ has been successfully synthesized in our experimental process. Electrochemical behaviors have been characterized by charge/discharge measurements. The initial discharge capacities of Li₃V₂(PO₄)₃ were 123 mAh g⁻¹ in the voltage range of 3.0–4.3 V and 132 mAh g⁻¹ in the voltage range of 3.0–4.8 V.     

Fe3O4/SiO2/Bi2WO6磁性复合光催化剂的制备及其光催化性能

钨酸铋(Bi₂WO₆),结构最简单的Aurivillius相化合物,是近期受到研究者关注的新型光催化材料。然而,光催化剂粉末在反应介质中难被回收,工业化应用成本较高。本文用三步方法合成了可回收的Fe₃O₄/SiO₂/Bi₂WO₆磁性复合光催化剂,通过溶剂热法合成具有磁性的Fe₃O₄,用溶胶凝胶法在Fe₃O₄表面覆盖SiO₂层,后将磁性颗粒与Bi₂WO₆纳米片相结合。光催化剂的形貌结构及性能通过XRD、SEM、PL、UV-vis进行表征测试。结果表明,直径约500 nm的Fe₃O₄微球附着在边长约500 nm的Bi₂WO₆纳米片的表面,SiO₂在两者之间起到了粘连作用。光催化剂Fe₃O₄/SiO₂/Bi₂WO₆对于罗丹明B的光降解活性较好,且有一定磁性,可以通过外加磁场将其从溶液中分离,有较大的应用潜力。     

Synthesis and performance of Li3V2(PO4)3/C composites as cathode materials

Carbon-coated Li₃V₂(PO₄)₃ cathode materials for lithium-ion batteries were prepared by a carbon-thermal reduction (CTR) method using sucrose as carbon source. The Li₃V₂(PO₄)₃/C composite cathode materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurement. The results show that the Li₃V₂(PO₄)₃ samples synthesized using sucrose as carbon source have the same monoclinic structure as the Li₃V₂(PO₄)₃ sample synthesized using acetylene black as carbon source. SEM image exhibits that the particle size is about 1 μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of Li₃V₂(PO₄)₃ powders is 122 mAh·g⁻¹ at the rate of 0.2C, and the capacity retains 111 mAh−g⁻¹ after 50 cycles.     

Synthesis of monodispersed ultrafine Bi2S3 nanocrystals

Monodispersed ultrafine Bi₂S₃ nanocrystals of ∼3 nm were synthesized via a facile and mild method, in which thioacetamide and bismuth oleate complex were used as the sulfur and bismuth precursors, respectively. The obtained Bi₂S₃ nanocrystals possessed a high surface area of 305 m² g⁻¹. The nanostructures of Bi₂S₃ nanocrystals were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and selective area electron diffraction (SAED) techniques. The optical property of the Bi₂S₃ nanocrystals was studied by photoluminescence spectroscopy. A remarkable blue shift and a band gap of ∼1.5 eV were observed. The shape of the Bi₂S₃ nanocrystals could be tuned by adjusting the initial Bi/S molar ratio and reaction temperature, respectively. A possible burst nucleation mechanism for this monodispersed ultrafine Bi₂S₃ nanocrystals was proposed.     

Thermodynamic analysis on reaction behaviors of silicates in (NH4)2WO4-(NH4)2CO3-NH3-H2O system

The reaction behaviors of silicate species in (NH₄)₂WO₄-(NH₄)₂CO₃-NH₃-H₂O system are crucial to developing a green manufacture technique for ammonium paratungstate. In order to efficiently remove silicon from the system, the reaction behaviors of silicate species were systematically investigated by thermodynamic analysis. The thermodynamic analysis shows that silicate in the tungstate clinker partly decomposes in the leaching process, with 150–160 mg/L silicon thermodynamically at 25 °C. The dissolved silicon can be removed by magnesium salts via forming insoluble MgSiO₃. The low carbonate and high ammonia concentrations in the system are beneficial to the removal of silicon, with silicon concentration reaching 8–10 mg/L thermodynamically, whereas MgSiO₃ precipitation is hardly formed when the concentration of total carbonate is more than 1.5 mol/L. The reaction behaviors of calcium and magnesium were also studied in the system. The results in the verification experiments consist with the theoretical calculation.