Co3O4纳米颗粒的制备及表征

以脱脂棉为碳源,硝酸钴为前驱物,采用碳辅助法焙烧制备了粒径为50nm Co3O4纳米颗粒。用X射线衍射(XRD)对不同焙烧温度(200~600℃)下样品的物相、晶粒度进行了研究,并结合傅立叶红外光谱(FT-IR)对Co3O4物相演变进行了分析,确定中间产物前躯体是CoCO3;通过扫描电镜(SEM)和透射电镜(TEM)对制备的Co3O4样品的形貌、粒径进行了分析;同时,X射线能谱(EDS)和氮气吸附-脱附曲线测试等表明制备的Co3O4表面存在碳元素和孔结构,具有较大的比表面积,有利于提升其光解水制氢能力。     

Sc2O3超细粉均相沉淀法的制备及表征

以(NH4)SO4为沉淀剂和分散剂,Sc(NO4)3为母盐,采用均相沉淀法合成了片状的碱式硫酸钪前驱沉淀物[Sc(OH)SO4].通过差热/热重分析了前驱体的热分解过程,并结合红外光谱、X-射线衍射、透射电镜联用X-射线光电子能谱等测试手段研究了前躯体及煅烧产物的成分、性质.结果表明,由该法制备出的Sc2O3超细粉具有纯度较高、颗粒粒度小(100 nm)、粒度分布均匀、分散性好、近似球形的优异性能.通过水洗-乙醇清洗-丙酮搅拌,结合超声-室温干燥-湿磨等方式处理,对粉体分散性的提高均起到了重要的作用.     

均相沉淀法制备Co3O4纳米颗粒及磁性研究

以Co（NO3）2·6H2O和（NH2）2CO为原料,在不引入高分子分散剂的条件下,采用均相沉淀法制备Co3O4纳米颗粒。用TGA、DSC、XRD研究了目标产物的前驱体及其分解过程,结果表明：Co3O4在焙烧阶段形成。Co3O4纳米颗粒结构、形貌、粒径分布和磁性能分别用XRD、TEM、粒径分析仪、VSM表征,Co3O4纳米颗粒平均粒径约为21nm,粒径分布均匀。5K时产物表现为铁磁性,矫顽力Hc=580Oe。     

Co3O4/碳复合超级电容器材料的研究进展

Co₃O₄作为超级电容器材料,因具有理论比容量高、价格成本低、无毒环保、储量丰富等优点而备受关注,但制备出电化学性能优异的Co₃O₄超级电容器材料仍是个巨大的挑战。通过与导电性突出的碳材料复合,增加了电子/离子的传输速度,提高了Co₃O₄超级电容器材料电化学性能。综述了Co₃O₄/碳复合超级电容器材料的合成方法,归纳了各个方法的优缺点,分析了影响Co₃O₄/碳复合超级电容器电化学性能的因素,最后,指出了Co₃O₄/碳复合超级电极材料所面临的问题和发展前景。     

用微波均相沉淀法合成Sc2O3纳米粉

以硫酸钪为母盐,尿素为沉淀剂,采用微波加热方式合成了水合碱式碳硫酸钪前驱体.用差式扫描量热法(DSC)、热重分析(TG)、红外光谱(IR)、X-射线衍射(XRD)分析了加热过程中前驱沉淀物的物相变化.采用高温煅烧和高能微波辐照两种方法制备了Sc2O3粉体.结果表明,将前驱沉淀物分别在1000℃煅烧3 h和在900℃微波...     

Co3O4负载rGO/g-C3N4臭氧光催化降解2,4-二氯苯氧乙酸活性研究

通过简单的水热法制备了Co₃O₄/rGO/g-C₃N₄催化剂,并在可见光照射下用于光催化臭氧氧化降解2,4-二氯苯氧乙酸(2,4-D)。利用XRD, SEM, TEM, XPS, UV-vis DRS, FT-IR和瞬态光电流对样品进行测试表征。研究表明,Co₃O₄, rGO和g-C₃N₄形成异质结后光生电子-空穴(e^--h⁺)对的分离效率,e^-的迁移能力以及光催化臭氧氧化活性都明显提升。此外,0.5Co₃O₄/0.25rGO/GCN对2,4-D具有100%的去除率,并具有最高反应速率(k=0.070 9 min^-1)。经过计算得出光催化臭氧氧化2,4-D的协同因子为3.91,表明光催化和臭氧氧化间具有较好的协同效应。活性组分的捕获实验结果表明h⁺和·OH是光催...     

Co3O4@MnSiO3@硅藻土三元复合材料的制备及赝电容性能提升机理

超级电容器是目前解决“能源短缺”与“环境污染”两大问题的重要手段之一,具有功率密度高、循环寿命长、可快速充放电、环境友好等特点。电极材料是决定超级电容器性能的关键因素。金属硅酸盐来源丰富、理论比容量高、结构可调、性质稳定,是发展低成本超级电容器的杰出候选电极材料,但面临着固有导电性较低、易团聚、循环稳定性不足等问题。因此,提出构建硅藻土基硅酸盐复合材料的思路,用于降低电极材料的生产成本、改善传统复合方式的缺陷。同时,提出利用硅藻土的多孔结构改善纳米材料的团聚问题,以提高硅酸盐电极材料的电化学性能,通过进一步负载导电性较好、氧化还原能力优异的Co₃O₄,构建多层次金属化合物“壳-核”结构,有助于提高界面活性、增加离子扩散通道、控制电极材料使用过程中的体积膨胀,进一步提升电化学性能。实验结果证明,Co₃O₄@MnSiO₃@硅藻土复合材料是一种形貌结构优良、循环稳定性突出、电化学性能良好、使用寿命长及成本低廉且绿色环保的新型电极材料。改善了硅酸盐电极材料导电性不足、循环稳定性较低等缺...     

室温固相反应制备纳米Co3O4粉体

以硝酸钴和碳酸氢铵为原料,采用室温固相反应首先制备出前驱物碱式碳酸钴,然后将前驱物在250℃分解3h,得到纳米四氧化三钴,用X射线粉末衍射、透射电镜、热分析仪、扫描电镜对产物的组成、大小、形貌及有关性质进行了表征。结果表明获得了平均粒径在13nm,分布均匀、无团聚的纳米粉体。     

直流电弧放电法合成In2O3纳米粒子

电弧放电法因能在瞬间产生高温使原料气化而成为一种高效的纳米材料制备方法。以金属In为原料,在无催化剂的条件下,采用直流电弧放电法直接合成了In2O3纳米粒子。XRD、SEM和TEM结果表明所制备的In2O3纳米粒子为立方结构,形貌为结晶良好的八面体,平均粒径为60～120nm。纳米粒子之间以点接触和面接触相连。     

均相沉淀法制备掺钕钇铝石榴石(Nd∶YAG)纳米粉末

采用均相沉淀法,以Al(NO3)3.9H2O、Y2O3、Nd2O3、(NH4)2SO4和NH4HCO3为原料,正硅酸乙酯为添加剂,制备Nd∶YAG纳米粉末;并探讨了均相沉淀法制备Nd∶YAG纳米粉末的反应机理。研究结果表明,粉体在800℃时为无定型态,当温度达到900℃时析出大量YAlO3(YAP)和少量Y3Al5O12(YAG)晶体,当温度达到1000℃时就全部转化为YAG立方晶相;混合溶液生成沉淀物是由Al 3+的沉淀所决定的;Al 3+首先均相成核,随后Y3+和Nd3+以Al沉淀物为异相核发生异相成核,形成的沉淀物覆着于Al沉淀物表面,推测沉淀物结构可能为钇包覆铝的核壳结构。     

Synthesis and characterization of Co3O4 hollow spheres

Co₃O₄ hollow spheres were hydrothermally prepared at 130 °C for 16 h in the presence of Poly-vinylpyrrolidone (PVP). The as-prepared products were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), infrared spectrum (IR), X-ray photoelectron spectrum (XPS), and optical absorption spectrum. PVP surfactant plays important roles in the formation of Co₃O₄ hollow spheres. These Co₃O₄ hollow spheres have average diameters of ca. 350 nm, and the wall thickness around the shell is about 42 nm. The possible formation mechanism of hollow Co₃O₄ spherical structures has simply been proposed.     

Synthesis of Co3O4 nanoparticles via the CTAB-assisted method

Cobalt oxide (Co₃O₄) nanoparticles were successfully synthesized by the cetyltrimethylammonium bromide (CTAB)-assisted method at normal pressure for the first time. The structure and morphology of the as-prepared Co₃O₄ nanoparticles were characterized by powder X-ray diffracton (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N₂-sorption analysis. XRD studies indicated that the as-prepared product was well-crystallized cubic phase of Co₃O₄ with a cell constant of α = 8.0722 Å. The EM images showed that the obtained Co₃O₄ sample consisted of dispersive quasi-spherical particles with the size ranged from 15 to 25 nm.     

Single crystalline Co3O4: Synthesis and optical properties

Crystals of Co₃O₄ have been prepared from thermal decomposition of molecular precursors derived from salicylic acid and cobalt (II) acetate or chloride at 500 °C. A cubic phase Co₃O₄ micro- and nanocrystals have been obtained. The as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The images of electron microscopes showed octahedral crystals of Co₃O₄. The volume and polarizability of the optimized structures of molecular precursors have been calculated and related to the particle size. The optical band gap of the obtained crystals has been measured. The results indicated two optical band gaps with values 2.65 and 2.95 eV for (E_g1) (E_g2), respectively.     

Structure cristalline de Mn0, 4Er4, 6S7

The crystal structure of Mn₀, ₄Er₄, ₆S₇ ($\text{a}\text{= 12,573 (4)}\text{A}\text{?}$, $\text{b}\text{= 11,390 (4)}\text{A}\text{?}$, $\text{c}\text{= 3,777 (4)}\text{A}\text{?}$, γ = 105,45°, space group B2/m, Z = 2) has been refined by a least square method to a final R = 0,045, with 1431 independant reflections. The octahedral positions are occupied either by Er and Mn atoms or by Er atoms only and the prismatic sites by Er atoms.     

Solvothermal synthesis of sheet-like Co3O4 and Ag/Co3O4 nanocomposites and their electrocatalysis performances

Precursors of Co₃O₄ and Ag/Co₃O₄ composites with sheet-like shape were synthesized with assistance of ethylene glycol via a solvothermal process. The final samples were obtained by calcining each precursor at 400 °C. The as-prepared samples were identified and characterized by thermogravimetric analysis (TG) and differential thermal gravimetric (DTG) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The Co₃O₄ and Ag/Co₃O₄ composite nanosheets were used as electrocatalysts modified on a glassy carbon electrode for p-nitrophenol and H₂O₂ reduction respectively in a basic solution. The electrocatalytic results showed that p-nitrophenol could be reduced by pure Co₃O₄ at a large peak current but a rather higher peak potential, and could be reduced effectively by Ag/Co₃O₄ composites at lower potential. Ag/Co₃O₄ composites with 6% Ag displayed the highest electrocatalytic activity for H₂O₂ reduction at the largest peak current and a lower peak potential. The reduction peak potentials of H₂O₂ all reduced a great deal using Ag/Co₃O₄ composite.     

含钛磷酸盐玻璃NaTi2(PO4)3-0.9Ca3(PO4)2的析晶行为

利用差热分析、X射线衍射仪、液氮吸附BET孔经测试仪对组成为NaTi2(PO4)3-0.9 Ca3(PO4)2的含钛磷酸盐玻璃的析晶行为进行了研究.通过对该玻璃相继进行成核、析晶和酸浸泡处理制备了NaTi2(PO4)3骨架多孔微晶玻璃.证明该玻璃在646℃8h成核处理过程中产生了旋节分解特征的成分偏聚,形成了富TiO2玻璃相和富CaO玻璃相交错生长的连通结构,成核处理后的玻璃在738℃析晶过程中依次在富钛相和富钙相中析出NaTi2(PO4)3和β-Ca3(PO4)2.成核过程对析晶的促进作用是通过促进NaTi2(PO4)3的析出而实现的.     

Preparation and properties of the Pb3(VO4)2Pb3(PO4)2 system

Single crystals of the pseudobinary system Pb₃(V_1?xP_xO₄)₂ were grown via the Czochralski technique and were studied over wide ranges of x, particularly with regard to the influence of substitution on the $\text{3}\text{?}\text{mF}\text{2}\text{m}$ transition as a function of temperature.     

Fabrication of Co3O4 cubic nanoframes: Facet-preferential chemical etching of Fe ions to Co3O4 nanocubes

The novel Co₃O₄ cubic nanoframes, sized in ca. 30 nm, were firstly fabricated via a facile solvothermal route. Based on the transmission electron microscopy and the powder X-ray diffraction analyses of the time-dependent products, a mechanism of facet-preferential chemical etching of Fe³⁺ ions to the pre-synthesized Co₃O₄ nanocubes is proposed for the formation of Co₃O₄ cubic nanoframes. This synthetic strategy can probably be extended to fabricate nanoframes of some other binary metal oxides, by designing similar chemical etching process.     

Preparation of (NH4)Zr2(PO4)3 and HZr2(PO4)3

(NH₄)Zr₂(PO₄)₃ has been prepared, hydrothermally, from α-zirconium phosphate in three different ways; (1) from amine intercalates at 300°C, (2) from mixtures of ZrOCl₂·8H₂O in excess (NH₄)H₂PO₄ and (3) reaction of NH₄Cl with Zr(NaPO₄)₂. Ammonium dizirconium triphosphate is rhombohedral with a = 8.676(1) and $\text{c}\text{= 24.288(5)}\text{A}\text{?}$. It decomposed on heating to HZr₂(PO₄)₃. Below 600°C a complex, as yet unindexed, X-ray pattern was obtained. A very similar X-ray pattern was obtained by washing LiTi_0.1Zr_1.9(PO₄)₃ with 0.3N HCl. Heating this phase or NH₄Zr₂(PO₄)₃, above 600°C resulted in the appearance of a rhombohedral phase of HZr₂(PO₄)₃ with cell dimensions a = 8.803(5) and $\text{c}\text{= 23.23(1)}\text{A}\text{?}$. The protons were not completely removed until about 1150°C. Decomposition of (NH₄)Zr₂(PO₄)₃ at 450°C yielded an acidic gas whereas at 700°C NH₃ was evolved. A possible explanation for this behavior is presented.     

Synthesis of sphere-like Co3O4 nanocrystals via a simple polyol route

A simple polyol method was developed to synthesize uniform sphere-like Co₃O₄ nanocrystals in ethylene glycol. Powder X-ray diffraction (XRD) and electron diffraction (ED) showed that the as-prepared sample was indexed as the cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the Co₃O₄ nanocrystals were spherical with the crystallite size in the range of 90-110 nm. Infrared spectra and Raman spectra confirmed the formation of the Co₃O₄ nanocrystals. The magnetic properties of the Co₃O₄ nanocrystals were measured by using a superconducting quantum interference device (SQUID) magnetometer, which showed that the as-prepared sample exhibited a tiny hysteresis loop with the magnetization value of 2.4 emu/g and the coercivity of 110 Oe.