O/W/O多重乳液法制备毫米级氧化铝空心球

采用O/W/O多重乳液法, 以液体石蜡为内核, 氧化铝溶胶为外壳层组成的复合液滴作为前驱体, 制备毫米级氧化铝空心球, 研究了装置几何结构对前驱体的形成和固化过程对空心球结构的影响。结果表明, 内部油相通过直流通道直接注射到水相液滴内部时, 形成的复合液滴具有均一核壳结构, 壁厚和直径在30~80 μm和800~2200 μm可控。液滴置于水平方向旋转固化, 保持转速在20~60 r/min, 所得凝胶球可以保持完整的球形度和核壳结构。1200℃高温煅烧制备出的氧化铝空心微球维持高的球形度和空心结构, 表面粗糙度大约22 nm, 壁厚达到几十微米, 直径达到毫米级, 主要晶型为稳定的α-Al₂O₃。     

SiO2空心微球的制备与表征

以自制的微米级碳酸钙颗粒为模板,正硅酸乙酯为硅源,通过溶胶-凝胶方法合成出CaCO3/SiO2核壳结构;随后通过高温煅烧、酸浸和干燥处理,制备出圆形度高、分散性好、结构完整的微米级SiO2空心球。并利用SEM、XRD、FTIR、TG和压缩实验等方法对空心微球的形貌、结构和抗压强度进行了分析和测定。SiO2空心微球的粒径为2-5μm,壳层厚度为0.42-0.85μm,比表面积为554.01m^2/g,最可几孔径为1.7nm,抗压强度在20~30MPa之间。     

O/W/O多重乳液法制备毫米级氧化铝空心球（英文）

采用O/W/O多重乳液法,以液体石蜡为内核,氧化铝溶胶为外壳层组成的复合液滴作为前驱体,制备毫米级氧化铝空心球,研究了装置几何结构对前驱体的形成和固化过程对空心球结构的影响。结果表明,内部油相通过直流通道直接注射到水相液滴内部时,形成的复合液滴具有均一核壳结构,壁厚和直径在30~80mm和800~2200mm可控。液滴置于水平方向旋转固化,保持转速在20~60 r/min,所得凝胶球可以保持完整的球形度和核壳结构。1200℃高温煅烧制备出的氧化铝空心微球维持高的球形度和空心结构,表面粗糙度大约22 nm,壁厚达到几十微米,直径达到毫米级,主要晶型为稳定的a-Al_2O_3。     

多孔C/Fe纳米复合材料的制备及表征

以商业活性炭为原料,采用真空浸渍法结合高温真空热处理工艺,制备出多孔C/Fe纳米复合材料.实验采用氮气吸附法测量了C/Fe纳米复合材料的比表面积和孔径分布,并利用XRD和TEM表征了其结构和形貌.实验结果显示:C/Fe纳米复合材料的比表面积为450～650m2/g,并保留了活性炭介孔尺度的多孔结构特性.C/Fe纳米复合材料由非晶碳、碳纳米带以及铁纳米粒子构成,纳米铁颗粒均匀分布在非晶碳基体中,石墨化的碳纳米带包裹纳米铁颗粒并向外伸展相互连接,形成碳纳米网络结构.并就反应过程以及过渡金属对非晶碳石墨化的催化机理进行了探讨.     

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431～912 m2/g;可几孔径为1.2～2.0nm.     

α-Ni(OH)2/SiO2核壳以及α-Ni(OH)2空心微球的制备及表征

采用以正硅酸乙酯(TEOS)水解为基础的硅溶胶种子生长法制备了粒径约为270nm的近单分散二氧化硅球型颗粒.采用一种新的溶液生长法,以氢氟酸作为溶液中镍离子配位剂,加入氨水调节溶液pH值的同时作为镍离子补充配位剂,60℃水浴条件下在已制得SiO2微球表面均匀包覆α-Ni(OH)₂得到Ni(OH)₂/SiO₂核壳结构,Ni(OH)₂壳层厚度约为35nm.结合多步包覆法提高Ni(OH)₂壳层厚度,三次包覆后壳层厚度达到约100nm,四次包覆后约为140nm.采用20wt％的强碱NaOH溶液对三次包覆后的Ni(OH)₂/SiO₂核壳结构进行处理,得到了壳层厚度约为95nm的α-Ni(OH)₂空心微球.空心微球具有较大的比表面积为141.06m²/g.     

氧化铈空心球可控合成及其对Pt基催化剂电催化性能的影响

采用水热合成法, 以碳球为模板, 改变焙烧升温速率, 控制影响铈物种的扩散、渗透及碳球结构的收缩率, 制备了单、双壳层CeO₂空心球。通过微波辅助乙二醇还原氯铂酸法制备了Pt-CeO₂/RGO催化剂, 研究了CeO₂空心球的添加对Pt基催化剂电催化性能的影响。利用X射线衍射仪(XRD)、比表面积及孔径分析仪(BET)、扫描电镜(SEM)和电子能谱(EDAX)、透射电镜(TEM)、X射线光电子能谱(XPS)对CeO₂及催化剂的微观结构进行了表征, 利用电化学工作站对催化剂进行电化学性能测试。结果表明: 单、双壳层CeO₂空心球的比表面积为124.44 m²/g、140.95 m²/g, 孔容为0.014427 cm³/(g·nm)、0.018605 cm³/(g·nm), 孔径分布在2~4 nm范围内。催化剂中的CeO₂保持原有的球状形貌, Pt纳米粒子主要分布在CeO₂附近; 当RGO∶CeO₂=1∶2时, 添加了双壳层CeO₂空心球的Pt-CeO₂/RGO催化剂的电催化性能最优, 电化学活性表面积为94.27 m²/g, 对乙醇氧化的峰电流密度值为613.54 A/g, 1000 s的稳态电流密度值为135.45 A/g。     

镍/碳微球复合材料的制备和表征

碳微球与微米镍粉按一定比例混合后,经过6h机械球磨并在1600℃真空热处理,合成了微米镍/碳复合材料。通过场发射扫描电镜(FESME)、高分辨透射电镜(HRTEM)和X射线衍射仪(XRD)对产物进行表征。结果表明,产物为碳包覆镍金属颗粒,粒径200～400nm的镍颗粒被30～100nm的碳层包覆,碳层的石墨化程度较高;产物石墨化碳层的形成缘于Ni3C的形成和分解。     

二氧化钛空心微球的制备及表征

采用模板法制备了可控制球壳厚度的亚微米二氧化钛空心微球.首先利用钛酸四丁酯乙醇溶液和聚苯乙烯粒子制备了二氧化钛/聚苯乙烯复合粒子,在空气中经500℃煅烧除去苯乙烯模板后得到锐钛矿二氧化钛空心微球.透射电镜和扫描电镜观察表明,二氧化钛/聚苯乙烯复合粒子煅烧后体积发生了急剧的收缩,形成具有空心结构二氧化钛微球.电子衍射和X射线衍射分析可知空心微球的二氧化钛球壳为锐钛矿.实验发现当钛酸四丁酯与乙醇的体积比从120提高到110时,二氧化钛空心微球的球壳厚度从20～25 nm增加到45～50nm;以不同粒径的聚苯乙烯粒子作模板,可以得到不同内孔直径的二氧化钛空心微球,其内孔直径比聚苯乙烯模板直径小15%～20%.     

碳包覆氧化亚钴纳米颗粒的制备与性能研究

采用直流电弧放电等离子体技术成功制备了碳包覆氧化亚钴纳米颗粒,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(XRD)、X射线能量色散光谱(XEDS)、拉曼散射光谱(Raman)和N_2吸-脱附等测试手段进行了分析。HRTEM表明该方法制备的碳包覆氧化亚钴纳米颗粒具有典型的核壳结构,颗粒形貌主要为球形或椭球结构,粒度均匀,分散性良好,粒径分布在20~60nm,平均粒径为40nm,外壳碳层的厚度为5nm。XRD证明样品的内核为面心立方结构的氧化亚钴纳米颗粒,外壳为碳层。XEDS图谱表明样品中主要存在Co、O和C元素的特征峰。Raman光谱说明样品中碳外包覆层的石墨化程度较低,发生了红移现象。样品的N_2吸附-脱附等温曲线属Ⅳ型,BET比表面积为33m~2/g,BJH脱附累积总孔孔容和脱附平均孔径分别为0.078cm~3/g和11nm。当量粒径为43nm,与TEM和XRD测得的结果基本一致。     

金属对炭黑转化为洋葱状中空结构纳米碳的影响

研究了炭黑分别在 Fe、Co、Ni 三种金属化合物作用下的催化转化行为, 以期使炭黑质点中不连续的无规则小石墨片层重新组装、构筑成洋葱状中空结构纳米碳. 采用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)和Raman光谱分析表征了炭黑及其催化炭化产物的微观形貌和结构. 结果表明: 尽管三种金属催化剂均可通过溶碳-析出机制形成过渡态碳包覆纳米金属颗粒, 继而构筑成由准球形同心石墨壳层组合的洋葱状中空结构纳米碳, 但三种金属催化剂显示不同的催化效果, 终碳产物的形态和纯度差异较大, 其中以Fe 的催化效果最好.     

A STUDY ON THE THERMAL STABILITY TO 1000°C OF VARIOUS CARBON ALLOTROPES AND CARBONACEOUS MATTER BOTH UNDER NITROGEN AND IN AIR

The thermal behavior of graphite, C₆₀ fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA-DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C₆₀ and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed.

The combustion reaction in air flow of graphite, C₆₀ and C₇₀ fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA-DTA at a heating rate of 20°C/min. C₇₀ fullerene and fullerene black have been found to be the most reactive carbon materials with O₂. The role played by C₇₀ in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O₂ attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C₆₀ fullerene appears closer to that of graphite although it appears to be more reactive with O₂. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA-DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed.     

碳原料结构对激光法合成纳米金刚石的影响

为了确定在较低激光能量密度下（10^6W／cm^2）激光法合成纳米金刚石最适宜的碳原料，研究了三种结构不同的碳原料（炭黑、片状石墨、土状石墨）对合成纳米金刚石的影响，采用拉曼光谱对碳原料的结构进行了分析，结果显示炭黑、土状石墨和片状石墨这三种碳原料的结晶程度依次增强，用Nd：YAG脉冲激光分别轰击不同碳原料的悬浮液，实验产物的透射电镜分析显示在激光照射炭黑和片状石墨的产物中没有金刚石生成，而在激光照射石墨的产物中发现了立方结构的金刚石，其颗粒尺寸约为5Bin．因此，在10^6W／cm^2的脉冲激光作用下，无序炭黑和结晶较完整的片状石墨均不利于合成金刚石，只有有序化程度适中的土状石墨有利于合成金刚石．     

Synthesis of carbon-encapsulated iron nanoparticles by pyrolysis of iron citrate and poly(vinyl alcohol): a critical evaluation of yield and selectivity

Carbon-encapsulated iron nanoparticles were synthesized by pyrolysis at 1000?°C of two solid precursors: poly(vinyl alcohol) and iron citrate. The weight ratio between the precursors controlled the reaction yield, crystallinity, morphological features and magnetic properties of the products. The encapsulation yield of iron nanoparticles in carbon shells was strongly influenced by the iron-to-carbon ratio and depended on the iron citrate content in the initial reactant mixtures. Despite the inherent simplicity of the process and the use of low cost starting materials the demonstrated route possesses limited selectivity, especially at high iron-to-carbon ratios. At these experimental conditions the as-obtained products contained non-encapsulated Fe particles and graphite in addition to magnetic carbon encapsulates. These by-products were effectively removed by a one-pot purification procedure that included acid treatment.     

The evolution of well-aligned amorphous carbon nanotubes and porous ZnO/C core-shell nanorod arrays for photosensor applications

Well-aligned amorphous carbon nanotube (a-CNT) and porous ZnO/C core-shell nanorod (NR) arrays were fabricated for the first time by a proposed deposition-etching-evaporation (DEE) route. The arrays were prepared by deposition of carbon on the surface of well-aligned ZnO NR arrays by thermal decomposition of acetone followed by spontaneous etching and evaporation of core-ZnO. By utilizing the decomposition of acetone as well as distinct degrees of interaction between intermediate products and ZnO, well-aligned nonporous ZnO/C core-shell NR, porous ZnO/C core-shell NR, and a-CNT arrays were separately prepared by varying the working temperature from 400 to 700?°C. Scanning electron microscopy and high-resolution transmission electron microscopy show that the thickness of carbon shells increases from 3 to 10 nm with the increase in working temperature. Raman spectra demonstrate slight sp(2) bonds of carbon, indicating small graphite regions embedded in amorphous carbon nanoshells. The E(2) peaks of ZnO reduce with the increase in substrate temperature. Photoresponse measurements of ZnO/C NR arrays shows enhancement of both photoresponsivity and response velocity, and the interference of humidity with regard to photosensing is effectively reduced by the capping of carbon nanoshells. The work not only provides an effective route to improve the photosensing of semiconductor nanomaterials for practical applications, but also sheds light on preparing various hollow carbon and porous ZnO/C core-shell nanostructures with distinct morphologies by employing the routes presented in the paper on diverse ZnO nanostructures for optoelectrochemical applications.     

The effects of carbonization time on the properties and structure of PAN-based activated carbon hollow fiber

Polyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, then further oxidized in air, carbonized in nitrogen and activated with carbon dioxide. The effects of carbonization time of PAN hollow fiber precursor on the microstructure, specific surface, pore-size distribution and adsorption properties of PAN-based carbon hollow fiber (PAN-CHF) and PAN-based activated carbon hollow fiber (PAN-ACHF) were studied in this work. After the activation process, the surface area of the PAN-ACHF increased very remarkably, reaches 506 m²g^{– 1}, when fibers are carbonized at 900C for 70 min and activated at 800C for 40 min. The different adsorption ratios to two adsorbates including creatinine and VB₁₂ reflect the number of micropores and mesopores in PAN-ACHF. The dominant pore sizes of mesopores in PAN-ACHF range from 2 to 5 nm     

基于工业化碳材料的锂氟化碳电池正极材料制备及性能EI北大核心CSCD

为实现锂氟化碳电池在更多领域的普遍应用,以工业化碳材料(活性炭、球形石墨、膨胀石墨和工业石墨烯)为碳源,制备了四种氟化碳正极材料。通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、拉曼光谱(Raman)、红外光谱(FTIR)、X射线能谱(XPS)、氮气吸脱附以及电化学测试等表征手段对材料的微观形貌、晶体结构、化学结构和电化学性能进行了系统的研究。研究表明:氟化工业石墨烯具有完全的单氟化碳结构、高比表面积以及稳定的碳结构,在20 mA·g^(-1)的放电电流下可以实现高达945.4 mAh·g^(-1)的比容量;氟化活性炭具有较多的半共价C-F键,其起始放电电压最高,但是由于其结构稳定性较差,电压平台快速下降,导致整体比容量较低;氟化膨胀石墨和氟化球形石墨与氟化工业石墨烯结构类似,但是由于高氟化碳原子(CF_(2)和CF_(3))的存在,其放电比容量要低于氟化工业石墨烯。不过在高放电电流密度下,氟化膨胀石墨、氟化球形石墨和氟化工业石墨烯的能量密度十分接近,因此,基于氟化膨胀石墨和氟化球形石墨的成本优势,氟化膨胀石墨和氟化球形石墨更适合于高功率应用场景。     

A STUDY ON THE THERMAL STABILITY OF THE PHOTOPOLYMER, THE OZOPOLYMER, AND THE PHOTOCHLORINATED DERIVATIVE OF C60 FULLERENE

The thermal stability of the C₆₀ photopolymer, the C₆₀ ozo-polymer, and photochlorinated C₆₀ was studied by thermogravimetric analysis (TGA) ultraviolet-visible (UV-vis) and TGA-differential thermal analysis techniques up to 950°C in comparison to graphite and pure C₆₀. The ozopolymer was found to be the least stable material followed by C₆₀Cl_x. The resulting residual carbonaceous matter formed by the decomposition of the photopolymer and the ozopolymer has been studied by Fourier transform-infrared (FTIR) spectroscopy and has been found to be completely comparable to carbon black. The thermal decomposition of the C₆₀ photopolymer prepared in solution yields negligible amounts of C₆₀. The main product is carbon black.     

Er3+掺杂TiO2空心球的制备及其光催化性能研究

以钛酸四丁酯、氧化铒、硝酸等为原料, 采用碳球模板法制备了TiO₂: Er³⁺空心球材料, 利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)等测试方法, 对样品的结构和形貌进行了表征。并利用紫外-可见(UV-Vis)分光光度计考察了TiO₂: Er³⁺空心球材料在催化染料罗丹明B、亚甲基蓝、茜素红、甲基橙的脱色降解过程中的应用性能。系统研究了Er³⁺掺杂浓度、不同离子型染料和染料水溶液的pH等因素对催化降解效率的影响。实验结果表明: 经600℃煅烧3 h制备的TiO₂: Er³⁺为锐钛矿晶型, 空心球结构, 尺寸均匀, 粒径约为120 nm, 比表面积约为60.5 m²/g; Er³⁺掺杂量为0.5mol%的样品对甲基橙染料的催化降解效率最高; 对四种不同离子型染料, 茜素红的催化降解效果显著, 在紫外光照射下, 催化效率较未掺杂Er³⁺的TiO₂提高了约30%。