[(2,2''''-bipy)_2VO_2](H_2BO_3)·3H_2O的水热合成和晶体结构

有机-无机杂化钒氧配合物的合成研究越来越引起人们浓厚的兴趣,这是由于它新颖的结构和在催化、电化学、光化学、吸附、离子交换和磁性能方面具有潜在的应用前景犤1～8犦。功能体系的有机-无机杂化材料的构筑取决于反应物相互作用的本性。近年来,将有机胺分子作为结构导向剂引入无机骨架中,获得了一系列结构新颖的化合物犤9,10犦。它们通过共价键和(或)氢键自组装成零维、一维、二维和三维网络犤11,12犦。例如零维的犤(N2C6H14)2VO(PO3OH)4(B3O3OH)犦犤13犦、一维钒氧链犤Cu(dien)V2O6犦犤11犦,犤Cu(NH3)2V2O6犦犤14犦,犤狖Co(phen…     

Co-SrTiO3上光催化分解水制氢的性能研究

氢能在使用过程中不会给环境带来任何污染,是未来最理想的能源。但目前的氢气生产方法能耗较高,同时伴随着严重的环境污染,显然不适合大规模生产能源用氢气。洁净化生产氢气方法的开发备受世人的关注,吸引了大量的科研人员从事这方面的研究。其中以半导体氧化物为催化剂,光催化分解水制氢被认为是最有前途的方法。经过几十年的努力,取得了很大的进步,先后开发出在紫外光照射下可以将蒸馏水分解为氢气和氧气的光催化剂,如TiO2犤1犦、SrTiO3犤2犦、Na2Ti6O13犤3犦、BaTi4O9犤4犦、K2La2Ti3O10犤5犦、K4Nb6O17犤6犦、ZrO2犤7犦等;可见…     

半化学法制备Pb(Fe2/3W1/3)O3陶瓷粉体的反应机理

铅系弛豫铁电陶瓷钨铁酸铅Pb(Fe2/3W1/3)O3(PFW)是一种重要的介电材料,具有较大的介电常数(8000)和较低的烧结温度(小于900℃),适用于制备低烧高介的多层陶瓷电容器犤1～4犦。在传统氧化物法合成PFW的过程中,易生成恶化介电性能的钨酸铅(PbWO4或Pb2WO5)或焦绿石相(Pb2FeWO6)等其他相犤3,4犦。尽管通过加入过量5%的Fe2O3可以消除这些其他相,但因含较多的变价铁离子(Fe3+和Fe2+)而产生介电老化的缺点犤5犦。虽然二次合成法被广泛用于制备铅系弛豫铁电陶瓷犤6犦,但对制备PFW陶瓷的效果并不明显,仍有少量的钨酸铅PbWO4存在,并且预烧…     

双金属洋葱结构纳米Mo0.9W0.1S2的合成

0 引言 继碳富勒烯和碳纳米管的发现,1992年R.Tenne等首次在Nature上发表了具有类富勒烯和纳米管结构的WS_2,开创了非碳无机类富勒烯(Inorganic Fullerene-like,简称IF)纳米化合物研究的新领域。由于具有与富勒烯碳或碳纳米管相类似     

三元金属二硫化物纳米管的制备

1992年和 1 993年 ,Tenne等[1,2 ] 先后报道了具有类富勒烯和纳米管状结构的 WS2 和无机类富勒烯 Mo S2 .此后 ,无机类富勒烯化合物的制备与合成成为国内外学者的关注热点之一 .但采用化学方法制备纳米金属二硫化物时 ,多面体或洋葱状结构的 Mo S2 或 WS2 晶体的形成概率小 (这与碳的情况相似 ,也许通过扩展反应区内的温度梯度可以增加形成上述两种结构的可能性 [3] ) .另外 ,采用气固相反应制备洋葱状 WS2 的过程中 ,当每批次的量超过 1 5g时 ,无机类富勒烯 (IF)纳米颗粒的质量降低 ;同时 ,若滤筛中粉末厚度过大 ,相当大的凝聚团块开…     

无机-有机杂化钼磷酸盐化合物(NH_3CH_2CH_2NH_3)_2Mo_5O_(15)(HPO_4)_2的合成与表征

0引言钼磷酸盐由于具有丰富的晶体结构特点和化学特性使得这种材料在催化、离子交换剂和材料科学等领域有着更加广阔的应用前景犤1～3犦。制备化学家已采用高温和水热的方法合成了一维聚体、二维层状和三维具有敞开结构的钼磷酸盐化合物犤3～8犦。尽管钼磷酸盐化合物结构复杂以及合成条件的不可裁剪性,但我们试图通过调节化学操作来调控产物的结构和性能。最近,当利用水热技术制备这类材料时,通过调节开始材料及合成条件得到了一种新的单晶化合物(NH3CH2CH2NH3)2Mo5O15(HPO4)2,新的无水化合物的结构是由聚阴离子犤Mo5O15(HPO4)2犦4-…     

石墨氧化过程的XRD/XPS研究

石墨用强氧化剂如硝酸、高氯酸、氯酸钾或高锰酸钾等处理后,在石墨层间形成一种没有化学计量的层间化合物,通常叫做氧化石墨,又称石墨酸犤1犦。氧化石墨的研究历史可追溯到1855年犤2犦,期间,有关氧化石墨的制备及表征的报导获得了广泛的重视。就目前的研究现状而言,普遍认为化学法制备的氧化石墨中存在羟基、环氧官能团和双键结构犤3犦,这一结果已经得到广泛的证实,如FTIR犤4犦结果表明氧化石墨中含有C-OH、-OH、C=O等基团,13CNMR犤5犦也检测到与醚或羟基相联的碳原子,并发现sp2杂化的碳原子,元素分析的结果表明犤6犦,氧化石墨中的C/…     

钛氧有机化合物常压低温液相合成纳米二氧化钛晶体的研究

二氧化钛晶体有三种晶型，锐钛矿型、金红石型和板钛矿型，每一种晶型都表现出不同的性质，如光折射指数、化学反应性和光催化活性。锐钛矿和金红石型纳米二氧化钛在催化剂犤１，２犦、太阳能转化犤３～６犦、功能陶瓷犤７～９犦、湿度和高温氧气的敏感元件犤１０犦、化妆品犤１１犦和无机膜犤１２犦等许多方面都有广泛的应用前景。金红石型TiO２比锐钛矿型稳定，有较高的硬度、密度、介电常数和折射率，因此在高级涂料、化妆品和电子陶瓷等方面有着更重要的应用价值。锐钛矿型纳米TiO２晶体已发展的制备法主要有Sol－Gel法犤１３，１４…     

柠檬酸溶胶凝胶法制备LiCoO_2电极材料及其表征

目前研究较多的锂离子电池正极材料主要有LiCoO2、LiNiO2和LiMn2O4犤1犦,虽然LiCoO2的成本相对较高,但LiCoO2具有最为优良的电化学性能,如高且平稳的充放电平台、高比容量以及良好的循环性能犤2犦,是目前应用最广泛的商品化电极材料。LiCoO2材料主要采用高温固相法犤3～5犦制备,该方法工艺简单,容易实现大规模生产,但缺点是需要较高的焙烧温度和较长的焙烧时间,且反应原料混合均匀程度有限,易导致非化学计量、非均相以及不规则的颗粒形貌等,因此材料的比容量、循环寿命等电化学性能以及反应的可控性还不甚理想。研究表明犤6犦电极材…     

水热法合成掺杂铁离子的小管径TiO2纳米管

碳纳米管这种一维结构的新材料的发现为物理、化学、材料科学和纳米科学开辟了全新的研究领域.近年来,非碳无机类富勒烯(Inorganic Fullerenelike,简称IF)纳米管也受到人们的广泛关注.     

制备均一形貌的长二氧化钛纳米管

在温和的水热条件下,用碱溶液处理不同粒径的锐钛矿相和金红石相二氧化钛 纳米粉体,得到了不同形貌的二氧化钛纳米管,并用TEM,XRD,FT-Raman和BET等 对其进行了表征。金红石相的超细纳米晶有利于形成均一形貌的纳米管,用粒径仅 为7.2 nm的金红石相纳米粉体为前驱体得到了长度为500 nm的长二氧化钛纳米管。 用纳米晶反应活性对晶粒尺寸的依赖性及晶相稳定性解释了长纳米管的形成机理。     

Synthesis and characterization of ultrahigh crystalline TiO2 nanotubes

Ultrahigh crystalline TiO2 nanotubes were synthesized by hydrogen peroxide treatment of very low crystalline titania nanotubes (TiNT-as prepared), which were prepared with synthesized TiO2 nanoparticles by hydrothermal methods in an aqueous NaOH solution. Thus, prepared ultrahigh crystalline TiO2 nanotubes (TiNT-H2O2) showed comparable crystallinity with high crystalline TiO2 nanoparticles. The details of nanotubular structures were elucidated by high resolution-transmission electron microscopy (HR-TEM), field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis in transmission electron microscopy (TEM-EDX), X-ray diffraction (XRD), photoluminescence (PL), and BET surface area. TiNT-H2O2 was found to be a multiwalled anatase phase only with an average outer diameter of approximately 8 nm and an inner diameter of approximately 5 nm and grown along the [001] direction to 500-700 nm long with an interlayer fringe distance of ca. 0.78 nm. The photocatalytic activity of TiNT-H2O2 was about 2-fold higher than those of TiNT-as prepared, synthesized TiO2 nanoparticles, and TiO2-P25 (Degussa) in the photocatalytic oxidation of trimethylamine gas under UV irradiation.     

掺锌的TiO2纳米粉的结构相变及发光性质

采用溶胶-凝胶法制备了掺锌的TiO₂纳米粉末,并用XRD、TEM、TG和DSC等技术考察了掺入的锌对TiO₂的锐钛矿→金红石结构相变的影响.研究结果表明,锌的掺入可促进TiO₂的结构相变,使相变温度显著降低.纳米态TiO₂存在室温光致发光现象,在TiO₂的纳米粉中掺入适量的锌,可显著增强体系的发光强度.     

TiO2纳米管电极金属离子掺杂的表征

采用浸渍法对TiO₂纳米管电极进行Zn²⁺、Fe³⁺、Cu²⁺离子的掺杂改性,并进行了各种性能表征.扫描电镜(SEM)及X射线衍射光谱(XRD)结果表明,金属离子掺杂后的TiO₂纳米管电极依然保持了良好的表面形态及锐钛矿晶型,纳米管的直径为60-100 nm,其晶面主要为101面;可见紫外漫反射光谱(DRS)分析表明,进行掺杂的TiO₂纳米管电极的光学性质有不同程度的改变,Zn²⁺、Fe³⁺和Cu²⁺掺杂的TiO₂纳米管电极的禁带宽度分别为3.37 eV3、.14 eV、2.86 eV.这表明掺Cu²⁺的TiO₂纳米管电极的吸收边带发生了明显的红移.     

Precise Size Control over Ultrafine Rutile Titania Nanocrystallites in Hierarchical Nanotubular Silica/Titania Hybrids with Efficient Photocatalytic Activity

Hierarchical‐structured nanotubular silica/titania hybrids incorporated with particle‐size‐controllable ultrafine rutile titania nanocrystallites were realized by deposition of ultrathin titania sandwiched silica gel films onto each nanofiber of natural cellulose substances (e.g., common commercial filter paper) and subsequent flame burning in air. The rapid flame burning transforms the initially amorphous titania into rutile phase titania, and the silica gel films suppress the crystallite growth of rutile titania, thereby achieving nano‐precise size regulation of ultrafine rutile titania nanocrystallites densely embedded in the silica films of the nanotubes. The average diameters of these nanocrystallites are adjustable in a range of approximately 3.3–16.0 nm by a crystallite size increment rate of about 2.4 nm per titania deposition cycle. The silica films transfer the electrons activated by crystalline titania and generate catalytic reactive species at the outer surface. The size‐tuned ultrafine rutile titania nanocrystallites distributed in the unique hierarchical networks significantly improve the photocatalytic performance of the rutile phase titania, thereby enabling a highly efficient photocatalytic degradation of the methylene blue dye under ultraviolet light irradiation, which is even superior to the pure anatase‐titania‐based materials. The facile stepwise size control of the rutile titania crystallites described here opens an effective pathway for the design and preparation of fine‐nanostructured rutile phase titania materials to explore potential applications.     

制备具有光催化活性的金红石相纳米氧化钛粉体

以TiCl4为原料，通过控制盐浓度和水解温度可以在温和条件下制备出晶粒尺 寸为6nm的金红石相氧化钛粉体，比表面积为175m^2/g。测定了粉体的X衍射、红外 和拉曼光谱。TEM照片显示粉体呈放射状颗粒，其粒径尺寸在200－400nm。苯酚的 光催化降解实验表明它比具有相同比表面积的锐钛矿粉体有更高的光催化活性。其 较大的团聚颗粒尺寸有利于光催化反应后的分离。     

纳米掺铁二氧化钛的sol-gel法制备与表征(Ⅰ)热重红外联用分析掺铁二氧化钛凝胶的热分解和晶化特性

本文通过热分析、红外联用和Ｘ射线衍射分析了不同煅烧温度下的纳米掺铁二氧化钛样品,研究了ｓｏｌ－ｇｅｌ方法制备的纯二氧化钛和掺铁二氧化钛干凝胶的热分解和晶化过程,结果表明,干凝胶有较为明显的两个阶段的热分解。在实验上得到的二氧化钛干凝胶粉为无定形,无定形二氧化钛加热晶化过程是一个持续的过程,没有明显的晶化温度。     

Preparation of High-Orderly TiO2 Nanotubes in Organic Solution and Characterization of C-doped TiO2

"High-orderly TiO2 nanotube arrays were fabricated by anodic oxidation of pure titanium substrate in organic electrolyte containing fluoride. Different morphological nanotubes of titania were obtained through controlling the different anodization voltages and durations. The length of the longest nanotubes was approximately 60 1m and the length-to-width aspect ratio was about 600. The nanotube layers were then annealed at different temperatures (450, 550, and 650 oC) in air for 2 h. The samples were characterized by scanning electron microscopy, X-ray diffraction (XRD), energy dispersive X-Ray (EDS) and UV-Vis spectrometer. The XRD results demonstrated that the as-anodized samples were amorphous and the structure changed to antanse and rutile when the samples were annealed at higher temperature. The EDS microanalysis indicated the presence of carbon in the TiO2 nanotubes. The result of degradation of methylene blue showed clearly that the photocatalytic activity of C-doped TiO2 nanotubes increased by 10%."     

The role of crystal phase in determining photocatalytic activity of nitrogen doped TiO2

Two series of nitrogen doped TiO(2) samples with different ratios of anatase to rutile phases were prepared by milling the mixture of P25 TiO(2) and C(6)H(12)N(4) in air and gaseous NH(3) atmosphere, respectively. Compared to air, NH(3) atmosphere plays an important role in delaying the crystallite transformation from anatase to rutile in the mechanochemical reaction of TiO(2) and C(6)H(12)N(4). In contrast to the previously reported results for pure TiO(2), it is found that nitrogen doped TiO(2) with higher content of rutile phase demonstrates higher photocatalytic activity in photodegrading pollutant Rhodamine B under both UV light and visible light irradiation (lambda>420 nm), and the amount of the surface-adsorbed water and hydroxyl groups on nitrogen doped TiO(2) have little correlations with their crystallite phases (anatase or rutile) and photocatalytic activity. The more abundant surface states characterized by photoluminescence spectroscopy together with the lowered valence band maximum of rutile TiO(2) by nitrogen doping are considered as the key factors for the higher activity of nitrogen doped TiO(2) with higher content of rutile phase.