B2O3/ZrO2催化剂的11B MAS NMR表征

 用11B MAS NMR技术研究了B2O3/ZrO2催化剂中B2O3活性组分的存在形式及作用状态. 结果表明,B2O3在ZrO2表面以三配位BO3与四配位BO4结构单元存在. ZrO2载体的预焙烧温度和硼含量对B2O3的作用状态具有重要的影响,并改变BO3与BO4结构单元之间的比例. 催化剂表面吸附水的存在对BO4与BO3之间的分布有很大的影响,催化剂焙烧脱水至少可使部分BO4转化为BO3. BO4结构形式容易在无定形的微孔大比表面积的ZrO2表面形成; BO3结构形式却倾向于在结晶形的中孔小比表面积的ZrO2上存在.     

Halogen bonds and metal bonds involving superalkalies M2OCN/M2NCO (M = Li,Na) complexes

Structural Chemistry - A new type of halogen bond formed by supermetals or superalkalies with dihalogen molecules was analyzed by means of ab initio at the MP2/aug-cc-pVTZ level. The results reveal...     

PbO2/Sb-SnO2/TiO2纳米管阵列电极电化学氧化降解罗丹明B

罗丹明B(RhB)在印染废水中广泛存在,具有难降解和易积累等特点,严重威胁生态系统和人类健康,因此寻找一种高效、清洁、经济的处理方法引起人们的广泛关注.电化学氧化法因其操作简单、环境友好等特点而广泛应用于难处理废水或有毒废水的降解,但过多的能源消耗限制了其进一步应用.在电化学氧化过程中,电极材料的选择是影响电催化性能的重要因素之一,目前的电极材料主要有硼掺杂金刚石电极、IrO_2电极、Ru O_2电极和PbO_2电极等.在这些电极材料中,PbO_2电极因价格低廉、导电性良好、化学稳定性好及析氧电位高等优点而成为具有潜力的电极材料之一.近年来,为了提高PbO_2电极的电催化活性和稳定性,研究者对其进行了一系列掺杂改性,如Cu, Bi, Ce, Fe和F等金属或非金属掺杂,以及与TiO_2, SnO_2, ZrO_2, Co3O4和TiN等其他化合物复合等.相比于传统的PbO_2电极基底Ti, TiO_2纳米管阵列具有高度有序、垂直取向、表面积大及亲水性良好等优势,这些特性可使其成为一个更好的载体,关于其做基底负载电催化活性层的研究引起了人们的广泛关注.本文以TiO_2纳米管阵列作为基体,通过微波法沉积Sb-SnO_2中间层,电沉积法沉积PbO_2b表层(含α-PbO_2内层和β-PbO_2外层),制得一种复合DSA阳极材料,并将其用于处理Rh B废水.通过扫描电镜(FE-SEM)、X射线衍射(XRD)和电化学测试等手段对该复合电极进行了表征,系统探讨了RhB初始浓度、电流密度、pH值、温度和氯离子浓度等因素对电化学氧化降解过程的影响,并对电极稳定性及Rh B降解机理进行了深入研究.SEM和XRD结果表明, PbO_2/Sb-SnO_2/TiO_2纳米管阵列电极表面涂层覆盖紧密,电化学测试结果表明该电极寿命达815h.RhB电化学氧化实验结果发现, RhB降解过程遵循准一级动力学模型,且高的电流密度、中性环境、低温和氯离子的添加均有利于其降解,但电流密度过高以及人工降温均会造成能耗过大,而氯离子的加入会带来潜在的二次污染,故在实际应用中需根据实际情况进行调节.此外,通过系统研究不同参数的影响,发现该复合电极对外界环境具有较强的适应性及催化能力,而降解机理的提出有利于我们更好地研究降解过程中变化.综上可知,该复合电极较强的稳定性及催化活性使其在电化学氧化降解废水中具有较大潜在应用前景.     

固相萃取-高效液相色谱/串联质谱检测谷物中黄曲霉毒素B1、B2、G1、G2和M1

建立了高效液相色谱/串联质谱(LC-MS/MS)同时检测谷物中的黄曲霉毒素B1、B2、G1、G2和M1的方法.并优化了液相色谱条件和质谱的相关参数.谷物样品经研磨成粉末后,直接经甲醇-水( V∶V=10∶90)提取,Oasis HLB固相萃取净化,乙腈-水(0.2％甲酸)梯度洗脱,选择电喷雾离子源(ESI),正离子扫描...     

CeO2对M2＋4B激光合金化层显微组织和耐磨性的影响

利用扫描电镜、Ｘ射线能谱仪、显微硬度计和干滑动摩擦磨损试验等，研究了稀土氧化物（ＣｅＯ２）对Ｍ２＋４Ｂ激光合金化层的显微组织和耐磨性的影响。结果表明：加入８％ＣｅＯ２能明显改善Ｍ２＋４Ｂ激光合金化层的显微组织和耐磨性。     

Fe3+-TiO2/SiO2光催化降解罗丹明B的研究

以硅胶为载体,采用溶胶-凝胶法制备了不同掺杂量的Fe3+-TiO2/SiO2光催化剂,并采用SEM,Raman和DRS等手段对其进行了分析和表征.以氙灯为光源,通过对可溶性染料罗丹明B的降解反应,考察了Fe3+-TiO2/SiO2催化剂的光催化活性,探讨了光催化反应中溶液pH值和起始浓度对催化反应的影响.     

M?ssbauer spectra of iron doped CuCrS2

M?ssbauer spectroscopy is used to study the state of iron atoms in samples with a composition of CuCr_1−x Fe _x S₂ (x = 0.01–0.30). It is shown that at x ≤ 0.02 samples are solid solutions in which iron atoms have an oxidation number of 3+ and replace chromium atoms in octahedral sites. When the iron concentration increases, the second phase — chalcopyrite CuFeS₂ — forms along with the solid solution. The relative iron concentration in this phase increases from 11% at x = 0.03 to 52% at x = 0.30. Original Russian Text Copyright ? 2009 by V. A. Varnek, V. V. Sokolov, I. Yu. Filatova, and S. A. Petrov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 2, pp. 365–368, March–April, 2009.     

M/Al2O3-CeO2（M=Pt-Ru，Ru，Pt）催化剂在甲胺催化湿式氧化中的活性与选择性

采用浸渍法制备了M/Al₂O₃-CeO₂（M=Pt-Ru,Ru,Pt）催化剂,并将其用于甲胺的催化湿式氧化反应（CWAO）.结果表明,Pt-Ru/Al₂O₃-CeO₂具有最佳活性和选择性.运用程序升温还原、X射线光电子能谱、X射线衍射、透射电子显微镜、N₂吸附和CO化学吸附等技术对催化剂的物化性质进行了表征.Pt组分的引入可有效提高双金属催化剂活性组分的分散度,从而明显提高了其催化性能.升降温过程中总有机碳（TOC）转化率与N₂选择性迟滞效应表明,甲胺CWAO遵循化学吸附-脱附机理.     

Transition-metal-centered nine-membered boron rings: MⓒB9 and MⓒB9(-) (M = Rh, Ir)

We report the observation of two transition-metal-centered nine-atom boron rings, Rh?B(9)(-) and Ir?B(9)(-). These two doped-boron clusters are produced in a laser-vaporization supersonic molecular beam and characterized by photoelectron spectroscopy and ab initio calculations. Large HOMO-LUMO gaps are observed in the anion photoelectron spectra, suggesting that neutral Rh?B(9) and Ir?B(9) are highly stable, closed shell species. Theoretical calculations show that Rh?B(9) and Ir?B(9) are of D(9h) symmetry. Chemical bonding analyses reveal that these complexes are doubly aromatic, each with six completely delocalized π and σ electrons, which describe the bonding between the central metal atom and the boron ring. This work establishes firmly the metal-doped B rings as a new class of novel aromatic molecular wheels.     

H2S-assisted growth of 2D MS2（M=Ti,Zr,Nb）

2D transition metal dichalcogenides（TMDCs） have drawn an enormous amount of attention due to their fascinating properties and application potential in next-generation information process and storage. However, the lack of proper synthesis approach limits their application. Here, we report a controllable synthesis method to grow ultrathin MS2（M = Ti, Nb, Zr） nanosheets with H2S-assisted chemical vapor deposition（CVD）. We found that the presence of H2S plays an important role to control the morphol...     

H2S-assisted growth of 2D MS2（M=Ti,Zr,Nb）

2D transition metal dichalcogenides（TMDCs） have drawn an enormous amount of attention due to their fascinating properties and application potential in next-generation information process and storage. However, the lack of proper synthesis approach limits their application. Here, we report a controllable synthesis method to grow ultrathin MS2（M = Ti, Nb, Zr） nanosheets with H2S-assisted chemical vapor deposition（CVD）. We found that the presence of H2S plays an important role to control the morphol...     

B,N-SnO2/TiO2光催化剂的制备及其光催化性能研究

为了提高TiO₂在可见光下的光催化活性, 采用聚合物前驱体法制备了B,N共掺杂的SnO₂/TiO₂(B,N-SnO₂/TiO₂)粉体型光催化剂. 进一步为了提高光催化剂的实用性, 通过浸渍-裂解法制备了氧化铝纤维毡负载的B,N-SnO₂/TiO₂光催化剂. 利用X射线衍射仪、场发射扫描电子显微镜、场发射透射电子显微镜、X射线光电子能谱、比表面积分析仪、紫外-可见分光光度计等对其进行了表征. 以氧氟沙星水溶液为模拟污染物, 考察了B,N-SnO₂/TiO₂粉体型光催化剂和负载型光催化剂的可见光催化活性及稳定性. 结果表明, 该粉体型光催化剂在可见光下光照15 min, 对氧氟沙星的降解率可达98.3%. 负载型光催化剂也表现出了良好的光催化性能及可重复性和稳定性, 在21次重复使用后光催化性能几乎不发生变化.     

B2O3/ZrO2催化剂稳定性和再生性能的研究

以气相环己酮肟重排反应合成己内酰胺是多相催化研究领域的重要课题之一[1,2]. 本研究小组曾首次报道了B2O3/ZrO2催化剂对该反应表现出较高的活性和己内酰胺选择性,但是该催化剂的稳定性和再生性能较差[3,4]. 而通过对催化剂的组成和结构与己内酰胺产率关系的研究表明,当B2O3在ZrO2载体(60 m2/g)表面平均形成约两个单层厚度的B2O3表面相时催化剂性能最好[2],这预示着增加ZrO2载体的比表面积可望改善B2O3/ZrO2催化剂的性能. 采用常规方法制备的ZrO(OH)2经600 ℃焙烧后所得ZrO2的比表面积一般不超过60 m2/g. 本文以蒸煮回流ZrO(OH)2水凝胶的方法制备了高比表面积的ZrO2,并考察了以其为载体的B2O3/ZrO2催化剂对气相环己酮肟重排反应的催化性能.     

H2 evolution from H2O/H2O2/MWO4 (M = Fe2+, Co2+, Ni2+) systems by photocatalytic reaction

H₂ evolution from H₂O/H₂O₂/MWO₄ (M = Fe²⁺, Co²⁺, Ni²⁺) systems was studied for the first time. The MWO₄ (M = Fe²⁺, Co²⁺, Ni²⁺) powders were synthesized by a salt aqueous solution reaction followed by calcination. The light band gaps of the FeWO₄, CoWO₄, and NiWO₄ powders determined from UV–vis absorption spectra were 1.83, 2.58, and 2.86 eV, respectively. The experiment on the H₂ evolution from H₂O/H₂O₂/MWO₄ (M = Fe²⁺, Co²⁺, Ni²⁺) systems indicated that the efficiency increased in order of FeWO₄ > CoWO₄ > NiWO₄ and was larger under sunlight with strong intensity than under visible light.     

固体电解质Li4.4M0.4Si0.6O4-xLi2O(M=Al,B)的低温合成及导电性

用溶胶－凝胶法,于７００℃合成了Ｌｉ４．４Ｍ０．４Ｓｉ０．６Ｏ４－ｘＬｉ２Ｏ（Ｍ＝Ａｌ,Ｂ;ｘ＝０．００－０．５０）离子导体材料,并用ＤＴＡ－ＴＧ、ＸＲＤ、ＳＥＭ及交流阻抗等技术对样品进行了测试,结果发现：用溶胶－凝胶法可降低Ｌｉ４．４Ｍ０．４Ｓｉ０．６Ｏ４的合成温度,随Ａｌ,Ｂ的掺杂,可提高基质材料的离子导电性,同时随Ｌｉ２Ｏ的掺入可增强样品的致密性并提高了其离子的导电性能。     

B掺杂TiO2/AC光催化剂的制备及活性

以硼酸和钛酸丁酯为主要原料，以活性炭(AC)为载体。用溶胶-凝胶法制备了B掺杂TiO2／AC光催化剂．用X射线衍射(XRD)、紫外可见漫反射吸收光谱(UV—VIS)对制得的光催化剂进行了表征．以甲基橙水溶液的光催化脱色反应和氧化乐果水溶液的光催化降解反应。考查了不同B掺杂TiO2／AC光催化剂的活性．结果表明，所有B掺杂TiO2／AC光催化剂均为锐钛矿晶相．B的掺杂未导致TiO2／AC光催化剂的吸收带边发生明显的移动．当B-TiO2质量分数分别为2．0％和2．5％时，TiO2／AC光催化剂的活性有明显的提高．B-TiO2质量分数2．0％时活性最高．但是，当B-TiO2质量分数分别为1．5％和3．0％时。TiO2／AC光催化剂的活性降低．B的缺电子特性可能改变了TiO2能带中的电子密度，使光催化反应中光生电子和空穴的俘获方式发生变化；同时。B的缺电子特性也会使光催化剂表面的Lewis酸强度增强，导致表面吸附OH-数量和目标反应物的吸附方式发生变化．这些可能是B-TiO2／AC光催化剂活性发生变化的主要原因．     

Li-storage and cycling properties of Sn–Sb-mixed oxides, (M1/2Sb1/2Sn)O4, M = In, Fe

The mixed oxide compounds, (M_1/2Sb_1/2Sn)O₄, M = In and Fe are prepared by the high-temperature solid-state reaction, at 800 °C for M = In and at 1,150 °C for M = Fe. High-energy ballmilling is used to reduce the particle size to nm-range. The compounds are characterized by X-ray diffraction, Rietveld refinement, scanning electron microscopy, and Brunauer–Emmett–Teller surface area methods. The Li-storage and cycling properties of the bare and ballmilled compounds are evaluated by galvanostatic cycling at ~0.15 C and in the voltage ranges 0.005–1.0 and 0.005–1.2 V vs. Li up to 50 (or 100) cycles and by cyclic voltammetry (CV) at room temperature. Effect of electrode heat treatment and carbon nanotube (CNT) addition is also studied. Initial reversible capacities in the range 425–550 mAh g^?1 are observed depending on the metal (M) upper cut-off voltage, CNT content and electrode heat treatment. Ballmilled (In_1/2Sb_1/2Sn)O₄ showed a stable capacity of 445 mAh g^-1 up to 30 cycles and 5 % capacity fading after 50 cycles. In all other cases, capacity fading is observed ranging from 9 to 60 %. The CV showed that the main cathodic and anodic peaks occur at 0.15–0.25 V and ~0.5 V vs. Li, respectively, for both M. The reaction mechanism involves alloying–de-alloying reactions of Sn and In with Li₃Sb or Fe acting as conducting matrix, and corroborated by the ex-situ X-ray diffraction data on (In_1/2Sb_1/2Sn)O₄.     

M(TNR)·H2O的热分解机理

本文用TG—DTA、DSC、IR和X光衍射分析考察了三硝基间苯二酚金属盐M(TNR)·H_2O(M=Pb、1/4Pb3/4Ba、Ba)的热行为及其热分解机理。结果表明,M(TNR)·H_2O晶体的热分解过程均分三个阶段进行。即脱水阶段;脱硝逸出NO_2伴随苯环碎裂成凝聚相产物的阶段和凝聚相产物分别生成PbO和少量碳;BaCO_3、PbO和少量碳;BaCO_3的阶段。     

B2O3/TiO2-ZrO2催化环己酮肟气相Beckmann重排反应研究 Ⅰ.B2O3含量的影响

 制备了不同B2O3含量（0～20％）的B2O3／TiO2－ZrO2固体酸催\r\n化剂，用XRD，FT－IR，N2吸附及NH3－TPD等方法测定了其结构、比表\r\n面积、孔分布和表面酸性．结果表明，当B2O3含量较低（≤5％）时，\r\n催化剂呈无定形态，样品中的B2O3主要以BO4结构存在．当B2O3含量较\r\n高（≥8％）时，催化剂中的TiO2－ZrO2以ZrTiO4晶相存在，分散于Ti\r\nO2－ZrO2表面的B2O3主要以玻璃体形式和BO3结构存在．随着B2O3含量\r\n的增加，催化剂的比表面积减小，孔径增大．300℃下的环己酮肟气相\r\nBeck－mann重排反应结果表明，随着B2O3含量的增加，己内酰胺的选择\r\n性逐渐增大，而己内酰胺的收率在B2O3含量为12％时达到最大值．讨论\r\n了B2O3／TiO2－ZrO2的催化性能与其表面酸性及孔径大小的关系．     

B离子掺杂TiO2催化剂(TiO2－xBx)光催化活性的研究

采用溶胶-凝胶法制备出纳米TiO₂和TiO_2－xB_x催化剂. 光催化实验证明, TiO_2－xB_x催化剂的紫外、可见光催化活性均高于TiO₂. XRD, XPS和Raman结果表明, B离子是以取代式掺杂占据了TiO₂的O^2－的晶格位置. UV-Vis和PL谱的结果表明, B离子的2p轨道与O的2p轨道形成混合价带, 产生可见光响应, B离子的掺入有效地阻止了光生载流子的复合, 促进了其分离, 是TiO_2－xB_x催化剂紫外、可见光催化活性提高的主要原因.