g-C3N4/ZnO复合光催化剂的制备及其光催化活性

以硝酸锌、三聚氰胺、氢氧化钠为原料,采用回流法合成g-C3N4/ZnO复合光催化剂.利用傅里叶红外光谱(FTIR),X射线衍射(XRD),扫描电子显微镜(SEM),紫外可见漫反射光谱(UV-Vis DRS)及N2吸附-脱附(BET)等技术对所合成样品的组成和形貌进行表征.在模拟太阳光条件下,以亚甲基蓝为模拟污染物评价催化剂的活性.结果表明,g-C3N4加入量为5wt;,煅烧温度500℃,煅烧时间2 h条件下制备的复合光催化剂具有最佳的光催化活性.5wt;g-C3N4/ZnO复合光催化剂在反应40 min时对亚甲基蓝的降解率可达到98.5;,其光催化降解速率为纯ZnO的2.8倍.     

Z机制光催化三元复合材料RGO/WO3/g-C3N4结构及光催化性能

以一步水热法合成了还原氧化石墨烯/三氧化钨/石墨相氮化碳(RGO/WO3/g-C3 N4)三元光催化复合材料,并对其结构、形貌及光电性能进行了表征.以罗丹明B(RhB)和盐酸四环素(TC-HCl)为降解目标物,评价了三元复合材料的光催化性能.基于自由基捕获实验和光催化反应结果分析了三元复合材料的光催化机制.结果表明:三元光催化复合材料中,三种物质紧密接触形成异质结构,与WO3和g-C3 N4单体及其二元复合材料相比,其可见吸收光谱有明显的红移,具有更低的光致发光光谱强度.复合材料有效的改善了电子-空穴对的复合,具有很好的光催化活性,最优配比组成的样品为0.2;RGO/WO3/g-C3 N4,光照240 min后,对RhB降解效果高达97.58;,其光催化效果优于WO3、g-C3 N4、RGO/g-C3 N4和WO3/g-C3 N4.催化降解过程中的主要活性物种是·O2-,其次是h+、·OH,反应过程中半导体的电子转移机制符合Z机制.     

Fe@Fe2O3/g-C3N4复合光催化剂的制备及其性能

通过高温煅烧三聚氰胺制备了石墨相氮化碳g-C3N4,再以硼氢化钠( NaBH4)为还原剂,室温下还原氯化高铁(FeCl3· 6H2O)制备出了具有核壳结构的Fe@Fe2O3纳米线.然后分别通过超声法和溶剂热法制备了Fe@Fe2 O3/g-C3N4复合光催化剂,并利用X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等表征方法对其进行表征.所得样品的光催化性能通过在可见光下(λ≥400 nm)光催化降解罗丹明B(RhB)溶液来评估.研究表明,超声法制备的Fe@Fe2O3/g-C3N4复合催化剂具有优良的可见光催化性能,其催化活性明显高于单组分的催化活性,一般认为Fe@Fe2O3与g-C3N4之间有一定的协同作用,从而可以提高材料的催化活性.同时,研究发现该催化体系中起关键作用的主要活性物种是超氧自由基.     

石墨相氮化碳基复合光催化剂的研究进展

石墨相氮化碳(g-C3N4)是一种新型的可见光光催化材料.通过构建耦合半导体复合物提高光生载流子的分离效率是目前增强光催化活性的有效方法之一.本文对g-C3N4基复合光催化材料的研究进展进行了综述,主要介绍了金属氧化物、金属硫化物、Ag系半导体、Bi系半导体与g-C3N4构筑复合物的相关研究,此复合物在光催化降解污染物、光解水制氢、光催化抗菌及光催化还原CO2为碳氢燃料等应用领域展现出优于单一g-C3N4的性能.     

Ag/g-C3N4纳米片的制备及可见光催化抗菌性能研究

在液相超声剥离制备g-C3 N4纳米片的基础上,通过光照还原法负载Ag纳米颗粒,成功构筑Ag/g-C3 N4纳米片,通过透射电子显微镜(TEM)、红外光谱仪(FT-IR)、X-射线衍射仪(XRD)、比表面积和孔分析仪(BET)和瞬态光电流等方法对制备的样品进行表征,考察可见光下杀灭E.coli能力以表征其光催化活性,并通过改进的Hom模型对样品的光催化抗菌动力学进行研究.研究结果表明,3;Ag/g-C3 N4纳米片具有最优的光催化抗菌活性,光催化抗菌曲线拟合的k2值是体相g-C3 N4的2.99倍,是3;Ag/体相g-C3 N4的1.45倍.大的比表面积和良好的光生载流子分离效率是3;Ag/g-C3 N4纳米片具有优异光催化抗菌活性的主要原因.     

g-C3N4/TiO2可见光催化降解磺胺二甲基嘧啶的研究

以商用TiO2颗粒和三聚氰胺为原料,采用高温煅烧法制备g-C3N4/TiO2复合光催化材料.利用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、低温氮气物理吸附和紫外-可见漫反射光谱仪(UV-vis)对g-C3N4/TiO2的进行表征,并研究在可见光条件下g-C3N4/TiO2对溶液中磺胺二甲基嘧啶(Sulfamethazine,SMT)的光催化降解效果.结果表明:TiO2颗粒附着在层状结构g-C3N4/表面,形成具有孔隙结构和更大比表面积的g-C3N4/TiO2,有利于污染物的吸附.g-C3N4/TiO2的光吸收带边移动到430 nm,具有可见光响应.在可见光照射下,当g-C3N4/TiO2投加量为0.2 g/L时,初始浓度为0.5 mg/L的SMT在3h内去除率可达98.8;.在相同条件下,g-C3N4和TiO2只能分别去除57.8;和9.7;的SMT.活性物质掩蔽实验表明g-C3N4/TiO2光催化降解SMT过程中,超氧自由基(·O2-)和光生空穴(h+)在降解SMT时起主要作用.     

Bi2 S3/TiO2复合光催化剂的制备及光催化还原Cr(Ⅵ)性能研究

环境中污染物的低耗能绿色处理方法,特别是环境中重金属Cr(Ⅵ)的绿色处理方法,是近年来的热点研究领域.本文首先制备了TiO2单晶颗粒,之后与不同量的Bi2 S3进行复合,制备了Bi2 S3/TiO2复合光催化材料.研究了不同的Bi2 S3复合量对所制备样品的组成、形貌、结构和光催化还原Cr(Ⅵ)性能的影响.通过XRD、SEM、TEM、DRS、SPV等方法对样品进行了表征.研究结果表明,TiO2表面复合有棒状的Bi2 S3,复合样品对Cr(Ⅵ)的可见光光催化还原效率明显高于纯TiO2,其中0.02 mol/L的Bi(NO3)3反应液制备的复合样品具有最高光催化还原效率.对样品催化机理研究表明,Bi2 S3/TiO2复合材料的带隙随着Bi2 S3含量的增加而变窄,对可见光的吸收和利用效率明显提高;并且TiO2与Bi2 S3的复合,可以减弱光生电子和空穴的复合,从而有效地利用了光生电子,提高了样品对Cr(Ⅵ)的光催化还原效率.     

Ag3PO4/Ag/ZIF-8复合光催化剂的合成及其光催化性能研究

以ZIF-8,NaH2PO4和AgNO3为原料,在室温条件下成功制备出一系列Ag3PO4/Ag/ZIF-8复合光催化剂.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(DRS)以及扫描电子显微镜(SEM)等手段对Ag3PO4/Ag/ZIF-8复合催化剂进行了表征分析.通过模拟太阳光下罗丹明B(RhB)降解实验来评价样品的光催化活性.结果表明:Ag3PO4/Ag/15;ZIF-8复合光催化剂的光催化活性最好,经过四次循环实验后RhB的降解率仍能达到87;,这归因于Ag3PO4与ZIF-8构成的异质结结构的协同作用以及单质Ag的电子传递作用.     

g-C3 N4的物理改性及光催化性能研究

块状g-C3 N4具有低比表面积和高电荷重组率,为了提高其可见光催化活性,分别采用超声剥离法和微波烧蚀法对其进行改性,并用X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、扫描电镜(SEM)、紫外-可见光漫反射吸收光谱(UV-vis)、物理吸附仪(BET)等对其结构进行表征,以亚甲基蓝(MB)为目标化合物,评价了改性前后g-C3 N4的光催化性能,结果发现超声剥离12 h和微波辐照30 min后的g-C3 N4的比表面积显著提高、光生电子和空穴的复合率降低,光催化活性增强,对MB的降解率分别达到96.4;和90.2;.     

Bi2O3/g-C3N4/TiO2三元复合物的制备及其可见光催化活性研究

以工业纳米TiO2,三聚氰胺(C3H6 N6)和硝酸铋(Bi(NO3)3·5H2O)为原料,通过高温煅烧制备Bi2O3/g-C3 N4/TiO2三元复合物,采用XRD、XPS、FT-IR、UV-vis、PL光谱等对其结构进行了表征.结果表明g-C3 N4和Bi2O3分散覆盖在TiO2表面,形成具有异质结结构的Bi2O3/g-C3N4/TiO2三元复合物,其带隙降低,对可见光的吸收增强,电子和空穴通过在Bi2O3、g-C3N4和TiO2三者界面间的转移有效延长了光生载流子的寿命,从而提高光催化效率.以亚甲基蓝为目标污染物评价其光催化活性.结果表明,当TiO2与C3H6N6质量比为1∶2.5,Bi(NO3)3·5H2O含量为0.35;,煅烧温度为520℃,煅烧时间为5h时制得的Bi2O3/g-C3 N4/TiO2三元复合物(即0.35Bi/C/T)活性最高,LED灯(12 W)光照180 min后对10mg/L亚甲基蓝溶液降解率达98.1;.     

The structures of three trimethylarsine-boron trihalide adducts: (CH3)3AsBCl3, (CH3)3AsBBr3, and (CH3)3AsBI3

An X-ray structure analysis of three trimethylarsine-boron trihalide adducts has been undertaken. Crystals of (CH₃)₃AsBCl₃ and (CH₃)₃AsBBr₃ are monoclinic with space groupP2₁/m (No. 11) withZ=2 while those of (CH₃)₃AsBI₃ are orthorhombic with space groupPnma (No. 62) withZ=4. For (CH₃)₃AsBCl₃,a=6.497(3) Å,b=10.735(3) Å,c=7.070(2) Å,=111.8(3)°,V=458.4(3) ų,R=0.0343. For (CH₃)₃AsBBr₃,a=6.672(4) Å,b=11.135(7) Å,c=7.199(4) Å,=111.5(1)°,V=497.7(5) ų,R=0.0434. For (CH₃)₃ÅsBI₃,a=13.113(7) Å,b=11.733(5) Å,c=7.387(3) Å,V=1136.5(5) ų,R=0.0329. The As-B bond lengths are 2.065(6), 2.04(1), and 2.03(1) Å, respectively, for the chloride, bromide, and iodide. These and other structural parameters are discussed with reference to previous predictions based on vibrational spectra and previous structural studies on the trimethyl-phosphine and trimethylamine adducts.     

Crystal and molecular structures of three trimethylamine-boron halide adducts: (CH3)3NBCl3, (CH3)3NBBr3, and (CH3)3NBI3

X-ray diffraction data from single crystals of the trimethylamine complexes of the three boron halides, BCl₃, BBr₃, and BI₃, lead to aP2₁/m monoclinic cell containing two molecules for each complex. The unit cell dimensions area = 6·68(1),b = 10·247(3),c = 6·502(6) Å, =116·2(1)° (chloro);a = 6·86(1),b = 10·612(4),c = 6·737(6) Å, = 115·8(1)° (bromo);a = 6·92(2),b = 10·86(1),c = 7·147(6) Å, = 93·9(1)° (iodo). The structures were solved by three-dimensional sharpened Patterson functions and show only the chloro and bromo compounds to be isomorphous. Refinement of 662,718 and 954 observed reflexions for the chloro, bromo and iodo complexes, respectively, using anisotropic thermal parameters yielded conventionalR factors of 0·045, 0·087 and 0·054.The molecules are shown to possess a B—N dative bond, a staggered conformation, and effective 3m (C _3v) symmetry. Average C—N bond lengths are 1·52(1) Å for all three complexes. Boronhalogen bond lengths average 1·864(4), 2·04(2) and 2·28(2) Å, while B—N bond distances are 1·609(6), 1·60(2) and 1·58(3) Å, respectively, for the chloro through iodo compounds. Bond angles are approximately tetrahedral with the C—N—C angle decreasing by several degrees in the Cl Br I series.Based in part on a dissertation submitted by Patty H. Clippard to the Rackham School of Graduate Studies of the University of Michigan, January 1969 in partial fulfillment of the requirements of the Ph.D. Degree.     

Second harmonic generation properties of Ca3(O3C3N3)2 ‐Sr3(O3C3N3)2 solid solutions

Solid solutions of the second harmonic generation (SHG) materials Ca₃(O₃C₃N₃)₂ (CCY) and Sr₃(O₃C₃N₃)₂ (SCY) were prepared via exothermic solid state metathesis reactions from appropriate amounts of the corresponding metal chlorides and potassium cyanate at 525 °C. The change in SHG intensity caused by the successive cation substitution is reported. Differential thermal analyses are used to explore the SCY–K(OCN) phase diagram as a medium for the growth of SCY crystals.     

Growth and characteristic of Sr3Tb(BO3)3 crystal

A new borate single crystal of Sr₃Tb(BO₃)₃ with dimension Ф20×25 mm² has been grown by the Czochralski method. The grown crystal was characterized by DTA–TGA, FTIR and X-ray powder diffraction analysis. The results showed the crystal with [BO₃]^3? is congruently melting at 1351.35 °C which belongs to hexagonal structure. The hardness of Sr₃Tb(BO₃)₃ crystal is 422.5 VDH, and is equal to 5.0 moh. The thermal expansion coefficients were determined to be 2.08×10^?5/°C along (1 0 0) direction and 7.43×10^?6/°C along (0 0 1) direction and the transmission spectrum was measured in 320–1800 nm at room temperature. The magnetic properties of the single crystal were studied which showed its paramagnetism and magnetic anisotropy. The specific Faraday rotation of single crystal was measured at room temperature in 532, 633, and 1064 nm wavelength. The Verdet constants and magneto-optical figures of merit were investigated. The primary emphasis is laid to explore a new magneto-optical material, all the magneto-optical properties of Sr₃Tb(BO₃)₃ are comparing to the ones of TGG.     

Growth and magnetic‐optical properties of Sr3Gd(BO3)3 and Sr3TbxGd1‐x(BO3)3 single crystals

Single crystals of Sr₃Gd(BO₃)₃ (SGB) and Sr₃Tb_xGd_1‐x(BO₃)₃ (TSGB) with dimension Ø 20 mm×20 mm have been grown by Czochralski method. The grown crystals were characterized by X‐ray powder diffraction analysis which showed the crystals belong to hexagonal structure with lattice parameters of a=b=1.254 nm, c=0.926 nm (SGB) and a=b=1.253 nm, c=0.925 nm (TSGB). In TSGB, x=17.7% was obtained by X‐ray fluorometry which showed the segregation coefficient of Tb is closed to 1. The transmission spectrum was measured, which indicated the crystals have high transmittance in 400‐1100 nm region. The Faraday rotation of single crystals at 532 nm wavelength was measured at room temperature. Finally, the Verdet constants were investigated, (SGB) V=17.9 degcm^‐1T^‐1 and (TSGB) V=21.3 degcm^‐1T^‐1. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Tb3+,Yb3+共掺杂LuBO3荧光粉的下转换发光

利用水热法成功合成了近红外量子剪裁荧光粉LuBO3∶15;Tb3+,x; Yb3+(x=0,1,2,4,8,12).通过X射线衍射(XRD)、光致发光谱(PL)、激发谱(PLE)和荧光寿命测试了合成物质的物相结构与发光性质.在286 nm(Tb3+∶7 F6→5D)紫外光激发下,观察到了Tb3∶5D4→7Fj(J=6,5,4,3)可见波段特征发射光和Yb3+:2F5/2→2F7/2的近红外光.研究了Yb3+浓度与激发发射光谱和荧光寿命之间的关系,表明Tb3+和Yb3+之间存在能量传递.当Tb3和Yb3+掺杂摩尔浓度分别为15;和2;时,近红外发射最强.计算得知,其最大下转换量子效率为160.74;.     

3-Methyl-3a,4-Dihydro-3H-Thiochromeno[4,3-c]isoxazol

Abstract  The crystal structure of the title compound, C₁₁H₁₁NOS, was determined by an X-ray diffraction analysis. The compound crystallizes in the monoclinic space group P2₁/c with cell parameters a = 10.533(2) ?, b = 12.7826(19) ?, c = 7.6491(17) ?, β = 107.997(17)^°, V = 979.5(3) ?³ and Z = 4. The S containing heterocycle adopts a sofa conformation, whereas the 5-membered ring adopts an envelope conformation. The crystal packing is characterized by weak C–H···N contacts and π-stacking interactions. Graphical Abstract  The title compound, 3-methyl-3a,4-dihydro-3H-thiochromeno[4,3-c]isoxazol was synthesized by an 1,3 dipolar cycloaddition reaction and its crystal structure determined. Single crystal X-ray diffraction analysis reveals that the aromatic 6-membered ring is planar, whereas the ring containing the S atom adopts a sofa conformation and the 5-membered ring an envelope conformation. The methyl group is in an equatorial position.      

Second harmonic generation in Na3Gd2(BO3)3 crystals

Na₃Gd₂(BO₃)₃ crystals with dimensions up to 22 × 20 × 5 mm³has been grown from NaBO₂ flux by the top‐seeded solution growth (TSSG) method for the first time. Differential scanning calorimetry (DSC) result shows that Na₃Gd₂(BO₃)₃ melts incongruently. The infrared spectrum indicates that Na₃Gd₂(BO₃)₃ contains characteristic triangular [BO₃]^3– groups responsible for the nonlinear optical effect. For the as‐grown crystal, the transmittance exceeds 80% in the wavelength range of 315 nm to 2670 nm, and the UV cutoff wavelength is 207 nm. The damage threshold is 0.47 GW cm^–2 at 1064 nm. Moreover, Na₃Gd₂(BO₃)₃ crystal exhibits an optical second harmonic generation effect which is 1.3 times as large as that of KH₂PO₄ (KDP). (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)