水热法制备WO3纳米棒阵列及其光催化性能

三氧化钨（WO₃）作为一种过渡金属氧化物半导体材料,具有良好的可见光响应能力,是理想的光催化材料之一. 然而,其光生电荷分离效率低的弊端始终阻碍其发展. 相比于WO₃,其水合形式（WO₃·nH₂O）由于具有更高的电荷转移分离效率而备受研究者的青睐. 本文针对近年来WO₃·nH₂O材料在光催化领域的应用与研究进展进行了系统的归纳整理. 首先介绍了WO₃·nH₂O光催化剂的晶体结构,接着从晶体结构、电子转移分离以及能带结构的角度分析了结晶水对WO₃的影响,并重点阐述了WO₃·nH₂O和WO₃·nH₂O基改性光催化剂的制备方法. 最后总结了WO₃·nH₂O及其所构建的复合材料在水分解析氢、CO₂还原和降解染料类污染物三个方面的应用,并对发展前景做出了展望. 本工作旨在为推动WO₃·nH₂O光催化体系发展提供有益参考.     

水热法制备La掺杂WO3及其光催化性能研究

采用水热法在不使用任何添加剂的情况下制备了La掺杂WO₃光催化剂材料。通过X射线衍射仪(XRD)、紫外-可见分光光度计(UV-Vis)、傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和比表面积测试仪(BET)对所制备材料的物理和化学性质进行了表征。XRD结果表明La掺杂WO₃具有斜方相结构。随着La掺杂量的增加,XRD图谱向低角度移动,表明La成功地掺入WO₃晶格中。通过XRD图谱和UV-Vis光谱可以发现,La掺杂WO₃样品的平均晶体尺寸和带隙能相比未掺杂WO₃的有所减小。SEM研究表明,掺杂和未掺杂的WO₃样品均由纳米颗粒团聚而成,且有很多纳米级孔结构。以亚甲基蓝(MB)为目标污染物研究了La掺杂WO₃样品的光催化活性。结果表明,掺杂(1%,质量分数)La的WO₃光催化活性明显高于纯WO₃的活性。     

钨酸钠水热法合成晶态WO3纳米棒及其表征

以钨酸钠为原料,硫酸钾为辅助盐,在强酸性反应体系通过水热法合成了WO3纳米棒.利用XRD、SEM、TEM和SAED对试样进行分析,研究结果表明:在水热法体系中合成WO3纳米棒时,随着pH值的增加和反应温度的升高,二者都有利于WO3纳米棒的合成.在pH值为1.5和反应温度为210℃下合成直径小于100 nm的晶态WO3纳...     

水热法制备氧化锌纳米棒阵列的生长动力学研究

采用低温水热方法,在经预先修饰的基底上制备出取向高度一致的ZnO纳米棒阵列.用SEM和XRD等手段对制备的纳米棒阵列进行了表征.ZnO纳米棒阵列水热生长动力学表明:当生长时间在8h内时,纳米棒的生长速度较快,之后纳米棒的生长近乎停止,棒的长度和直径基本不再改变.在生长速度较快的8h内时,纳米棒的径向生长由两个明显的动力学过程组成,即由生长时间在1.5h内的快速生长步骤和随后的慢速生长步骤组成;纳米棒的长度以约5.5nm·min^-1的生长速度增加至2.4μm.     

微波水热法快速合成氧化锌纳米棒及其光催化性能

以硫酸锌、醋酸锌和氢氧化锌为原料,制备出氢氧化锌前驱体和氧化锌晶种,在微波水热条件下快速合成了氧化锌纳米棒。通过X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）和紫外?可见分光光度计（UV-vis）对氧化锌纳米棒的形貌、结构和光学性质等进行了表征,并通过降解罗丹明B（RhB）测试了样品的光催化性能,探讨了微波辐射作用对产物的催化活性的影响。实验结果表明,氢氧化锌作为前驱体在微波作用下30 min,生成为基于氧化锌纳米棒自组装的三维笼状结构,与常规方法制备的氧化锌纳米棒相比,微波辐射作用下生成的样品结晶度更高。紫外?可见分光光度计结果表明微波辐射会导致合成的氧化锌纳米棒吸收边红移,缩小带隙能量,从而提升氧化锌纳米棒的催化活性。光催化测试表明微波辅助合成的氧化锌纳米棒具有更好的可见光吸收特性,在紫外和可见光照射下,对罗丹明B都具有较好的降解效率,在紫外光照射下80 min内罗丹明B的降解率可达到98.5%。这种微波辅助的合成方法能够在短时间内合成大量的氧化锌纳米材料,具有高效批量制备、清洁环保等优点。      

WO3催化材料的制备及性能研究

以仲钨酸铵和盐酸为主要原料,采用水热法制备了100℃、120℃、140℃和160℃水热温度下的WO₃粉体并进行热处理。利用扫描电镜(SEM)对WO₃粉体进行表征分析,并进行光催化性能测试。研究结果表明：随着水热温度的升高,WO₃粉体形貌由颗粒团聚结构变成针状团聚结构,团聚程度下降,结构空隙增多,说明水热温度与热处理会影响WO₃粉体的晶体结构。由光催化测试结果可知,在100℃水热温度下制备的WO₃粉体经热处理对罗丹明B降解效率在50min时达到最高,约为50.06%,进而说明WO₃粉体晶体结构的结构空隙和团聚程度又会对其催化性能有一定影响。     

五氧化二铌纳米棒合成及其光催化性能

在醋酸溶剂中,以氢氟酸和氨水活化得到的铌酸(Nb2O5·nH2O)为前驱物,溶剂热合成出一种纳米线状结构氧化铌,结合在400℃下焙烧样品1h,制备了Nb2O5纳米棒。通过XRD、SEM、TEM分析表明,制备的Nb2O5纳米棒为六方晶相结构,晶型单一,沿c轴[001]方向结晶生长。以亚甲基蓝和罗丹明B为例,测试焙烧后的Nb2O5纳米棒光催化活性,发现Nb2O5纳米棒对两种有机染料均具有较高的光催化效果;染料浓度增高,催化效率降低。同时发现,由于存在对亚甲基蓝强吸附作用,所以对亚甲基蓝移除效果优于对罗丹明B的移除效果。     

温度对水热法合成WO3亚微米棒形貌和光吸收特性的影响

以钨酸钠为W源和硫酸钾为辅助盐,在酸性体系中对水热法合成WO3亚微米棒进行了研究。利用X射线衍射(XRD)、热场发射扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射(SAED)对试样进行分析,结果表明:随着反应温度的升高和pH值的增加,它们都有利于合成WO3亚微米棒;在反应温度为240℃、pH值为1.5和反应时间48h下合成径向尺寸<200nm的晶体结构的WO3亚微米棒,此WO3亚微米棒径向分布较均匀。对不同条件下水热法合成的WO3进行紫外可见光的吸收光谱(UV-VIS)分析可得:随着反应温度的升高和pH值的增加,获得的WO3的紫外光吸收能力是逐渐增加的;WO3亚微米棒具有良好的紫外光吸收能力。     

磁性TiO2空心球的制备及其光催化性能

分别制备Fe3O4和ZnFe2O4粉体并以它们作为磁芯,葡萄糖为模板剂,氟钛酸铵为钛源,通过水热法制备出Fe3O4/C/TiO2和ZnFe2O4/C/TiO2前驱体,煅烧后获得磁性Fe3O4/TiO2和ZnFe2O4/TiO2空心球。采用扫描电子显微镜、X射线衍射仪、X射线光电子能谱仪分析了产物的形貌、结构和化学组成,用振动样品磁强计测试了样品的磁化强度。结果表明,以Fe3O4为磁芯得到的Fe3O4/TiO2空心球的比饱和磁化强度是ZnFe2O4为磁芯得到的ZnFe2O4/TiO2空心球的20倍。以亚甲基蓝溶液为降解模型,考察了磁芯Fe3O4添加量对Fe3O4/TiO2空心球在紫外光下的催化降解能力。结果显示,Fe3O4的添加量对Fe3O4/TiO2空心球的光降解性能影响较小,且Fe3O4/TiO2空心球的紫外光降解能力均比纯TiO2空心球略低,但Fe3O4/TiO2空心球具有在外加磁场下易于回收的优势,具有潜在的应用前景。     

高分子凝胶法制备纳米ZnO/La2O3及光催化性能

以Zn(CH3COO)2·2H2O,AgNO3为原料,丙烯酰胺为单体,N,N'-亚甲基双丙烯酰胺为网络剂,采用高分子凝胶法在550℃下制得纳米ZnO/La2O3.通过XRD物相分析,得知沉积稀土氧化物La2O3的ZnO纳米粒子样品的物相均是六方晶系纤锌矿结构;TEM形貌观察,粒子基本为球形,纳米ZnO/La2O3的平均粒径约为26 nm,红外光谱分析高分子的分解程度,在550℃时分解完全.水溶液中次甲基蓝染料在ZnO/La2O3半导体光催化条件下,pH值为9时,能迅速分解,在降解90 min时,次甲基蓝的降解率达到81%.     

Preparation, spectral characteristics and photocatalytic activity of Eu-doped WO3 nanoparticles

Eu³⁺-WO₃ nanoparticles were successfully prepared by the modified method of Pechini. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and UV-vis spectroscopy. Results showed that the Eu³⁺-WO₃ nanoparticles, which had an average external diameter of 10–25 nm, were composed of the different shapes of puncheon and catenary after being pretreated by pH, pressure vessal, and surfactant. Moreover, structural transformation matrix contained different crystals of anorthic and orthorhombic structure. The photocatalytic activities of the nanoparticles were evaluated by photocatalytic decomposition of rhodamine B. Eu³⁺-WO₃ nanoparticles were more efficient than WO₃ and TiO₂ on sunlight use ratio. Photocatalysis experiments indicated that the Eu³⁺-WO₃ nanoparticles exhibited the highest photocatalytic activity.     

H2O2氧化-水热结晶法合成纳米WO3的研究

以钨粉为原料, H2O2氧化金属钨粉生成的过氧聚钨酸为前驱体, 采用水热法制备了WO3 及其水合物. 低于180 ℃水热反应12 h, 得到正交晶型的WO3·0.33H2O和单斜WO3; 在180 ℃水热反应24和45 h则生成单斜WO3和六方WO3. 结果表明, 一定的水热反应温度和时间对晶化是必须的, 本实验180 ℃水热反应24和45 h后干燥均得到不含水合物的WO3粉体. 水热反应温度的升高和时间的延长均有利于正交WO3·0.33H2O向六方WO3和单斜WO3转化. 所制得的纯WO3 粉体晶形良好, 晶粒尺寸达到了纳米级, 并探讨了其水热机制.     

石墨烯/二氧化锰复合材料的制备及其电化学性能

通过水热法在160℃条件下成功制备了手风琴状石墨烯/MnO₂复合材料.通过场发射扫描电镜、透射电镜、X射线衍射、X射线能量色散谱、BET法以及拉曼光谱对材料进行表征.结果表明,手风琴状二氧化锰与层状石墨烯之间具有十分高效的贴合,这种创新性设计有效地利用了石墨烯的高电导率、大比表面积以及二氧化锰的优秀赝电容行为.电化学测试结果给出在0.2 A·g^-1时,样品的比电容高达138 F·g^-1,数倍增强于单独的二氧化锰或石墨烯样品.     

Hydrothermal synthesis and crystal structure study of two novel 3-D mellitates {Nd2[C6（COO）6] （H2O）6} and {Ho2[C6（COO）6]（H2O）6}

Two novel 3-D coordination compounds, Nd2[C6（COO）6]（H2O）6 （1）and Ho2[C6（COO）6]（H2O）6 （2）, were hydrothermaily synthesized from mellitic acid and neodymium perchlorate （or holmium perchlorate） in the alkaline aqueous solution and characterized with elemental analysis, TG, IR spectrum, and single crystal X-ray diffraction. The two compounds were isostructural and crystallized in the orthorhombic system, space group Pnnm, with a=1.3531 （4） nm, b=0.6687 （2） nm, c=1.0224（3） nm, V=0.92523（5） nm^3, Z=4, D=2.630 g/cm^3, F（000）=696.0, Goof=1.052. Final R indices [1 〉2∑（Ⅰ）]： R1=0.0195, wR2=0.0382 for 1; a=1.3411 （2） nm, b=0.6586（1） nm, c=1.0116（2） nm, V=0.8935（3） nm^3, Z=4, D=2.877 g/cm^3, F（000）=724.0, Goof=1.061. Final R indices [1 〉2∑（Ⅰ）]： R1=0.0200, wR2=0.0479 for 2. In the two compounds 1 and 2, the mellitic acid ligand, in which all the carboxylate groups were deprotonated, had only one kind of coordination mode to bridge metal ions to form four-connected three-dimensional diamondiod networks.     

Hydrothermal Synthesis of RbLn2F7 and VUV Spectroscopy of RbLn2 F7 ：Eu^3＋（Ln=Gd, Y）

RbLn2F7（Ln = Gd, Y, Er, Yb and Lu）, crystallized in the hexagonal RbEr2F7 structure type, is synthesized by a hydrothermal method. The excitation spectra of Eu^3 ＋ -doped RbGd （Y）2F7 suggest that the oxygen content is very low in the samples obtained by hydrothermal synthesis. Only the f-f transitions of Gd^3＋ ions are observed in the excitation spectrum of RbGd2F7：Eu^3＋ （0.5mol%）, while those of Eu^3＋ ions do not appear. When the Gd^3＋ ions are excited, the absorbed energy is transferred efficiently from Gd^3＋ to Eu^3＋ . The spectra show that the doped Eu^3＋ ions are located in non-centrosymmetric sites in hexagonal RbLn2F7.     

Preparation and Photocatalytic Behaviors of Nanoporous Polyoxotungstate-Anatase TiO2 Composites

Nanoporous anatase TiO2 crystalline particles coupled with Keggin or Wells-Dawson unit, H3PW12O40/TiO2 or H6P2W18O62/TiO2, were prepared at a low temperature （200℃ ） using sol-gel method combined with hydrothermal treatment at programmed temperature. The as-prepared composites have uniform anatase phase, and they exhibit both micrand mesoporosities with pore sizes of 0.6 and 4.0 nm, respectively, and their average size is lower than 10 nm. Photocatalytic tests show the composites exhibit relatively higher photocatalytic activities to decompose the organocholorine pesticide hexachlorobenzene（HCB） than anatase TiO2, the starting polyoxotungstates, and EuEOa/TiO2 prepared by using sol-gel method, and this was attributed to （ 1 ） the synergistic effect of photoactive anatase TiO2 with the polyoxotungstate, and （2） the fascinating physical and chemical properties of the porous materials.     

Luminescent properties of Eu~（3＋） doped Gd_2WO_6 and Gd_2（WO_4）_3 nanophosphors prepared via co-precipitation method

Eu3+ doped Gd2WO6 and Gd2(WO4)3 nanophosphors with different concentrations were prepared via a co-precipitation method. The structure and morphology of the nanocrystal samples were characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The emission spectra and excitation spectra of samples were measured. J-O parameters and quantum efficiencies of Eu3+ 5D0 energy level were calculated, and the concentration quenching of Eu3+ luminescence in different matrixes were studied. The results indicated that effective Eu3+:5D0-7F2 red luminescence could be achieved while excited by 395 nm near-UV light and 465 nm blue light in Gd2WO6 host, which was similar to the familiar Gd2(WO4)3:Eu. Therefore, the Gd2WO6:Eu red phosphors might have a potential application for white LED.     

水热法合成Ag2C03／ZnO异质结复合光催化剂及其光催化性能

采用水热法合成了一系列不同Ag2CO3含量的新型Ag2CO/ZnO异质结复合光催化剂,运用X射线粉末衍射（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、傅里叶变换红外光谱（FT-IR）、紫外-可见漫反射吸收光谱（UV-visDRS）等系列手段对所制备的光催化剂进行了表征,并以紫外光（254nm）为光源,评价了催化剂光催化降解甲基橙的活性,考察了不同Ag2CO3复合量、不同水热温度对ZnO复合光催化剂反应活性的影响．结果表明．当Ag2CO3含量为2％、水热温度为140℃,复合光催化剂具有最大的光催化活性,降解率达到86．31％．Ag2CO3/ZnO异质结复合光催化剂具有更高的光催化活性主要原因是复合光催化剂对紫外光有很强的吸收能力,适量A龅C03能提高光生电子一空穴对的分离效率,并改善催化剂的物理性能．     

Synthesis, structure and luminescence properties of KEu0.01Gd0.19Yb0.8（WO4）2 powder

The synthesis of co-doped KEu_0.01Gd_0.19Yb_0.8(WO₄)₂ was achieved by a modified Pechini method at 750 °C. The structure of obtained compound was confirmed using X-ray diffraction measurement and Raman spectroscopy. The Scherrer's formula was used to confirm the grain sizes visualized by TEM technique. The grain sizes of about 100 nm of monoclinic KGW were successfully obtained by this methodology. In order to study spectroscopic properties of the prepared system the emission spectra were measured. The effective down- and up-conversion processes in non-resonant system were investigated.