WC/TiO_2纳米复合材料晶相形成机理及电催化性能

以金红石相纳米TiO_2为载体,偏钨酸铵为钨源,采用表面修饰技术制备了纳米复合材料的前体,将前体在甲烷/氢气气氛下还原碳化并采用XRD对其进行表征,研究了还原碳化温度、时间对纳米复合材料晶相组成的影响,并探讨了WC/TiO_2纳米复合材料的形成机理。通过扫描电子显微镜、热重-差热分析等手段对WC/TiO_2纳米复合材料的形态结构和热稳定性进行了表征。采用循环伏安法研究了纳米复合材料物相组成与电催化性能之间的关系,结果表明由WC和TiO_2两相组成的WC/TiO_2纳米复合材料对对硝基苯酚电还原反应的电催化性能最佳。     

碳化钨/碳纳米管纳米复合材料的制备及其对硝基苯的电催化活性

采用表面修饰技术和原位还原碳化技术制备了纳米碳化钨（WC）/碳纳米管（CNT）纳米复合材料,通过X射线衍射（XRD）、扫描电子显微镜（SEM）和热重-差热分析（TG-DTA）等手段对WC/CNT纳米复合材料的晶相组成、形态结构和热稳定性进行了表征,结果显示样品是由WC和CNT两相构成,纳米WC颗粒均匀地分散在碳纳米管上,粒径细小;在空气气氛中,WC/CNT纳米复合材料在470℃以下保持稳定。采用循环伏安法研究了WC/CNT纳米复合材料对硝基苯的电催化活性和电化学稳定性。结果表明,WC/CNT纳米复合材料对硝基苯的电催化活性优于纳米WC和CNT,且WC/CNT纳米复合材料在硝基苯电还原过程中保持良好的化学稳定性。     

WC/MMT纳米复合材料制备及其对PNP的电催化活性

以剥离后的蒙脱石(MMT)为载体,将浸渍法与原位还原技术相结合制备了碳化钨/蒙脱石(WC/MMT)纳米复合材料。采用X射线衍射、扫描电子显微镜和透射电子显微镜等手段对样品进行了表征。结果表明,剥离后蒙脱石的片层厚度为10～15 nm,层间距增大,边缘发生卷曲;复合材料由碳化钨(WC)、碳化二钨(W₂C)和蒙脱石组成,碳化钨颗粒均匀地分布于蒙脱石外表面。采用循环伏安法测试了样品对对硝基苯酚(PNP)的电化学还原性能,结果表明,WC/MMT纳米复合材料对对硝基苯酚具有良好的电催化活性,且具有较好的稳定性。蒙脱石是碳化钨基复合电催化材料良好的载体。     

活性炭载碳化钨复合材料的制备及其对对硝基苯酚的电催化性能

以浓度为10%的偏钨酸铵溶液为前驱体、CH4/H2为还原碳化气氛,采用表面修饰技术和还原碳化技术制备了碳化钨(WC)/活性炭(C)复合材料。通过FT-IR、XRD、SEM等对制备的WC/C材料进行表征,结果表明,酸处理后的活性炭外表面大幅度增加了羟基和羰基,WC/C复合材料是由WC、W2C和C三相组成,碳化钨均匀地分散于活性炭表面,粒径约50～100nm。采用循环伏安法研究了碱性介质中WC/C-PME对对硝基苯酚的电还原行为,结果表明,该材料对对硝基苯酚的电催化活性优于WC和C,且WC/C材料在对硝基苯酚电还原过程中保持良好的化学稳定性。     

纳米二氧化钛/石墨烯改性水性聚氨酯抗菌涂料的制备与评价

通过简单高效的方法制备纳米二氧化钛 /还原氧化石墨烯（ TiO₂/rGO）复合材料,对复合材料进行红外光谱（ FT-IR）、扫描电镜（ SEM）以及 X射线衍射（XRD）表征,结果表明：成功制备了氧化石墨烯、锐钛型纳米 TiO₂,并将纳米 TiO₂均匀负载于氧化石墨烯片层,经水热还原得到 TiO₂/rGO复合材料。将制备的 TiO₂/rGO复合材料添加到水性聚氨酯涂料中,制备涂膜并测定其光催化降解能力,结果表明：纳米 TiO₂/rGO填料复合的聚氨酯涂膜具有较高的光催化能力。依据 HG/T 3950—2007标准测定涂膜抗菌性能,结果表明：水性聚氨酯涂料的抗菌能力达到国家 Ⅰ级标准,可以有效替代有机抗菌剂。该环保复合涂料在物理性质和应用性能上均符合化工行业标准要求。     

载银TiO2/碳纳米管复合材料的制备及其催化杀菌性能

采用溶胶-凝胶法, 在450℃下煅烧制备载银TiO₂/碳纳米管纳米复合材料;采用XRD、SEM以及N₂吸脱附对样品的晶体结构及样品微观形貌进行表征;通过UV-vis漫反射光谱表征了复合材料对紫外可见光的吸收性能;以甲基橙为模型污染物, 评价了样品紫外光光催化降解甲基橙的活性, 以大肠杆菌和枯草芽孢杆菌为菌种, 采用抑菌圈法表征样品的杀菌性能。结果表明, 载银TiO₂/碳纳米管纳米复合材料比纯TiO₂纳米颗粒有更好的紫外光光催化活性, 其中掺碳纳米管(CNTs)1%(质量分数)的效果最好, 紫外光照射150min, 降解率达到76.5%;载银TiO₂/碳纳米管纳米复合材料比TiO₂纳米颗粒、Ag纳米粒子、CNTs(纯化处理后)的杀菌效果都要好很多, 其中掺CNTs 10%(质量分数)的样品的杀菌效果最好, 抑菌圈直径达到25.8mm。     

Sn掺杂TiO2/ACF复合材料的制备、表征及光催化性能

以Ti(OC₄H₉)₄为前体,SnCl₄为Sn源,采用胶溶-回流法制备了Sn掺杂的TiO₂,利用浸渍提拉法将其负载到活性炭纤维(ACF)表面,并运用SEM、XRD、XPS、DRS等手段对TiO₂/ACF复合材料进行表征,考察了复合材料光催化降解气相甲醛的性能。研究结果表明,Sn元素掺入TiO₂晶格中,有利于抑制TiO₂晶粒的生长,促进TiO₂由锐钛矿型向金红石型的转化,光吸收范围发生一定程度红移;HNO₃的用量为0.015mol、掺锡量为6%、负载两层的TiO₂/ACF-50复合材料在紫外光照射下对甲醛的去除率复合材料可达85.2%,而在可见光下仅为65.3%。     

硝基苯在碳化钨/碳纳米管粉末微电极上的电化学行为

采用表面修饰和原位还原碳化技术制备了碳化钨（WC）/碳纳米管（CNT）纳米复合材料,并以其为电催化剂制成了WC/CNT纳米复合材料粉末微电极（WC/CNT-PME）。采用计时电流法、循环伏安法和原位红外反射光谱技术研究了酸性溶液中硝基苯在WC/CNT-PME上的电化学行为,讨论了扫描速率和温度对其电化学行为的影响。结果表明,WC/CNT纳米复合材料对硝基苯的电催化活性明显高于碳纳米管和纳米碳化钨;硝基苯在WC/CNT-PME上的还原反应是一受吸附控制的不可逆过程,其还原产物为对氨基苯酚。     

活性炭纤维负载Pr3+:Y2SiO5/TiO2复合材料的制备与性能

为了提高纳米TiO₂对太阳光的利用率和实现光催化剂的回收再利用,采用溶胶-凝胶法将上转换荧光材料与纳米TiO₂复合,通过负载于活性炭纤维（ACF）表面制备了Pr³⁺：Y₂SiO₅/TiO₂/ACF复合材料。运用XRD、FT-IR、SEM、FS、UV-vis DRS等对材料的结构及性能进行了综合表征,并以亚甲基蓝为模拟污染物评价复合材料的可见光催化活性,考察了材料制备过程中煅烧温度、负载次数等制备条件对复合材料可见光下催化性能的影响。结果表明,在浸渍2次、800℃煅烧的制备条件下,复合材料中TiO₂为锐钛矿相（占34.1%）与金红石相（占65.9%）的混合相,亚甲基蓝（15 mg·L^-1）12 h内去除率高达93.8%,反应符合拟一级动力学,反应速率常数为0.2471 h^-1,回收再生利用4次后去除率仍保持在75%以上。     

PEG/GO/TiO2纳米复合材料改性PVDF膜的制备及其抗污性能

为改善聚偏氟乙烯(PVDF)膜的抗污性能,以聚乙二醇2000接枝的GO/TiO₂(PEG/GO/TiO₂)纳米复合材料为添加剂,通过非溶剂诱导沉淀相分离法制备了一系列PEG/GO/TiO₂/PVDF复合超滤膜。采用FTIR、SEM和接触角测试仪对其结构和形貌进行了表征,采用超滤法评价其纯水通量和抗污性能。结果表明,当PEG/GO/TiO₂纳米复合材料质量分数为0.60%时,制备的PEG/GO/TiO₂/PVDF复合超滤膜(记为0.60%PEG/GO/TiO₂/PVDF)表现出最佳的亲水性和抗污性能,其接触角比PVDF膜下降8.2°,总孔隙率增加13.40%,PEG/GO/TiO₂纳米复合材料在PVDF膜中分散较均匀。在0.08 MPa的工作压力下,0.60%PEG/GO/TiO₂/PVDF的纯水通量高达282.44 L/(m²·h),对腐植酸溶液的过滤通量为131.96 L/(m^2...     

Room temperature visible light oxidation of CO by high surface area rutile TiO2-supported metal photocatalyst

Visible light-active rutile TiO₂ with a high surface area of 200 m²/g was obtained by a low-temperature sol–gel synthesis, based on a long aging duration of a titania sol to stabilize the rutile phase. Decorated by an adequate amount of metallic nanoparticles, this non-doped TiO₂ displays high and stable performances for the on-stream room temperature oxidation of CO by visible light photocatalysis.     

Development of the efficient TiO2 photocatalyst in photoassisted selective catalytic reduction of NO with NH3

Photoassisted selective catalytic reduction (photo-SCR) of NO with NH₃ in the presence of O₂ takes place at room temperature over TiO₂ photocatalyst. From the results of photo-SCR reaction over various TiO₂, we found that JRC-TIO-11 exhibited the best activity. The reaction activity correlated to the amount of acid sites of TiO₂, but did not depend on the specific surface area and crystal diameter. The mixture of rutile and anatase shows higher activity than any of the corresponding TiO₂ single phase catalyst.     

Influence of temperature schedules on particle size and crystallinity of titania synthesized by vapor-phase oxidation route

Crystalline TiO₂ particles were produced in a tubular flow reactor by chemical vapor synthesis using titanium tetrachloride as a starting material in oxygen containing atmospheres. The dependence of particle size, morphology and crystalline phase of titania on temperature schedules including the reactor temperature, the oxygen preheated temperature and the product cooling measure were explored. It is found that there are two opposite effects of temperature on particle size and crystalline phase content. The particle size distribution, SEM and TEM of resulting powders show that the grain size is controlled by the relative magnitudes of the nucleation rate and growth rate, both of them being subject to the temperature schedules. XRD indicates that particles crystalline phase is predominately anatase and the rutile content increment is not consistent with temperature increase. Anatase titania can be converted to rutile by addition of crystal modifier AlCl₃. The element analysis by EDS shows that Al enriches on the particle outer surface.     

Synthesis of nanosized TiO2/SiO2 particles in the microemulsion and their photocatalytic activity on the decomposition of p-nitrophenol

Nanosized pure TiO₂ particles were prepared by hydrolysis of TTIP in the sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. TiO₂/SiO₂ nanoparticles were also prepared from TEOS as a silicon source and TTIP as a titanium source. These particles were characterized by TEM, XRD, FT-IR, BET, TGA and DTA. From thermal analysis and XRD analysis, the anatase structure of pure titania appeared in the 300–600 °C calcination temperature range and the rutile structure was showed above 700 °C. However, no rutile phase was observed for the TiO₂/SiO₂ particles up to 800 °C. The crystallite size decreased and the surface area of TiO₂/SiO₂ particles monotonically increased with an increase of the silica content. From FT-IR analysis, the band for Ti–O–Si vibration was observed and the band intensity for Si–O–Si vibration increased with an increase of the silica content. The micrographs of TEM showed that the TiO₂/SiO₂ nanoparticles had a spherical and a narrow size distribution. In addition, TiO₂/SiO₂ particles showed higher photocatalytic activity than pure TiO₂ and the TiO₂/SiO₂ (90/10) particles showed the highest activity on the photocatalytic decomposition of p-nitrophenol.     

Local structure and photocatalytic activity of B2O3–SiO2/TiO2 ternary mixed oxides prepared by sol–gel method

The local structure and the photoactivity of B₂O₃–SiO₂/TiO₂ ternary mixed oxides (SiO₂ content was fixed as 30 at.% with respect to TiO₂) was investigated by using XRD, FT-IR, BET, UV-vis spectra, and electron paramagnetic resonance (EPR) measurement. In FT-IR analysis, boron was incorporated into the framework of titania matrix with replacing Ti---O---Si with Si---O---B or Ti---O---B bonds. Also, paramagnetic species such as O⁻ and Ti³⁺ defects were formed by the boron incorporation. In SiO₂/TiO₂ mixed oxides, a blue shift in the light absorption band was observed due to the quantization of band structure. All B₂O₃–SiO₂/TiO₂ samples had pure anatase phase and no rutile phase was formed even though the calcination temperature was over 900 °C. Incorporating boron oxides of more than 10% enlarges the grain size of anatase phase and causes a red shift of the light absorption spectrum. The surface area was monotonically decreased with increasing the content of boron content. As a result, the photoactivity of B₂O₃–SiO₂/TiO₂ ternary mixed oxides was greatly influenced by the content of boron oxide. The highest photoactivity (g moles/min l) was obtained when the boron content was 5% and seven times higher than that of silica/titania binary mixed oxide. In addition, the specific photoactivity (g moles/m² l) was maximum still at 5%. It was concluded that the large reduction of surface area, the change of band structure, and more formation of bulk Ti³⁺ sites are responsible for the deterioration in the photoactivity of B₂O₃–SiO₂/TiO₂ ternary mixed oxides when the content of boron is over 10%, although their crystallinity was enhanced by increasing the calcination temperature with keeping anatase phase.     

二氧化钛相变研究现状

综述了二氧化钛由锐钛矿型向金红石型转变的影响因素,重点研究了温度调控与添加剂调控对二氧化钛锐钛矿型向金红石型转变的影响和作用机理。结果表明：温度调控能直接有效地促进二氧化钛锐钛矿型向金红石型转变;掺杂熔点低于TiO2的金属氧化物V2O5、SnO2等,离子半径与Ti4+半径相近的Fe3+、V4+、Ce4+等,以及体积小的低价阴离子Cl-、F-等都能促进TiO2由锐钛矿型向金红石型转变。     

Effect of substrate on the phase transformation of TiO2 in pearlescent pigment

The TiO₂/substrate pearlescent pigments were prepared by the hydrolysis of TiOCl₂ on the substrate followed by a calcinations process. The natural mica (muscovite), synthetic mica (fluorophlogopite) and -alumina flake were selected as the substrates for pearlescent pigments. The effect of substrate on the anatase to rutile (A–R) phase transformation of TiO₂ was studied. The A–R phase transformation of TiO₂ during the preparation of pearlescent pigments and their proportion in the TiO₂ layer have been analyzed by XRD measurements. The phase compositions of TiO₂ layer in each pearlescent pigment are quite different depending on the substrates. The TiO₂ layer deposited on -alumina has higher rutile fraction than those on the natural and synthetic mica. The XPS analysis showed that the cations originally present in the substrates diffused into the TiO₂ layer. The TiO₂ layer deposited on -alumina contains Al, while those on the natural and synthetic mica substrates contain Si and K in addition to Al. The metal cations diffusing from the substrate into TiO₂ layer might retard the A–R phase transformation of TiO₂. The suppressing effect on the A–R transformation of TiO₂ by mixed cations seems to be much stronger than that of single cation, resulting in relatively higher rutile fraction in the case of TiO₂ layer deposited on -alumina.     

TiO2、ZnO和TiO2/ZnO三种氧化物粉体材料的抗菌性能对比

氧化物具有化学性质稳定、原材料丰富易得的优点,其作为抗菌材料日益受到关注。对氧化物的抗菌性能及影响因素开展深入研究,能够为新型抗菌材料的开发提供科学依据。通过溶胶-凝胶法制备出了TiO₂/ZnO复合粉体,并将其与TiO₂、ZnO进行对比,分别对它们的晶相结构、微观形貌和粒径进行了表征。利用大肠杆菌ATCC25922作为受试菌株,通过抑菌环试验和菌液接触试验对3种氧化物粉体材料的抗菌性能进行测试。考察了钛锌比、光照等条件对抗菌效果的影响。结果表明,所使用的TiO₂主要由锐钛矿相和金红石相组成,ZnO主要为六方纤锌矿相,制备出的TiO₂/ZnO则主要是锐钛矿型TiO₂在六方纤锌矿型ZnO的孔隙间沉积而成,这3种粉体材料的粒径由大到小分别为TiO₂/ZnO、TiO₂和ZnO。从抑菌环和菌液接触试验的结果可以看出,ZnO粉体材料的抗菌效果明显优于TiO₂粉体材料,ZnO和TiO₂/ZnO在黑暗条件下仍有良好的抗菌性能,但在可见光照射条件下抗菌效果更佳。ZnO含量是TiO₂/ZnO复合材料抗菌性能的关键因素。制备TiO₂/ZnO粉体材料时的煅烧温度对其抗菌性能没有明显影响。     

Photoactivity of anatase–rutile TiO2 nanocrystalline mixtures obtained by heat treatment of homogeneously precipitated anatase

Nanosized titanium dioxide photocatalysts with varying amount of anatase and rutile phases have been synthesized. Homogeneous precipitation of aqueous solutions containing TiOSO₄ with urea was used to prepare porous spherical clusters of anatase TiO_2. Photoactive titania powders with variable amount of anatase and rutile phases were prepared by heating of pure anatase in the temperatutre range 800–1150 °C. The structure evolution during heating of the starting anatase powders was studied by XRD analysis in overall temperature range of phase transformation. The morphology and microstucture characteristics were also obtained by HRTEM, BET and BJH. The spherical particle morphology of TiO₂ mixtures determined by SEM was stable in air up to 900 °C. The photocatalytic activity of the sample titania TIT85/825 heated to 825 °C in air, contained 77.4% anatase and 22.6% rutile was higher than that nanocrystalline anatase powder. Titania sample TIT85/825 reveals the highest catalytic activity during the photocatalyzed degradation of 4-chlorophenol in aqueous suspension.     

Al2O3@TiO2复合生物载体的制备及其BSA吸附特性

通过钛酸盐和氧化钛溶胶两种制备途径在氧化铝（Al₂O₃）支撑体外包覆介孔氧化钛（TiO₂）层,分析了这两种途径制备的氧化钛表面结构与性质的差异及其对于BSA蛋白吸附性能的影响。以粒径分别为0.37、10.4和21.8 mm的三种氧化铝支撑体作为基材,用XRD、Raman分析了两种路径制备的氧化钛晶型均为锐钛矿相;N₂吸脱附分析其比表面积均在（100±10）m²·g^-1,两者具有相似的介孔结构。FESEM分析发现钛酸钾溶胶制备的氧化钛的形貌受到支撑体孔径的影响。对于在牛血清蛋白（BSA）吸附实验中,钛酸钾溶胶法包覆的20 mm粒径复合载体（SP20@K-TiO₂）吸附量为22.18 mg·g^-1,高于相同条件下氧化钛溶胶制备的Al₂O₃@TiO₂复合载体。SP20@K-TiO₂ 中TiO₂吸附量为150.88 mg·g^-1,相比于TiO₂粉体,复合载体中TiO₂对BSA蛋白吸附的性能得到提升。