不同基底对TiO2和SiO2薄膜的光学性能的影响

采用溶胶-凝胶法分别在K9玻璃、单晶硅和石英玻璃基底上制备了纳米TiO₂和SiO₂薄膜。利用SEM、UV-Vis及反射式椭圆偏振光谱仪对薄膜的微观结构及光学特性进行了表征和分析。结果表明：3种基底中, 单晶硅基底上TiO₂和SiO₂薄膜折射率最大;在非晶态K9玻璃和石英玻璃基底上TiO₂薄膜折射率和透光率差异较大;SiO₂薄膜在非晶态基底上折射率、透光率相近;3种基底上薄膜的折射率和消光系数都有随波长增大而减小的趋势, 同时Cauchy模型能较好的描述单晶硅基底上两种薄膜在400~800 nm波段的光学性能。     

微乳法制备纳米TiO2 /SiO2的结构及光催化研究

Nanosized TiO₂ and TiO₂/SiO₂ particles were prepared by hydrolysis of tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS) in the TX-100 reverse microemulsion. These particles were characterized by TG-DSC, XRD, FTIR, TEM，N₂ adsorption-desorption. Their photocatalytic activity was tested by degradation of methyl orange. The result shows that TiO₂/SiO₂ nanoparticles are with a monodispersed spherical phase and a uniform size distribution，and TiO₂ particles are dispersed on the surface of SiO₂. The band for Ti-O-Si vibration in FTIR was observed, the Ti-O-Si bond increased the stability of anatase TiO₂, suppressed the phase transformation of titania from anatase to rutile. And due to the addition of SiO₂, the average size of titania decreased from 38 nm in pure TiO₂ to 5 nm in TiO₂/SiO₂. It was found, under UV light irradiation, TiO₂/SiO₂ particles showed higher activity than pure TiO₂, and TiO₂/SiO₂(1/1) particles showed the highest photocatalytic activity on the photocatalytic decomposition of methyl orange, which was influenced by crystal structure, particle size, crystallinity and Surface area Characteristics.     

具有光催化性能的TiO2-SiO2/TiO2两层增透膜的设计与制备

采用膜层设计理论设计了以TiO₂为内层膜,TiO₂-SiO₂复合膜为外层膜的两层增透膜,以钛酸丁酯（TBOT）和正硅酸乙酯（TEOS）作为前驱体,采用溶胶-凝胶法制备了TiO₂溶胶以及SiO₂溶胶,将两种溶胶按比例混合得到了TiO₂-SiO₂复合溶胶,在高硼硅玻璃上镀膜测试。透过率测试结果表明,在波长为550nm处的透过率最高能达到99.4%。在光催化实验中,采用罗丹明B模拟有机污染物,考察了TiO₂对光催化反应的影响。结果表明,在TiO₂存在的情况下,罗丹明B的降解速度大大提高,光催化效率显著增加。     

CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.     

多重射流燃烧反应制备的TiO2/ SiO2纳米复合颗粒的形态和结构

TiO₂-SiO₂ nanocomposite particles were prepared in premixed H₂ / Air flame, and the morphology and structure of these nanocomposites were characterized by FTIR, XRD, TEM and HRTEM. The morphology of SiO₂ / TiO₂ nanocomposites was different from that of pure TiO₂ or SiO₂ nanoparticles, and the chemical bond of Ti-O-Si was found in the nanocomposites indicating that the TiO₂ / SiO₂ nanocomposites were not merely a physical mixture of TiO₂ and SiO₂. TiO₂ nanocrystalline grains with sizes of 1～2 nm were homogeneously dispersed in the amorphous SiO₂ matrix when TiCl₄ and SiCl₄ were mixed at molecular level in the flame. The particle size and rutile content decreased with increasing of SiO₂ molar ratio.     

TiO2 / SiO2核 / 壳结构复合粒子的组装及其电化学性能

TiO₂ coated SiO₂ materials as anode for lithium-ion batteries were synthesized via an in situ hydrolysis of tetraethyl orthosilicate under ultrasonic irradiation using nanometer-sized TiO₂ colloids as precursors. The XRD patterns indicate that the as-prepared core/shell particles remain anatase after calcining below 800 ℃. TEM observation shows that the particle size of TiO₂ / SiO₂ composites is ca. 200 nm, and a homogeneous SiO₂ layer is coated on the surfaces of TiO₂ particles. FTIR spectra demonstrate that SiO₂ could have been coated on the surfaces of TiO₂ particles via a chemical bonding. In addition, the first specific charge and discharge capacities of the coated particle electrode were 66.4 mAh·g^-1 and 90.7 mAh·g^-1, respectively, which indicates that the TiO₂ / SiO₂ particles are more stable than the monodispersed TiO₂. Meanwhile, the new material has good lithium intercalation-deintercalation performances.     

纳米TiO2-SiO2复合光催化剂的超临界流体干燥法制备及其光催化性能研究

本文以廉价无机盐Na₂SiO₃·9H₂O和TiCl₄溶液为原料,采用化学包覆结合超临界流体干燥(SCFD)法制备纳米级TiO₂-SiO₂复合光催化剂。利用XRD、TEM、NMR等手段对复合粉体进行了表征。结果表明,采用超临界流体干燥法可直接制得锐钛矿型TiO₂-SiO₂纳米复合光催化剂,其中SiO₂以单分散、无定形形式存在。以苯酚和邻苯二酚紫光催化降解为反应模型,考察了TiO₂-SiO₂复合光催化剂的催化性能。证明掺入适量SiO₂的TiO₂-SiO₂纳米复合光催化剂既减少了TiO₂的用量、降低了成本,又在某种程度上提高了TiO₂的光催化活性。SiO₂的引入可以有效抑制纳米粒子粒径的长大和晶相的转变,增强了二氧化钛纳米粒子的热稳定性。二氧化硅的最优掺杂量为15%(质量分数)。     

SnO2TiO2 复合半导体纳米薄膜的研究进展

本文概述了SnO₂TiO₂ 复合半导体纳米薄膜的发展历史和研究现状,对比分析了“混合”、“核壳”和“叠层”3 种复合薄膜的结构和性能特点,着重论述了叠层结构的SnO₂ /TiO₂复合薄膜的光电化学和光催化特性。结合作者的研究工作,探讨了SnO₂ /TiO₂双层复合薄膜上下层厚度对其光催化活性的影响,指出复合薄膜光催化活性的提高可归因于电子从TiO₂ 向SnO₂ 的迁移。最后对SnO₂ /TiO₂复合薄膜的局限性和发展潜势做一简要分析,强调了该复合薄膜本身的应用特点。     

磁载光催化剂TiO2/SiO2/Ni0.5Fe2.5O4的制备及其催化氧化性能

采用固相反应法制备磁载体(SiO₂/Ni_0.5Fe_2.5O₄),溶胶-凝胶法得到易于磁分离回收的磁载光催化剂TiO₂/SiO₂/Ni_0.5Fe_2.5O₄。用XRD、SEM、IR和UV-Vis等进行表征。研究了太阳光下催化剂对亚甲基蓝溶液的脱色性能。结果表明,在太阳光下,磁载光催化剂TiO₂/SiO₂/Ni_0.5Fe_2.5O₄可使亚甲基蓝溶液迅速脱色；3次循环使用后脱色率仍为95%以上,回收率为98.8%。     

CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.     

Antireflective and Self-cleaning Properties of SiO2/TiO2 Double-Layer Films Prepared by Cost-E ective Sol-Gel Process

SiO₂/TiO₂ double-layer films with antireflective and self-cleaning properties were prepared by dip-coating glass substrate into cost-effective SiO₂ and TiO₂ sol successively and subse-quently being calcined at 500 oC. The optical and structural properties of films have been in-vestigated by UV-visible spectrophotometer and field emission scanning electron microscope, respectively. At the same time, self-cleaning property generated from superhydrophilicity and photocatalysis was obtained. The results indicated that the as-prepared SiO₂/TiO₂ double-layer films show maximum transmittance of 95% and self-cleaning property.     

Influence of surfactant and annealing temperature on optical properties of sol–gel derived nano-crystalline TiO2 thin films

Titanium dioxide thin films have been synthesized by sol–gel spin coating technique on glass and silicon substrates with and without surfactant polyethylene glycol (PEG). XRD and SEM results confirm the presence of nano-crystalline (anatase) phase at an annealing temperature of 300 °C. The influence of surfactant and annealing temperature on optical properties of TiO₂ thin films has been studied. Optical constants and film thickness were estimated by Swanepoel's (envelope) method and by ellipsometric measurements in the visible spectral range. The optical transmittance and reflectance were found to decrease with an increase in PEG percentage. Refractive index of the films decreased and film thickness increased with the increase in percentage of surfactant. The refractive index of the un-doped TiO₂ films was estimated at different annealing temperatures and it has increased with the increasing annealing temperature. The optical band gap of pure TiO₂ films was estimated by Tauc's method at different annealing temperature.     

Surface chemistry and optical property of TiO2 thin films treated by low-pressure plasma

The low temperature RF plasma treatment was used to control the surface chemistry and optical property of TiO₂ thin films deposited by RF magnetron sputtering with a very good uniformity at 300 °C substrate heating temperature. The XRD pattern indicates the crystalline structure of the film could be associated to amorphous structure of TiO₂ in thin film. The plasma treatment of TiO₂ film can increase the proportion of Ti³⁺ in Ti2p and decrease in carbon atoms as alcohol/ether group in C1s at the surface. The optical transmittance of the film was enhanced by 50% after the plasma treatment. The surface structure and morphology remain the same for untreated and low-pressure plasma-treated films. Therefore, increase in the optical transmission could be due to change in surface chemistry and surface cleaning by plasma treatment.     

一种简单的提高无定形TiO2光催化活性的方法及其在增透膜中的应用

通过简单的溶胶-凝胶法制备得到了小粒径的无定形TiO_2粒子,并将其沉积在多孔SiO_2膜层表面,多孔SiO_2膜层大的表面积有助于无定形TiO_2的良好分散,高度分散的无定形TiO_2粒子对膜层的光学性能影响较小,通过匹配合适的低折射率的SiO_2膜层,制备得到的SiO_2无定形TiO_2(SiO_2amorphous-TiO_2)膜层表现出和理想单层增透膜相似的光学性能。同时SiO_2amorphous-TiO_2的光催化性能显著提高,明显高于单层无定形TiO_2。而且SiO_2无定形TiO_2膜层甚至表现出比相应的负载锐钛矿型TiO_2的膜层,即SiO_2锐钛矿TiO_2,更高的光催化活性,这一反常现象的原因是,无定型TiO_2膜层表面丰富的羟基有助于减少空穴-电子对的复合,其相对疏松的结构能够加快光生电子-空穴的转移速率,而这些因素的影响超过了晶型结构对光催化活性的影响。同时SiO_2膜层的孔隙结构在浸渍-提拉镀制过程中,自发形成并不需要后续热处理过程,因此,整个SiO_2无定形TiO_2膜层的制备均可在室温下完成,能够实现其在不耐热基片上的应用。     

掺杂钒和硅对TiO2薄膜超亲水性的影响

0引言 TiO2薄膜是众多氧化物半导体薄膜中研究最为广泛的一种材料．其表面的超亲水性和表面自清洁效应开辟了光催化薄膜功能材料的新的研究领域，已成为众多研究者研究的对象。但是如果薄膜仅由TiO2组成，当光照停止，水在TiO2薄膜表面的润湿角逐渐升高．并恢复原始状态。TiO2的禁带较宽，普通光线如太阳光等都不能将其激发．限制了其实际应用。因此如何使TiO2材料的光谱响应范围由紫外光反扩展到可见．光区一日如何更长时间地保持薄膜良好的亲水性是目前研究的重点。     

Preparation and properties of SiO2-TiO2 thin films from silicic acid and titanium tetrachloride

The preparation of SiO₂-TiO₂ thin films by the sol-gel method using silicic acid and titanium tetrachloride as starting materials was studied. The homogeneous sols were obtained by the condensation reaction of silicic acid with titanium tetrachloride in methanol-tetrahydrofuran. The dipcoating of slide glasses and silicon wafers followed by heat treatment gave oxide thin films of 88–93% transmittance, 3000–4500 Å thickness, and 1.45–1.80 refractive index, depending on heat-treatment temperature and TiO₂ content. FT-IR measurement showed that the Si-O-Ti bond is formed even in the sol and films. The variations of film thickness and refractive index on transformation from the gels into the oxides were found to be quite low.     

Recent advances in heterogeneous TiO2 photocatalysis

Current progress in the area of photocatalysis is presented, particularly regarding technological applications. Highly efficient TiO₂ films on different substrates such as tile and glass have been developed for indoor environmental clean-up. TiO₂ films coated on SiO₂-precoated soda lime glass showed about 80% transparency and high photocatalytic activity towards the decomposition of thin oil films. A novel phenomenon, superhydrophilicity, has been observed on these transparent TiO₂ coatings. In addition, we have made use of a microelectrode system to monitor oxidation and reduction products separately. The mechanistic and kinetic aspects of TiO₂ photocatalysis are discussed.     

Electrochromic properties of sputtered TiO2 thin films

TiO₂ thin films were deposited on ITO/Glass substrates by the rf magnetron sputtering in this study. The electrochromic properties of TiO₂ films were investigated using cyclic voltammograms (CV), which were carried out on TiO₂ films immersed in an electrolyte of 1 M LiClO₄ in propylene carbonate (PC). As- deposited TiO₂ thin film was amorphous, while the films post-annealed at 300~600°C contained crystallized anatase and rutile. With the increase of the annealing temperature, the surface roughness of film increased from 1.232 nm to 1.950 nm. Experimental results reveal that the processing parameters of TiO₂ thin films will influence the electrochromic properties such as transmittance, ion-storage capacity, inserted charge, optical density change, coloration efficiency and insertion coefficient.     

Formation of cadmium sulfide (CdS) nanofilm on a Cd(OH)2/SiO2 precursor layer

Dense thin nanostructured films of cadmium sulfide CdS obtained by chemical deposition from aqueous solutions are strongly bound to a substrate due to the formation of cadmium hydroxide Cd(OH)₂ in the system. By X-ray reflectometry and grazing incidence diffraction it is found that at the beginning of the deposition a dense Cd(OH)₂/SiO₂ layer is produced on the surface of a silicon or glass substrate. This layer is formed through the atomic-layer adsorption of crystalline 1–3 nm thick Cd(OH)₂ film by the oxygencontaining substrate surface. During sulfidation of this cadmium-containing substrate layer, a surface nucleation layer of CdS/Cd(OH)₂/SiO₂ forms, which provides the growth, denseness, and strong adhesion to the substrate of nanostructured CdS film with a disordered structure. According to the obtained experimental data, a “hydroxide scheme” of film deposition is confirmed and refined, and the stages of CdS nanofilm formation are determined.