不同暴露比例(001)晶面锐钛矿相TiO2纳米方块的合成及气敏性能

在众多提高TiO_2气敏性能的尝试中,晶面调控的方法引起了极大的关注。主要通过调整水热反应的制备工艺,实现TiO_2的(001)晶面暴露不同比例,对其进行气敏性能的研究。通过改变反应物浓度完成了一系列不同晶面暴露比的TiO_2纳米方块的可控水热合成,实现了对TiO_2纳米方块形貌以及晶面的调控。合成TiO_2纳米方块暴露(001)晶面的比例从33.33%增加到83.33%。随(001)晶面暴露比例的提高,对于丙酮气体的灵敏度从14.3提高到了27.8。     

TiO2薄膜的自组装及其光电性能研究

采用蒸发诱导自组装方法,在导电玻璃基体上制备了具有高热稳定性、高比表面积的TiO_2薄膜。运用扫描电子显微镜、X射线衍射分析仪对TiO_2薄膜的形貌和结构进行了分析,表明制备出的纳米晶TiO_2薄膜具有多孔的锐钛矿结构,晶粒平均尺寸d为29.2nm。以D102染料敏化的TiO_2薄膜为阳极,0.3mol/L KI溶液为电解液,铂电极为阴极,组成太阳能电池,通过电流-电压曲线研究了太阳能电池的性能。结果表明:太阳能电池的J短路为17.80mA·cm-2,U开路为0.60V,填充因子FF为0.54,光电转换效率为0.39%。     

室内照明空气净化生态环境技术发展态势分析

通过2005-2015年间室内照明(可见光)空气净化TiO_2光催化氧化生态环境技术领域的文献定量分析,结合定性调研,表明相关研究主要集中在中国、日本、美国、韩国、法国、英国、印度、德国、意大利、西班牙这10个国家。近10年来,这个领域的技术前沿是:对TiO_2进行改性,提供更优异的光催化氧化性能;在拓展TiO_2可见光催化活性的同时,又不影响紫外光的催化活性;TiO_2的失活。未来的发展趋势是利用前沿技术解决大规模商业化生产和利用面临的挑战问题。     

p-n异质结NiO/TiO2纳米复合材料的构建及应用研究进展

TiO_2和NiO分别作为n型和p型半导体材料,通过复合构建p-n异质结NiO/TiO_2纳米复合材料可以促进光生电子-空穴对的分离,从而提高光电性能。综述了不同形貌的p-n异质结NiO/TiO_2纳米复合材料的构建,如纳米球、纳米棒和纳米带等,以及其在光催化、锂离子电池、染料敏化太阳能电池和传感器等领域中的最新研究进展。     

可见光下利用ZrO2(Er3+)/TiO2光催化降解海水中柴油污染

通过共沉淀法自制上转换材料与TiO_2复合的纳米光催化剂;利用SEM、XRD等方法对光催化剂进行表征;通过改变催化剂掺杂比、pH值、催化剂投入量、光照时间和柴油初始浓度研究了可见光下光催化降解海水中柴油污染的影响因素以及复合光催化剂ZrO_2(Er3+)/TiO_2的利用效率,通过正交试验优化海水中柴油污染的降解;进行动力学分析,计算总反应速率表达式。结果表明,当柴油初始浓度为0.20g/L,催化剂投加量为0.8g/L,催化剂掺杂比为40%,pH为7,光照时间为2.5h时,复合光催化剂的利用效率最高,柴油的去除率达到87.74%。ZrO_2(Er3+)/TiO_2在可见光下能够有效地降解海水中的柴油污染。     

不同形貌Ag修饰TiO_2的制备及其光催化性能研究进展

TiO_2凭借其优越的光催化性能,在环境治理方面得到了广泛应用。为了增加纯TiO_2的可见光利用率以及提高其量子效率,Ag修饰TiO_2得到了广泛的研究。根据光催化剂形貌分类,综述了近年来Ag修饰TiO_2微粒、薄膜、纳米管、纳米线的制备工艺以及光催化性能研究,并展望了Ag改性后的TiO_2应用前景。     

TiO_2晶须的制备与应用进展

TiO_2晶须因其特有的棒状结构具有良好的分散性、优异的消光效果以及光催化性能在不同领域有着较为广泛的应用前景。介绍了近年来TiO_2晶须材料的制备方法,并对TiO_2晶须的研究现状和发展趋势进行了概述。     

TiO2纳米晶薄膜的制备及其体外细胞毒性的实验研究

分别采用高功率脉冲磁控溅射(HPPMS)技术和直流磁控溅射(DCMS)技术在单晶硅基片上制备出两种晶粒尺寸的TiO_2纳米晶薄膜;采用ISO10993-5:1999标准中的浸提液法对TiO_2薄膜的体外细胞毒性进行评价和研究。实验结果表明,在TiO_2纳米晶薄膜浸提液中细胞生长相对增殖率(RGR)为93%~96%,细胞毒性评级为1级,TiO_2纳米晶薄膜作为生物医学材料满足临床应用的要求;对两种晶粒尺寸的薄膜进行体外细胞毒性的评级,结果无差异。     

不同种类金属掺杂改性TiO2材料光催化性能的研究进展

半导体光催化剂因可以直接利用太阳光进行光催化且不产生二次污染,成为一种应用于环境污染治理领域较为理想的材料。其中TiO_2光催化剂具有较高的光稳定性、良好的化学性质、无毒、较低的成本、高的光催化效率等特点,目前受到广泛的研究与关注。然而,TiO_2快速复合的电子-空穴及较大的禁带宽度等自身缺陷,导致其量子产率不高,TiO_2中的电子只能在紫外光下被激发,这些因素使得它的光催化性能受到了制约。因此,近年来通过研究不同的金属元素掺杂TiO_2基光催化剂及研究不同特殊微纳结构来克服TiO_2自身缺陷以改善其光催化性能并取得较大的进展。研究发现,通过将不同金属(如Ag、Fe、Cu、Ce等)以一元、二元、多元的形式掺入TiO_2中,可改善TiO_2的自身缺陷,并在催化剂表面产生不同作用,使其光响应范围增大,光催化性能显著提升。此外,研究者们还发现,特殊微纳结构的存在可以加快金属掺杂TiO_2基光催化材料的电子转移,从而提高TiO_2光生电子-空穴的分离效率,增加了其量子产率。金属掺杂后,TiO_2对有机物的降解率及其产氢能力、光能转化率都得到了显著的提高,使其不仅在紫外光下具有优异的性能,而且在可见光下也能进行良好的光催化。掺杂后TiO_2的抗菌效果与防雾性能也得到了显著的提升。本文一方面综述了不同金属掺杂体系(一元、二元复合以及多元复合掺杂)对TiO_2结构及其光催化性能的改变,总结不同制备工艺对TiO_2结构与性能的影响规律,并分析光催化性能的增强机制。另一方面概述了金属掺杂TiO_2基复合材料的一些特殊微纳结构包括石墨烯包覆结构、核-壳结构以及其他结构的制备工艺,并讨论了不同微纳结构与金属掺杂在增强TiO_2光催化性能上所起的作用。最后简单综述了不同金属掺杂TiO_2纳米复合材料的不同应用,展望了未来研究方向及应用领域。     

Fe2O3/TiO2纳米管光催化降解微环境苯系物的实验研究

采用阳极氧化-阴极沉积-阳极氧化法制备了三氧化二铁/二氧化钛(Fe2O3/TiO_2)复合纳米管阵列,以室内空气典型污染物苯系物为模拟反应物,研究了湿度与催化剂用量对苯系物气体光催化降解效果的影响,并分析了Fe2O3/TiO_2复合纳米管光催化降解苯、甲苯、乙苯、二甲苯、苯乙烯的反应历程。结果表明:该Fe2O3/TiO_2复合纳米管排列整齐均匀,相对纯TiO_2具有较高的可见光响应特性;光功率密度为0.9W/cm2、停留时间为10min,不同湿度和催化剂用量条件下总苯系物的降解率可以达到75%~95.3%;当湿度为60%,光催化剂用量为50cm2或62.5cm2时,各组分的降解率达到最高;湿度为0~30%,催化剂用量为25~37.5cm2时,各组分的降解率较高;在不同湿度下,苯系物各组分的氧化历程主要受正水离子及超负氧离子的数量影响。     

Fabrication of photocatalytic heat-mirror with TiO2/TiN/TiO2 stacked layers

The photocatalytic heat-mirror based on TiO₂/TiN/TiO₂ stacked layers is prepared by reactive magnetron sputtering on quartz substrates under substrate-heating condition. We find that the addition of a thin Ti interlayer between the TiN and the outer TiO₂ layers drastically improves the heat-insulating performance. This type of stacked layer also exhibits higher photocatalytic activity for decomposition of acetaldehyde gas, compared with a TiO₂ single layer. The optical property of the TiN in TiO₂/TiN/TiO₂ stacked layers is the key not only revealing excellent heat-insulating effect but also improving the photocatalytic performance of the outer TiO₂ layers in the stacked layers.     

等离子体电解氧化法制备多孔TiO2/V2O5复合物膜层及其增强光催化产氢活性

较差的光催化产氢效率极大地阻碍了TiO₂光催化剂的工业化应用。为此,本文在含有NH₄VO₃的磷酸盐溶液中,采用等离子体电解氧化(PEO)法制备了多孔TiO₂/V₂O₅复合膜光催化剂,通过扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、X射线光电子谱(XPS)和紫外可见漫反射光谱(UV-Vis DRS)对其组成、结构及光吸收性质进行了表征,并采用气相色谱评价了薄膜催化剂的光催化产氢性能,研究了电解液中NH₄VO₃含量对膜的结构、组成和光催化产氢性能的影响。结果表明:复合膜催化剂主要由锐钛矿和金红石型TiO₂组成,具有微孔结构,V₂O₅主要以无定形形式存在于膜中,与TiO₂有很强的相互作用,影响TiO₂的晶面间距。研究发现,元素V抑制了TiO₂的结晶和金红石型TiO₂的形成,扩大了薄膜的光学吸收范围。针对Na₂S+ Na₂SO₃溶液中的光催化产氢性能的研究显示,在质量浓度为1 g/L NH₄VO₃的电解液中制备的TiO₂/V₂O₅薄膜的光催化活性最高,优于近年来报道的其他光催化剂。光催化重复实验表明,该复合膜催化剂具有较高的稳定性和较为恒定的光催化活性。     

基于BP神经网络的Cu-Ce掺杂TiO2光催化剂性能预测组合模型研究

采用环境测试舱模拟可见光下的室内环境,以甲醛气体的光催化降解为探针反应,评价了Cu-Ce/TiO2光催化剂的光催化活性及对甲醛气体的去除效果。利用指数平滑-神经网络ES-BP组合模型对Cu-Ce/TiO2光催化剂的性能做预测分析。结果表明:经过Cu-Ce/TiO2光催化剂处理后细木工板中甲醛释放浓度明显降低,平均光催化降解甲醛气体效率为42.8%;ES-BP组合预测模型在Cu-Ce/TiO2光催化剂的性能预测中取得了较好的效果,平均绝对误差为-0.00011mg/m3,平均相对误差为-0.317%;ES-BP组合预测模型实现了BP神经网络模型和指数平滑模型的优势互补,提高了对数据长期预测的准确性。     

Photocatalytic performance of very thin TiO2/SnO2 stacked-film prepared by magnetron sputtering

TiO₂/SnO₂ stacked-layers are synthesized by reactive sputter deposition on the glass substrate. Very thin TiO₂/SnO₂ bilayer-photocatalysts exhibited a very high photocatalytic activity for a degradation of gaseous acetaldehyde. Both the control of an electronic structure of TiO₂ overlayer in the near-surface region and the interfacial separation of photogenerated electrons/holes in the TiO₂/SnO₂ stacked-layer are keys to improve the photocatalytic performance.     

Enhancement of photocatalytic properties of TiO2 nanobelts through surface-coarsening and surface nanoheterostructure construction

In this work, heterostructures were obtained by uniformly assembling NiO nanoparticles on the surface-coarsened TiO₂ nanobelts through a precipitation process. The uniform assembling of NiO nanoparticles led to a large number of nano-p-n-junction heterostructures on the surface of the TiO₂ nanobelts, where NiO and TiO₂ are p- and n-type semiconductors, respectively. Compared with both pure NiO nanoparticles and TiO₂ nanobelts, NiO nanoparticles/TiO₂ surface-coarsened nanobelt heterostructured composite exhibited a greatly enhanced photocatalytic activity in the decomposition of a model dye compound methyl orange under ultraviolet light irradiation. It was argued that the nano-p-n-junctions effectively reduce the recombination of electrons and holes, thus resulting in enhanced photocatalytic property of the heterostructured composites. The better performance of the surface-coarsened nanobelts is due to the increased photo absorption and production of charge carriers, which renders the composites with further enhanced photocatalytic performance. The established approach allows the control of the nano-p-n junction heterostructure on the nanobelts, and hence, their photocatalytic effect.     

Synthesis of iron-doped TiO2 nanoparticles by ball-milling process: the influence of process parameters on the structural,optical, magnetic,and photocatalytic properties

Titanium dioxide (TiO₂) absorbs only a small fraction of incoming sunlight in the visible region thus limiting its photocatalytic efficiency and concomitant photocatalytic ability. The large-scale application of TiO₂ nanoparticles has been limited due to the need of using an ultraviolet excitation source to achieve high photocatalytic activity. The inclusion of foreign chemical elements in the TiO₂ lattice can tune its band gap resulting in an absorption edge red-shifted to lower energies enhancing the photocatalytic performance in the visible region of the electromagnetic spectrum. In this research work, TiO₂ nanoparticles were doped with iron powder in a planetary ball-milling system using stainless steel balls. The correlation between milling rotation speeds with structural and morphologic characteristics, optical and magnetic properties, and photocatalytic abilities of bare and Fe-doped TiO₂ powders was studied and discussed.     

双通TiO2纳米管阵列膜制备及应用研究

双通TiO_2纳米管阵列膜的成功制备可有效提高TiO_2纳米管阵列膜的光催化活性,同时还可扩展其在太阳能电池、气体敏感器等方面的应用,具有很强的实际意义。在大量文献调研的基础上,综述了双通TiO_2纳米管阵列膜的阳极氧化制备方法及其在催化与制氢、氢敏特性、分子过滤等方面的应用进展,并侧重讨论了双通TiO_2纳米管阵列膜的分离机制。最后,对双通TiO_2纳米管阵列膜的后续发展方向和应用前景进行了展望。     

Novel method for doping nano TiO2 photocatalysts by chemical vapour deposition

Highly active photocatalytic Fe-doped nano TiO₂ was successfully synthesised by chemical vapour deposition (CVD) method using FeCl₃ as Fe source. CVD was carried out by evaporating FeCl₃ at 350°C in nitrogen flow during 30–90?min. The amount of Fe incorporated into TiO₂ framework is adjusted by the amount of FeCl₃ used and the evaporation time. The obtained sample was characterised by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), energy dispersive X-ray spectroscopy (EDS), UV-Vis, Fourier transform-infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities of the samples were tested in photocatalytic decomposition of 2-propanol in liquid phase using visible light instead of UV light irradiation. Non-doped TiO₂ and high Fe loading TiO₂ samples showed very low photocatalytic activity, whereas the low Fe loading TiO₂ sample exhibited high photocatalytic activity under visible light. The high photocatalytic activity of this sample was rationalised by the existence of defects (Ti–OH groups) as the active sites.     

Photocatalytic degradation of 2,4-dichlorophenol wastewater using porphyrin/TiO2 complexes activated by visible light

The use of TiO₂ as photocatalyst to degrade the organic compounds is an effective method of oxidation process and has been widely studied in environmental engineering. However, TiO₂ absorbed the UV light which is only small part of sunlight reaching earth surface to activate photocatalytic procedure effectively is a major disadvantage. Therefore, studies on the development of new TiO₂ wherein its photocatalytic activity can be activated by visible light which is the major part of sunlight will be valuable for field application. In this study, we evaluate the photocatalytic degrading efficiency of porphyrins/TiO₂ complexes on the organic pollutants under irradiation with visible light (λ = 419 nm). The results showed that the photodecomposition efficiency of 2,4-dichlorophenol (2,4-DCP) wastewater by using porphyrin/TiO₂ irradiated under visible light for 4 h was up to 42-81% at pH 10. These evidences reveal that the system of porphyrin/TiO₂ complexes has also significantly efficiency of photocatalytic degradation for some hazardous or recalcitrant pollutants under visible light irradiation.     

Structural,morphological and photocatalytic characterisations of Ag-coated anatase TiO2 fabricated by the sol–gel dip-coating method

This study reports on the synthesis, characterisation and environmental applications of immobilised Titanium dioxide (TiO₂) as photocatalyst. Nanostructured thin films have been prepared on glass substrates using a layer-by-layer dip-coating method. The crystalline phase and surface morphology of the thin films were investigated by X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM), respectively. The XRD results show that the TiO₂ thin films crystallise in anatase phase and we have found that the thin films consist of titanium dioxide nanocrystals. SEM shows that the nanoparticles are sintered together to form a compact structure and TiO₂ particles coated with silver nanoclusters were observed. Ag-coated TiO₂ films demonstrated photocatalysis performance when irradiated, and the Ag carrier further showed an electron-scavenging ability to mitigate electron–hole pair recombination, which can improve the photocatalytic efficiency. With the oxidisation and electron-scavenging ability of Ag and the photocatalysis ability of TiO₂, Ag-coated TiO₂ can decolour methyl orange (MO) more than bare TiO₂. It is a new approach to form Ag-coated TiO₂ nanoparticles with a simple system and non-toxic materials. The high photocatalytic effect of Ag-coated TiO₂ nanoparticles on pollutant (MO) suggests that it may have a promising future for water and wastewater treatments.