Fabrication of highly homogeneous Al‐doped TiO2 nanotubes by nanolamination of atomic layer deposition

Conformal parallel arrays of Al‐doped TiO₂ nanotubes were fabricated by atomic layer deposition. TiO₂/Al₂O₃ bilayered shells were grown on a polycarbonate template by various cyclic sequences of TiO₂ and Al₂O₃. The doping level of Al could be tuned by the fraction of cycle number of Al₂O₃. From the depth profiles measured by second ion mass spectrometry, Al is uniformly distributed across the thickness, which is also supported by the analyses of X‐ray diffraction, X‐ray photoelectron spectroscopy, and Raman spectroscopy. A uniform bulk solubility of ~7 at.% and the surface concentration of ~18 at.% were observed with the cycle ratio of Al₂O₃: TiO₂ at 0.04.     

聚丙烯腈/二氧化钛杂化纳米活性碳纤维制备与结构变化规律

以聚丙烯腈(PAN)溶液中掺入二氧化钛(TiO2)为纺丝液,用静电纺丝法通过滚筒接收得到PAN/TiO2平行排布的纳米纤维,对该纳米纤维进行预氧化和活化以期得到一种兼具吸附-光催化的掺杂TiO2的活性纳米碳纤维。分别采用X射线衍射分析(XRD)、红外光谱分析(IR)、扫描电镜分析(SEM)等手段进行表征。通过磷酸活化,最终制得了一种新型的PAN-ACF/TiO2纳米纤维,其纳米纤维的平均直径400nm,孔洞平均直径为37nm。     

二氧化钛纳米管稳定Pickering乳液制备PS/TiO2纳米管复合微球

利用γ-甲基丙烯酰氧基丙基三甲氧基硅烷（KH-570）,对水热法制备的TiO₂纳米管进行了表面改性,并用改性的纳米管为稳定剂,采用Pickering乳液聚合法制备了聚苯乙烯/TiO₂纳米管复合微球。采用红外光谱（IR）、光学显微镜、高分辨透射电镜（HRTEM）、高分辨扫描电子显微镜（FESEM）、X射线光电子能谱（XPS）等分析手段,对改性前后TiO₂纳米管以及复合微球的结构和形貌进行了表征,用三相接触角仪测试并优化了TiO₂纳米管的表面润湿性。研究结果表明,当m_KH-570/m_TiO2=15%时,改性TiO₂纳米管表面润湿性最佳,能很好地稳定Pickering乳液聚合,聚合后可以得到壳层为致密均匀TiO₂纳米管,核为聚苯乙烯的复合微球。     

Investigation of nanostructured TiO2 surface and interface electric fields with photoreflectance spectroscopy

The electrical properties of buried solid–solid interfaces are essential to the optimization of devices such as dye‐sensitized solar cells and photocatalysts. The degree of fixed charge buildup at these interfaces can be sample‐dependent, influenced by only a small fraction of total surface sites, and challenging to quantify. This work describes the applicability of photoreflectance spectroscopy (PR) to the characterization of thin film nanostructured TiO₂. The approach involves the synthesis of polycrystalline anatase TiO₂ on quartz and Si(100) by atomic layer deposition with Ti(OCH(CH₃)₂)₄ and H₂O as precursors. PR reveals negligible band bending at the TiO₂ free surface. A distinct spectral feature at 299.0 ± 0.3 kJ/mol (3.10 ± 0.0031 eV) is attributed to electronic states at the TiO₂‐Si interface. Temporal variations in the magnitude of this feature are discussed in the context of bulk carrier concentration, solid–solid interface chemical reactions, and charge exchange between interface and grain boundary states and the bulk bands. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1049–1055, 2013     

TiO2中空纤维的制备及光催化性能

采用模板法制备了不同温度的TiO2中空纤维光催化材料,并利用X射线衍射、扫描电镜对其晶型及表面形貌进行了表征.以亚甲基蓝(MB)的脱色降解为模式反应,考察了温度对TiO2中空纤维光催化性能的影响.     

ACF负载TiO2处理甲醛过程中催化剂的失活控制

利用ACF负载TiO2光催化降解处理有机废气,以甲醛为处理对象,采用紫外光 水蒸气、紫外光 臭氧的两种控制方法进行对比研究;考察ACF的吸附及催化剂的使用、催化剂的活性状况;在实验基础上分析催化剂失活控制的规律,比较了两种控制方法在不同情况下的优劣。     

Nano‐engineered nickel catalysts supported on 4‐channel α‐Al2O3 hollow fibers for dry reforming of methane

A nickel (Ni) nanoparticle catalyst, supported on 4‐channel α‐Al₂O₃ hollow fibers, was synthesized by atomic layer deposition (ALD). Highly dispersed Ni nanoparticles were successfully deposited on the outside surfaces and the inside porous structures of hollow fibers. The catalyst was employed to catalyze the dry reforming of methane (DRM) reaction and showed a methane reforming rate of 2040 Lh^?1gNi^?1 at 800°C. NiAl₂O₄ spinel was formed when Ni nanoparticles were deposited on alpha‐alumina substrates by ALD, which enhanced the Ni‐support interaction. Different cycles (two, five, and ten) of Al₂O₃ ALD films were applied on the Ni/hollow fiber catalysts to further improve the interaction between the Ni nanoparticles and the hollow fiber support. Both the catalyst activity and stability were improved with the deposition of Al₂O₃ ALD films. Among the Al₂O₃ ALD coated catalysts, the catalyst with five cycles of Al₂O₃ ALD showed the best performance. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2625–2631, 2018     

Atomic layer deposition of Al2O3 on porous polypropylene hollow fibers for enhanced membrane performances

Porous polypropylene hollow fiber (PPHF) membranes are widely used in liquid purification.However,the hydrophobicity of polypropylene (PP) has limited its applications in water treatment.Herein,we demonstrate that,for the first time,atomic layer deposition (ALD) is an effective strategy to conveniently upgrade the filtration performances of PPHF membranes.The chemical and morphological changes of the deposited PPHF membranes are characterized by spectral,compositional,microscopic characterizations and protein adsorption measurements.Al2O3 is distributed along the cross section of the PP hollow fibers,with decreasing concentration from the outer surface to the inner surface.The pore size of the outer surface can be easily turned by altering the ALD cycles.Interestingly,the hollow fibers become much more ductile after deposition as their elongation at break is increased more than six times after deposition with 100 cycles.The deposited membranes show simultaneously enhanced water permeance and retention after deposition with moderate ALD cycle numbers.For instance,after 50 ALD cycles a 17％ increase in water permeance and one-fold increase in BSA rejection are observed.Moreover,the PP membranes exhibit improved fouling-resistance after ALD deposition.     

Improvement of interfacial shear strengths of polybenzobisoxazole fiber/epoxy resin composite by n‐TiO2 coating

Smooth polybenzobisoxazole (PBO) fiber has limited interfacial interaction with resin matrix. In this article, nano‐TiO₂ coating on PBO fiber is applied to improve the interfacial adhesion between PBO fiber and epoxy resin. The test results suggest that the PBO fiber had good interaction with epoxy resin matrix after its treatment with n‐TiO₂ sol. Nano TiO₂ particle embedded onto PBO fiber surface, acting as a chock, which made fiber implanted into the resin better. This greatly improved the shear strengths (IFSS) of PBO fiber/epoxy resin composite. It has been found that a 56% increase in interfacial IFSS has achieved without sacrificing mechanical properties of fiber. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

活性炭纤维负载二氧化钛复合催化剂降解甲基橙性能研究

制备了活性炭纤维负载二氧化钛复合催化剂ACF/TiO2,并在紫外光下降解甲基橙以考察其催化活性。并在同等条件下,对未负载二氧化钛的活性炭纤维空白样品进行了对比实验;同时还考察了ACF/TiO2的循环使用寿命。结果表明,ACF/TiO2降解能力大于未负载的活性炭纤维,其降解能力是吸附性能和光催化性能的协同作用,并拥有较长的循环使用寿命。     

纳米TiO2涂层在低碳钢上的防腐蚀性能

采用溶胶-凝胶法与浸渍提拉法在经过黑化处理后的普通低碳钢上制备了纳米TiO2涂层。分别研究了不同热处理温度以及不同提拉次数所得的纳米TiO2/Ironoxides/Fe在25g/LNaHCO3溶液中,在无光照和紫外光照射下的腐蚀电位。结果表明,在无光照和紫外光照射下,纳米TiO2/Ironox-ides/Fe的腐蚀电位均低于基体的腐蚀电位。纳米TiO2涂层可作为光生阳极从而对低碳钢基体起到阴极保护作用。其最佳工艺条件为提拉4~5次,400℃下热处理1h。     

掺硅TiO2纤维光催化降解活性艳红X-3B的研究

以水中活性艳红X-3B为研究对象评价了自制掺硅TiO2纤维的光催化活性,结合TG-DSC、N2吸脱附、XRD及SEM等手段,探讨了制备过程中升温方式、活化温度及掺硅量等工艺条件对光催化活性的影响.结果表明:(1)采用分段程序升温工艺,前驱体经700℃水蒸气活化2 h,硅的摩尔分数为15%时制得的TiO2纤维光催化活性最佳,反应75 min后X-3B的降解率达99.3%,其降解过程分为脱色和矿化两个阶段;(2)掺硅可有效抑制TjO2的晶相转变及晶粒生长,提高热稳定性并改善表面织构.掺硅TiO2纤维光催化活性高又易于分离回收,是一类新型的水处理光催化功能材料.     

Plasma etching and plasma polymerization coating of carbon fibers. Part 2. Characterization of plasma polymer coated carbon fibers

Unsized AS-4 carbon fibers were subjected to RF plasma etching and/or plasma polymerization coating in order to enhance their adhesion to vinyl ester resin. Ar, N₂ and O₂ were utilized for plasma etching, and acetylene, butadiene and acrylonitrile were used for plasma polymerization coating. Etching and coating conditions were optimized in terms of plasma power, treatment time, and gas (or monomer) pressure by measuring the interfacial adhesion strength. Interfacial adhesion was evaluated using micro-droplet specimens prepared with vinyl ester resin and plasma etched and/or plasma polymer coated carbon fibers. Surface modified fibers were characterized by SEM, XPS, FT-IR, α-Step, dynamic contact angle analyzer (DCA) and tensile strength measurements. Interfacial adhesion between plasma etched and/or plasma polymer coated carbon fibers and vinyl ester resin was reported previously (Part 1), and characterization results are discussed is this paper (Part 2). Gas plasma etching resulted in preferential etching of the fiber surface along the draw direction and decreased the tensile strength, while plasma polymer coatings altered neither the surface topography of fibers nor the tensile strength. Water contact angle decreased with plasma etching, as well as with acrylonitrile and acetylene plasma polymer coatings, but did not change with butadiene plasma polymer coating. FT-IR and XPS analyses revealed the presence of functional groups in plasma polymer coatings.     

Preparation and properties of the three-dimensional highly thermal conductive carbon/carbon-silicon carbide composite using the mesophase-pitch-based carbon fibers and pyrocarbon as thermal diffusion channels

The novel three dimensional highly thermal conductive carbon/carbon-silicon carbide (C/C-SiC) composite was successfully prepared using the mesophase-pitch-based carbon fibers and pyrocarbon as the thermal diffusion channels. The results show that the highly thermal conductive C/C-SiC composite with 221.1 W m^?1K^?1 in the ablation direction exhibits a smaller temperature gradient, and the surface temperature is 470 °C lower than that of the lowly thermal conductive C/C-SiC composite. The mass and linear ablation rates of the highly thermal conductive C/C-SiC composite are 0.56 mg·cm^?2 s^?1 and 0.11 μm·s^?1, respectively.     

N2等离子体改性介孔TiO2的可见光催化性能及机理

在石英平板介质阻挡放电（DBD）反应器中,采用氮气（N₂）低温等离子体改性制备介孔TiO₂光催化剂（M-TiO₂）。借助XRD、TEM、BET、UV-vis DRS和XPS等手段对M-TiO₂进行表征分析。结果表明,N₂等离子体与煅烧相结合的处理方式下制得的M-TiO₂较单纯煅烧处理方式具有更优的可见光催化性能。当CTAB/Ti摩尔比为1/3时,三种M-TiO₂中M-TiO₂(CTP+C)的比表面积最高（238.2m²/g）,禁带宽度最窄（2.51eV）,O_V/O最大（35.7%）;可见光持续照射240min时,M-TiO₂(CTP+C)对甲基橙（MO）的光降解率最高,达90%以上,且循环稳定性良好。N₂低温等离子体改性过程可有效改善M-TiO₂晶粒的分散性,促进Ti⁴⁺向Ti³⁺的转化,其可见光催化活性的提高主要归因于氧空位、间隙碳和间隙氮三者的共同作用。活性物种捕获实验和莫特-肖特基曲线测试结果表明,可见光下降解甲基橙的过程中起主要作用的是O₂^▪-和h⁺。在此基础上,给出了M-TiO₂(CTP+C)可见光催化的机理模型。     

天然炭纤维负载二氧化钛颗粒的制备与光催化活性

以棉花制备的炭纤维为载体,钛酸丁酯为钛源,采用水热法制备炭纤维负载二氧化钛复合材料(CF/TiO2),利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等对CF/TiO2复合材料进行结构表征.用紫外-可见光吸收光谱(UV-vis)分析比较了TiO2、炭纤维和CF/TiO2,热处理温度以及溶液的pH值在紫外光照下对甲基蓝溶液的光催化降解性的影响,以及对CF/TiO2复合材料的失活性能研究.结果表明:炭纤维负载TiO2对甲基蓝光催化降解性较好,有效利用了炭纤维的吸附性与TiO2的催化活性;当热处理温度为220℃,pH =5时,甲基蓝溶液的吸附-光催化性能最大为85.9％;复合光催化剂使用后在紫外线照射后,其活性恢复,可以循环利用.     

改性活性炭负载TiO2光催化降解硝基苯

制备经铁改性的活性炭负载TiO2的光催化剂,以40 W紫外线灯为光源,对硝基苯的光降解反应进行了研究。探讨了经铁改性活性炭负载TiO2光催化剂的用量、降解的反应时间、硝基苯初始浓度、溶液pH、反应温度对反应的影响。结果表明,在紫外灯光照射下,以0.01－0.08 g该催化剂处理25 mL的10－100 mg/L硝基苯溶液,均有明显的降解效果,最佳的降解时间和pH分别为40 min和6.6。     

Pushing the limits of high performance dual‐layer hollow fiber fabricated via I2PS process in dehydration of ethanol

The immiscibility induced phase separation (I²PS) process was introduced as a novel method to fabricate hollow fibers with exceptionally high water permeance and reasonably high water/ethanol selectivity in dehydration of ethanol by pervaporation. As a continuation of the previous work, this study discloses the mechanisms to enhance the performance of hollow fibers spun via I²PS by elucidating the material selection at the inner‐layer. Moreover, it revealed the methods to reduce mass‐transport resistance by enhancing surface porosity for both inner and outer surfaces to further improve the permeation flux of the membranes. The continuous performance test demonstrates that the fibers spun from the I²PS possess a stable dehydration performance throughout the monitored period of 300 h. A comparison with pervaporation membranes in the literatures verifies the superiority of the membranes spun via I²PS process with the highest water permeation flux of 9.5 kg/m² h and the permeate water purity of 95.8 wt % at 80°C. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3006–3018, 2013     

微乳液法制备纳米TiO2/活性炭复合体的研究

纳米TiO2是一种高效的光催化剂,而光催化剂的制备和固化是光催化技术应用的关键。采用油酸/正丁醇/NaOH溶液制备了纳米TiO2/活性炭复合材料。用微乳体系制备出纳米二氧化钛前驱体,然后由表面活性剂稳定和保护的纳米粒子在氢键吸附等作用力下包覆于活性炭载体的表面。用热重-差热分析、扫描电镜、红外光谱法对其结构进行分析。结果表明:所制得TiO2粒径为20 nm左右,呈球形分布于活性炭表面。用分光光度法测得TiO2的包覆率为28.2%。     

Optical and thermal properties of TiO2-doped Y2O3 transparent ceramics synthesized by hot isostatic pressing

Highly transparent Y₂O₃ ceramics using TiO₂ as an additive were synthesized by presintering and hot isostatic pressing (HIP). The effects of TiO₂ contents and sintering conditions on the optical properties of the final transparent ceramics were investigated. A small amount (0.04-0.16 wt%) may decrease the densification temperature by about 200°C. The Y₂O₃ ceramics doped with 0.16 wt% TiO₂ revealed a transparency of 82% in the wavelength range 1-6 μm. The thermal conductivity of the samples is about 11.8 W/m K at 25°C, which is close to that of the undoped Y₂O₃ ceramics.