Enhancing visible-light activity of the self-cleaning TiO2-coated cotton fabrics by loading AgI particles

While extending the application of TiO₂ to substrates with low thermal resistance, enhanced visible-light activity of the self-cleaning TiO₂-coated cotton fabrics has been realized by loading AgI particles. Several characterization tools, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy, were employed to study the phase structures, morphologies and optical properties of the samples. The photocatalytic properties of the prepared products were measured with the degradation of methyl orange at room temperature under visible light irradiation. In comparison with TiO₂-cotton fabrics, the dramatic enhancement in the visible light photocatalytic performance of the AgI-TiO₂-cotton fabrics could be attributed to AgI with narrow band gap and the effective electron-hole separations at the interfaces of the two semiconductors. The photocatalytic performances of the AgI-TiO₂-cotton fabrics were maintained for the cycling experiments. In addition, based on the XRD patterns of the AgI-TiO₂-cotton fabrics before and after reaction, AgI was stable in the composites under visible irradiation, indicating that AgI-TiO₂-cotton fabrics could be used as stable and efficient visible-light-induced self-cleaning materials.     

Preparation and photocatalytic properties of sillenite Bi12TiO20 films

Sillenite Bi₁₂TiO₂₀ thin films with high photocatalytic activity have been successfully fabricated by means of chemical solution decomposition, and characterized by X-ray diffraction, energy-dispersive spectroscopy, atomic force microscopy, scanning electron microscopy and UV-Vis spectrophotometry. The photocatalytic activity of Bi₁₂TiO₂₀ thin films has been evaluated by photodegrading methyl orange solution and the effect of processing conditions on the photocatalytic activity has been studied in detail.     

热喷涂法制备的La3+掺杂纳米TiO2粉末的表征

采用等离子热喷涂法以钛酸四丁酯为主要原料制备出稀土离子掺杂的纳米TiO2光催化剂.通过XRD,XPS,TEM,UV-Vis等检测手段对样品进行表征,同时检测了其光催化性能,并分析了掺杂对TiO2的影响机理.结果表明,所制备的La3 掺杂纳米TiO2是锐钛矿相和金红石相混晶结构,粒径分布在10～50nm之间;La3 掺杂能够促进锐钛矿向金红石的转变,同时抑制TiO2晶粒的长大;La3 掺杂使TiO2紫外-可见吸收光谱发生红移;适量La3 掺杂能显著提高TiO2的光催化活性,最佳掺杂浓度为0.5%(与Ti原子摩尔比),甲基橙降解率在90min内可达到82.4%.比纯TiO2高出13.2%.     

Synthesis of monodispersed ultrafine Bi2S3 nanocrystals

Monodispersed ultrafine Bi₂S₃ nanocrystals of ∼3 nm were synthesized via a facile and mild method, in which thioacetamide and bismuth oleate complex were used as the sulfur and bismuth precursors, respectively. The obtained Bi₂S₃ nanocrystals possessed a high surface area of 305 m² g⁻¹. The nanostructures of Bi₂S₃ nanocrystals were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and selective area electron diffraction (SAED) techniques. The optical property of the Bi₂S₃ nanocrystals was studied by photoluminescence spectroscopy. A remarkable blue shift and a band gap of ∼1.5 eV were observed. The shape of the Bi₂S₃ nanocrystals could be tuned by adjusting the initial Bi/S molar ratio and reaction temperature, respectively. A possible burst nucleation mechanism for this monodispersed ultrafine Bi₂S₃ nanocrystals was proposed.     

Modification of TiO2 nanorods by Bi2MoO6 nanoparticles for high performance visible-light photocatalysis

In this work, TiO₂ nanorods were prepared by a hydrothermal process and then Bi₂MoO₆ nanoparticles were deposited onto the TiO₂ nanorods by a solvothermal process. The nanostructured Bi₂MoO₆/TiO₂ composites were extensively characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the Bi₂MoO₆/TiO₂ composites was evaluated by degradation of methylene blue. The Bi₂MoO₆/TiO₂ composites exhibit higher catalytic activity than pure Bi₂MoO₆ and TiO₂ for degradation of methylene blue under visible light irradiation (λ > 420 nm). Further investigation revealed that the ratio of Bi₂MoO₆ to TiO₂ in the composites greatly influenced their photocatalytic activity. The experimental results indicated that the composite with Bi₂MoO₆:TiO₂ = 1:3 exhibited the highest photocatalytic activity. The enhancement mechanism of the composite catalysts was also discussed.     

Low-temperature synthesis of N-TiO2 sol and characterization of N-TiO2 coating on cotton fabrics

To extend the application of N-TiO₂ to substrates with low thermal resistance, N-TiO₂ sol has been successfully synthesized at low temperature by reflux method and N-TiO₂ coating on cotton fabrics has been successfully prepared in a dip-coating process. Several characterization tools, such as X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy, were employed to study the phase structures, morphologies, the chemical states and optical properties of the samples. The photocatalytic properties of the prepared products were measured with the degradation of methyl orange at room temperature under visible light irradiation. In comparison with TiO₂-cotton, the remarkable enhancement in the visible light photocatalytic performance of the N-TiO₂-cotton could be attributed to the existence of N-TiO₂ with narrow band gap. The photocatalytic performances of the N-TiO₂-cotton were maintained for the cycling experiments, indicating that N-TiO₂-cotton could be used as stable and efficient visible-light-induced self-cleaning materials.     

无模板剂的溶胶-水热法合成具有可见光响应的氮掺杂混晶 TiO2(锐钛矿/金红石/板钛矿)纳米棒束

采用无模板剂的溶胶-水热法制备了具有可见光响应的N掺杂锐钛矿/金红石/板钛矿型TiO_2(N-TiO_2)纳米棒束,并利用X射线衍射(XRD)、透射电镜(TEM)、紫外-可见光漫反射光谱(UV-Vis DRS)、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段对获得的样品进行了表征。以甲基橙为模型反应物,评价了N-TiO_2纳米棒束的光催化活性。表征结果结合光催化活性评价结果显示,与P25-TiO_2相比,N掺杂、混晶及纳米棒束之间的协同作用是所制备的混晶N-TiO_2纳米棒束具有良好光催化活性的主要原因,并对混晶N-TiO_2纳米棒束光催化降解甲基橙的机理进行了探讨。     

SnO2@TiO2核-壳纳米线的制备及其光催化性能研究

本文通过固-液-气(VLS)生长机制,利用化学气相沉积法(CVD)制备SnO₂纳米线。利用原子层沉积(ALD)以钛酸四异丙酯为前驱体在SnO₂纳米线表面沉积不同厚度的TiO₂壳层,形成SnO₂@TiO₂核-壳纳米线结构。通过中间Al₂O₃插层,分别制备出金红石和锐钛矿两种不同晶型的TiO₂,从而制备出两种不同复合结构的SnO₂@TiO₂核-壳纳米线。实验研究该复合结构中TiO₂的厚度与晶型对紫外光下光催化降解甲基橙溶液活性的影响。     

Polyacrylamide gel synthesis and photocatalytic performance of Bi2Fe4O9 nanoparticles

In this report, a polyacrylamide gel route is introduced to synthesize Bi₂Fe₄O₉ nanoparticles. It is demonstrated that high-phase-purity Bi₂Fe₄O₉ nanoparticles can be prepared using different chelating agents. Interestingly, however, the particle size of the products is found to be dependent on the choice of chelating agent. The use of EDTA as the chelating agent allows the production of Bi₂Fe₄O₉ nanopowder with a relatively smaller particle size. The photocatalytic experiments reveal that the as-prepared Bi₂Fe₄O₉ nanoparticles possess excellent photocatalytic activity for oxidative decomposition of methyl red under ultraviolet and visible light irradiation. Magnetic hysteresis loop measurement shows that the Bi₂Fe₄O₉ nanoparticles exhibit a weak ferromagnetic behavior at room temperature.     

离子液体辅助制备AgCl/Ag2O复合光催化剂

在离子液体[CPMIm]Cl辅助下,采用沉淀法原位制备了AgCl/Ag2O复合光催化剂。采用X射线衍射仪(XRD)、能量散射光电子能谱(EDS)、扫描电镜(SEM)、比表面仪(BET)和紫外-可见漫反射光谱(UV-Vis DRS)等对AgCl/Ag2O复合光催化剂结构、组成、形貌、比表面积和光吸收性能进行了表征;运用表面光电压谱(SPS)对异质结光催化剂的光生电荷分离特性进行了研究。考察了AgCl/Ag2O复合光催化剂对模拟污染物甲基橙的光催化降解性能。结果表明,AgCl的存在抑制了Ag2O颗粒的生长,增加了复合光催化剂的比表面积和孔容积。AgCl与Ag2O的原位复合有效提高了复合光催化剂光生e^-/h⁺对分离速率,增强了复合光催化剂对甲基橙的光催化降解。捕获测试表明?O2^-是光催化降解甲基橙的主要活性自由基。     

Fabrication of Dy2Ti2O7 nanocrystalline at 700 °C and its photocatalytic activity

Dy₂Ti₂O₇ nanocrystalline was fabricated by a soft-chemistry route named as citric acid sol–gel method (CAM). The fabricating process was monitored by XRD, FT-IR and TG-DTA methods. It was found that compared with traditional solid state reaction (SSR), Dy₂Ti₂O₇ was synthesized at a relatively low temperature (700 °C) and with shortened reaction time (2 h). The morphology and surface composition of obtained products were determined by TEM and SEM-EDX experiments. Results showed that the obtained Dy₂Ti₂O₇ with good dispersibility were all square-like; the average size was about 50 nm and there was ample oxygen-deficient (40%) on the product interfaces. Also, the obtained products had higher BET surface area (25.10 m²/g). These properties are very helpful for a catalyst to achieve excellent photocatalytic activity. Photodecomposition of methyl orange was used as the model system to evaluate its photocatalytic property. It was found that Dy₂Ti₂O₇ showed good photocatalytic activity and the decomposition rate of methyl orange was about 99% within 60 min.     

Effect of calcination temperature on microstructure and photocatalytic activity of BiOX (X=Cl,Br)

A series of BiOX (X=Cl, Br) were prepared by simple hydrolysis and then calcined at various temperatures and they were characterized by XRD, Raman, SEM, DSC–TGA, BET and UV–Vis. The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) solution under simulated solar light irradiation. The results show that the phase structure, crystallite size, morphology, specific surface area, porous structure, and the absorption band-edges are related to the calcination temperature. For BiOBr, it has completely transformed to Bi₂₄O₃₁Br₁₀ at 600 °C and begins to transform to Bi₂O₃ at 800 °C. As for BiOCl, it begins to transform to Bi₂₄O₃₁Cl₁₀ at 600 °C and completely transforms to Bi₂₄O₃₁Cl₁₀ at 800 °C. Finally, the photocatalytic activity of BiOCl decreases with the temperature increasing owing to decrease of the specific surface areas and pore size, while the photocatalytic activity of BiOBr increases in the first stage and then decreases, which is related to good crystallization and three-dimensional structure.     

Fast fabrication of Co3O4 and CuO/BiVO4 composite photocatalysts with high crystallinity and enhanced photocatalytic activity via ultrasound irradiation

A facile and efficient approach for the fabrication of Co₃O₄ and CuO/BiVO₄ composite photocatalysts was developed by intense ultrasound irradiation at room temperature. The as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, UV-vis diffuse reflectance spectra (UV-vis DRS), and Brunauer-Emmett-Teller (BET) surface areas. The photocatalytic activity of the composite catalysts was evaluated by photocatalytic degradation of acid orange II under visible light (λ > 420 nm) irradiation. Results showed that under intense ultrasonic irradiation, the precursors of copper acetate and cobaltous acetate could transform into CuO and Co₃O₄, respectively and the amorphous BiVO₄ can easily crystallize to highly crystalline BiVO₄. The composite photocatalysts exhibited much higher photocatalytic activity than that of pure BiVO₄. The enhanced photocatalytic performance could be attributed to the high crystallinity of BiVO₄ and the formed p-n heterojunction of Co₃O₄/BiVO₄ or CuO/BiVO₄. These two factors can effectively suppress the recombination of photogenerated hole-electron pairs.     

Fe3O4/SiO2/Bi2WO6磁性复合光催化剂的制备及其光催化性能

钨酸铋(Bi₂WO₆),结构最简单的Aurivillius相化合物,是近期受到研究者关注的新型光催化材料。然而,光催化剂粉末在反应介质中难被回收,工业化应用成本较高。本文用三步方法合成了可回收的Fe₃O₄/SiO₂/Bi₂WO₆磁性复合光催化剂,通过溶剂热法合成具有磁性的Fe₃O₄,用溶胶凝胶法在Fe₃O₄表面覆盖SiO₂层,后将磁性颗粒与Bi₂WO₆纳米片相结合。光催化剂的形貌结构及性能通过XRD、SEM、PL、UV-vis进行表征测试。结果表明,直径约500 nm的Fe₃O₄微球附着在边长约500 nm的Bi₂WO₆纳米片的表面,SiO₂在两者之间起到了粘连作用。光催化剂Fe₃O₄/SiO₂/Bi₂WO₆对于罗丹明B的光降解活性较好,且有一定磁性,可以通过外加磁场将其从溶液中分离,有较大的应用潜力。     

Novel AgCl/Ag<Subscript>2</Subscript>CO<Subscript>3</Subscript> heterostructured photocatalysts with enhanced photocatalytic performance

A series of novel AgCl/Ag₂CO₃ heterostructured photocatalysts with different AgCl contents (5 wt%, 10 wt%, 20 wt%, and 30 wt%) were prepared by facile coprecipitation method at room temperature. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), respectively. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of methyl orange (MO) under UV light irradiation. With the optimal AgCl content of 20 wt%, the AgCl/Ag₂CO₃ composite exhibits the greatest enhancement in photocatalytic degradation efficiency. Its first-order reaction rate constant (0.67 h^?1) is 5.2 times faster than that of Ag₂CO₃ (0.13 h^?1), and 16.8 times faster than that of AgCl (0.04 h^?1). The formation of AgCl/Ag₂CO₃ heterostructure could effectively suppress the recombination of the photo-generated electron and hole, resulting in an increase in photocatalytic activity.     

室温水溶液法制备 Cu2O 纳米颗粒及其光催化性能

以乙酸铜为铜源,β-环糊精为表面活性剂,NaOH为添加剂,KBH4为还原剂,在室温水溶液中制备了直径约为50 nm的Cu2O,对产物的组成、能隙、光催化性能进行了分析。研究表明:产物结晶性良好,粒径分布较均匀,且产率高;此外,该纳米Cu2O由于比表面积大,对甲基橙在30 min内的催化效率高达94.9%,甲基橙几乎全部被降解,显示出良好的催化活性。     

Influence of fluorine on the structure and photocatalytic activity of TiO2 film prepared in tungstate-electrolyte via micro-arc oxidation

TiO₂ films were prepared on pure titanium substrate via micro-arc oxidation (MAO) technique in tungstate-electrolyte. The influence of fluorine ion concentration in electrolyte on the microstructure and photocatalytic activity of TiO₂ films was investigated. The results showed that the porosity, element content and phase composition of TiO₂ films were affected by fluorine ion concentration in electrolyte. The number of pores, the content of tungsten and the content of anatase phase all increased when appropriate fluorine ion was added into the electrolyte. Thus, the photocatalytic activity of TiO₂ films could be promoted by adding appropriate fluorine ion into the electrolyte. The addition of fluorine ion did not alter the iso-electric points of TiO₂ films. It was confirmed by UV–Vis spectrophotometer that the photocatalytic activity of the film prepared in electrolyte containing 2 g/L NaF was higher than that of the films prepared in other electrolytes during the degradation of methyl orange.     

Photoluminescence behavior and visible light photocatalytic activity of ZnO,ZnO/ZnS and ZnO/ZnS/α-Fe2O3 nanocomposites

In order to achieve effective, economic, and easily achievable photocatalyst for the degradation of dye methyl orange (MeO), ZnO, ZnO/ZnS and ZnO/ZnS/α-Fe₂O₃ nanocomposites were prepared by simple chemical synthetic route in the aqueous medium. Phase, crystallinity, surface structure and surface behavior of the synthesized materials were determined by X-ray diffraction (XRD) and Brunauer–Emmett–Teller analysis (BET) techniques. XRD study established formation of good crystalline ZnO, ZnO/ZnS and ZnO/ZnS/α-Fe₂O₃ nanomaterials. By using intensity of constituent peaks in the XRD pattern, the compositions of nanocomposites were determined. From the BET analysis, the prepared materials show mesoporous behavior, type IV curves along with H4 hysteresis. The ZnO/ZnS/α-Fe₂O₃ composite shows the largest surface area among three materials. From the UV–visible spectra, the band gap energy of the materials was determined. Photoluminescence spectra (PL) were used to determine the emission behavior and surface defects in the materials. In PL spectra, the intensity of UV peak of ZnO/ZnS is lowered than that of ZnO while in case of ZnO/ZnS/α-Fe₂O₃, the intensity further decreased. The visible emission spectra of ZnO/ZnS increased compared with ZnO while in ZnO/ZnS/α-Fe₂O₃ it is further increased compared with ZnO/ZnS. The as-synthesized materials were used as photocatalysts for the degradation of dye MeO. The photo-degradation data revealed that the ZnO/ZnS/α-Fe₂O₃ is the best photocatalyst among three specimens for the degradation of dye MeO. The decrease of intensity of UV emission peak and the increase of intensity of visible emission cause the decrease of recombination of electrons and holes which are ultimately responsible for the highest photocatalytic activity of ZnO/ZnS/α-Fe₂O₃.     

Formation of Al2O3-Bi4Ti3O12 nanocomposite oxide films on low-voltage etched aluminum foil by sol-gel processing

A water-based bismuth titanate Bi₄Ti₃O₁₂ (BTO) sol was synthesized by mixing bismuth nitrate, tetra-n-butyl titanate, lactic acid, acetic acid and distilled water. The sol was applied to low-voltage etched aluminum foil by dip-coating. The crystallization process of Bi₄Ti₃O₁₂ on low-voltage etched aluminum foil was measured by thermal gravimetry-differential scanning calorimetry (TG-DSC) and high-temperature X-ray diffraction (HT-XRD). It was found that Bi₄Ti₃O₁₂ sol first converted into intermediate phase Bi_1.74Ti₂O_6.624, then transformed into perovskite phase Bi₄Ti₃O₁₂. After annealed at 600 °C for 30 min in air, the low-voltage etched aluminum foil covered with Bi₄Ti₃O₁₂ sol was anodized galvanostatically in 15 wt.% ammonium adipate solution. The voltage-time variation during anodizing was monitored and recorded. The structure and composition of samples were investigated by field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the anodic composite oxide film was composed of an inner Al₂O₃ layer and an outer Bi₄Ti₃O₁₂ layer. The specific capacitance and the product of specific capacitance and withstanding voltage of samples with a BTO coating were about 56.64% and 43.77% larger than that without a BTO coating.     

纳米LiInO2光催化剂的溶胶-凝胶法制备与表征

本文利用溶胶-凝胶法制备了LiInO₂纳米材料,采用X-射线衍射(XRD)、扫描电镜(SEM)和紫外-可见吸收光谱等测试手段,研究了制备条件对LiInO₂微观结构的影响因素,并以亚甲基蓝为目标降解物研究了LiInO₂的光催化性能。研究结果表明：制备的LiInO₂纳米粒子具有LiFeO₂的晶型,颗粒尺寸约50-100纳米,制备样品的焙烧温度对其结构和性能产生了明显地影响,在氙灯(300W)照射90 min条件下,纳米LiInO₂对亚甲基蓝的光催化降解率达92%,活性位点捕获实验表明光生空穴在降解亚甲基蓝的机制中占主导作用。