室温下介孔MnO2降解低浓度甲醛的研究

本文以KMnO₄和P123为原料采用溶胶-凝胶法在不同条件下制备了介孔MnO₂。研究了反应物比和pH对催化剂结构和催化降解性能的影响。溶胶-凝胶法制备介孔MnO₂的最佳条件为：原料配比为10：1,pH值为7。合成材料的结构和性能采用XRD、N₂吸脱附、FT-IR的测试方法表征,结果表明P123和KMnO₄合成的介孔MnO₂具有较大的比表面积和孔径,且有良好的HCHO催化降解性能。最后讨论了介孔MnO₂催化氧化HCHO的影响因素,发现在pH7 的情况下最有利于介孔MnO₂的活性稳定;在原料比为10：1情况下生成的介孔MnO₂比表面积较大,催化降解性能较强,在10h内保持在对甲醛的降解率为95%以上。     

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。     

g-C3N4/MoS2纳米片异质复合物的球磨法制备及可见光催化性能研究

采用球磨法制备g-C₃N₄/MoS₂纳米片异质复合物,运用X-射线衍射仪、高分辨透射电镜、紫外可见漫反射光谱和荧光发射光谱对异质复合物的结构和形貌进行了表征。结果表明：MoS₂纳米片可进入g-C₃N₄的层间形成异质复合物。以罗丹明B为模拟污染物,在可见光照射下考察了复合物的光催化特性。结果显示,含有2%的MoS₂纳米片与g-C₃N₄形成的异质复合物在120min内对罗丹明B降解率为98%,其降解动力学常数是体相g-C₃N₄为的4.3倍。g-C₃N₄/MoS₂纳米片异质复合物具有十分优良的光催化特性。其催化活性的提高主要归因于光生电子和空穴的有效分离和传输,并根据光捕获实验提出复合物可能的光催化机理。     

溶胶凝胶法制备含铁介孔催化剂用于二苯甲烷的合成

本文采用溶胶凝胶法以柠檬酸铁为铁源合成含Fe纳米介孔材料。室温下凝胶样品60 ℃真空干燥后得到的干凝胶采用热重分析(TG)。最终400 ℃焙烧3 h得到介孔Fe₂O₃/SiO₂纳米粒子。合成材料的结构和性能采用XRD、N₂吸脱附、TEM、FT-IF、及H₂-TPR测试方法表征,结果显示合成了尺寸约50 nm的带有30-45? 介孔孔道的球形的Fe₂O₃/SiO₂纳米粒子,并且成功引入了高分散的Fe₃₊物种。催化性能是通过傅克烷基化法合成二苯甲烷的反应测试的,实验结果表明该催化剂具有优异的催化性能,高达100 % 苄基氯的转化率和相对较高的二苯甲烷的选择性,并且能够重复利用。     

溶胶-凝胶法制备ErFeO3及其可见光催化性能研究

钙钛矿结构的ErFeO₃是一种新型的光催化材料。本文以Er(NO₃)₃.5H₂O、Fe(NO₃)₃×9H₂O、柠檬酸和尿素为主要原料,采用溶胶-凝胶法制备得到ErFeO₃的凝胶,将凝胶于80 ℃烘箱中48 h得到干凝胶,然后将干凝胶于700-1000 ℃煅烧制备ErFeO₃。通过热重-差示扫描量热法(TG-DSC)、X射线衍射谱(XRD)、扫描电镜(SEM)、傅立叶红外光谱(FT-IR)和漫反射谱(DRS)等对ErFeO₃进行表征。以甲基橙溶液为模拟污水,研究了ErFeO₃的可见光催化性能。结果表明：制备得到了钙钛矿结构的ErFeO₃,其平均晶粒粒径为80-100 nm左右,带隙宽度为2.0 eV。在可见光光照下, ErFeO₃对甲基橙表现出了优良的可见光催化活性。溶胶-凝胶法制备的ErFeO₃在光催化降解有机污染物领域具有实际应用前景。     

溶胶凝胶法制备LaMn1-XVXO3及光催化氧化性能

以La(NO₃)₂、MnC₄H₆O₂、柠檬酸和乙二醇(EG)为主要原料,NH₄VO₃为掺杂试剂,采用溶胶凝胶法制备LaMnO₃和LaMn_1-XV_XO₃粉体。采用XRD进行晶体结构表征;采用甲基橙(MO)模拟污水,进行光催化降解实验。研究了煅烧温度、催化剂用量和掺杂量对光催化氧化降解率的影响,讨论MO降解的动力学规律。结果表明700-900 ℃煅烧温度不影响LaMnO₃晶体结构和光催化氧化降解率;掺杂量影响LaMn_1-XV_XO₃晶体结构,光催化氧化降解率随着掺杂量增加而呈下降趋势;光催化氧化实验中,LaMn_1-XV_XO₃粉体效果高于LaMnO₃,两者均符合一级动力学方程。     

水热法制备C3N4/CuGaO2 复合物及其气敏性能

采用简单水热法合成了一系列C₃N₄/CuGaO₂复合材料。采用XRD、SEM、TEM和XPS对制备的样品进行了表征。研究了一系列C₃N₄/CuGaO₂复合材料的气敏性能。结果表明,基于C₃N₄/CuGaO₂-0.3复合材料（C₃N₄与CuGaO₂的摩尔比为0.3:1）的气体传感器对甲苯的传感性能优于CuGaO₂传感器。相比较于CuGaO₂传感器的工作温度（140 ℃）,C₃N₄/CuGaO₂-0.3复合材料传感器的最佳工作温度仅为25 ℃,对100 μL/L甲苯气体的响应达到28,检出限低至0.01 μL/L。对100 μL/L甲苯气体的响应时间和恢复时间分别为114.2和27.4 s。此外,用于检测甲苯的C₃N₄/CuGaO₂-0.3复合材料传感器还具有优异的长期稳定性、良好的重复性和优异的抗湿性能。     

等离子喷涂致密La0.6Sr0.4Co0.2Fe0.8O3-δ透氧膜氧传输行为的研究

本文采用超音速等离子喷涂(SAPS)和等离子物理气相沉积方法(PS-PVD)制备了结构致密的钙钛矿型(ABO₃)La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ(LSCF)透氧膜。利用氧程序升温脱附(O₂-TPD)、XPS等手段,比较了两种膜在200-900℃间氧物种在表面及体相中的传递变化情况。O₂-TPD结果显示：SAPS膜的物理吸附氧脱附量、化学吸附氧脱附量和晶格氧脱附量分别超过PS-PVD膜的2倍、3倍和6倍;而XPS结果显示：SAPS膜表面吸附氧与晶格氧O1s峰面积比也高于PS-PVD膜。以上结果表明SAPS膜对氧具有更好的吸附及解离能力、更多的本征氧空位及更高的空位生成能力。     

电化学法研究La-F两步共掺杂纳米TiO2的催化机理

以钛酸四丁酯、硝酸镧和氟化钠等为原料,采用原位掺杂的方式制备了La-F两步共掺杂TiO₂光催化剂。通过XRD、SEM、XPS和UV-Vis对样品进行了表征,并对样品进行了光催化性能及电化学交流阻抗的测试。结果表明所制样品均为锐钛矿型TiO₂,La-F共掺杂使TiO₂的晶格发生了较大畸变且晶粒得到了细化,两步共掺杂会加剧样品颗粒间的团聚,同时两步共掺杂也使TiO₂的吸收带边发生红移,禁带宽度降低。两步共掺杂样品中TiO₂与Lax-Fy-TiO₂之间形成的n-n异质结,由于二者费米能级不同而形成的内建电场,对半导体内部电子起到定向的迁移作用,从而有效降低光生电子-空穴的复合,提高载流子浓度。当La和F的掺杂比例分别为1.5%和10%时,两步共掺杂样品的载流子浓度为1.5×10₂₀/cm_-3,对亚甲基蓝表现出优异的可见光降解效果,120min降解率达到96%,为同等条件下纯TiO₂的2.6倍。     

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。     

Characteristics of N-doped TiO2 nanotube arrays by N2-plasma for visible light-driven photocatalysis

N-doped TiO₂ nanotube arrays were prepared by electrochemical anode oxidation of Ti foil followed by treatment with N₂-plasma and subsequent annealed under Ar atmosphere. The morphologies, composition and optical properties of N-doped TiO₂ nanotube arrays were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectrometer (XRD), Photoluminescence (PL) and UV-vis diffusion reflection spectroscopy (UV-vis DRS). Methylene blue (MB) solution was utilized as the degradation model to evaluate the photocatalytic activity of the samples under visible light irradiation. The results suggested N₂-plasma treatment created doping of nitrogen onto the surface of photoelectrodes successfully and the N-doped TiO₂ nanotube arrays display a significantly enhancement of the photocatalytic activity comparing with the pure TiO₂ nanotube arrays under the visible light irradiation.     

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。     

空心结构ZnSn(OH)6立方体制备及其可见光催化性能研究

以乙酸锌、锡酸钠、氟化铵为原料,利用NH₄F刻蚀,采用水热法制备了尺寸250 nm的空心结构ZnSn(OH)₆立方体,通过X射线衍射(XRD)、红外光谱(FTIR)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)、荧光光谱(PL)等来表征ZnSn(OH)₆的晶体结构、形貌和光学性能,研究水热时间对ZnSn(OH)₆形貌的影响,通过降解亚甲基蓝(MB)来探索不同形貌的ZnSn(OH)₆的光催化性能。结果表明,水热2 h制备的ZnSn(OH)₆具有完整的空心结构,且对亚甲基蓝(MB)在可见光下降解效率最优,在降解过程中·O^2-起主要作用,其稳定性良好。说明空心ZnSn(OH)₆立方体光催化材料是一种具有广阔应用前景的可见光催化降解材料。     

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.     

Photocatalytic activities of N doped TiO2 coatings on 316L stainless steel by plasma surface alloying technique

Nitrogen doped titanium dioxide (N-TiO₂) coatings were fabricated by oxidation of the TiN_x coatings in air. TiN_x coatings were prepared on stainless steel (SS) substrates by plasma surface alloying technique. The reference TiO₂ sample was also deposited by oxidation of the Ti coatings in air. The as-prepared coatings were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and ultra violet-visible absorption spectroscopy (UV-Vis). The formation of anatase type TiO₂ is confirmed by XRD. SEM measurement indicates a rough surface morphology with sharp, protruding modules after annealing treatment. The band gap of the N-doped sample is reduced from 3.25 eV to 3.08 eV compared with the undoped one. All the N-doped samples show red shift in photoresponse towards visible region and improved photocurrent density under visible irradiance is observed for the N-doped samples. The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue (MB) in aqueous under visible light irradiation. The results reveal that the N-doped samples extend the light absorption spectrum toward the visible region. The degradation rate of N-TiO₂ is 20% in visible irradiation for 150 min.     

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.     

Enhanced visible-light-response photocatalytic activity of bismuth ferrite nanoparticles

Multiferroic BiFeO₃ nanoparticles were prepared by a sol-gel rapid calcination technique with average diameter of 35 nm with narrow size distribution. The band gap was determined to be 2.06 eV, indicating their potential application as visible-light-response photocatalyst. The photocatalytic behaviors of BiFeO₃ nanoparticles were estimated by the degradation of Rhodamine B (RhB) under visible light irradiation. And the photocatalytic activities under different pH values were further studied for the first time. The result shows that the BiFeO₃ nanoparticles exhibit the highest photocatalytic activity in the solution with the lowest pH value, almost 100 times higher than that of the bulk.     

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.     

Microstructure characterization and photocatalytic activity of mesoporous TiO2 films with ultrafine anatase nanocrystallites

A series of mesoporous TiO₂ films on borosilicate glass with ultrafine anatase nanocrystallites were successfully synthesized using a non-acidic sol gel preparation route, which involves the use of nonionic surfactant Tween 20 as template through a self assembly pathway. The microstructure of these TiO₂ films was characterized by XRD, SEM, HR-TEM, UV-Vis spectroscopy, and N₂ adsorption-desorption isotherm analysis. Their photocatalytic activities were investigated by using creatinine as a model organic contaminate in water. It was found that all mesoporous TiO₂ films prepared with Tween 20 exhibited a partially ordered mesoporous structure. The photocatalytic activity of the TiO₂ films could be remarkably improved by increasing Tween 20 loading in the sol at the range of 50% (v/v), which yielded large amount of catalyst (anatase) on the glass support and enhanced specific surface area. The optimum Tween 20 loading was 50% (v/v) in the sol, above which good adhesion between TiO₂ films and borosilicate glass could not be maintained. The final TiO₂ film (Tween 20: final sol = 50%,v/v) exhibits high BET surface area (∼ 120 m²/g) and pore volume (0.1554 cm³/g), ultrafine anatase nanocrystallinity (7 nm), uniform and crack free surface morphology, and improved photocatalytic activity.     

Micro-arc oxidation of TC4 substrates to fabricate TiO2/YAG:Ce compound films with enhanced photocatalytic activity

This paper introduces a process for “in situ” preparing TiO₂ photocatalytic film compounded with YAG:Ce³⁺ semiconductor upon titanium alloy by using micro-arc oxidation (MAO). The surface morphology, chemical compositions, phase structures and photocatalytic properties of the films were characterized and measured by field emission gun scanning electron microscope (FEG-SEM), energy-dispersive X-ray spectrometer (EDS), X-ray diffractometer (XRD), electro-chemical workstation and UV-vis spectrophotometer. The results show that the YAG:Ce³⁺ semiconductor particles which were added in the electrolyte had been homogenously compounded within the TiO₂ film during MAO. Compared with the pure TiO₂ film, the compounded film exhibited much larger specific surface area, stronger absorption in the visible light and higher photo-generated current density, which improves the photocatalytic property markedly. It is expected that MAO will provide a simple, economic and promising approach for preparing a superior photocatalytic TiO₂ film.