煅烧温度对TiO2/硅藻土晶型结构与光催化性能的影响

以多孔非金属矿物硅藻土为载体, 钛酸四丁酯为前驱体, 采用溶胶–凝胶法制备TiO₂/硅藻土复合光催化材料。通过X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、紫外-可见分光光度计(UV-Vis spectroscopy)等方法对硅藻土及不同温度处理得到的复合样品的晶体结构、表面性能及形貌进行表征。结果表明: 载体硅藻土能够提高TiO₂的晶型转变温度, 并且使TiO₂纳米颗粒分散均匀, 有效抑制了团聚行为的发生。以10 mg/L的罗丹明B溶液为目标降解物, 250 W汞灯为光源, 研究不同热处理温度对TiO₂/硅藻土复合材料的光催化活性的影响。结果表明: 750℃煅烧2 h的样品光照120 min对罗丹明B的去除率接近100%, 与Degussa P25的去除率相当。此时样品中具有两种TiO₂晶型(A:R=9:1), 说明TiO₂的混晶效应能够有效地抑制光生电子-空穴复合, 使样品具有比单一锐钛矿型TiO₂更好的光催化性能。     

煅烧对纳米TiO2/蛋白土复合材料光催化性能的影响及机理

纳米TiO₂/蛋白土复合材料是一种采用钛盐水解沉淀法在蛋白土表面负载纳米TiO₂的新型光催化剂。本文结合晶型与晶粒度、比表面积和孔结构等性质, 讨论了煅烧工艺对其光催化性能的影响机理。结果表明, 复合材料升温到800℃时仍无金红石相出现, 说明载体蛋白土对TiO₂的晶型转变起到抑制作用。以染料罗丹明B溶液为目标降解物, 250 W汞灯为光源, 评价纳米TiO₂/蛋白土复合材料的光催化性能, 其中600℃煅烧2 h得到的样品具有较优的光催化性能, 照射4 h后, 对罗丹明B的去除率达到97.24%。     

Preparation and visible photocatalytic dye degradation of Mn-TiO2/sepiolite photocatalysts

The performance of Mn-TiO₂/sepiolite photocatalysts prepared by the sol-gel method and calcinated at different temperatures was studied in the photocatalytic degradation of direct fast emerald green dye under visible light irradiation, and a series of analytical techniques such as XRD, SEM, FTIR, TG-DSC, XPS, UV-vis-DRS and Raman spectroscopy were used to characterize the morphology, structure and optical properties of the photocatalysts. It is found that the anatase TiO₂ was formed in all photocatalysts. Mn⁴⁺ might incorporate into the lattice structure of TiO₂ and partially replace Ti⁴⁺, thus causing the defects in the crystal structure and the broadening of the spectral response range of TiO₂. At the same time, TiO₂ particles were dispersed on the surface of the sepiolite, which immobilized TiO₂ particles with sepiolite via the bond of Ti−O−Si. Mn-TiO₂/sepiolite calcined at 400 °C exhibits the highest photocatalytic activity and the degradation rate of direct fast emerald green is up to 98.13%. Meanwhile, it also shows good stability and universality.     

以海藻酸钠为基体的Ag/AgBr/TiO2整体式光催化剂的高效制备及其光催化性能

以海藻酸钠为基体制备出尺寸均一的整体式光催化剂SA-Ag/AgBr/TiO₂, 通过SEM、TEM、HRTEM、XPS、FT-IR以及BET等手段对产物形貌、结构、比表面积和光学性质进行表征, 并测定了其对罗丹明B(RhB)溶液的光催化性能。结果表明, 整体式光催化剂SA12-Ag/AgBr/TiO₂(Ag/AgBr/TiO₂催化剂的质量分数为12%)的结构稳定, 且具有良好的光催化活性, 即在紫外光照60 min内, RhB溶液降解完全, 在可见光照120 min下RhB的降解率可达到54.1%, 且在5次重复试验中仍保持96%以上的催化活性, 稳定性良好。这种整体式光催化剂有效解决了粉体材料难回收、二次污染和固定化后光催化效率低等问题。     

Large-sized nano-TiO2/SiO2 mesoporous nanofilm-constructed macroporous photocatalysts with excellent photocatalytic performance

Novel large-sized mesoporous nanofilm-constructed macroporous SiO₂ (LMNCMS) with two sets of well-defined 3D continuous pass-through macropores (pore size of 0.5–1.0 μm, wall thickness of 40–50 nm) was prepared through a dual-templating approach, and used as an advanced support for TiO₂ nanocrystalline photocatalyst. The structural and optical properties of the as-prepared materials were investigated by various characterization techniques in order to explore the connections between catalysts’ features and catalytic performance. The photocatalytic activities were evaluated by degradations of methylene blue (MB) and phenol under the simulated sunlight irradiation. To gain insight into the impact of preparation and operation conditions on photocatalytic degradation processes, experiments were conducted at wide ranges of the TiO₂ loading content, calcination temperature, solution pH, and photocatalyst dosage. Nano-TiO₂/LMNCMS exhibited high photocatalytic activity and stability. Rapid matter transport, good accessibility of pollutants to TiO₂ and high light harvesting could mainly account for the superior photocatalytic performance. The trapping experiments were performed to identify the main reactive species in the catalytic reactions.     

NiFe2O4/TiO2纳米棒阵列薄膜光电化学性能和光催化性能研究

用水热法制备一维有序纳米棒状TiO₂薄膜(TiO₂ NRAs), 并采用浸渍沉积煅烧得到NiFe₂O₄/TiO₂ NRAs。借助SEM、TEM、XRD、Raman、XPS、UV-Vis等对样品的物相和形貌结构进行了表征, 结果表明: NiFe₂O₄纳米颗粒均匀沉积在金红石相TiO₂ NRAs表面, 使TiO₂光谱吸收范围拓展至可见光区。利用电化学工作站对其光电转换性能进行研究, 发现NiFe₂O₄改性后的TiO₂在可见光下光电流响应显著增大, 在电压-电流曲线和电流随时间开关灯变化中, NiFe₂O₄/TiO₂ NRAs的光电流密度分别是纯TiO₂ NRAs的12倍和8倍。NiFe₂O₄/TiO₂ NRAs可见光下降解偏二甲肼(UDMH)的效率是单纯TiO₂ NRAs降解率的3倍, 并对光催化降解机理进行了探讨。     

TiO2/静电纺PAN基碳复合材料的制备及光催化性能

为了同时提高催化剂的光催化和回收能力,以聚丙烯腈(PAN)和钛酸四丁酯(TBT)作为碳纳米纤维(CNFs)和TiO₂前驱体,通过静电纺丝和热处理方法制备了TiO₂/CNFs复合材料,并通过SEM、XRD、Raman、UV-vis分光光度计等对TiO₂/CNFs复合材料的形貌、晶体结构、光吸收性能、导电性和光催化性能进行了研究。结果表明:随TBT添加量的逐渐增多,TiO₂/CNFs复合材料在热处理过程中卷曲形态逐渐消失,并且TBT在碳化过程中完全转化为锐钛矿TiO₂;TiO₂/CNFs复合材料光吸收边缘由纯TiO₂的紫外光区扩展至可见光区,提高了催化剂对太阳光的利用率;同时,在模拟太阳光照射180 min,TiO₂/CNFs复合材料对RhB的光催化降解率最大可达到95.71%,并且在连续重复使用5次后光催化降解效率仍可达到约90%。      

Synthesis of visible-light responsive nitrogen/carbon doped titania photocatalyst by mechanochemical doping

Nitrogen and/or carbon doped titania photocatalysts TiO_2−x A _y (A = N, C) were prepared by a novel mechanochemical method. The samples were prepared by a high-energy ball milling of P25 titania with different nitrogen/carbon sources such as hexamethylenetetramine, admantane or ammonium carbonate, followed by calcination in air at 400 °C. The high mechanical energy accelerated the phase transformation of anatase to rutile, while the existence of the chemical reagents tended to block the transformation. The prepared powders possessed two absorption edges around 400 and 540 nm and showed excellent photocatalytic ability for nitrogen monoxide oxidation under visible light irradiation. Under the irradiation of visible light of wavelength >510 nm, 37% of nitrogen monoxide could be continuously removed by the carbon and nitrogen co-doped titania prepared by planetary ball milling of P25 titania–10% hexamethylenetetramine mixture followed by calcination in air at 400 °C. This mechanochemical technique might be widely useful for doping oxides with nonmetallic elements.     

TiO2-g-C3N4复合材料的制备及其在水泥石表面的应用

以Ti(SO₄)₂和尿素为原料,采用均匀沉淀法及不同煅烧温度制备了TiO₂-g-C₃N₄复合材料。利用XRD和SEM对g-C₃N₄和TiO₂-g-C₃N₄复合材料的结构及形貌进行了表征,并以模拟太阳光为光源,甲基橙为目标降解物,对其光催化活性进行了研究。将高催化性能的TiO₂-g-C₃N₄复合材料与水泥石表面结合制备了具有光催化性能的水泥石。结果表明:在300℃和400℃条件下煅烧制备的TiO₂-g-C₃N₄复合材料具有牢固异质结,而在500℃条件下煅烧产生N掺杂的TiO₂。其中400℃条件下煅烧所得TiO₂-g-C₃N₄复合材料的光催化性能最好,模拟太阳光光照60 min降解率达到91%。通过拟合计算,发现400℃条件下TiO₂-g-C₃N₄复合材料的光催化速率最快。与400℃ TiO₂-g-C₃N₄复合材料结合的水泥石也具有较好的光催化降解性能,模拟太阳光光照240 min降解率可达到90%以上,TiO₂-g-C₃N₄复合材料在400°C可以降低水泥石的初凝终凝时间,并提高其抗压强度。      

铕掺杂的TiO2空心微球的制备及光催化性能

通过溶胶-凝胶法制备未掺杂和铕掺杂的TiO₂空心微球, 采用XRD、SEM、TEM、HRTEM、BET和XPS等技术对样品进行表征, 以亚甲基蓝的光催化降解为目标反应, 评价其光催化活性。结果表明, 钛酸四丁酯(TBOT)的加入量对微球的形貌影响较大, 当滴加1.5 mL的TBOT时, 可得结构清晰、分散性良好的TiO₂空心微球。XRD分析表明, 400℃煅烧的纳米TiO₂空心微球为锐钛矿, 掺铕可抑制TiO₂的晶相转变。光催化实验表明, 铕掺杂能显著提高TiO₂空心微球的活性。当铕掺量为0.7%时, 所得样品粒径和孔径最小, 比表面积最大, 光催化活性最高。     

RuO2–TiO2 mixed oxides prepared from the hydrolysis of the metal alkoxides

The hydrolysis of ruthenium alkoxide/titanium tetraethoxide mixtures to gels and powders containing 30–40 mol% Ru was investigated. Basic or neutral conditions led to powders consisting of 2–10 nm diameter crystalline RuO₂ nanoparticles embedded in a matrix of crystalline (anatase) and amorphous TiO₂. Acid hydrolysis conditions gave gels containing smaller, amorphous RuO₂ nanoparticles (1–3 nm). In all samples the RuO₂ nanoparticles tended to clump into aggregates up to 0.5 μm across. Acid or neutral hydrolysis of ruthenium ethoxide gave samples which displayed lower surface Ru:Ti ratios as measured by XPS compared to the bulk (XRF), and also contained more low-valent Ru (as measured by XRF), probably due to incomplete hydrolysis of the precursors. These samples also contained more Ru metal after calcination (XRD). Calcination (450 °C) was accompanied by Ru-promoted combustion of organic material and led to crystalline (anatase) TiO₂ and Ti_xRu_1−xO₂ solid solution (rutile phase).     

Preparation and visible-light-driven photoelectrocatalytic properties of boron-doped TiO2 nanotubes

In the present study, chemical vapour deposition (CVD) was applied to dope boron into TiO₂ nanotubes anodized Ti in C₂H₂O₄·2H₂O + NH₄F electrolyte with the goal of improving the photocatalytic (PC) activity under visible light. The undoped TiO₂ nanotubes had a highly self-organized structure. However, after doping through CVD, TiO₂ nanotubes suffered from an observable disintegration of morphological integrity. X-ray diffraction (XRD) results confirmed that annealing temperature had an influence on the phase structure and boron impurities could retard anatase–rutile phase transition. Diffuse reflectance absorption spectra (DRS) analysis indicated that B-doped samples displayed stronger absorption in both UV and visible range. B-doped TiO₂ nanotubes electrode annealed at 700 °C through CVD showed higher photoelectrocatalytic (PEC) efficiency in methyl orange (MO) degradation than that annealed at 400 °C and 550 °C. MO degradation was substantially enhanced with the increasing applied bias potential. Moreover, there was a synergetic effect between the electrochemical and photocatalytic processes, and the synergetic factor R reached 1.45. B-doped TiO₂ nanotubes electrode showed good stability after 10 times by repeating photoelectrocatalysis of MO.     

Ce-La-Ag共掺杂TiO2/玄武岩纤维复合光催化剂的制备和性能

以玄武岩纤维(BF)为载体,用溶胶凝胶法将Ce-La-Ag共掺TiO₂负载于BF上制备出Ce-La-Ag共掺杂TiO₂/玄武岩纤维复合光催化剂。用光催化降解氨氮废水,研究了烧结温度和废水的pH值对Ce-La-Ag-TiO₂/BF光催化活性的影响。结果表明：Ce-La离子与纳米Ag颗粒的协同作用使TiO₂的禁带宽度由3.2 eV降至2.15 eV。Ce-La-Ag-TiO₂的光催化活性优于纯TiO₂、Ag-TiO₂和Ce-La-TiO₂,负载到BF使其光催化活性进一步提高。当复合光催化剂的烧结温度为600 ℃、氨氮废水的pH值为10.5、模拟可见光的照射时间为360 min时,Ce-La-Ag-TiO₂/BF对氨氮废水重复降解5次的降解率仍高于88.2%。     

N、Fe共掺杂纳米TiO2的制备和性能

以钛酸丁酯为钛源,用醇热法制备了N、Fe单掺杂及共掺杂纳米TiO₂。对样品的晶型结构、表面形貌、比表面积、紫外可见吸收、光致发光和分解水制氢催化性能分别进行了表征。结果表明,在500℃退火的N、Fe共掺杂TiO₂样品均为锐钛矿相棱形纳米颗粒,分散性较好,平均粒径约20 nm;N、Fe共掺杂的摩尔分数分别为5.0%和2.0%时,样品具有良好的可见光吸收活性,对光的吸收从387 nm（未掺杂锐钛矿相TiO₂）红移至510 nm处。主要原因可能是,N和Fe共掺杂在其禁带中产生杂质能级,导致其禁带宽度减小;N、Fe单掺杂及共掺杂改性,有效抑制了电子-空穴的复合,提高了光生载流子的分离效率;在可见光下（λ>400 nm）N、Fe共掺杂TiO₂具有较高的光催化分解水制氢活性,氢气生成速率为299.2μmol·g^-1·h^-1。     

金红石二氧化钛纳米片的性质及其光催化活性

采用溶胶-凝胶、质子交换和层状剥离的方法, 制备出金红石TiO₂纳米片。利用X射线电子衍射谱(XRD)、透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、X光电子能谱(XPS)的价带谱和荧光光谱(PL)等对样品进行了表征, 研究了光生载流子的转移过程。结果证明: 金红石TiO₂纳米片具有较大的比表面积(185.7 m²/g), 厚度约5 nm, 与金红石TiO₂样品相比, 金红石TiO₂纳米片的禁带宽度增加, 氧化还原能力增强; 此外, 纳米片结构能够促使光生载流子快速转移到纳米片的表面并产生有效分离, 阻止了光生电子和空穴的复合, 提高了光催化反应中光生载流子的利用率。金红石纳米片的这些特性导致其具有较高的光催化活性, 紫外光催化降解对氯苯酚的实验表明: 金红石TiO₂纳米片的光催化活性高于金红石TiO₂和锐钛矿TiO₂样品。     

Hydrophilicity on carbon-doped TiO2 thin films under visible light

Carbon-doped TiO₂ thin films in the anatase phase with dopant concentrations of 1.1, 0.9, and 0.7 mol% were fabricated by a radio-frequency magnetron sputtering method. Dopant carbons were located at the oxygen sites. Carbon substitution caused the absorbance edge and/or the shoulder of TiO₂ to shift to a higher wavelength region. Carbon-doped TiO₂ thin films underwent a hydrophilic conversion when irradiating with visible light (400–530 nm). The hydrophilic property under visible light was inferior to that under ultraviolet light, which is explained by considering that the visible light sensitivity originates from the localized C 2p formed in the band-gap.     

MoS2/Sb2S3复合光催化剂的制备及其可见光催化性能

通过一步水热法制备出MoS₂/Sb₂S₃可见光复合催化剂,采用XRD、SEM、紫外可见漫反射（UV-Vis DRS）和XPS表征手段对MoS₂/Sb₂S₃复合光催化剂进行了表征,以罗丹明B（RhB）作为目标污染物进行降解实验。与纯Sb₂S₃和MoS₂相比,MoS₂/Sb₂S₃复合光催化剂对RhB的光催化降解具有更高的效率,表现出优异的吸附性能和光催化性能。同时在相同的实验条件下,与TiO₂、Bi₂S₃、C₃N₄、Sb₂S₃等催化剂相比,MoS₂/Sb₂S₃复合光催化剂表现出更为优异的光催化性能。此外,探究了MoS₂/Sb₂S₃复合光催化剂光催化降解机制,阐述了光催化反应机制,提供了一种适用于降解较高浓度有机废水的光催化剂制备方法,具有一定的应用价值。      

Ag/TiO2纳米粒子的制备及其光催化降解苯酚的性能研究

采用溶胶-凝胶法制备了TiO₂和Ag/TiO₂纳米粒子,采用涂覆法制备了TiO₂和Ag/TiO₂纳米粒子光催化剂基板样品。使用XRD、SEM和拉曼光谱等手段,对TiO₂和Ag/TiO₂纳米粒子进行了晶格结构和表面形貌研究;通过UV-Vis,研究了TiO₂和Ag/TiO₂纳米粒子光催化剂基板样品在光催化反应器中对苯酚的光催化降解性能。结果表明,制备的TiO₂和Ag/TiO₂纳米粒子均为纯净的金红石相,二者表面形貌并没有明显区别,Ag单质粒子成功负载在TiO₂纳米材料上;Ag单质粒子的负载,明显增强了TiO₂纳米粒子对可见光的吸收,且Ag/TiO₂纳米粒子薄膜对苯酚的光催化降解性能明显优于TiO₂纳米粒子薄膜;在光催化降解1 h后,TiO₂纳米粒子薄膜仅催化降解了溶液中30%(质量分数)的苯酚,且光催化降解出现了饱和趋势,而Ag/TiO₂纳米粒子薄膜可催化降解溶液中50%(质量分数)的苯酚,且在光催化降解3 h后,仍未出现饱和趋势。     

离子液体对可磁分离TiO2光催化材料结构和性能的影响

采用溶胶-凝胶法分别在离子液体1-丁基-3-甲基咪唑四氟硼酸盐[BMim]BF₄、1-丁基-吡啶四氟硼酸盐[BPy]BF₄和1-丁基-3-甲基咪唑醋酸盐[BMim]Ac的辅助下制备可磁分离TiO₂/CoFe₂O₄(TCF)光催化材料, 采用X射线衍射分析(XRD)、N₂吸附-脱附分析(BET)和透射电子显微镜(TEM)研究了离子液体结构对可磁分离TiO₂的结构和性能的影响。结果显示: 200 ℃焙烧后样品[BMim]BF₄-TCF和[BPy]BF₄-TCF有锐钛矿相TiO₂ 生成, 而样品[BMim]Ac-TCF和TCF只有经400 ℃焙烧才出现锐钛矿相的衍射峰。当焙烧温度为800 ℃时, 样品[BMim]BF₄-TCF主要以锐钛矿相TiO₂存在(相对含量为92.6%), 说明离子液体中含有[BF₄^-]基团能降低锐钛矿相的晶化温度和能提高锐钛矿相高温稳定性。400 ℃焙烧后[BMim]BF₄-TCF和[BPy]BF₄-TCF的比表面积分别为125.7和120.3 m²/g, 高于[BMim]Ac-TCF(77.8 m²/g)和不加离子液体所制备样品TCF(63.7 m²/g)。说明阴离子BF₄^-有利于形成较大比表面积的TiO₂。在模拟太阳光照射120 min后, 经400 ℃焙烧后的样品[BMim]BF₄-TCF、[BPy]BF₄-TCF、[BMim]Ac- TCF对亚甲基蓝的降解速率分别为96%、87%、64%。     

还原氧化石墨烯@Ag2O改性TiO2基复合材料的制备及其可见光催化性能

制备了还原氧化石墨烯（rGO）@Ag₂O共同改性TiO₂基复合材料（rGO@Ag₂O/TiO₂）,并研究了其可见光催化性能。结果表明,三元复合材料rGO@Ag₂O/TiO₂的可见光催化性能远优于一元纳米TiO₂和二元rGO/TiO₂、Ag₂O/TiO₂复合材料,当可见光照射120 min后,溶液中约100%的罗丹明B分子被rGO@Ag₂O/TiO₂降解。rGO@Ag₂O/TiO₂三元复合材料可见光催化效率的提高主要源于窄带隙半导体Ag₂O和高电导率材料rGO的引入,使形成的rGO@Ag₂O/TiO₂三元复合材料具有强的可见光吸收能力和光生电子空穴对分离能力。