纤维状TiO2/Bi2O3光催化剂的制备及其光催化性能

以C₁₆H₃₆O₄Ti和Bi(NO₃)·5H₂O为原料,以棉花纤维为生物模板,合成了系列纤维状TiO₂/Bi₂O₃光催化剂．采用XRD、SEM、UV-Vis等测试技术对样品的相结构、形貌和吸光性能等进行了表征分析．结果表明,样品中的Bi₂O₃为单斜相和四方相共存的混晶,纤维长度达到毫米级,     

高比表面积TiO2与g-C3N4复合材料的光催化性能及机理研究

本文通过简单的溶剂热法制备了g-C₃N₄与高比表面积的TiO₂复合材料,该方法操作简单且能耗低. 甲基橙降解实验结果表明,高比表面积的TiO₂有效提高了光催化活性. 光电化学测试结果表明,与g-C₃N₄复合后,TiO₂的电荷载流子迁移速率得到明显改善. g-C₃N₄/高比表面积-TiO₂的光催化活性很强,在100分钟内,6%-g-C₃N₄/高比表面积-TiO₂对甲基橙的降解程度可达92.44%. 6%-g-C₃N₄/高比表面积-TiO₂不仅具有良好的光催化降解性能,还具有较高的稳定性. 本文对6%-g-C₃N₄/高比表面积-TiO₂的光催化机理也进行了系统的研究.     

TiO2/SiO2多层膜的带隙结构及光催化性能

利用传输矩阵法设计了由SiO2、TiO2组成的多层膜高透射率光子晶体结构,并分析了其透射谱特性,根据等效层原理改变多层膜一维光子晶体的自身结构来提高通带内特征波长附近的透射率,获得了最佳结构参数。研究结果表明,当晶格参数为150nm,填充比为0.346,周期数为6时,400nm波长附近吸收带处的透射率最低也可达96.5%,并且不论是TM模式还是TE模式,入射角在0°～45°范围内仍保持高的透射率,该结构可望用于空气净化装置以提高SiO2、TiO2光催化剂的光催化效率。     

具有异质结的富勒烯C60/酞菁纳米复合材料的可见光响应光催化应用

通过再沉淀法制备了富勒烯C60/酞菁的复合纳米微粒。这种复合纳米微粒由于C60分子和酞菁分子间的-相互作用而具有电子给体-受体（donor-acceptor）结构,而且这种微粒的尺寸可通过选择再沉淀过程中使用的溶剂来进行控制。此外,这种微粒与Nafion结合后,表现出去除三甲胺的光催化性能,而且其光催化活性优于C60微粒/Nafion或酞菁微粒/Nafion复合物。该结果表明电子给体-受体结构可通过促进有机半导体的电荷分离来增强光催化的性能,从而揭示了一种新颖的基于电子给体-受体结构的有机光催化剂。     

球磨处理的TiO2光谱特征及其光催化性能研究

为改变TiO₂的颗粒尺寸和提高其光催化性能,采用高能球磨法处理TiO₂粉末,研究球磨时间对样品微观形貌、晶体结构、拉曼光谱、荧光光谱和光催化性能的影响;分析荧光光谱和光催化性能之间的关系,确定光催化机理为快速判断其光催化性能提供依据。结果表明：随着球磨时间的增加样品颗粒由规则形状变成无规则形状且表面变得粗糙。所有样品均主要为锐钛矿结构,有少量的金红石结构,随着球磨时间的增加金红石结构的(110)衍射峰逐渐增强说明在球磨过程中少量的TiO₂发生了相转变,晶粒尺寸先减小后增加。所有样品均出现锐钛矿型TiO₂拉曼散射峰,而未发现金红石晶型的拉曼散射峰。各个拉曼峰的半高宽随着球磨时间的增加都有所增加,这表明样品的表面质量下降,表面缺陷和氧空位逐渐增加导致。所有样品在470 nm附近均出现荧光峰,且球磨后的样品该荧光峰得到增强,经过球磨后的TiO₂样品在397, 452, 483, 500和536 nm等处出现荧光峰,且球磨4 h后的TiO₂荧光峰强度最强,表明其表...     

Cu掺杂纳米TiO2光催化还原CO2实验研究

利用溶胶凝胶法制备不同掺杂量的CuO-TiO₂纳米粉体,采用热重差热分析仪（TG-DTA）,X射线衍射仪（XRD）,场发射扫描电镜（FSEM-EDX）等手段对其进行表征;在波长为253.7nm的紫外灯照射下,进行CO₂光催化还原实验研究,探究CO₂光催化资源化利用可行性,。结果表明,溶胶凝胶法制备所得CuO掺杂TiO₂纳米粉体,粒径大小在20～30 nm之间;CO₂光催化还原主要产物为甲醇,掺杂量为5%（质量分数）CnO-TiO₂纳米粉体催化效果最好,反应10 h后得到甲醇产量为27mg·（g-cata）^-1;随着反应时间的增加,产物中甲醇含量也逐渐增加。     

圆盘状Bi2WO6-BiPO4异质结的水热合成及光催化性能 (cited: 1)

采用水热法制备Bi₂WO₆-BiPO₄异质结光催化剂．利用模拟太阳光照射下的罗丹明B降解实验评价了Bi₂WO₆-BiPO₄复合物的光催化性能．结果表明,Bi₂WO₆-BiPO₄光催化活性比Bi₂WO₆和BiPO₄高得多．当Bi₂WO₆与BiPO₄的摩尔比为1:1时复合光催化剂对罗丹明B的降解率最高．Bi₂WO₆-BiPO₄催化活性增强主要归结为两者之间形成了有效的异质结结构,其内建电场能够促进光生载流子的分离．同时,Bi₂WO₆的加入增强了其对可见光的吸收．研究表明O₂· ^-和h⁺在光催化降解过程中是主要的活性物种     

TiO2/SnO2复合光催化剂的制备及性能

采用特殊液相沉淀法制备纳米级的TiO2/SnO2复合粒子,对制备的纳米TiO2/SnO2采用XRD、TEM等手段进行了表征。用它做催化剂在日光下对甲基橙溶液进行了光催化实验。结果表明,纳米级TiO2/SnO2复合催化剂比纯TiO2的催化活性好,当SnO2摩尔百分数为20%时效果最佳,在60min内对10mg/L的甲基橙水溶液的降解率高达90.2%,具有较好的光催化活性。     

TiO2禁带宽度和光吸收系数对其光催化性能的影响

为了研究TiO₂禁带宽度和光吸收系数对其光催化性能的影响,使用Materials Studio的Dmol3和CASTEP模块分别对Ag⁺、Fe³⁺、Pt⁴⁺、La³⁺ 4种金属离子掺杂TiO₂的能带结构和光学性质进行分析。分子模拟表明:金属离子掺杂使TiO₂的禁带宽度变窄、吸收波长红移,相同光照条件下光吸收系数增加,影响了TiO₂的光催化性能。光催化反应实验表明:在254 nm照射条件下,TiO₂的禁带宽度为1.09 eV时光催化性能最好,TiO₂的光吸收系数越大,光催化性能越好。     

BiVO4的晶体结构和光学观察

对于提拉法合成的BiVO₄单晶进行了X射线衍射分析。室温下该晶体属于单斜晶系,空间群为B2/b,z=4,晶胞参数为:a=7.247?,b=5.096?,c=11.702?,γ=134.18°。进行了二维、三维帕特逊分析和三维电子密度计算。全矩阵最小二乘法修正给出335个独立反射的R=0.067,R_w=0.058。经吸收和次级消光校正后,R=0.058。Bi和V原子各占据一套4e特殊点系,O原子占据两套一般点系。V³⁺是四配位,形成规则的VO₄四面体。Bi³⁺是八配位,形成畸变Bi-O十二面体。BiVO₄在T_c温度上下空间群各为I4₁/a和I2/b(或B2/b)。由四方到单斜相变没有正交中间变体。相变显然是由Bi-O多面体孤对畸变所驱动。Bi³⁺和V⁵⁺沿c轴上下交替位移,这就显示单斜BiVO₄具有层状结构的特征。这一特征由光学观察得到证实。该晶体在垂直干c轴的方向极易开裂而产生平坦的解理面。选取具有胞状结构圆盘形晶体、自然解理晶片和粉末晶粒三种试样进行了光学观察,并研究了晶体透过率与波长关系。 关键词：     

BiVO4空心微球的合成及其光催化降解亚甲基蓝的性能研究

以BiNO₃·5H₂O和NH₄VO₃为原料,柠檬酸为络合剂,成功合成了BiVO₄空心纳米球．采用TEM、XRD、UV-Vis等测试技术对样品的形貌、相结构以及光吸收性能等进行了表征．结果表明,所制备的BiVO₄空心微球在紫外区和可见区均有较强的光吸收,空心球平均粒径为160 nm,空腔直径为10～80 nm．以亚甲基蓝染料溶液的脱色降解实验为模型反应研究了样品的光催化性能．光催化实验结果表明,在可见光照射下,反应150 min后,样品对亚甲基蓝溶液的脱色率可达到95%以上．此外,考察了柠檬酸添加量对空心球形貌的影响,并提出了BiVO₄空心纳米球的可能形成机理．     

Bi2MoO6纳米片/TiO2纳米棒阵列复合材料的制备及其可见光响应光电催化性能研究

Novel Bi₂MoO₆/TiO₂ heterojunction was fabricated by growing Bi₂MoO₆ nanosheets arrays on the vertically aligned TiO₂ nanorods arrays via a two-step solvothermal method. The obtained Bi₂MoO₆/TiO₂ hierarchical heterojunction showed excellent visible light photoelectrochemical performance. Compared with the pure TiO₂ and Bi₂MoO₆, the photocurrent density of the heterojunction was increased 57 and 29 times, respectively. Furthermore, the hydrogen generation rate of the Bi₂MoO₆/TiO₂ for photoelectrocatalytic water-splitting was about 6 times higher than that of the pure Bi₂MoO₆. The improved performance can be attributed to the synergistic effects of enhanced absorption of visible light, increase of migration rate and separation efficiency of photo-induced carriers.     

Hydrothermal synthesis and photoelectric properties of BiVO4 with different morphologies: An efficient visible-light photocatalyst

Different morphologies of monoclinic BiVO₄ with smaller size were hydrothermal synthesized by simply adjusting the amount of surfactant (polyvinyl pyrrolidone PVP K30) added. The detailed field emission scanning electron microscope (FESEM) analysis revealed that the amount of PVP added could significantly affect the morphology and size of BiVO₄. Their photocatalytic activities were evaluated by the decolorization of methylene blue (MB) aqueous solution under visible-light irradiation (λ > 400 nm), and the as-prepared sample with well-assembled flower-like morphology showed a much higher photocatalytic activity due to larger specific surface area and higher separation efficiency of photo-induced carriers. The relationship between the behavior of photo-induced carriers and photocatalytic activity was studied using the surface photovoltage spectroscopy (SPS) and corresponding phase spectra.     

水热法制备不同形貌和结构的BiVO4粉末

采用水热合成法,选择不同比例的起始原料、反应温度、反应时间、pH值和表面活性剂,制备出不同形貌和结构的BiVO₄粉末.采用X射线衍射、透射电子显微镜、扫描电子显微镜、拉曼、傅里叶红外和紫外-可见吸收光谱技术对产物进行分析表征.结果表明,提高n_Bi/n_V或反应液pH值,可得到纯的单斜晶系白钨矿型BiVO₄粉末;水热温度和水热时间的不同则得到不同尺寸和内部结构的BiVO₄粉末.另外,不同表面活性剂的加入则主要影响BiVO₄的微观形貌. 关键词： 4')" href="#">BiVO₄ 水热法 光催化     

Photocatalytic decomposition of methylene blue and 4-chlorophenol on nanocrystalline TiO2 films under UV illumination: A ToF-SIMS study

The photocatalytic degradation of methylene blue and 4-chlorophenol on nanocrystalline TiO₂ (nc-TiO₂) under UV irradiation was investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Nanocrystalline TiO₂ films were prepared from suspensions containing TiO₂-crystallites of different average sizes, the smallest one being 12 nm. The organic substances (either methylene blue or 4-chlorophenol) were applied to these films. The specimens were studied in the pristine state and upon UV exposure. The UV illuminations were carried out both under atmospheric conditions and in situ under ultrahigh vacuum in the ToF-SIMS instrument. Distinct mass signals from the parent molecules and from fragment ions are observed for the as-prepared samples. Upon irradiation with UV light under atmospheric conditions, the surface composition is significantly changed, an observation ascribed to photocatalytic reactions induced by UV photons: the parent molecule signals are strongly diminished whereas fragmentation products are identified to be present at the TiO₂ surfaces. UV irradiations carried out under different vacuum conditions in the ToF instrument (ultrahigh vacuum, air or oxygen adsorption) indicate that varying ambient conditions may influence the photocatalytic reaction on the nanocrystalline TiO₂ films.     

石墨相氮化碳的制备条件优化用以提高其在可见光下的光催化活性

通过染料的光降解实验和敏感性数学分析探讨了石墨相氮化碳(g-C₃N₄)的制备条件与其稳定性和光催化活性之间的联系. 结果表明,相比于焙烧时间,焙烧温度的改变更为显著地影响了g-C₃N₄ 的光催化活性. 制备条件优化之后的g-C₃N₄在可见光照射下催化降解罗丹明B(RhB)的活性比未优化时提高了约100倍,归因于材料比表面积的增大和表面光生电子-空穴迁移速度的增强.     

Synthesis and characterization of Ag/BiVO4 composite photocatalyst

Ag/BiVO₄ composite photocatalysts were hydrothermal synthesized and characterized by XRD, SEM, XPS and DRS techniques. Their photocatalytic activities were determined by oxidative decomposition of methyl orange in aqueous solution under visible light irradiation. It revealed that the doped Ag species greatly improved the visible light absorption abilities and morphologies of the composites, and thus lead to enhanced photocatalytic activities compared with that of the pure BiVO₄.     

Photocatalytic Activity of N-doped TiO2 Photocatalysts Prepared from the Molecular Precursor (NH4)2TiO(C2O4)2

用不同温度控制分解草酸氧钛铵制备N掺杂TiO₂光催化剂．利用XRD、IR、热分析、N₂吸-脱附等温线、XPS、紫外可见漫反射光谱和SEM表征了N-TiO₂光催化剂的结构．400～600 oC焙烧的N-TiO₂光催化剂为纯锐钛矿相,而700 oC焙烧的N-TiO₂光催化剂为锐钛矿和金红石混合相．N掺杂在TiO₂的间隙位使锐钛矿相TiO₂带隙变窄．在光降解甲基橙的反应中,600和400 oC焙烧的N-TiO₂催化剂分别在紫外光和全波长光照射下有最好活性;700 oC焙烧的N-TiO₂催化剂无论在紫外光和全波长光下都表现出最好的比活性,即最高的光量子效率,这可以归因于700 oC焙烧的N-TiO₂光催化剂良好的结晶程度和锐钛矿-金红石异相结的存在．     

Enhanced photoactivity of CuPp-TiO2 photocatalysts under visible light irradiation

Three novel porphyrins, 5,10,15-tri-phenyl-20-[4-(3-phenoxy)-propoxy]phenyl porphyrin, 5,15-di-phenyl-10,20-di-[4-(3-phenoxy)-propoxy]phenyl porphyrin and 5-phenyl-10,15,20-tri- [4-(3-phenoxy)-propoxy]phenyl porphyrin, and their corresponding copper(II) complexes were synthesized and characterized spectroscopically. The photocatalytic effects of TiO₂ samples impregnated with copper(II) porphyrins was investigated by photodegradation of 4-nitrophenol (4-NP) in aqueous solution under visible light. The photocatalysts were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis spectra and FT-IR spectra. The results indicated that CuPps were successfully loaded and interacted with the surface of TiO₂ microsphere, which is crucial to enhance the activity of the catalytic composite under visible light.