超声波制备介孔结构的氮掺杂TiO2纳米晶及其可见光催化性能

采用超声波辐射法制备了具有介孔结构的高浓度氮掺杂TiO₂纳米晶(N/TiO₂).采用N₂物理吸附、X射线粉末衍射、X射线光电子能谱、透射电镜、光致发光谱和紫外-可见漫反射光谱等手段对N/TiO₂进行了表征.以波长为400~660nm的可见光为光源,以水体污染物邻苯二甲酸二甲酯为降解对象,考察了不同制备方法对N/TiO₂光催化性能的影响.结果表明,超声波辐射使氮掺杂浓度提高了2.2倍,该法制备的N/TiO₂同时具有较好的介孔结构,表现了更高的光催化降解邻苯二甲酸二甲酯的活性.其活性提高的主要原因是N/TiO₂含有更高浓度的氮和对可见光具有更强的吸收能力.     

三维有序大孔CdS/TiO2薄膜的制备及其可见光催化性能

采用胶体晶体模板辅助溶胶-凝胶法以及S2-离子交换法合成了三维有序大孔CdS/TiO₂膜.结果表明,该薄膜材料在可见光催化降解污染水中罗丹明B和对氯苯酚的反应中表现出高活性.这可归因于修饰剂CdS的光敏化作用实现可见光催化,CdS-TiO₂之间形成了异质结,促进了电子和空穴的分离; 另一方面,有序大孔结构有利于光的利用以及反应物的扩散和吸附.     

有机改性TiO2光催化剂的制备及可见光催化性能

以染料黄叱精(Chrysoidine G)和TiO₂ (Degussa P25)为原料, 利用甲苯二异氰酸酯为桥连体, 成功合成了一种有机改性的TiO₂光催化剂. 采用XRD, TEM, FT-IR, UV-Vis对所得催化剂进行了表征, 以亚甲基蓝降解为探针反应, 考察其可见光催化性能. 结果表明: 甲苯二异氰酸酯在黄叱精和TiO₂之间形成了稳定的化学键, 从而实现了对TiO₂的表面有机改性; 改性后的TiO₂在可见光区(400～550 nm)有明显的吸收; 与未改性TiO₂相比, 有机改性的TiO₂催化剂在可见光照射下表现出了很好的光催化性能.     

铋掺杂二氧化钛纳米颗粒的制备及其可见光催化性能

采用水热法,以纳米管钛酸为前驱物制备了Bi掺杂的TiO₂,并利用X射线衍射、透射电子显微镜、X射线光电子能谱、紫外-可见漫反射光谱等手段对样品进行了表征. 以甲基橙的光催化降解为模型反应评价了样品的可见光催化性能. 结果表明,Bi离子并没有进入TiO₂的晶格中,而是以BiOCl的形式存在. 所制得的BiOCl/TiO₂复合物对甲基橙降解表现出较优越的可见光催化活性;当Bi/Ti摩尔比为1%,水热温度为130℃时,所制催化剂的光催化性能最佳,并对光催化活性提高的机理进行了讨论. 同时,该催化剂对4-氯苯酚降解也表现出较高的光催化性能.     

溶胶-凝胶法低温制备N掺杂TiO2可见光光催化剂

为了满足低温制备可见光光催化材料的需要,采用溶胶-凝胶法制备TiO₂纳米晶溶胶,再与聚乙烯基吡咯烷酮(PVP)直接反应制备N掺杂TiO₂可见光光催化剂。通过XPS分析,说明N取代了部分晶格中的O,UV-Vis漫反射吸收光谱显示,光催化剂具有明显的可见光响应,这是由于N原子的2p轨道位于O原子的2p轨道之上,从而使得价带和导带间的能量带隙变窄,引起吸收带红移,产生明显的可见光吸收。依靠亚甲基兰(MB)的可见光降解实验证明,N掺杂光催化剂具有良好的可见光光催化活性,16 h MB降解率接近25％。     

Cu/Ni助催化剂对TiO2光催化制取苯酚性能的影响

以TiO₂纳米粒子为主催化剂, 采用“浸渍-还原法”构筑了铜、镍共负载的二氧化钛基光催化系统。以苯为起始原料, H₂O₂为氧化剂, 研究了Cu/Ni助催化剂对TiO₂可见光催化制取苯酚性能的影响并对Cu/Ni助催化剂的作用机制进行了探讨。结果表明, 在可见光照射下, 纯TiO₂纳米粒子对苯氧化制取苯酚反应没有催化活性。铜、镍的引入可以明显地增强TiO₂可见光催化制取苯酚的活性。当使用负载有铜、镍的TiO₂作为催化剂时, 苯酚的产率可达到18%。结果还表明Cu、Ni之间存在着很强的协同作用。在该协同作用下, Cu、Ni共负载的TiO₂纳米粒子表现出了较单一金属负载的TiO₂纳米粒子高得多的光催化活性。     

Cu/Ni助催化剂对TiO2光催化制取苯酚性能的影响

以TiO₂纳米粒子为主催化剂,采用"浸渍-还原法"构筑了铜、镍共负载的二氧化钛基光催化系统。以苯为起始原料,H₂O₂为氧化剂,研究了Cu/Ni助催化剂对TiO₂可见光催化制取苯酚性能的影响并对Cu/Ni助催化剂的作用机制进行了探讨。结果表明,在可见光照射下,纯TiO₂纳米粒子对苯氧化制取苯酚反应没有催化活性。铜、镍的引入可以明显地增强Ti₀₂可见光催化制取苯酚的活性。当使用负载有铜、镍的TiO₂作为催化剂时,苯酚的产率可达到18%。结果还表明Cu、Ni之间存在着很强的协同作用。在该协同作用下,Cu、Ni共负载的TiO₂纳米粒子表现出了较单一金属负载的TiO₂纳米粒子高得多的光催化活性。     

PW11Cu/TiO2膜光催化剂的制备及可见光催化性能

以PW₁₁Cu为可见光活性组分,TiO₂为载体结构组分,采用溶胶-凝胶法制备了PW₁₁Cu/TiO₂复合膜可见光催化剂,并用UV-Vis DRS、IR、Raman、XRD、SEM、TEM等手段对催化剂的光吸收性质、化学组成、晶相、表面结构和形貌进行了表征,同时,以模型污染物RhB的可见光降解为探针评估了它的光催化活性,考察了膜处理温度、PW₁₁Cu含量和溶液酸性对催化活性的影响,最后,通过催化剂循环降解RhB试验评估了PW₁₁Cu/TiO₂膜的稳定性。实验结果表明,PW₁₁Cu/TiO₂膜对可见光有明显吸收,低温(100℃)处理的膜为无定形态,高温(500℃)处理的膜为多晶态;低温处理的膜具有较高的可见光催化活性,用于RhB的可见光催化降解,在中性条件下反应80 min,RhB的降解率为100%,TOC去除达32%(4 h);提高溶液酸性有利于催化剂活性的提高,在pH=2.5的条件下,达到100%的RhB降解仅需30 min。在本实验条件下,PW₁₁Cu的最佳剂量是3.0 g。经过10次循环降解RhB,催化剂的光催化活性仍保留约90%。     

PW11Cu/TiO2膜光催化剂的制备及可见光催化性能

以PW₁₁Cu为可见光活性组分, TiO₂为载体结构组分, 采用溶胶-凝胶法制备了PW₁₁Cu/TiO₂复合膜可见光催化剂, 并用UV-Vis DRS、IR、Raman、XRD、SEM、TEM等手段对催化剂的光吸收性质、化学组成、晶相、表面结构和形貌进行了表征, 同时, 以模型污染物RhB的可见光降解为探针评估了它的光催化活性, 考察了膜处理温度、PW₁₁Cu含量和溶液酸性对催化活性的影响, 最后, 通过催化剂循环降解RhB试验评估了PW₁₁Cu/TiO₂膜的稳定性。实验结果表明, PW₁₁Cu/TiO₂膜对可见光有明显吸收, 低温(100 ℃)处理的膜为无定形态, 高温(500 ℃)处理的膜为多晶态;低温处理的膜具有较高的可见光催化活性, 用于RhB的可见光催化降解, 在中性条件下反应80 min, RhB的降解率为100%, TOC去除达32%(4 h);提高溶液酸性有利于催化剂活性的提高, 在pH=2.5的条件下, 达到100%的RhB降解仅需30 min。在本实验条件下, PW₁₁Cu的最佳剂量是3.0 g。经过10次循环降解RhB, 催化剂的光催化活性仍保留约90%。     

Si掺杂TiO2纤维的溶胶-凝胶法制备及其光催化活性

采用溶胶-凝胶法并结合水蒸气活化制备了Si掺杂TiO₂纤维, 通过TG-DSC, XRD, FT-IR, UV-Vis-DRS, N₂吸附-脱附, SEM等手段对纤维样品的结构参数及其表面形貌进行了表征, 并以活性艳红X-3B模拟废水体系评价了其光催化活性．结果表明, 与纯TiO₂产物相比, 适量Si掺杂制得的产物是具有丰富介孔结构的TiO₂长纤维, 不仅热稳定性和晶型稳定性俱佳, 而且光催化活性得以显著提高, 经900 ℃热处理后仍能保持结晶完好的锐钛矿相; 在Si/Ti摩尔比为0.15时, 其比表面积和孔容最大, 光催化活性最佳, 该纤维作为光催化剂反应75 min, 水中X-3B的降解率可达99.6%.     

Improvement of the Visible‐Light Photocatalytic Performance of TiO2 by Carbon Mesostructures

An improvement in the photodegradation performance for dyes due to interaction between carbon and titania in a self‐assembled mesoporous C? TiO₂ composite catalyst, even for the difficult degradation of azo dyes, is reported herein. The dye removal process involves adsorption of the dye from water by the mesoporous carbon–titania, followed by photodegradation on the separated dye‐loaded solid. Such adsorption–catalysis cycles can be carried out more than 80 times without discernible loss of photocatalytic activity or the anatase content of the composite. In each run, about 120 mg dye per g catalyst can be degraded. The mesoporous carbon–titania catalyst also exhibits a high capacity for converting methyl orange in aqueous solution under visible light. Characterization by XRD, TEM, and N₂ sorption techniques has revealed that the self‐assembled composite catalyst has an ordered mesostructure, uniform mesopores (4.3 nm), a large pore volume (0.30 cm³ g^?1), and a high surface area (348 m² g^?1). The pore walls are composed of amorphous carbon and anatase nanoparticles of size 4.2 nm, which are well dispersed and confined. X‐ray photoelectron spectroscopy (XPS), surface photovoltage spectroscopy (SPS), and UV/Vis absorption results indicate doping of carbon into the anatase lattice and a change in the bandgap of the semiconductor. The synergistic improvement in the composite catalyst can be attributed to the following features: (1) carbon doping of the anatase lattice modifies its bandgap and enhances its activity under visible light; (2) confinement within carbon pore walls prevents aggregation of tiny anatase nanoparticles, improving their activity and stability; (3) the mesopores provide a confined space for photocatalysis; and (4) the strong adsorption ability of porous carbon for organic substances ensures that large quantities can be processed and inhibits further diffusion of the adsorbed organic substances, thereby enhancing the mineralization on anatase.     

Visible light photocatalyst: iodine-doped mesoporous titania with a bicrystalline framework

Iodine-doped (I-doped) mesoporous titania with a bicrystalline (anatase and rutile) framework was synthesized by a two-step template hydrothermal synthesis route. I-doped titania with anatase structure was also synthesized without the use of a block copolymer as a template. The resultant titania samples were characterized by X-ray diffraction, Raman spectroscopy, Fourier transform infrared, nitrogen adsorption, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-visible absorption spectroscopy. Both I-doped titania samples, with and without template, show much better photocatalytic activity than commercial P25 titania in the photodegradation of methylene blue under the irradiation of visible light (>420 nm) and UV-visible light. Furthermore, I-doped mesoporous titania with a bicrystalline framework exhibits better activity than I-doped titania with anatase structure. The effect of rutile phase in titania on the adsorptive capacity of water and surface hydroxyl, and photocatalytic activity was investigated in detail. The excellent performance of I-doped mesoporous titania under both visible light and UV-visible light can be attributed to the combined effects of bicrystalline framework, high crystallinity, large surface area, mesoporous structure, and high visible light absorption induced by I-doping.     

中孔氧化硅负载铬催化剂上苯高选择性生成苯酚：响应曲面分析法用于反应条件优化

以硝酸铬为前驱体,中孔氧化硅SBA-16为载体,采用简单浸渍法制备了Cr/SBA-16催化剂,并采用广角和小角X射线衍射、N2吸附-脱附、透射电镜和紫外-可见光谱等技术对其进行了表征.同时将该催化剂用于以H2O2为氧化剂的苯直接羟基化制苯酚反应以考察其催化性能.将中心组合设计与响应曲面分析法(RSM)相结合,对影响反应性能的操作变量如反应温度、反应时间及H2O2和催化剂用量进行了优化.结果表明,独立变量和苯酚产率之间的关系可用二阶多项式模型来表达,其相关系数(R2)高达0.985,表明用RSM预测的数值与实验值吻合较好.得到的苯酚选择性较高时的操作条件为：反应温度324 K,反应时间8 h, H2O2和催化剂用量分别为3.28 mL和0.09 g.由此可见,将RSM法用于苯羟基化制苯酚反应条件优化是可靠的.     

Electrospinning fabrication of mesoporous nano Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-TiO<Subscript>2</Subscript>@activated carbon fiber membrane for hybrid removal of phenol from waste water

A mesoporous iron–titanium mixed-oxides@activated carbon(AC) fiber membrane was fabricated by an electrospinning method and applied to the treatment of phenol waste water. The physical and chemical properties of the composite fiber membrane were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption, UV–Vis light diffuse reflectance spectroscopy (DRS), Raman spectroscopy, respectively. The results indicate that the composite nanofiber membrane is composed of α-Fe₂O₃, anatase TiO₂ and activated carbon phases with a specific surface area of 231 m² g^–1 and narrow pore size distribution of 3–6 nm. DRS reveals that the composite membrane has high photons absorption from both ultraviolet light and visible light irradiation owing to the combination of Fe₂O₃, TiO₂ and carbon. The prepared nano Fe₂O₃–TiO₂@AC fiber membrane can act as an efficient reusable photocatalyst and adsorbent for 100% remo val of phenol pollutant. This hybrid technique is hopeful to be widely used in the treatment of various organic waste waters.     

Enhanced photocatalytic activity and stability of AgBr/BiOBr/graphene heterojunction for phenol degradation under visible light

In this work, we have reported synthesis of AgBr/BiOBr photocatalyst supported on graphene (Gr) using facile precipitation method. AgBr/BiOBr/Gr was characterized using various spectral techniques like FESEM, TEM, XRD, FTIR, XPS, Raman and PL analyses. AgBr/BiOBr/Gr had improved visible light absorption. PL studies indicated the reduction in recombination of photogenerated electron hole pair of AGBr/BiOBr/Gr. AFM analysis confirmed the thickness of AGBr/BiOBr/Gr was less than 8.0 nm. The higher dispersibility of photocatalyst was ascertained by Tyndall effect. AgBr/BiOBr/Gr photocatalyst was effectively used for the photodegradation of phenol from simulated water. The phenol degradation process was remarkably influenced by adsorption process. The concurrent adsorption and photocatalytic was effective for degradation of phenol. The phenol was completely mineralized into CO₂ and H₂O in 6 h. The degradation process followed pseudo first order kinetics. The results confirmed that integration of AgBr/BiOBr with graphene caused an increase in photocatalytic activity due to reduced recombination of photogenerated electron hole pair and electron sink behavior of graphene for photogenerated electrons of BiOBr. AgBr/BiOBr/Gr photocatalyst displayed significant stability and recyclability for ten catalytic cycles.     

The effects of the crystallization rate of the mesoporous TiO2 on the stability of the mesoporous structure after reflux

A simple synthetic method was employed to prepare mesoporous titania with anatase crystalline walls and high photocatalytic activity. The properties and structures of mesoporous titania were characterized by means of low angle and wide angle X-ray diffraction (XRD), Fourier transform (FT)-IR spectra, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and N₂ adsorption–desorption. The characteristic results clearly show that crystallization rate of the mesoporous titania affects the stability of the mesoporous structure after reflux, and that the anatase crystal in the mesoporous wall of mesoporous titania can stabilize the mesoporous structure. The photocatalytic activity of titania powder was evaluated from an analysis of the photodegradation of methyl orange under UV irradiation. The results indicate that the titania powder with mesoporous structure shows the highest photocatalytic activity.     

A Novel Route to the Synthesis of Mesoporous Titania with Full Anatase Nanocrystalline Domains

A porous, high surface area TiO₂ with anatase or rutile crystalline domains is advantageous for high efficiency photonic devices. Here, we report a new route to the synthesis of mesoporous titania with full anatase crystalline domains. This route involves the preparation of anatase nanocrystalline seed suspensions as the titania precursor and a block copolymer surfactant, Pluronic P123 as the template for the hydrothermal self-assembly process. A large pore (7–8 nm) mesoporous titania with a high surface area of 106–150 m²/g after calcination at 400°C for 4 h in air is achieved. Increasing the hydrothermal temperature decreases the surface area and creates larger pores. Characteristics of the seed precursors as well as the resultant mesoporous titania powder were studied using XRD analysis, N₂-adsorption/desorption analysis, and TEM. We believe these materials will be especially useful for photoelectrochemical solar cell and photocatalysis applications.     

介孔碳CMK-3对苯酚的吸附动力学和热力学研究

研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的.     

Enhanced photocatalytic degradation of rhodamine B under visible light irradiation on mesoporous anatase TiO2 microspheres by codoping with W and N

Mesoporous anatase TiO₂ microspheres were prepared via solvothermal method. Ammonium tungstate was used as the W source, and ammonia gas flowing in an ammonothermal reactor as the N source for codoping. TiO₂:(W,N) mesoporous microspheres, which were prepared from solvothermal treatment at 160 °C for 16 h and thermal ammonolysis at 500 °C for 2 h after calcination, have high specific surface area of 106 m² g⁻¹. XPS results indicate the presence of N_O, N_i and W⁶⁺ in the codoped mesoporous TiO₂ microspheres. Monodoping with N shifts the absorption band edge of anatase TiO₂ from ultraviolet region to visible region. Although codoping with W makes the visible light absorbance decrease a little, the photocatalytic degradation of a cationic dye rhodamine B (RhB) on mesoporous TiO₂:(W,N) microspheres is increased to 1.7 times of that on mesoporous TiO₂:N microspheres. This may due to decreasing recombination centers by W-doping charge compensation.     

铽负载介孔二氧化钛的制备、表征和协同效应

以嵌段共聚物P123为模板剂,采用蒸发诱导自组装法制备了铽负载介孔TiO2光催化剂,并利用XRD、N2吸附解吸和UV-Vis吸收光谱等技术手段对样品进行了表征。 制备的样品为锐钛矿和金红石混合晶相,以罗丹明B为模拟有机降解物,样品显示了良好的可见光催化活性。 研究发现0.7%的铽负载和380 ℃的煅烧温度是较佳的制备条件。 介孔结构所具有的高的比表面积、小的晶粒尺寸、铽负载诱导的电荷分离和可见光吸收增强协同提高了光催化活性。 同时,提出了铽负载二氧化钛诱导增强光催化作用的机理。