BiPO4/BiVO4复合材料的制备及可见光催化活性

采用水热-溶剂热两步法制备了BiPO₄/BiVO₄复合材料. FESEM和TEM分析结果表明, BiVO₄呈高{010},{110}暴露晶面的截角双锥状, BiPO₄纳米颗粒较均匀地附着在BiVO₄表面上, 形成了异质结. 光电流测试结果表明, 异质结能促进光生载流子的有效转移和分离. 在可见光作用下, BiPO₄/BiVO₄可有效降解罗丹明B, 当BiPO₄与BiVO₄的投料摩尔比为3:10时, 样品的光催化活性最优.     

CuAPTPP-TDI-TiO2光催化微球的合成及其光催化性能 (cited: 1)

采用Adler法合成了5-(4-氨基苯基)-10,15,20-三苯基卟啉铜配合物(CuAPTPP),通过甲苯二异氰酸酯(TDI)的桥联作用对TiO₂微球进行表面修饰,使TDI分子中的两个活性TDI基团分别与TiO₂表面的羟基和CuAPTPP的氨基反应,将CuAPTPP敏化剂分子以化学键合的方式固定在TiO₂表面,形成光催化微球CuAPTPP-TDI-TiO₂．通过FT-IR、XRD、SEM、EA、UV-Vis和DRS等测试手段对CuAPTPP-TDI-TiO₂进行结构表征．讨论了桥联分子TDI修饰量对光催化微球性能的影响,确定了TDI与TiO₂的最佳摩尔比．以亚甲基蓝(MB)为降解对象,考察了CuAPTPP-TDI-TiO₂微球的可见光催化性能．结果表明,桥联分子TDI在CuAPTPP与TiO₂微球表面形成了牢固的化学键,复合微球在150 W氙灯辐照下降解10 mg/LMB溶液,120 min降解率可达98.7%,其降解率过程服从一级动力学规律,测得降解速率常数为5.1×10^-2 min^-1,半衰期为11.3 min．催化微球在回收4次的条件下,对MB的降解率仍保持在90%以上．     

一步水热合成铜纳米颗粒负载二氧化钛复合纳米管及其可见光催化活性

采用一步水热法合成了Cu纳米粒子负载二氧化钛纳米管材料. 利用透射电子显微镜(TEM)、X射线衍射仪(XRD)、能谱仪(EDS)等对材料的相组成、形貌以及形成过程进行了研究. 制得的Cu-TiO₂复合纳米材料长度约为100 nm, 直径10-15 nm, 其上负载的Cu纳米粒子尺寸约为5 nm. BET比表面积测试表明实验制备的Cu-TiO₂复合纳米管的比表面积为154.67 m²·g^-1. 通过调节水热反应时间和钛前驱体种类, 研究了该复合纳米管材料的形成机制. 结果表明: 非晶态的钛源对于成功一步合成Cu-TiO₂复合纳米管至关重要. 同时, 实验中观察到铜纳米粒子的尺寸随水热反应时间延长而减小(反奥氏陈化过程), 这一现象有助于纳米粒子的可控合成.紫外-可见吸收光谱表明该复合纳米管在350-800 nm范围内有较强的吸收, 并在550-600 nm范围观察到Cu的表面等离子激元吸收带. Cu-TiO₂界面处形成的肖特基势垒有助于加快光生载流子的输运, 提高光生电子-空穴对的分离效率. 光催化实验表明Cu-TiO₂复合纳米管在可见光下具有较高的催化活性.     

N掺杂富含(001)晶面TiO_2纳米片的制备及N掺杂浓度对可见光催化活性的影响(英文)

采用水热法制备了富含(001)晶面的锐钛矿型TiO2纳米片,并通过改变热处理过程中NH3流速制备不同N掺杂浓度的TiO2纳米片.运用X射线衍射、场发射扫描电镜、高分辨率透射电子显微镜、紫外-可见漫反射光谱、X射线光电子能谱和荧光光谱对光催化剂进行了结构和性能表征,并以罗丹明B为目标降解物,考察了N掺杂浓度对TiO2纳米片可见光催化活性的影响.结果表明,NH3流速为40ml/min时制备的N掺杂TiO2纳米片具有最低的光生电子-空穴复合速率,最高的OH产生能力并表现出最高的光催化活性.同时,讨论了N掺杂浓度对TiO纳米片可见光催化活性影响的机理.     

Visible-Light Activities of Erbium Doped BiVO4 Photocatalysts

Er-doped BiVO₄ composite photocatalyst was hydrothermal synthesized and characterizedby X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray Spectroscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectra techniques. The activity of the catalyst was determined by oxidative decomposition of methyl orange in aqueous solution under visible-light irradiation. X-ray photoelectron spectroscopy and energy-dispersive X-ray Spectroscopy analysis revealed that the doped Er existed in the form of Er₂O₃. It also showed that the Er doping can enhance the visible-light absorption abilities of catalysts and their visible-light-driven photocatalytic activities in comparison with those of pure BiVO₄.     

Bifunctional metal-free photo-organocatalysts for enantioselective aerobic oxidation of β-dicarbonyl compounds

A series of bifunctional metal-free photo-organocatalysts have been developed by grafting the photosensitizer to cinchona-derived phase-transfer catalysts. Using air as a green oxidant and visible light as the driving force, these catalysts are applied to the oxidation of a range of β-dicarbonyl compounds in good yields (up to 97%) and enantioselectivities (up to 93:7 er).     

Intermolecular [2+2] photocycloaddition of chalcones with 2,3-dimethyl-1,3-butadiene under neat reaction conditions

The intermolecular [2 + 2] photocycloaddition of chalcones with 2,3-dimethyl-1,3-butadiene under visible-light irradiation for the synthesis of cyclobutane derivatives has been developed. Without using any photosensitizer, metallic catalyst and solvent, the reaction proceeded with high regioselectivity and moderate to high stereoselectivity. Mild reaction conditions and no additives make the reaction easy to operate. Control experiments and density functional theory (DFT) computations demonstrated that the reaction takes place via visible-light activation of chalcones, which is different from the previously reported [2 + 2] cycloaddition of chalcones.     

Visible-light-induced photocatalytic difluoroalkylation of 3-substituted benzo[d]isoxazoles via direct and regioselective CH functionalization

The difluoroalkylation of unactivated benzo[d]isoxazoles with ethyl difluorobromoacetate by visible-light photoredox catalysis via direct and regioselective CH functionalization has been efficiently achieved under mild reaction conditions. The difluoroalkylated adducts could be readily converted to a variety of corresponding CF₂-containing heterocycles, demonstrating the synthetic utility of the present approach.     

NiFe2O4/g-C3N4 heterojunction composite with enhanced visible-light photocatalytic activity

Spinel structure nickel ferrite (NiFe₂O₄) doped graphitic carbon nitride (g-C₃N₄) photocatalyst NiFe₂O₄/g-C₃N₄ was synthesized by the coprecipitation route to enhance the photocatalytic activity for the visible-light driven degradation of methyl orange. The NiFe₂O₄ doping content is responsible for the microstructure and photocatalytic activity of NiFe₂O₄/g-C₃N₄ samples. Compared with pure NiFe₂O₄ and g-C₃N₄, the 2-NiFe₂O₄/g-C₃N₄ composite with NiFe₂O₄ doping of 2.0 wt% exhibited excellent photocatalytic activity and superior stability after five runs for degrading methyl orange under visible light irradiation. The catalytic activity of 2-NiFe₂O₄/g-C₃N₄ sample produced using the coprecipitation route was higher than those of conventional 2-NiFe₂O₄/g-C₃N₄ bulks prepared by the impregnation approach. The prepared samples for the photocatalytic degradation of methyl orange followed pseudo-first-order reaction kinetics. It’s ascribed to the synergistic effect between NiFe₂O₄ and g-C₃N₄, which can inhibit the recombination of photoexcited electron-hole pairs, accelerate photoproduced charges separation, and enhance the visible light absorption.     

Synthesis of 3D hierarchical porous TiO2/InVO4 nanocomposites with enhanced visible-light photocatalytic properties

Three-dimensional (3D) hierarchical porous TiO₂/InVO₄ nanocomposites were fabricated by loading TiO₂ nanoparticles on the surface of porous InVO₄ microspheres. X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence spectroscopy (PL) were adopted to analyze the structure–property relationship of samples. The results show that the surface of as-prepared TiO₂/InVO₄ nanocomposites are composed of uniformly interconnected bi-phase nanocrystals, forming a close interface between these two components, which is favorable for the highly efficient interparticle electron transfer to achieve enhanced photocatalytic properties. However, the adsorption ability is decreased due to the loading of TiO₂ nanoparticles on the surface of InVO₄. Therefore, under the joint action of these factors, the TiO₂/InVO₄ nanocomposites achieve the best photocatalytic activity when the mole ratio of In:Ti reaches 4:1, and the visible-light photocatalytic activity is about as 3.3 times high as that of pure InVO₄ without modification.