g-C_3N_4/TiO_2复合光催化剂的制备及其性能研究

以四异丙醇钛和三乙胺为原料,通过水解法合成TiO2。三聚氰胺于580℃煅烧得到g-C3N4,g-C3N4与TiO2按一定比例混合,在超声波条件下加入适量的甲醇得到复合材料g-C3N4/TiO2。以甲基橙为光催化反应模型考察了复合材料的紫外光催化活性。结果表明,g-C3N4/TiO2具有良好的光催化活性,用量3%时,甲基橙脱色率达96.6%。     

Ag3PO4/g-C3N4异质结催化剂可见光降解黄连素

采用原位生长法制备Ag₃PO₄/g-C₃N₄异质结催化剂,在可见光照射下,催化氧化降解废水中的药物大分子黄连素。通过X射线衍射（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-vis DRS）分析催化剂的组成和结构,并测试了Ag₃PO₄/g-C₃N₄降解黄连素的光催化活性。结果表明：利用可见光照射,g-C₃N₄掺杂量为0.7 g时,Ag₃PO₄/g-C₃N₄对黄连素的光催化降解活性最好,可见光反应15 min降解率达到100%,重复4次实验后降解率降至73.2%,其具有较好的光稳定性。自由基捕获实验证明h⁺和·O₂^-在降解黄连素废水中起主要作用,结合UV-vis DRS分析可知,Ag₃PO₄/g-C₃N₄遵循Z型异质结机理。     

Modified g-C3N4 derived from ionic liquid and urea for promoting visible-light photodegradation of organic pollutants

In this work, modified g-C₃N₄ was fabricated successfully by calcination of ionic liquid (IL) and urea. The addition of IL changed the polymerization mode of urea, induced the self-assembly of urea molecules, modified the morphological structure of the tightly packed g-C₃N₄, and extended the electron conjugation system. When using 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a modifier, the heteroatom Cl could be inserted into the g-C₃N₄ to optimize the electronic structure. The results of characterizations indicate that the unique structure of modified g-C₃N₄ has an expanded electron delocalization range, introduces an interlayer charge transmission channel, promotes the charge transmission, reduces the band gap, enhances the absorption of visible light, and inhibits electron-hole recombination. Modified g-C₃N₄ showed excellent photocatalytic performance for the degradation of rhodamine B and tetracycline. Furthermore, the effect of different anions in 1-butyl-3-methylimidazolium salts ([Bmim]Cl, [Bmim]Br, [Bmim][BF₄], and [Bmim][PF₆]) on the structure and function of g-C₃N₄ are discussed.     

Pulsed laser ablation in liquid synthesis of ZnO/TiO2 nanocomposite catalyst with enhanced photovoltaic and photocatalytic performance

In this work, we employed an impurity-free nanoparticle synthesis technique, known as pulsed laser ablation in liquid (PLAL), to integrate titanium dioxide nanoparticles (TiO₂ NPs) into zinc oxide nanorods (ZnO NRs) with varying relative proportions. The main objective of this integration was to enhance the charge carrier separation of photo-generated electron hole pairs during solar irradiation. For the synthesis process, an Nd:YAG laser at 532 nm wavelength was applied as an ablation source, along with deionized water as a solvent medium in which the precursor materials were dispersed prior to laser irradiation. The nanocomposites were characterized by X-ray diffraction (XRD), UV–vis absorption and in-situ Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM). The synthesized nanocomposites were primarily utilised in two applications: firstly, as a catalyst in the degradation of methyl orange (MO) and secondly, as photo-anode in dye sensitized solar cell (DSSC). Our research has demonstrated that optimal performance was obtained for the nanocomposite containing 10% and 90% (by weight) TiO₂ NPs and ZnO respectively, which we define as the ideal nanocomposite. Relative to pure ZnO, the photo-conversion efficiency of the ideal composite was improved substantially by 63.73%, whilst the photo-degradation rate was enhanced by 3 fold. The oxidation state and the microstructural of the segregated ideal nanocomposite confirms that oxygen vacancy defects were created when perfect surface integration occurs between TiO₂ and ZnO. Nonetheless, we believe that the performance enhancement is predominantly due to the excellent charge carrier separation and fast interfacial electron flow in this nanocomposite.     

有机酸介导合成WO3/g-C3N4及其光催化性能

采用水热法制备了WO3/g-C3N4复合物,并探讨了草酸、柠檬酸、乙酸和水杨酸对复合物结构、形貌及催化活性的影响.结果表明,复合物中棒状WO3分布在片层状的g-C3N4上,二者结合紧密形成异质结构.以1 mol/L草酸为介导剂制备的WO3/g-C3N4的光催化活性最佳,当WO3和g-C3N4质量比为1:1时,可见光下反...     

MoO2/g-C3N4催化剂的制备及其氧化脱除模拟油中的硫化物

采用高温煅烧MoO₂和g-C₃N₄混合物制备了不同MoO₂含量的MoO₂/g-C₃N₄催化剂。采用X射线粉末衍射（XRD）、傅里叶红外光谱（FTIR）、扫描电镜（SEM）和N₂吸附脱附对催化剂的结构和性能进行了表征。以MoO₂/g-C₃N₄作为催化剂,H₂O₂为氧化剂,离子液体为萃取剂研究了反应体系的氧化脱硫性能。这项研究中考察了不同煅烧温度下制得的催化剂、负载量、氧化剂使用量、催化剂加入量、反应温度、萃取剂使用量、反应时间、硫化物类型等不同反应参数对脱硫率的影响。结果表明,在H₂O₂的使用量为0.2mL,MoO₂/g-C₃N₄加入量为0.03g,1-乙基-3-甲基咪唑硫酸乙酯离子液体1.0mL,反应温度为70℃,反应时间60min的最佳工艺条件下,24%-MoO₂/g-C₃N₄催化剂脱硫率可以达到94.8%,催化剂循环使用5次后活性没有明显下降。此外,研究了MoO₂/g-C₃N₄在离子液体中的催化氧化反应机理。     

Synthesis of g-C3N4/Nb2O5 heterostructures and their application in the removal of organic pollutants under visible and ultraviolet irradiation

This paper describes the synthesis of a new series of g-C₃N₄/Nb₂O₅ heterostructures and their application in the removal of organic pollutants from water, as a combined strategy of photocatalysis and adsorption processes. The heterostructures were synthesized at different weight ratios through thermal oxidation and hydrothermal treatment, leading to an uniform assembly of Nb₂O₅ nanoparticles onto g-C₃N₄ surface. The heterostructures exhibited improved textural and electronic properties (narrowing in band gap) when compared to pure g-C₃N₄ and Nb₂O₅, respectively. Although adsorption capacities were shown to be influenced by Nb₂O₅ content, g-C₃N₄ was essential to increase the photocatalytic response of the g-C₃N₄/Nb₂O₅ heterostructures, which displayed an enhancement of photocatalytic performance on the degradation of methylene blue and rhodamine B dyes under visible and ultraviolet irradiation. The enhanced photoactivity was explained by the increase in the lifetime of the charge carries due to formation of heterojunctions between Nb₂O₅ and g-C₃N₄. A mechanistic investigation on the photocatalytic process was conducted by using different reactive scavenger species. The superoxide (O₂^−•) radical was found to be the main active specie on the dye photodegradation activated by visible radiation.     

Research on the ablation mechanism and ablation threshold of CMC-SiCf/SiC by using dual-beam coupling nanosecond laser

Due to the excellent properties of high hardness, oxidation resistance and high temperature resistance, silicon carbide fiber silicon carbide ceramic matrix composite (CMC-SiC_f/SiC) is a typical difficult-to-process material, and is a high-performance advanced material in the aerospace field. In this paper, two groups of ablation experiments (experiment 1 and experiment 2) were performed on CMC-SiC_f/SiC using a dual-beam coupling nanosecond laser, and the ablation morphology was observed by confocal laser microscope. The dual-beam coupling angle of experiment 2 is obtained by experimental method. And through the method of calculation, we get the dual-beam coupling angle of experiment 1 and experiment 2. According to the dual-beam coupling ablation mechanism, based on the theoretical calculation model of non-destructive method D²-lnP₀, combined with the Equivalent Diameter Calculation Method (EDCM) and Equivalent Area Calculation Method (EACM), the laser ablation threshold corresponding to different beam waist size was calculated and compared. The results show that the ablation region of CMC-SiC_f/SiC surface can be divided into three parts: ablation boundary, recast layer area and SiO₂ coverage area. When the pulse energy increases gradually from 300 μJ to 1500 μJ, the variation trend of hole depth is first increase, second decrease, increase again, and finally decrease. The angle between two laser beams affects the waist radius, which in turn affect the laser ablation threshold. The waist of the dual-beam coupling is elliptical, and the orifice of the ablation hole is elliptical. When the waist radius of nanosecond laser is 57 μm, the laser ablation threshold is calculated to be 3.12 J/cm². The main factors affecting the laser ablation threshold are laser pulse repetition frequency (f), beam waist radius (ω₀), laser pulse width (τ), minimum laser power (P_th), and laser wavelength (λ).     

Ag/g-C3N4光催剂的构建及降解7-氨基头孢烷酸机理

研究了Ag/g-C₃N₄光催化剂的制备及降解7-氨基头孢烷酸的性能和机理。通过贵金属表面沉积法制备 Ag/g-C₃N₄光催化剂,利用扫描电镜（SEM）和透射电镜（TEM）研究催化剂的形貌和微观结构,通过X光射线能谱（XRD）研究催化剂的晶体结构,采用红外光谱（FTIR）研究催化剂的表面化学官能团,紫外可见光谱（UV-vis）研究催化剂的能带结构和光学性质,通过光催化降解7-氨基头孢烷酸评价Ag/g-C₃N₄的催化性能。结果表明,本研究制备得到了高纯度和高催化性能的Ag/g-C₃N₄光催化剂,与单体g-C₃N₄相比,Ag/g-C₃N₄的吸光性能得到了明显提升,光生电子-空穴的分离和传输性能得到了增强。可见光照射120min时,7%-Ag/g-C₃N₄对7-ACA的降解效率约为78.55%,是单体g-C₃N₄降解效率的1.38倍。本研究为拓宽g-C₃N₄基催化剂在光催化领域的应用提供了崭新的研究思路。     

g-C3N4/Bi2MoO6/Ag3PO4复合材料制备及其可见光催化性能

以三聚氰胺、二水合钼酸钠和五水合硝酸铋为原料,采用溶剂热法制备了g-C3N4/Bi2MoO6前驱体,然后通过共沉淀法将Ag3PO4纳米粒子负载在前驱体上,得到g-C3N4/Bi2MoO6/Ag3PO4复合材料。通过XRD、FTIR、XPS、SEM、UV-Vis DRS等对复合材料进行表征。结果表明,g-C3N4、Bi2MoO6和Ag3PO4之间形成了异质结结构,促进光生电子-空穴对的有效分离。以盐酸四环素（TC）为目标降解物,分析材料的光催化活性。在可见光照射下,30 mg g-C3N4/Bi2MoO6/Ag3PO4在50 min内对40 mL 10 mg/L的TC溶液的降解率达到93%。降解速率常数为0.033 min-1,分别是g-C3N4、Bi2MoO6和Ag3PO4降解速率常数的33倍、3.6倍和1.5倍;g-C3N4/Bi2MoO6/Ag3PO4对TC进行降解,循环利用4次后,对TC的降解率为71%,说明g-C3N4/Bi2MoO6/Ag3PO4具有较好的稳定性。自由基捕获实验结果表明,g-C3N4/Bi2MoO6/Ag3PO4光催化降解TC的主要活性物种为·OH和·O2-。最后提出了TC可能的降解机理和降解路径。     

Removal of methyl orange dye and Na2SO4 salt from synthetic waste water using reverse osmosis

The efficiency of reverse osmosis (RO) membranes used for treatment of colored water effluents can be affected by the presence of both salt and dyes. Concentration polarization of each of the dye and the salt and the possibility of a dynamic membrane formed by the concentrated dye can affect the performance of the RO membrane. The objective of the current work was to study the effect of varying the Na₂SO₄ salt and methyl orange (MO) dye concentrations on the performance of a spiral wound polyamide membrane. The work also involved the development of a theoretical model based on the solution diffusion (SD) mass transport theory that takes into consideration a pressure dependent dynamic membrane resistance as well as both salt and dye concentration polarizations. Control tests were performed using distilled water, dye/water and salt/water feeds to determine the parameters for the model. The experimental results showed that increasing the dye concentration from 500 to 1000 ppm resulted in a decrease in the salt rejection at all of the operating pressures and for both feed salt concentrations of 5000 and 10,000 ppm. Increasing the salt concentration from 5000 to 10,000 ppm resulted in a slight decrease in the percent dye removal. The model’s results agreed well with these general trends.     

Insight into the adsorption and photocatalytic properties of in-situ synthesized g-C3N4/SnS2 nanocomposite

In this paper, a novel g-C₃N₄/2 wt% SnS₂ nanocomposite was successfully synthesized using an in-situ growth of SnS₂ on g-C₃N₄. X-ray diffraction (XRD), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET) method, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectrometer were used to characterize the photocatalysts. Exploring adsorption behavior, as an importatnt stage during photocatalytic reactions, is of great importance. Hence, both adsorption and photocatalytic performance of the synthesized photocatalysts have been investigated in detail. The adsorption isotherm fittings exhibited that Freundlich and Langmuir-Freundlich models can be applied to the methylene blue (MB) adsorption on the photocatalysts, indicating surface heterogeneity should be considered. A pseudo-second-order model was fitted to explore the adsorption kinetics. According to the observed redshift in the Fourier transform infrared spectroscopy (FTIR) result of g-C₃N₄/SnS₂ nanocomposite, π-π interaction was dominant during MB adsorption. Also, a slight redshift and significant PL intensity reduction in g-C₃N₄/SnS₂ nanocomposite led to 96% photocatalytic efficiency after 180 min under visible light radiation. The kinetics of photodegradation over g-C₃N₄/SnS₂ was about 9 and 3 times higher than those of g-C₃N₄ and SnS₂ photocatalysts, respectively. The superoxide and hydroxyl radicals were the main reactive species in the photocatalytic degradation with a Z-scheme charge transfer mechanism. The g-C₃N₄/SnS₂ nanocomposite was found to be remarkably stable after three consecutive cycles of MB degradation.     

固相反应合成ZnO/g-C3N4光催化剂及光催化性能

以乙酸锌、氢氧化钠和g-C₃N₄粉末为原料,并添加十二烷基苯磺酸钠粉末作为表面活性剂,采用室温固相研磨法制备了ZnO/g-C₃N₄光催化剂。并研究了复合材料的光催化性能。研究结果表明,经固相研磨后,会形成ZnO/g-C₃N₄复合材料,g-C₃N₄充分细化成薄片状。添加十二烷基苯磺酸钠粉末促进了g-C₃N₄发生相变。当g-C₃N₄含量较低时,产物的形貌呈现为纳米花,实际上是因为大量的氧化锌纳米片负载到g-C₃N₄片上。当g-C₃N₄含量较高时,产物为二维纳米片,由氧化锌纳米颗粒负载到g-C₃N₄片上。合成的ZnO/g-C₃N₄复合材料对亚甲基蓝表现出良好的可见光催化活性。     

A facile and effective procedure for the synthesis of 4-thiazolidinone derivatives using Y(OTf)3 as catalyst

A one-pot three-component reaction for the synthesis of 4-thiazolidinone derivatives has been established by reacting readily available and inexpensive starting materials of amines, aldehydes and thioglycolic acid using Y(OTf)₃ (5?mol%) as catalyst in tetrahydrofuran. This method is very efficient due to low catalyst loading and mild reaction conditions and provides an efficient and promising synthetic strategy for the construction of the thiazolidinone skeleton.     

单分散Co3O4@SiO2核壳催化剂的制备及N2O催化分解性能

N₂O是一种重要的温室气体,且对臭氧层有很大的破坏作用,而直接催化分解法是除去N₂O最经济有效的方法之一。针对目前报道较多的钴氧化物催化剂活性较差的问题,将包覆型Co₃O₄核壳材料引入N₂O直接催化分解反应,利用核壳结构的限域特性与壳层的多孔孔道使Co₃O₄分散性增加,粒径减小,金属载体相互作用与接触反应界面增强,从而提高了催化剂在N₂O直接催化分解反应中的低温活性。此外,还制备了一系列不同金属含量的Co₃O₄@SiO₂球形核壳催化剂来研究包覆结构对催化剂性能的影响,通过X射线荧光光谱（XRF）、透射电镜（TEM）、X射线衍射（XRD）、N₂物理吸附、H₂-程序升温还原（H₂-TPR）等表征,证实在保证稳定单分散核壳结构的前提下,活性Co₃O₄位点越多,催化剂反应活性越好。     

Bi2O2CO3/Fe3O4磁性复合物在环境污染治理领域中的应用

以Fe₃O₄纳米粒子和Bi₂O₂CO₃为原料,采用溶剂热法制备Bi₂O₂CO₃/Fe₃O₄磁性复合物,并通过对印染废水中染料的去除、剩余污泥厌氧消化过程中产甲烷潜力的影响两方面探讨其在环境污染治理中的应用。借助X射线衍射（XRD）、扫描电镜（SEM）、傅里叶红外光谱（FTIR）和比表面积及孔径分析对Bi₂O₂CO₃/Fe₃O₄复合物进行表征分析,SEM分析结果表明复合物表面较粗糙,BET结果显示复合物的比表面积为9.2294m²/g,Fe₃O₄的引入大幅度增加了Bi₂O₂CO₃的比表面积,使其具有明显的介孔结构。一方面,以甲基橙（MO）为目标污染物,研究了不同实验条件下该材料对染料的去除效果,结果表明,最大吸附量可达14.373mg/g,且该吸附反应过程符合拟二级动力学和Langmuir吸附等温模型,趋于单分子层吸附;另一方面,评估了复合物对污泥厌氧消化产甲烷潜力的影响,结果表明,复合物的引入对污泥厌氧消化产甲烷过程有一定的促进作用,累积产甲烷量相比于对照组提高了10%。分别用一级动力学模型和修正Gompertz模型模拟厌氧消化过程,模拟结果显示一级动力学模型可以更好地描述引入Bi₂O₂CO₃/Fe₃O₄磁性复合物的污泥厌氧消化过程。