光催化剂改性及固定的研究进展

提高光催化剂的光催化活性及将光催化剂固定是多相光催化技术能否工业化应用的关键,单一半导体光催化剂的光催化活性一般都不高,通过改性可以提高光催化活性甚至在提高活性的同时扩展光谱响应范围,提高太阳光的利用率,而光催化剂的固定则可免却光催化剂的分离回收以及消除粉末悬浮体系中存在的易聚集,流失等缺点。     

Novel Z-Scheme ZnIn2S4-based photocatalysts for solar-driven environmental and energy applications:Progress and perspectives

Benefiting from strong redox ability,improved charge transport,and enhanced charge separation,Z-scheme heterostructures of ZnIn2S4 based photocatalysts have received considerable interest to tackle energy needs and environmental issues.The present review highlights the properties of ZnIn2S4 which make it a promising photocatalyst,and a suitable combination with oxidation photocatalyst to form Z-scheme,leading to improve their photocatalytic properties dramatically.As the central part of this review,various types of Z-scheme heterojunction developed recently based on ZnIn2S4 and their application in pollutant degradation,water splitting,CO2 reduction,and toxic metals remediation.Some analytical techniques to detect or trap the active radical and study the charge separation and lifetime of charge carriers in these Z-schemes are highlighted.This review offers its readers a broad optical window for the structural architecture of ZnIn2S4-based Z-schemes,photocatalytic activity,stability,and their tech-nological applications.Finally,we discuss the challenges and opportunities for further development on Z-Scheme ZnIn2S4-based photocatalysts toward energy and environmental applications based on the recent progress.     

N掺杂TiO2光催化剂的制备及其可见光降解甲醛

采用水解沉淀法制备了纯的和N掺杂的TiO2纳米光催化剂,并用二次离子质谱、X射线衍射、紫外-可见漫反射光谱、比表面积、透射电镜等技术进行了表征。以GaN基兰色发光二极管为光源,研究了催化剂光催化降解甲醛的活性。实验表明,在最佳反应条件下,N掺杂的TiO2纳米光催化剂在可见光下对甲醛有良好的光催化活性。     

可见光降解有机污染物催化剂研究进展

光降解水中有机污染物是解决环境问题非常有前途的策略。主要介绍了近年来光催化降解有机污染物的国内外最新研究进展,重点介绍了钛酸盐光催化剂、钽酸盐光催化剂、铌酸盐光催化剂、无机层状化合物、金属硫化物、Z型光催化反应体系。着重总结了金属硫族化合物催化剂降解有机污染物存在的问题及可行的解决方案,并对以后可见光催化降解有机物的研究发展趋势进行了展望。     

海藻基CDs-Cu-TiO2复合材料的制备及其光催化性能

光催化降解技术能够高效去除废水中的有机污染物, 具有广阔的应用前景。本研究以海藻为碳源, 采用微波水热法制备海藻基碳量子点(CDs), 并进一步合成CDs-Cu-TiO₂复合材料作为可见光催化剂用于污染物降解。结果表明, 复合材料中CDs、Cu²⁺与TiO₂紧密结合在一起, 可见光区吸收明显增强, 荧光发射效率降低。CDs与Cu²⁺的引入产生协同效应, 使复合材料的禁带宽度降低到2.35 eV, 并有效抑制了电子-空穴的复合。以罗丹明B为污染物模型的光催化性能实验显示, 海藻基CDs-Cu-TiO₂复合材料在可见光照射下降解RhB的一级反应速率常数能够达到纯TiO₂纳米颗粒的6.4倍, 150 min降解率接近100%, 是TiO₂纳米颗粒的2倍。     

一种新型的半导体光催化剂——纳米氧化亚铜

半导体光催化技术是解决环境污染问题的有效手段,从光催化的催化机理出发,在分析了二氧化钛光催化剂的局限性的基础上,介绍了一种新型的可见光型半导体光催化剂--纳米氧化亚铜,对其制备方法和在光催化剂方面的研究进展作了综述,并对光催化剂的应用及未来研究方向进行了展望.     

活性炭负载纳米TiO2光催化降解气相丙酮

以钛酸四丁酯为前驱体,采用溶胶-凝胶法制得Fe、N离子共掺杂的以活性炭(AC)为载体的光催化剂(TiO2/AC),在紫外光照射下进行了气相丙酮的光催化降解研究。探讨了丙酮初始质量浓度、紫外光光强、催化剂用量、反应器内湿度等因素对其降解率的影响。结果表明,活性炭与TiO2的协同作用大大提高了对丙酮的降解效果;紫外光光强的增加对丙酮降解率有一定提高;使用3g光催化剂,丙酮的初始质量浓度为39.40mg/L;反应器内相对湿度为63%时,丙酮的降解效果最好,降解反应155min后丙酮的降解率达92.63%;催化剂循环使用6次后丙酮的降解率为83.91%。     

酞菁化合物可见光降解水中有机污染物的机理及应用

当前水环境污染已成为全球性普遍关注的重要课题,而利用光催化氧化技术处理水中难降解有机污染物的方法己经引起了国内外水处理专家的广泛关注。自1907年由A.Braun教授和T.C.Tcherniac教授第一次发现酞菁化合物以来,有关利用酞菁化合物对水中污染物进行光催化降解的研究备受瞩目。酞菁化合物由于具有18π电子体系的共轭结构,能吸收可见光区的光,因而显现出独特的光电特性。对酞菁化合物可见光催化降解水中有机污染物研究现状进行了综述,分别介绍了酞菁化合物的典型结构及其特性,并对其催化降解有机污染物反应机理进行阐述,总结了近年来酞菁化合物在降解水中有机污染物方面的应用,从环境可持续发展角度来看,具有十分重要的意义。     

二氧化氯去除水体污染物机理探讨

论述了二氧化氯去除水体污染物的机理,说明源水严重污染或水体中有机物含量高时,二氧化氯是最佳选择。     

生物降解聚酯——聚乙丙交酯的合成研究及应用

本文介绍了生物降解聚乙丙交酯(PLGA)的合成、降解机理及影响因素,以及PLGA在国内外生物医学领域中的应用开发状况。     

Raising the Sensitivity of a Bipolar Magnetotransistor

Test results are given for a bipolar magnetotransistor (BMT), whose sensitivity is determined by the recombination mechanism, and also of a BMT with its base in a well (BMTBW), which has a response threshold. The relative current sensitivity of the BMTBW is dependent on the magnetic induction, and it increases in weak magnetic fields and attains 2000 T^–1 in measurement of the Earths magnetic field. The sensitivity changes sign as the bias voltage changes.__________Translated from Izmeritelnaya Tekhnika, No. 2, pp. 55–60, February, 2005.     

聚氨酯的热分解研究进展

介绍了有关聚氨酯热性能研究的状况,着重阐述了聚氨酯在不同气氛下的热解机理及热解动力学,同时也阐述了聚氨酯今后研究的发展方向。     

TiO2/HZSM-5的制备及光催化性能的表征

以钛酸四丁酯为钛源,采用溶胶-凝胶法在HZSM-5分子筛表面合成TiO2前驱体,程序升温处理制得TiO2/HZSM-5负载型光催化剂。采用X射线衍射、扫描电镜、傅里叶变换红外光谱、X射线光电子能谱对光催化剂晶相结构、表面形貌及化学组成进行了表征。结果表明,HZSM-5可提高TiO2分散性能,降低TiO2晶粒的尺寸。TiO2/HZSM-5中的Ti都以TiO2形式存在,没有Ti—O—Si键生成。甲基橙溶液的光催化降解结果表明,负载后提高了TiO2对甲基橙溶液的光催化降解活性。TiO2的质量分数为30%,400℃下煅烧2h时的催化剂光催化性能最好。     

Deposition of CuWO4 nanoparticles over g-C3N4/Fe3O4 nanocomposite: Novel magnetic photocatalysts with drastically enhanced performance under visible-light

Novel g-C₃N₄/Fe₃O₄/CuWO₄ nanocomposites, as magnetic visible-light-driven photocatalysts, fabricated through a simple refluxing-calcination process. The synthesized photocatalysts were characterized by a series of techniques including XRD, EDX, SEM, TEM, HRTEM, FT-IR, TGA, BET, UV–vis DRS, PL, and VSM. The results showed that heterojunctions are formed between g-C₃N₄, Fe₃O₄, and CuWO₄, which favor suppression of the photogenerated electron/hole pairs from recombination. The resultant g-C₃N₄/Fe₃O₄/CuWO₄ (30%) sample exhibited superior photocatalytic performance. The degradation rate constants on the g-C₃N₄/Fe₃O₄/CuWO₄ (30%) nanocomposite were almost 10.5, 17, 12.5, and 42.5 times higher than those of the pristine g-C₃N₄ for degradations of RhB, MB, MO, and fuchsine, respectively. Moreover, the photocatalyst was magnetically separated and recycled with negligible loss in the activity, which is important for the sustainable photocatalytic processes. Thus, the ternary nanocomposite could have potential applications in different photocatalytic processes.     

聚丁内酰胺的生物降解性研究进展

目的 介绍聚丁内酰胺(Polybutyrolactam,PA4)的生物降解性研究现状,综述聚丁内酰胺及其衍生物在海洋、土壤、堆肥等自然环境中的生物降解速率及降解机制,为聚丁内酰胺的改性和应用研究提供指导.方法 采用分类总结的方法,对比聚丁内酰胺及其衍生物在不同环境下的降解行为,阐述目前关于其降解机制的研究进展.结论 聚丁内酰胺可在自然环境中短期内降解,其优异的生物降解性与亲水性有关,同时自然环境中长期存在的某些菌群能够分泌胞外酶水解酰胺键,使得聚丁内酰胺可在自然环境中快速降解.结构改性对聚丁内酰胺的降解速率具有一定影响,探究聚丁内酰胺改性后生物降解性的变化,有助于开拓控制其降解速率的新思路.聚丁内酰胺具有极高的气体阻隔性和出色的力学性能,未来作为可降解材料在食品包装方面应用具有极高的应用前景,通过合适的改性手段实现PA4热塑加工,并保留PA4良好的生物降解性,明确环境微生物对PA4及其改性产物的代谢和降解途径,也是未来研究的难点和热点.     

Novel ternary g-C3N4/Fe3O4/MnWO4 nanocomposites: Synthesis,characterization, and visible-light photocatalytic performance for environmental purposes

The g-C₃N₄/Fe₃O₄/MnWO₄ nanocomposites were prepared by a refluxing-calcination procedure. Visible-light-induced photocatalytic experiments showed that the g-C₃N₄/Fe₃O₄/MnWO₄ (10%) nanocomposite has excellent ability to degrade a range of contaminants including rhodamine B, methylene blue, methyl orange, and fuchsine, which is about 7, 10, 25, and 31 times of the g-C₃N₄ photocatalyst, respectively. Reactive species trapping experiments revealed that superoxide anion radicals play major role in the photodegradation reaction of rhodamine B (RhB). After the treatment process, the utilized photocatalyst was magnetically recovered and reused with negligible loss in the photocatalytic activity, which is vital in the photocatalytic processes. Finally, a mechanism was proposed for the enhanced interfacial carrier separation and transfer and the improved photocatalytic performance.     

水热合成不同形貌的纳米三氧化钨及形成机理探讨

以钨酸钠和盐酸为原料,柠檬酸、酒石酸、对硝基苯甲酸、对氨基苯甲酸和尿素为辅助试剂,在一定温度下通过水热法制备出不同形貌的纳米三氧化钨。对所得产物进行X射线衍射(XRD)、透射电镜(TEM)和扫描电镜(SEM)的分析。结果表明:使用不同的助剂将制备不同形貌的纳米三氧化钨,推测可溶性有机酸在水热反应中起到"软模板剂"的作用,尿素在高压下产生的气体有助于增强产物的分散性,得到尺寸均匀的纳米粉体。     

Controllable synthesis of SnO2 photocatalyst with superior photocatalytic activity for the degradation of methylene blue dye solution

SnO₂ photocatalyst was successfully synthesised by novel chemical route in hydrothermal environment and annealed at two different temperatures viz 550 and 600 °C, respectively. The crystal structure, optical properties, surface and bulk morphology have been characterised using various tools like X-ray diffraction (XRD), UV visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). Cubic, spheres and porous like morphology of SnO₂ photocatalyst was successfully confirmed using SEM micrographs and TEM. In addition to this the photocatalytic activity was evaluated towards the degradation of methylene blue dye solution. SnO₂ photocatalyst annealed at 600 °C exhibits excellent photocatalytic efficiency which may be attributed to the unique morphology, high crystalline nature and charge separation. The photocatalyst efficiency was further tested towards the concentration of dye, catalyst dosage and pH of the dye. The involvement of ?OH in the photocatalytic reaction was evidenced using trapping experiment by employing different scavengers. The photocatalyst was moderately active, stable upto its fifth usage and stability of the photocatalyst before and after the photocatalytic reaction was also been studied using XRD and SEM.