光催化：电子的奇妙之旅

半导体光催化技术可以利用太阳能光催化分解水制备氢气和降解有机污染物以解决能源问题和环境污染问题,并且具有反应低能耗、低温深度反应和反应具有光谱性等优点,是解决环境和能源问题领域中最具有应用前景的新技术之一。本文通过将半导体光生电子拟人化,以电子先生的旅游视角介绍了光催化反应中电荷的转移过程,介绍了光催化技术在制氢和降解有机污染物领域中的应用。     

二氧化钛选择性光催化降解有机污染物研究进展

半导体二氧化钛已被广泛应用于有机污染物的光催化降解,但其主要是通过光与二氧化钛作用产生的羟基自由基与有机污染物发生自由基氧化反应,这种自由基反应在降解污染物时没有选择性,当几种有机污染物共存时,它优先催化降解吸附在其表面的高浓度污染物,而低浓度的有机污染物因吸附量少而达不到有效降解。因此,研究开发具有高选择性的能降解低浓度高毒性有机污染物的二氧化钛材料是环境科学领域亟待解决的热点之一。本文综述了近十年来二氧化钛选择性光催化降解有机污染物的研究动态和主要成果,并对未来发展趋势进行展望。     

几种典型有毒有机污染物的光催化降解研究

本文研究了氯代苯酚和苯胺类化合物的光催化降解,探讨了这些有机污染物分子的氯取代和化合物毒性与光催化降解之间的关系.研究表明,氯代苯酚和苯胺类化合物的光催化降解均符合表观一级反应动力学模型.有机物分子中氯取代基的引入加快了化合物的光催化降解,且反应速率随氯取代基个数的增多而增大.光催化降解的表观速率常数与正辛醇-水分配系数之间存在有较好的线性关系:logk=alogKow+b,该模型可以用于有机污染物的光催化降解性预测.     

用于降解印染废水中有机污染物的光催化剂的研究进展

纺织工业印染废水的大量排放是造成水体污染物增多的主要因素之一,对人体健康和生态环境的良性循环造成严重威胁。目前,采用的物理吸附法、化学氧化法以及生物分解法等废水处理技术成本高昂、治污不彻底且容易产生二次污染,加快研发经济高效的处理技术对降低水资源消耗、保护环境意义重大。光催化降解法是催化剂受光辐照后在反应体系中产生活性自由基,自由基进一步与有机污染物反应,使其完全降解。由于该方法经济高效,不易造成二次污染,符合绿色环保的发展要求,已成为污染物降解的研究热点。本文主要综述了近10年光催化技术在降解有机污染物领域的具体方法与研究进展,指出无机半导体、金属有机框架和有机小分子材料作为光催化剂存在的弊端,而多孔共轭聚合物兼具优异的光催化降解和吸附性能,具有很好的发展前景。     

挥发性有机污染物光催化氧化动力学中的L-H模型*

挥发性有机污染物的光催化氧化（PCO）过程反应动力学多数符合L-H模型。本文综述了近年来在L-H模型基础上提出的改进的动力学模型的研究进展。除流速、污染物的初始浓度外,光强度、相对湿度、反应器系数、对流传质系数、电子-空穴对的结合速率以及中间产物等因素对PCO反应同样起不可忽略的作用;分析了通过反应动力学模型判断光催化反应速率控制步骤的方法;总结了适用于L-H模型的实验条件如反应器类型、催化剂、光源、污染物类型等。     

多溴联苯醚的光催化还原脱溴

多溴联苯醚(PBDEs)在生态环境中是普遍存在的并已证实具有潜在的毒性,因此PBDEs引起了环境化学领域的广泛关注。光催化技术具有可利用太阳能、反应选择性高且反应条件温和等优点,其在降解PBDEs这类污染物方面具有独特的优势。近年来光催化在降解含卤有机污染物的研究中取得长足进展。本文就多卤代芳烃类化合物中最为典型的PBDEs的光催化还原研究现状进行介绍,并着重阐述TiO_2催化剂对PBDEs的光催化还原脱溴反应的基本过程、提高光催化还原效率的途径以及光催化还原脱溴机理等。除此之外,本文也对PBDEs未来光催化还原脱溴的前景进行了简单的展望。     

多孔炭材料在二氧化钛光催化水处理中的应用

光催化水处理技术是利用光照具有能带结构的半导体光催化剂诱发强氧化自由基(·OH),使有机污染物在常规条件下催化降解. 光催化反应条件温和、转化率高,而且二次污染小,具有良好的应用前景.     

共价有机框架材料在光催化领域中的应用

共价有机框架(COFs)材料是有机构筑基元通过共价键连接而形成的晶态有机多孔材料. COFs具有孔道结构规整、 及比表面积高等特点, 被广泛地应用于气体储存与分离、 催化、 传感、 储能及光电转化等领域. 将具有可调吸光能力的有机构筑基元引入到COFs中, 可使其展现出强大的光催化潜力. 近年来, COFs在光催化领域中发展迅猛. 本文总结了COFs在光催化产氢、 光催化二氧化碳还原、 光催化有机反应以及光催化污染物降解等方面的研究进展, 并展望了其在光催化领域的应用前景.     

TiO2光催化降解苯和甲苯的动力学研究

利用溶胶-凝胶法制备了粒径约为13nm、晶型为锐钛矿相和金红石相混晶的TiO2光催化剂,并利用此催化剂对挥发性有机污染物苯和甲苯进行了光催化降解研究,对不同的催化剂用量、光源、污染物的初始浓度以及氧气对光催化反应速率的影响进行了研究。结果表明,光催化降解甲苯和苯的反应均符合假一级动力学方程,光强与光催化降解甲苯的反应的速率常数之间呈指数关系,光波长对光催化降解苯的影响也很显著;随着甲苯和苯初始浓度的增加,光催化反应速率常数降低;氧气加快了光催化降解甲苯和苯的速率;对于光催化降解初始浓度为37.6μmol/L的甲苯而言,催化剂的最佳使用量为0.30g,对于光催化降解初始浓度为9.0μmol/L的苯来说,催化剂的最佳用量为0.10g。     

有毒难降解有机污染物的光催化降解

有毒难降解有机污染物的光催化降解在原理、过程和效率等方面仍然存在着巨大的挑战,特别是光催化剂的构效关系、可见光的利用、分子氧的活化和污染物分子矿化分解的机理仍然是今后的研究热点.本文就近年来在半导体光催化和负载型铁离子光催化降解有毒有机污染物的两个重要方面的研究进展进行了评述.     

水蒸气对有机污染物微波光催化氧化反应的影响

 以C2H4和C2HCl3为模型有机污染物,考察了不同反应条件下水蒸\r\n气对微波催化反应性能的影响．结果表明,水蒸气的存在是影响微波光\r\n催化反应性能的重要因素．由于微波对物质的极化作用不同,在加水的\r\n微波光催化反应过程中微波能量主要被水吸收,微波场对水的脱附有利\r\n于提高加水条件下C2H4微波光催化氧化活性,但不利于需要水的C2HCl\r\n3氧化反应的进行．     

TiO<Subscript>2</Subscript> Photocatalytic Oxidation: II. Gas-Phase Processes

The results of studies on the TiO₂ photocatalytic oxidation of model air pollutants are summarized. The kinetics of photocatalytic oxidation of CO and the vapors of a number of simple organic substances was studied in detail. It was found that, in the course of reaction, all of the test substances underwent complete mineralization. Gaseous substrates were converted with the participation of several types of reaction centers. The photocatalytic oxidation of sulfur- and phosphorus-containing substances resulted in gradual deactivation of the photocatalyst; however, its activity can be restored by washing the photocatalyst with water. It was found that, along with oxidation, the steps of hydrolysis play an important role in the photocatalytic degradation of air pollutants, such as dimethyl methylphosphonate and 2-chloroethyl sulfide.__________Translated from Kinetika i Kataliz, Vol. 46, No. 3, 2005, pp. 450–465.Original Russian Text Copyright © 2005 by Vorontsov, Kozlov, Smirniotis, Parmon.     

光催化技术在降解有机染料污染物方面的应用

光催化技术是一种新兴的高效节能现代污水处理技术,本文从半导体光催化技术研究现状、反应机理、反应动力学、光催化技术发展及其存在的问题等方面对半导体光催化技术在降解常见有机染料方面的应用加以综述.     

构建光催化氧化-还原体系的研究进展

光催化氧化-还原体系能够同时驱动光催化氧化反应和还原反应,产生协同效应,从而提高光催化反应的活性。在此,提出了构建光催化氧化-还原体系的原则,并介绍了光催化还原硝基芳烃耦合氧化有机物、光催化还原重金属离子协同氧化有机物、光解水制氢协同氧化有机物三个方面的实例。接着,阐述了光催化氧化-还原体系的反应机理,期望通过构建光催化氧化-还原体系,更有利于太阳能转化并缓解环境和能源问题。     

双功能S-型g-C3N4/Bi/BiVO4复合光催化剂驱动人工碳循环（英文）

长期以来,陆地、大气和海洋之间的碳循环维持了大自然碳平衡.随着密集人类活动和高度工业发展,碳燃料、碳化学品和碳材料广泛应用于各个领域,导致碳排放过量,碳平衡已被严重破坏,碳污染已成为一个严峻问题.例如,持久性有机污染物和挥发性有机化合物过量排放到环境中,威胁着人类的健康和生态平衡.人们陆续开发出各种先进的环境技术,如微生物分解,去除空气和水中的碳基污染物,将有毒有害的有机化合物转化为无害CO2.但是,CO2本身是大气中的主要温室气体,它在大气中的浓度早超过了天然碳循环所能维持的环境自洁净能力.基于先进催化技术建立人工碳循环,将有机污染物矿化生成的CO2进一步转化为有价值的有机化学品(如太阳能燃料)是一种理想的低碳方法.光合作用是自然碳循环中核心过程之一,是降低大气中CO2浓度的关键.受到光合作用启发,科学家们积极开发人工光合成技术推动CO2资源化.人工光合成技术本质上基于半导体光催化过程.半导体光催化过程具有双重作用.一方面,基于有氧光催化氧化过程,有机污染物可以矿化生成无毒CO2.另一方面,基于缺氧光催化还原过程,CO2可以转化为碳氢化合物太阳能燃料.理论上,结合上述两个过程,为建立人工碳循环奠定基础,但是,至今很少有人成功建立有氧氧化-无氧还原串联光催化工艺,实现人工碳循环.难点在于有机污染物的有氧氧化反应和CO2的无氧还原反应的操作条件与反应机制是完全不同的,目前缺乏同时适用于上述两种反应的双功能光催化剂.本文成功构建了具有双功能的g-C3N4/Bi/BiVO4三元复合光催化剂,它不仅在降解有机污染物方面表现出优异的有氧光催化氧化性能(以降解染料罗丹明B为例),而且还表现出优异的缺氧CO2光催化还原性能.此外,基于“一锅法”厌氧耦合氧化-还原反应,g-C3N4/Bi/BiVO4三元复合光催化剂成功实现同步罗丹明B降解与太阳能燃料生成,构建了从毒害有机污染物到高品质太阳燃料的碳循环.结合牺牲剂实验分析与密度泛函理论理论计算,作者提出g-C3N4/Bi/BiVO4复合光催化剂的双功能性与g-C3N4与BiVO4界面内建S-型复合异质结有关.S-型复合异质结既促进界面电荷转移与分离,又维持了最佳电荷氧化还原电位.此外,S型g-C3N4/Bi/BiVO4复合光催化剂中原位生成的具有等离子体效应的Bi纳米颗粒具有双重作用,既促进界面电荷定向转移,又促进可见光吸收.本文开发的新型双功能S-型g-C3N4/Bi/BiVO4复合光催化剂系统为进一步开发集成式有氧-缺氧光催化碳循环反应系统奠定基础.     

Electrocatalytic and photocatalytic applications of atomically precise gold-based nanoclusters

With advances in cluster chemistry, atomically precise gold nanoclusters(NCs) with well-defined composition and tunable structure provide an exciting opportunity to uncover the specific roles of the geometrical and electronic structures as well as the capped ligands in overall catalytic performances. The Au NCs possess quantum energy levels and unique optical properties,which have exhibited unexpected photocatalytic and electrocatalytic activities. In this review, we first highlight the electrocatalytic applications of Au NCs, including hydrogen evolution reaction, oxygen reduction reaction, CO_2 reduction and catalytic oxidation reactions, and then present Au NCs-driven photocatalytic applications such as selective organic reactions, decomposition of pollutants and energy conversion reactions. Finally, we conclude this review with a brief perspective on the catalytic field of Au NCs.     

石墨烯量子点修饰的BiOI/PAN柔性纤维的制备及其增强的光催化活性

In environment remediation, photocatalytic oxidation is a promising technique for removing organic pollutants. Compared to adsorption, biodegradation, and chemical oxidation, photocatalytic oxidation can eliminate organic pollutants completely, conveniently, and cheaply in an environmentally friendly manner. Visible-light-driven photocatalytic oxidation is particularly advisable because of the high proportion of visible light energy in solar energy. Bismuth oxyiodide (BiOI) is a promising visible-light-driven photocatalyst for the oxidization of pollutants, not only because of its narrow band gap, but also for its relatively low valence band (VB), which is adequate for photogenerated holes to oxidize a variety of organic compounds. However, the shortcomings of BiOI powder, such the difficulty of recycling it, its low surface area, and fast carrier recombination, limit its practical applications. Meanwhile, the flexibility and hierarchical structure of photocatalysts are particularly advisable because these properties are beneficial for the convenient operation, recycling, and performance improvement of these materials. Herein, based on an electro-spun polyacrylonitrile (PAN) nanofiber substrate, a hierarchical BiOI/PAN fiber was prepared through an in situ reaction. In the as-prepared BiOI/PAN fibers, BiOI flakes were aligned vertically and uniformly around the PAN fibers. BiOI nuclei generated from pre-introduced Bi(Ⅲ) in the PAN fiber act as seeds for the growth of BiOI nanoplates, which is crucial for the formation of a hierarchical structure. Such a hierarchical structure can improve both the light absorption and carrier generation of the BiOI/PAN fibers, as demonstrated by UV-Vis diffuse reflectance spectra and photoluminescence emission. Therefore, the BiOI/PAN fibers exhibited higher photocatalytic activity than BiOI powder. When the BiOI/PAN fibers were decorated with pre-prepared graphene quantum dots (GQDs), a GQD-modified BiOI/PAN fibrous composite (GQD-BiOI/PAN) was fabricated. The morphology of the obtained GQD-BiOI/PAN fibers was nearly the same as that of the BiOI/PAN fibers. A step-scheme (S-scheme) heterojunction was formed between the GQDs and BiOI, which was confirmed by the fabrication method, photoluminescence emission, reactive radical tests, and XPS analysis. This kind of S-scheme heterojunction can not only effectively suppress the recombination of photogenerated holes, but can also reserve the more reductive electrons on the lowest unoccupied molecular orbital of GQDs and the more oxidative holes on the VB of BiOI, for the photocatalytic degradation of phenol. Because of the fibrous hierarchical structure and S-scheme heterojunction, GQD-BiOI/PAN outperformed BiOI nanoparticles and BiOI/PAN nanofibers in the photocatalytic oxidation of phenol under visible light. In addition, because of tight bonding, GQD-BiOI/PAN can be tailored and operated by hand, which is convenient for recycling. During recycling, no obvious loss of sample or decrease in photocatalytic activity was observed. This work provides a new pathway for the fabrication of flexible photocatalysts and a new insight into the enhancement of photocatalysts.      

多金属氧酸盐光催化降解有机污染物研究进展

光催化作为一种高级氧化技术在有机污染物的降解方面得到广泛研究。本文概述了多金属氧酸盐光催化降解有机卤化物、染料、农药等有机污染物的研究进展,介绍了多金属氧酸盐与半导体氧化物、层状双氢氧化物、分子筛与介孔材料、离子交换树脂形成的复合材料,以及与半导体氧化物、聚乙烯醇等形成的复合膜材料的相关研究。     

碳点修饰多孔ZnO纳米棒增强光催化性能

Porous ZnO nanorods that displayed excellent photocatalytic degradation of organic pollutants (RhB and phenol) were prepared via a solvent thermal method followed by surface modification with carbon dots (C-dots) using a deposition method. The photocatalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-Vis) spectroscopy. The degradation of the organic pollutants using the nanorods was tested under Xe-light illumination and was enhanced following C-dot modification. Nanorods that were modified by the C-dots at a mass fraction of 1.2% (CZn1.2) exhibited the highest photocatalytic activity for the degradation of RhB, which was 2.5 times of the pure porous ZnO nanorods. Additionally, the modified nanorods with strangely oxidation ability could catalyze the degradation of phenol by open-rings reaction under Xe-light illumination. The improved photocatalytic activity was attributed to the effective separation of the photogenerated electrons and holes, in which the C-dots served as the receptor of the photogenerated electrons.     

光催化降解水中有机污染物研究现状与展望

光催化技术是一种新兴、高效、节能、现代污水处理技术。从半导体光催化技术研究现状、反应机理、常见有机污染物光催化降解的现状、提高半导体光催化剂活性的途径、光催化技术发展中存在问题等方面对半导体光催化技术加以综述和讨论。目前不论从光催化技术、光催化的基础研究以及光催化应用研究方面都需进行大量的、深入研究工作。