太阳能光催化制氢反应体系及其材料研究进展

光催化制氢是利用太阳能获取氢能的重要途径,是当前研究热点。长期以来,人们致力于各种新型可见光光催化制氢材料的研究并取得较大进展。反应体系的设计和选择是实现高效光催化制氢和能否走向工业化的核心问题之一,因此,近年来研究者开始对光催化制氢反应体系加大研究。光催化制氢主要有非均相光催化制氢(HPC)和光电催化制氢(PEC),不同的体系具有各自的优缺点和应用范围。重点介绍光催化制氢半反应、光催化完全分解水和光电催化分解水3种主要反应体系,分析各种反应体系的特点,阐述各个体系涉及的光催化材料的发展进程,并展望太阳能光催化制氢研究前景,其中,新型高效的PEC-PV(光伏)耦合光化学转化系统有望为光解水制氢实现工业化提供一种重要的发展途径。     

Photocatalytic Degradation of Butanol in Aqueous Solutions by TiO2 Nanofibers

Removal of butanol from aqueous solutions was studied using both custom made and commercial TiO₂ photocatalysts. The custom made photocatalytic materials were nanofibers of titanium dioxide doped with nitrogen and subsequently decorated with nanoparticles of platinum or palladium. Pd-decorated photocatalysts were found to be highly efficient in the degradation of butanol under UV-A irradiation compared to Pt-decorated nanofibers or to commercial Degussa P25.     

CdSe纳米颗粒敏化TiO_2纳米管阵列的光催化降解及光电催化制氢

采用胶体化学法制备不同尺寸的硒化镉纳米颗粒(CdSe-NP)胶体,并利用原位吸附法将CdSe-NP与由阳极氧化法得到的TiO2纳米管阵列(TN)复合,在可见光下降解甲基橙溶液和外加偏压制氢,分别考察CdSe-NP敏化的TiO2纳米管阵列(CdSe-NP/TN)的光催化性能和光电催化性能。对比TN,CdSe-NP/TN表现出明显增强的光催化活性及更优异的光电催化性能,而过大的CdSe-NP尺寸则不利于复合材料的催化活性。表征结果表明,CdSe-NP/TN优异的性能是由于敏化CdSe-NP后吸收边红移以及光生电子和空穴复合率降低。     

配合法制备InNbO_4及其光催化活性的研究

以配合法制备InNbO4催化剂,研究了在甲醇为电子给体,Pt为助催化剂的条件下,InNbO4光催化分解水的产氢活性。并与固相合成法制备的InNbO4光催化活性进行对比。通过X-射线衍射和比表面分析对两种方法制备的催化剂进行表征。研究发现,在焙烧温度为900℃、时间为12 h时,配合法制备的InNbO4光催化产氢活性最高(87.27μmol),为固相合成法的2倍。     

Porous ceramics based on hybrid inorganic tetrapodal networks for efficient photocatalysis and water purification

The present work demonstrates a very simple and unique strategy for efficient photocatalysis using ZnO ceramic nano- and microtetrapods synthesized by a flame transport synthesis approach. Due to their three-dimensional (3D) morphology, highly porous interconnected networks as flexible ceramics with sufficient mechanical strength can be easily fabricated and efficiently utilized in applications like e.g., photocatalysis, liquid filtering, and membranes. The photocatalytic response can be further enhanced by hybridization of the ZnO tetrapods with different metal oxides which has been explored in detail here. The Cu- and Bi- hybridized ZnO tetrapodal ceramic networks showed the least and highest photocatalytic activities against methylene blue, respectively, whereas, the others exhibited intermediate responses. The observed photocatalytic behaviors of pure and hybrid ZnO tetrapods based flexible ceramic 3D networks are briefly presented and discussed.     

以污染物作为电子给体的新型光催化制氢体系的研究进展

以污染物作为电子给体进行的光催化制氢体系代表着一种新型的现代水处理技术,在污染物被降解的同时还可以将太阳能转化为清洁的氢能,有效地缓解了环境污染和能源短缺两大难题。为此,本文结合光催化制氢协同污染物降解反应的机理,概述了近年来国内外在该方向上的主要研究成果,列举了几种常用的催化剂,分析了不同的操作参数,如污染物种类、催化剂类型和组分、催化剂的微观结构、催化剂投加量、pH、污染物浓度、溶液中存在的不同阴阳离子及其他共存物、反应温度以及光照强度对光催化降解率和产氢活性的影响。最后,指出了以污染物作为电子给体的光催化水处理技术在光催化材料的选择上依然面临种类偏少、产氢效率偏低的挑战,并且在反应影响因素的探究上仍存在不充分、不全面的问题。同时,评述了将多项工艺结合起来的多单元水处理系统是未来水处理领域的一个主流模式。     

CdSe/TiO2 core-shell nanoparticles produced in AOT reverse micelles: applications in pollutant photodegradation using visible light

CdSe quantum dots with a prominent band-edge photoluminescence were obtained by a soft AOT water-in-oil (w/o) microemulsion templating method with an estimated size of 2.7 nm. The CdSe particles were covered with a TiO2 layer using an intermediate SiO2 coupling reagent by a sol-gel process. The resulting CdSe/TiO2 core/shell nanoparticles showed appreciable photocatalytic activity at λ = 405 nm which can only originate because of electron injection from the conduction band of CdSe to that of TiO2.     

NiO掺杂InVO4光催化降解甲酸水溶液产氢的研究

以有机污染物为电子供体可达到制氢与治污的双重目标.通过高温固相法制备了新型NiO/InVO4复合光催化剂.采用XRD,SEM,UV-VIS,BET等测试手段对复合光催化剂的物理和光学性质进行了表征,考察了NiO/InVO4复合光催化剂降解甲酸水溶液制氢的光催化反应.结果表明:NiO/InVO4复合光催化剂为正交晶相结构...     

光催化分解水制氢中硫化物空心结构的研究进展

利用太阳能进行的分解水制氢技术,可以促进太阳能的有效利用和清洁能源氢能的研发。在光催化制氢中,半导体光催化材料的性能是光催化反应性能提升的核心要素,制备优异、高效的光催化剂是提升光催化反应活性的关键步骤。本文从材料形貌和制备角度出发,选取金属硫化物为光催化中的主体半导体,对国内外金属硫化物空心结构的研究、应用和进展进行了回顾,分析了空心结构对增大材料比表面积、增强太阳光吸收、加速载流子分离以及提升反应活性的重要性,提出了空心结构在光催化发展中的优势,对空心结构的发展提出了展望,为这些新型材料的未来研发提供参考,从而能尽快提高光催化反应的太阳光利用率和氢气产量,有助于进一步实现光催化技术的工业化应用。     

太阳能光解水制氢催化剂研究进展

利用太阳能制氢是将太阳能转换成氢能的有效方式。近年来国内外发展了不同类型的太阳能光解水制氢催化剂：金属配合物、金属氧化物、无机层状化合物、Z型光催化制氢反应体系和光生物催化反应体系等,通过金属负载、离子掺杂、复合半导体、燃料光敏化、电子捕获剂、表面螯合及衍生作用、外场耦合等途径可以有效提高光催化剂活性,开发具有特殊结构的新型光催化剂、无贵金属负载催化剂以及循环使用牺牲剂将是未来太阳能光解水制氢的发展方向。     

自牺牲模板法制备CdSe负载的CdS纳米线及其表征

以六方相CdS纳米线为前驱物,在不同浓度的Na2SeSO3水溶液中,采用水热合成法制备了负载量可控的CdSe沉积的CdS纳米线复合材料。采用XRD、SEM、TEM、UV-vis、PL和FTIR对该复合材料的物相、组成、形貌及光学性能进行了详细表征。结果表明,CdSe呈纤锌矿型六方相结构的纳米层形态沉积在CdS表面,其负载量受Na2SeSO3水溶液浓度、反应温度和反应时间控制;与CdS纳米线相比,纳米复合材料的可见光吸收范围明显扩大,覆盖了可见光的大部分区域,而其中的CdS纳米线荧光因CdSe的存在出现猝灭现象,同样,也未观察到CdSe的荧光。该文详细讨论了相关的光学性质以及纳米复合物的反应机理。     

Catalytic activity of gold supported on ZnO tetrapods for the preferential oxidation of carbon monoxide under hydrogen rich conditions

It is reported that 3 nm gold nanoparticles deposited on ZnO tetrapods show high activity for the selective oxidation of carbon monoxide in hydrogen rich streams; the catalytic activity of this system is at least twice as high as the values hither to observed on any conventional support for this reaction.     

Molecule assembly of heterostructured TiO2@BiOCl via fenton-like reaction for enhanced solar energy conversion

In this work, we applied the fenton-like reaction to fabricate TiO₂ nanocrystalline, and employed molecular self-assembly with TiO₂ and BiOCl to form composite photocatalyst with cookie-like nano-heterostructure for enhanced solar energy to hydrogen. The TiO₂@BiOCl photocatalyst with cookie-like nano-heterostructure exhibited excellent photocatalytic performance for the photocatalytic hydrogen evolution under sunlight irradiation compared to the single TiO₂ or BiOCl. Besides, the TiO₂@BiOCl photocatalyst displayed outstanding reusability and stability in the photocatalytic reaction. Meanwhile, the possible mechanisms of cookie-like nano-heterostructure formation and photocatalytic redox reaction have been proposed. What's more, this work demonstrated a new perspective for the design and mass preparation of TiO₂-based composite photocatalytic materials at atmospheric condition, which demonstrated that this method has enormous potential to achieve mass preparation of efficient photocatalyst for photocatalytic application.     

自牺牲模板法制备CdSe负载的CdS纳米线及其表征

以六方相CdS纳米线为前驱物，在不同浓度的Na2SeSO3溶液中，采用水热合成法制备了负载量可控的CdSe沉积的CdS纳米线复合材料。采用XRD、SEM、TEM、UV-Vis、PL和FTIR对该复合材料的物相、组成、形貌及光学性能进行了详细表征。结果表明，CdSe呈纤锌矿型六方相结构的纳米层形态沉积在CdS表面，其负载量受Na2SeSO3溶液浓度、反应温度和反应时间控制；与CdS纳米线相比，纳米复合材料的可见光吸收范围明显扩大，覆盖了可见光的大部分区域，而其中的CdS纳米线荧光因CdSe的存在出现淬灭现象，同样，也未观察到CdSe的荧光。文章详细讨论了相关的光学性质以及纳米复合物的反应机理。     

Pt/TiO2上的污染物降解耦合光解水制氢研究

以三乙胺和乙醚为目标污染物,研究了Pt/TiO₂上光催化分解水产氢和污染物同时降解的光催化反应。研究了作为电子给体的污染物浓度对光解水制氢反应的影响,污染物本身的降解规律符合Langmuir-Hinshelwood准一级动力学方程。使用拉曼光谱仪和紫外-可见光分光光度计对降解产物浓度进行了表征,讨论了可能的降解反应机理。     

Effect of inorganic salts on ferric oxalate-induced decomposition of CI Acid Black 234 under different weather conditions

In this study, sodium chloride and sodium sulphate were used for investigating their effects on photocatalytic decomposition of a triazo acid dye, CI Acid Black 234, used widely for the coloration of leather and wool products by the Fe ⁱⁱⁱ -oxalate complexes/hydrogen peroxide system under different weather conditions, respectively. Moreover, the photocatalytic degradation and mineralisation of CI Acid Black 234 was also examined by ultraviolet–visible spectrum and total organic carbon measurements. The results indicated that photocatalytic decoloration of CI Acid Black 234 was significantly limited in the presence of inorganic salt. Increasing the concentration of inorganic salt led to a lower decoloration percentage and kinetic reaction constant. The effect of inorganic salt on dye decomposition varied with solar light intensity. Sodium chloride exhibits a much stronger reduction effect on photocatalytic decoloration, degradation and mineralisation than sodium sulphate at similar reaction conditions, especially on a cloudy day.     

Capability of coupled CdSe/TiO2 heterogeneous structure for photocatalytic degradation and photoconductivity

Highly ordered TiO₂ nanotube arrays (TiO₂-NTAs), with a uniform tube size on titanium substrate, were obtained by means of reoxidation and annealing. A composite structure, CdSe quantum dots@TiO₂ nanotube arrays (CdSe QDs@TiO₂-NTAs), was fabricated by assembling CdSe quantum dots into TiO₂-NTAs via cyclic voltammetry electrochemical deposition. The X-ray diffractometer (XRD), field-emission scanning electron microscope (SEM), and transmission electron microscope (TEM) were carried out for the determination of the composition and structure of the tubular layers. Optical properties were investigated by ultraviolet-visible spectrophotometer (UV-Vis). Photocurrent response under visible light illumination and photocatalytic activity of samples by degradation of methyl orange were measured. The results demonstrated that the photo absorption of the composite film shifted to the visible region, and the photocurrent intensity was greatly enhanced due to the assembly of CdSe QDs. Especially, photocurrent achieved a maximum of 1.853 μA/cm² after five voltammetry cycles of all samples. After irradiation under ultra violet-visible light for 2 h, the degradation rate of composition to methyl orange (MO) reached 88.20%, demonstrating that the CdSe QDs@TiO₂-NTAs exhibited higher photocatalytic activity.     

Morphology-controlled synthesis of CdSe microspheres on graphene oxide sheets and their photocatalytic properties

Different morphologies of CdSe microspheres have been synthesized on reduced graphene oxide (rGO) sheets by a simple hydrothermal process using Cadmium nitrate and Se powder as the raw materials. The hybrid CdSe/rGO samples were intensively investigated by XRD, EDS, XPS, SEM and UV–vis absorption spectrum. It was found that the EDTA/Cd²⁺ molar ratio is crucial for the formation of morphology of CdSe grown on rGO sheets. The results of XRD reveal that the as-prepared CdSe microspheres have zinc blend structure. The results of Raman spectra, EDS, XPS and SEM show that the CdSe microspheres are grown on rGO sheets. In addition, UV–vis absorption spectrum indicates that the CdSe/rGO nanocomposites are believed to serve as photosensitizers to extend the absorption spectrum to visible light region. Superior photocatalytic activity of urchin-like CdSe microspheres grown on rGO sheets relative to those of other CdSe/rGO nanocomposites was observed under visible light irradiation. The growth mechanism for the formation of CdSe microspheres grown on rGO sheets was also described.     

Cd2+前体反应时间对CdSe量子棒长径比的调控及其光学特性研究

CdSe量子棒是一种具有良好光学特性的半导体纳米材料,不同长径比的量子棒可应用于光电材料及器件制备。采用高温油相合成法制备CdSe量子棒,在只改变前体反应时间的前提下,探究其对于CdSe量子棒长径比的变化机理并对其光学特性进行对比分析。实验结果表明CdSe量子棒随着反应时间的增长粒径增大并且发射峰的峰位产生了红移的现象。通过透射电子显微镜表征后发现量子棒随着前体反应时间的增加长度逐渐变长,长径比逐渐变大。因此可以用该方法可以控制量子棒的生长。     

Phenol photodegradation with oxygen and hydrogen peroxide over TiO2 and Fe-doped TiO2

Photodegradation of phenol was investigated with two types of oxidant agents in water, oxygen and hydrogen peroxide, at two different reaction pH with a series of nanosized iron-doped anatase TiO₂ catalysts with different iron contents. The catalysts have been prepared by a sol–gel/microemulsion method. Firstly, iron-doped titania catalysts were studied with respect to their activity behavior when oxygen was used as oxidant agent in the photocatalytic degradation of aqueous phenol in comparison with un-doped reference catalysts. Secondly, two catalysts (TiO₂ and 0.7 wt.% Fe-doped TiO₂) were selected to extend the study for the employment of hydrogen peroxide as oxidant at different concentrations and two initial reaction pHs. An enhancement of the photocatalytic activity is observed only for relatively low doping level (ca. 0.7 wt.%) in catalyst calcined at 450 °C preferably using hydrogen peroxide as oxidant agent which is attributable to the partial introduction of Fe³⁺ cations into the anatase structure. Nevertheless, it has been demonstrated that catalyst surface properties can play an important role during phenol photodegradation process on the basis of the analysis of differences found in the photoactivity as a function of reaction pH.