纳米氧化锌光催化降解有机染料性能的研究

用自制的纳米ZnO在室外阴天、太阳光照射、室内紫外灯照射等条件下对不同有机染料的降解性能作了系统的研究。结果表明纳米ZnO在太阳光照射条件下对弱碱性有机染料溶液的降解效果较好。本文还比较了自制纳米ZnO与纳米TiO2对有机染料的降解性能，结果表明ZnO的降解效果优于TiO2。     

Synthesis of sponge-like TiO2 with surface-phase junctions for enhanced visible-light photocatalytic performance

Maximizing adsorption and catalytic active sites and promoting the photo-excited charge separation are two key factors to achieve excellent photocatalytic performance. In this study, we report a sol-gel synthesis approach to obtain non-metal doped TiO₂ with sponge-like structure and surface-phase junctions all at once. While doping of carbon and nitrogen shifted the activation wavelength to the visible-light region, the innovative use of perchloric acid as a pore-making agent led to the formation of three-dimensional lamellar and porous structure with surface-phase junctions. High surface area with catalytic active sites rendered by the sponge-like structure and surface-phase junctions contributed to the much improved photocatalytic degradation efficiency toward rhodamine B, tetracycline and Disperse Red 60 with excellent reusability and stability. The improved generation and separation efficiency of the photo-induced charge carriers of the as-prepared TiO₂ were supported by electrochemical impedance measurements and transient photocurrent responses. This method could also be applied to other photocatalysts to achieve structural alteration and element doping simultaneously.     

Synthesis of visible light-activated TiO2 photocatalyst via surface organic modification

A visible light-activated TiO₂ photocatalyst was successfully synthesized by the surface organic modification to sol-gel-hydrothermal synthesized TiO₂. The surface hydroxyls of TiO₂ nanoparticles reacted with the active -NCO groups of tolylene diisocyanate (TDI) to form a surface complex that was confirmed by the FT-IR and XPS spectra. Due to the existence of surface complex, the absorption edge of as-prepared TDI-modified TiO₂ nanomaterial extended well into visible region. Compared with unmodified TiO₂ and Degussa P25, the TDI-modified TiO₂ photocatalysts showed higher activity for the photocatalytic degradation of methylene blue under visible light irradiation.     

Fast electron transfer and enhanced visible light photocatalytic activity by using poly-o-phenylenediamine modified AgCl/g-C3N4 nanosheets

Exfoliation of bulk graphitic carbon nitride (g-C₃N₄) into two-dimensional (2D) nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g-C₃N₄ nanosheets (CN) have larger specific surface areas and more reaction sites. In addition, poly-o-phenylenediamine (PoPD) can improve the electrical conductivity and photocatalytic activity of semiconductor materials. Here, the novel efficient composite PoPD/AgCl/g-C₃N₄ nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach. The obtained photocatalysts have larger specific surface areas and could achieve better visible-light response. However, silver chloride (AgCl) is susceptible to agglomeration and photocorrosion. The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density, which is three times that of CN. Obviously enhanced photocatalytic activities of PoPD/AgCl/g-C₃N₄ are revealed through the photodegradation of tetracycline. The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly. Furthermore, ?O₂^? and h⁺ are the main active species, which are confirmed through a trapping experiment and ESR spin-trap technique. Therefore, the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst, in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles. This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.     

Visible light-sensitized semiconductor photocatalytic degradation of 2,4-dichlorophenol

Sensitized-photocatalytic decomposition of 2,4-dichlorophenol (2,4-DCP) using xan-thene dyes as photosensitizer on TiO2 particles under visible light irradiation was studied. 2,4-DCP can be decomposed efficiently by this method and the decomposition efficiency of 2,4-DCP decreases in the following order: eosin Y ≈ rose bengal > erythrosine B > rhodamine B.     

碱金属掺杂的石墨相氮化碳在可见光光催化制氢中的比较研究(英文)

利用半导体光催化技术将太阳能转化为清洁化学能源是解决能源危机和环境问题的最有潜力的途径之一.过去几十年,许多半导体包括氧化物、硫化物和氮化物均表现出光催化活性.然而,半导体光催化的实际应用仍然受制于其较低的太阳能转化效率.解决上述问题的方法之一是发展高效的可见光光催化制氢材料.近年来,石墨相氮化碳(g-C_3N_4)作为一种聚合物半导体材料,受到了光催化研究人员的广泛关注.g-C_3N_4具有可见光吸收能力、合适的导带价带位置、良好的热稳定性和化学稳定性,且制备方法简单和结构易调控,是一种极具潜力的光催化制氢材料.然而g-C_3N_4仍然仅能吸收波长450 nm以下的光,且其光生电子和空穴极易复合,因而光催化制氢效率较低.目前,研究人员采用了多种改性方法来增强g-C_3N_4的光催化性能,其中通过元素掺杂进行能带结构调控是一种非常有效的策略.而碱金属原子(Li,Na和K)被认为可有效进入g-C_3N_4的内部结构,通过引入缺陷来拓宽g-C_3N_4的光吸收范围和提高光生电荷的分离效率.不过到目前为止,尚未见系统的比较研究来深入理解不同碱金属元素掺杂的g-C_3N_4在可见光光催化制氢中的性能差异.本文采用X射线衍射(XRD)、氮气吸附-脱附测试、紫外可见漫反射光谱(UV-visDRS)、时间分辨荧光光谱(TRPL)、X射线光电子能谱(XPS)、光电化学测试和光催化制氢测试等表征和测试手段比较研究了不同碱金属元素掺杂的g-C_3N_4在结构、光学性质、能带结构、电荷转移能力和光催化性能等方面的差异.XRD结果表明,碱金属掺杂可导致g-C_3N_4的层间距离增大,且碱金属原子半径越大,g-C_3N_4的层间距离越大.氮气吸附-脱附测试结果表明,碱金属掺杂可提高g-C_3N_4的比表面积,其中Na掺杂的最高.UV-vis DRS和XPS谱结果表明,依Li,Na,K的顺序,碱金属掺杂导致g-C_3N_4带隙逐渐变窄,使得可见光吸收能力逐渐增强,且其导带和价带位置逐渐下移.TRPL和光电化学测试结果显示,碱金属掺杂有效抑制了g-C_3N_4的光生载流子复合和促进了光生载流子的转移,其中Na掺杂的g-C_3N_4的光生载流子利用效率最高.可见光光催化制氢实验表明,碱金属掺杂显著提升了g-C_3N_4的光催化性能,其中以Na掺杂的g-C_3N_4性能最佳,其产氢速率(18.7mmol h–1)较纯的g-C_3N_4(5.0mmol h–1)可提高至3.7倍.由此可见,g-C_3N_4的掺杂改性是一个对其微结构和能带结构的优化调控过程,最终获得最优的光催化性能.     

Sunlight assisted photocatalytic degradation of organic pollutants using g-C3N4-TiO2 nanocomposites

The photocatalytic degradation of environmentally non-benign, toxic organic pollutants such as bisphenol A (BPA), brilliant green (BG), or mixture of dyes have been carried out using g-C₃N₄-TiO₂ (GNT) nanocomposites. The GNT nanocomposites were synthesized by using hydrothermal method with different compositions and these nanocomposites were characterized using the different techniques. X-ray diffraction revealed that the anatase phase of TiO₂ has been retained in composites; while characteristic reflection of g-C₃N₄ at 27.07° (d = 3.22 Å) is not observed due to its lower content in the nanocomposites. Raman spectra confirms the formation of composites between TiO₂ with g-C₃N₄. Furthermore nano-scale dimensions of the bare or composites have been proved by FE-SEM and HR-TEM analysis. X-ray photoelectron spectroscopy (XPS) shows the presence of C, N, Ti and O as a constituents, with peaks due to CC, NCN of g-C₃N₄. Among the different nanocomposites, g-C₃N₄-TiO₂ catalyst having 30% g-C₃N₄ and 70% TiO₂ in molar proportion (i.e. 30-GNT) is exhibiting the highest efficiency for degradation of the different dyes in correlation to its higher surface area, lower optical band gap as well as more visible-light absorption (i.e., λ > 400 nm) in the electromagnetic spectrum.     

新型可见光响应的 InVO4-Cu2O-TiO2三元纳米异质结：制备及其光催化性能

由于日益严重的环境和能源危机,可见光催化剂的开发已成为当今最具挑战和紧迫的任务之一.将 TiO2和其它窄禁带半导体复合,已被证明是一种有效的可提高其可见光光催化性能的策略. Cu2O是一种禁带宽度为2.0 eV的 p型窄禁带半导体, InVO4则是一种禁带宽度为2.0 eV的 n型半导体,因它们可用于可见光光解水产氢和有机污染物的可见光降解而在过去的数年中引起了人们广泛的关注.但是纯的 Cu2O和 InVO4由于光生电子空穴对在其内部快速地复合,光催化活性通常都比较低.基于能带工程的策略本文设计了一种新型的可见光响应的 InVO4-Cu2O-TiO2三元纳米异质结,并通过普通的湿化学法进行制备：先通过水热法制备 InVO4,再通过溶胶-凝胶法制备 InVO4-TiO2二元复合物,最后通过沉淀和还原过程制备得到 InVO4-Cu2O-TiO2三元纳米异质结.
　　在10%InVO4-40%Cu2O-50%TiO2三元纳米异质结的 X-射线衍射谱中没有观察到明显的杂质峰;通过透射电子显微技术和高分辨透射电子显微技术观察到了它们之间异质结的形成,纳米颗粒的尺寸范围在5?20 nm;经紫外可见漫反射光谱估算得到10%InVO4-40%Cu2O-50%TiO2的禁带宽度为2.78 eV,在可见光区域具有较强的吸收.以普通的9 W节能灯作为可见光光源光照甲基橙5 h后,纯的 InVO4, TiO2和 Cu2O几乎没有光催化活性;10%InVO4-90%TiO2的光催化活性也很低,甲基橙降解率为8%;70%Cu2O-30%TiO2对甲基橙降解率达84%,但初始活性较低;10%InVO4-40%Cu2O-50%TiO2对甲基橙降解率接近90%,并且循环使用6次后,其光催化活性的保持率还维持在90%以上,而50%Cu2O-50%TiO2光催化活性的保持率只有74%.
　　经对使用过的10%InVO4-40%Cu2O-50%TiO2进行 X射线光电子能谱表征发现,存在一弱小的 Cu(II)震动卫星峰,表明在 InVO4-Cu2O-TiO2的光催化过程中 Cu2O的光蚀并不严重.从能带工程的角度分析, InVO4-Cu2O-TiO2三元纳米异质结具有优异的可见光催化性能的主要原因为： InVO4的导带电极电位约为?0.5 eV(vs. SHE,下同),价带电位约为+1.5 eV, Cu2O的分别约为?1.6和+0.4 eV,与 TiO2(导带和价带电极电位分别约为?0.23和+2.97 eV)相比,它们的导带位置更负,将它们组装成三元复合结构,可见光激发的导带电子就可能从 InVO4和 Cu2O的导带迁移到 TiO2的导带上去.同时, n型的 TiO2和 InVO4都与 p型的 Cu2O形成 p-n异质结, n型的 TiO2和 InVO4之间形成 n-n异质结,由于 p-n异质结中内电场的存在以及不同能级相互耦合,可进一步促进可见光激发的导带电子从 InVO4和 Cu2O的导带迁移到 TiO2的导带上去,以及可见光激发的价带空穴从 InVO4的价带迁移到 Cu2O的价带上去,从而实现光生载流子空间上的有效分离.本文有望为新型可见光响应的半导体复合催化剂的设计和制备提供新的思路.     

Structural,optical and photocatalytic activity of cerium doped zinc aluminate

Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl₂O₄:Ce³⁺) increased the photocatalytic activity of zinc aluminate.     

溶剂辅助合成介孔g-C3N4及其增强的可见光催化去除NO性能研究

类石墨相氮化碳(g-C3N4)具有特殊的层状二维结构、独特的电子结构、合适的能带结构、良好的热稳定性和化学稳定性等理化性能,因而在可见光催化净化环境污染物领域广受关注.但原始块状g-C3N4的可见光催化活性较弱,还不能满足实际应用需求.因此,亟需开发一种高效的改性方法来提高g-C3N4的光催化性能.本课题组发展了一种有效的改进g-C3N4方法,以硫脲为前驱体,去离子水(制备样品标记为CN-W)或无水乙醇(制备样品标记为CN-E)为溶剂,通过一步高温缩聚制得具有高可见光催化性能的介孔g-C3N4.然而,对于不同溶剂效应原位改性g-C3N4及其增强可见光催化性能的机理还不清楚.因此,本文采用X射线衍射(XRD)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)、荧光光谱(PL)、N2吸附和元素分析等手段研究了去离子水和无水乙醇作为溶剂原位改性g-C3N4的理化性能差异及增强可见光催化性能的原因.XRD结果表明,去离子水和无水乙醇不会改变g-C3N4的晶体结构,但会抑制其晶体结构的生长.由TEM图像可见,因去离子水和无水乙醇在热聚合过程中产生的气泡可以作为软模板,导致CN-W和CN-E纳米片均为酥松多孔层状结构,其中CN-W更薄更小.元素分析测试结果表明,无水乙醇和硫脲在热聚合过程中导致碳自掺杂g-C3N4.UV-Vis DRS结果显示,CN-W和CN-E分别发生了相对的蓝移和红移现象.荧光寿命测试结果显示,CN的短荧光寿命和长荧光寿命(0.805 ns,3.269 ns)明显高于CN-W(0.756 ns,3.125 ns)和CN-E(0.743 ns,2.749 ns),表明CN-W和CN-E纳米薄片可以促进光生电子的储存和往复运动,有利于光生电子的迁移.此外,通过理论计算得CN-E的电子迁移速率(1.04×108 s?1)明显快于CN-W(0.81×108 s?1),表明CN-E和CN-W都有利于光生电子的迁移猝灭.另外,BET-BJH测试结果显示,CN-W(32.73 m2/g,0.22 cm3/g)和CN-E(25.59 m2/g,0.18 cm3/g)的比表面积和孔容均显著高于未改性的g-C3N4(13.81 m2/g,0.12 cm3/g),表明溶剂和前驱体在热聚合过程中产生的H2O,C2H5OH,H2S,CO2和NH3气体有利于层状结构和丰富孔结构的形成,因而CN-W和CN-E的比表面积和孔容显著增加.由此可见,无水乙醇和去离子水在辅助制备介孔g-C3N4过程中表现出不同的作用.可见光催化去除NO的测试结果表明,CN-E(48.3%)和CN-W(37.2%)的光催化活性明显高于g-C3N4(19.5%),CN-E和CN-W的可见光催化活性也明显优于我们以前报道的BiOBr、C掺杂TiO2和BiOBr/C3N4异质结.结合表征结果,CN-E和CN-W可见光催化性能增强的原因主要有两个:(1)CN-E和CN-W增大的的比表面积和孔容有利于NO的吸附、反应中间产物的转移和提供更多的活性位点参与光催化氧化反应;(2)更薄的纳米片结构和C掺杂g-C3N4有利于促进光生电子的迁移,从而显著提高其光催化活性.     

一步低温法制备可见光响应的棕色纳米TiO2及其光催化性能

光催化作为一种具有前景的技术,被广泛运用于有机物降解、废水处理、空气净化、抗菌、太阳能电池等领域.在众多的光催化材料中,纳米TiO2因具有性质稳定、耐腐蚀、廉价和无毒等优点而受到广泛关注.但纳米TiO2禁带宽度较大(3.2 eV)、只对紫外光有响应及电子-空穴对易复合等特性限制了它的应用.因此,提高纳米TiO2的可见光响应一直是研究的热点.本文发展了一种在低温下制备棕色纳米TiO2的改良溶胶-凝胶法.该法以钛酸四丁酯为钛源,无水乙醇为溶剂,形成溶胶后无需陈化和高温高压,在简单温和的条件下即可制备出棕色纳米TiO2.比较了低温干燥和高温焙烧两种处理方法,结果表明,随着制备温度的升高,样品的粒子尺寸增大,比表面积减小,颜色从白色转变为棕色,在更高的温度又变浅.样品的可见光吸收在180℃时达到最大,随后减弱.在优化温度180℃下制备的TiO2-180℃纳米粒子不仅具有较小的粒径(5.0 nm),较大的比表面积(213.45 m2/g),且在整个紫外-可见光区都具有较强的吸收,其禁带宽度低至1.84 eV.X-射线光电子能谱结果表明,TiO2粒子表面的–OH/H2O含量随制备温度升高而先增加后下降.Raman光谱中Eg峰的移动和变宽表明TiO2晶格可能存在缺陷或氧空位,而TiO2-180℃纳米粒子的电子顺磁共振图谱的g值在2.003左右,对应氧空位中的未成对电子,验证了以上推测.其中TiO2-180℃纳米粒子呈现为最强的EPR信号,表明其晶格内存在最高浓度的氧空位,这是其具有强可见光吸收的原因.光催化实验结果表明,在可见光照射下,TiO2-180℃可高效降解亚甲基蓝(MB).当C(MB)=10 mg/L,pH=4,催化剂添加量为0.07 g时,TiO2-180℃催化剂的光催化活性达到最佳,光照1 h后MB降解率达到99.33%,反应速率常数(0.08287 mg/(L·min))约为同条件下P25(0.01342 mg/(L·min))的6倍.同时,TiO2-180℃催化剂在不同单色光下的光催化活性与它对单色光的光响应大致相符.循环降解实验证明TiO2-180℃催化剂具有很好的稳定性.光猝灭实验表明,·OH在光催化降解过程占主导作用,而TiO2-180℃样品表面含有较多的–OH,有利于·OH的产生,乃至光催化反应.研究表明,晶格内高浓度的氧空位导致的强可见光响应,得益于低温制备条件而保留了大量–OH/H2O的纳米粒子表面以及更大的比表面积,共同促成了TiO2-180℃优越的光催化活性.所制备的棕色纳米TiO2经过进一步修饰后有望运用于实际应用中.     

Comparison of catalytic activity of carbon-based AgBr nanocomposites for conversion of CO2 under visible light

The catalytic activities of carbon-based AgBr nanocomposites (AgBr/CNT, AgBr/GP, AgBr/EG, and AgBr/AC) for CO₂ reduction to hydrocarbons under visible light were investigated in this study. The carbon-based AgBr nanocomposites were prepared on carbon-based supporting materials (CNT, GP, EG, and AC) by the deposition–precipitation method in the presence of cetyltrimethylammonium bromide (CTAB). The photocatalytic activities of AgBr nanocomposites on different supporting materials (CNT, GP, EG, and AC) were investigated by CO₂ reduction yield in the presence of water under visible light (λ > 420 nm). The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that AgBr nanoparticles were well dispersed on the surface of supporting materials. AgBr/CNT and AgBr/GP had a relatively higher reduction yield under visible light due to the transfer of photoexcited electrons from the conduction band of well-dispersed AgBr to carbon supporting materials. In addition, the carbon-based AgBr nanocomposites were stable in the repeated uses under visible light. The total product yields of carbon-based AgBr nanocomposites after the 5 repeated uses almost remained about 83% of the first run. Therefore, carbon-based AgBr nanocomposite is an effective and stable visible-light-driven photocatalyst for CO₂ photoreduction.     

高效稳定的Ag_xS的制备及其光催化性能(英文)

分别采用水热法(AgxS-H)和原位离子交换法(AgxS-IE)制备了AgxS.采用扫描电镜(SEM)、X射线衍射光谱、紫外可见近红外吸收光谱、N2吸附-脱附、X射线光电子能谱和表面光电压测试对催化剂进行了表征.以光(λ≥420 nm)降解亚甲基蓝为模型反应,考察了AgxS的光催化性能.与AgxS-IE相比,AgxS-H具有较小的粒径、较大的禁带宽度、较低光生电荷复合率,因此具有较高的光催化活性.此外,AgxS-H还表现了较好的稳定性,循环使用五次仍能够保持较高的光催化活性.结果表明,AgxS光催化降解亚甲基蓝主要以羟基自由基氧化为主,光生空穴氧化为辅的光催化氧化过程.AgxS-H作为一种有效的光催化剂,在降解有机染料污水方面具有潜在的应用价值.     

Sm-doped g-C_3N_4/Ti_3C_2 MXene heterojunction for visible-light photocatalytic degradation of ciprofloxacin

A heterojunction of Sm-doped g-C_3N_4/Ti_3C_2 MXene(SCN/MX) was constructed via prepolymerization and solid mixture-calcination method.The modified g-C_3N_4 presented a hollow porous seaweed-like shape which can increase its specific area and active sites.In SCN/MX composite,the optical properties,no matter optical absorption ability or separation performance of photo-induced electrons and holes,were enhanced.Among them,Sm-doping may play an important role on transferring the photogenerated electrons to suppress their recombination,and Ti_3C_2 MXene would broaden light absorption and further improve the carrier migration efficiency.The SCN/MX presented higher photocatalytic degradation efficiency( 99%) of cipro floxacin under visible light irradiation.The quenching experiments and electron spin-resonance spectroscopy confirmed that the dominated active materials were superoxide radical and holes.The degradation mechanisms of ciprofloxacin(CIP) over the SCN/MX were attacking of the active materials on the piperazine ring and quinolone ring,and the final products were CO_2,H_2O and F~-.     

网络状纳米氧化锌光催化降解水中有机染料的研究

在太阳光照射条件下用自制的网络状纳米氧化锌对不同有机染料溶液的降解性能作了系统的研究。结果表明,网络状纳米氧化锌对弱碱性有机染料溶液的降解效果较好。本文还比较了自制网络状纳米氧化锌与纳米二氧化钛对有机染料的降解性能,氧化锌的降解效果明显优于二氧化钛。     

Preparation, characterization of the Ta-doped ZnO nanoparticles and their photocatalytic activity under visible-light illumination

This paper describes a novel catalyst of the Ta-doped ZnO nanocrystals prepared by a modified polymerizable complex method using the water-soluble tantalum precursor as the sources of Ta. The catalysts were characterized by means of various analytical techniques as a function of Ta content (x=0–4 mol%) systematically. A remarkable advantage of the results was confirmed that dopant Ta enhanced the visible-light absorption of ZnO and the low-solubility tantalum doping could restrain the growth of crystal and minish the particle size. The relationship between the physicochemical property and the photocatalytic performance was discussed, and it was found that the photocatalytic activity in the photochemical degradation of methylene blue under visible-light irradiation (λ420 nm) was dependent on the contents of the dopant, which could affect the particle size, concentration of surface hydroxyl groups and active hydrogen-related defect sites, and the visible-light absorption. The highest photocatalytic activity was obtained for the 1.0 mol% Ta-doped ZnO sample.     

Preparation of ZnS-Fluoropolymer nanocomposites and its photocatalytic degradation of methylene blue

The ZnS particles were immobilized on the surface of poly(vinylidene difluoride) (PVDF) mixing methacrylic acid (MAA)-trifluoroethyl acrylate (TFA) copolymer electrospun nanofibers. The PVDF and MAATFA copolymer nanofibers were prepared by electrospinning. Zinc ions were introduced onto the surface of nanofibers by coordinating with the carboxyls of MAA, and then sulfide ions were added to react with zinc ions to form ZnS particles under hydrothermal condition. The size and the amount of ZnS particles increased with the reaction time prolonging. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results reveal that a chemical interaction exists between ZnS and fluoropolymer fibers. The degradation rate of methylene blue in ZnS-fluoropolymer nanocomposite system was considerably higher than in that of ZnS powders system under UV irradiation. There may be an adsorption-migration-photodegradation process during the degradation of methylene blue by using ZnS-fluoropolymer nanocomposites as photocatalyst. The photocatalytic activity of ZnS-fluoropolymer nanocomposites changes indistinctively after 10 times repeating tests.     

一步温和水热法制备具有改善光催化活性和稳定性的碳包覆CdS纳米粒子

首次报道在130oC低温条件下,以乙酸镉和葡萄糖分别作为镉源和碳源,硫脲同时充当硫源和葡萄糖水热碳化的催化剂,通过一步水热碳化法制备了碳包覆的CdS (CdS@C)纳米材料。与相同条件下制备的纯CdS相比,合成的CdS@C粒子具有更小的粒子尺寸、良好的分散性以及更均匀的粒子分布。而且,葡萄糖在水热碳化过程中能够促使CdS优先形成立方晶相。此外,粒子表面的碳物种能拓宽CdS的可见光吸收范围,稍微降低它的带隙能,减缓CdS的光生电子-空穴对的复合和光腐蚀。因此,它能改善CdS在可见光辐射下催化氧化降解甲基橙的活性和稳定性。     

Bi3.25La0.75Ti3O12纳米线的可见光催化性能

研究了用一步水热法制备的掺镧钛酸铋(Bi_3.25La_0.75Ti₃O₁₂, BLT)纳米线的光学和可见光催化性能, 并对其晶体结构和微观结构用X射线衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段进行了表征. 结果表明, 制备的纳米线为纯相的Bi_3.25La_0.75Ti₃O₁₂, 平均直径约为25 nm. 室温光致发光谱(PL)显示BLT纳米线在433和565 nm附近有较强的发射峰, 分别对应激子发射和表面缺陷发光. 紫外-可见漫反射光谱(UV-Vis DRS)表明BLT样品的带隙能约为2.07 eV. 利用可见光(λ>420 nm)照射下的甲基橙降解实验评价了BLT样品的光催化性能. 结果表明, BLT的光催化活性比商用TiO₂催化剂P25、掺氮TiO₂和纯相钛酸铋(Bi₄Ti₃O₁₂, BIT)高得多. BLT光催化剂具有更高催化活性的原因是La³⁺离子掺杂拓展了BIT对可见光的吸收范围, 同时抑制了BIT的光生电子-空穴的复合.     

前驱体改性法制备薄层多孔富氨基的石墨相氮化碳用于光催化降解RhB和光催化制氢

半导体光催化是一种利用半导体将太阳能转换为高能化学能的绿色技术,在可再生清洁能源生产和污染物修复领域有着巨大的应用前景.石墨相氮化碳(g-C3N4)作为一种环境友好的非金属半导体,因其制备工艺简单、来源丰富、热稳定性和化学稳定性好、可见光吸收范围及特殊的电子性能而受到广泛关注.但一般常用氮源前驱体如二氰二胺、三聚氰胺等...