Q[6]/CdS-Ag2S复合光催化剂的合成及光催化性质

CdS因具有独特的光电化学性能而被广泛用于光催化研究, CdS与窄带隙半导体和有机物复合是重要的光催化研究方向。研究采用化学沉淀法制备了六元瓜环(Q[6])复合和Ag₂S掺杂的硫化镉光催化剂(Q[6]/CdS-Ag₂S), 通过不同手段对复合催化剂进行表征。实验以可见光为光源, 罗丹明B为模拟污染物, 考察了六元瓜环对CdS-Ag₂S光催化性能的影响。结果表明: 经Q[6]复合后的Q[6]/CdS-Ag₂S形貌为菜花状, 颗粒粒径变小。复合催化剂Q[6]/CdS-Ag₂S的催化性能明显优于CdS-Ag₂S, 光催化反应110 min, 15 mg复合催化剂对100 mL 6 mg/L罗丹明B溶液的催化降解效率达到92.4%。     

高暴露(001)面BiOBr/Ti3C2复合光催化剂的制备及其可见光催化性能

通过水解法合成具有高暴露(001)面的BiOBr/Ti₃C₂复合光催化剂, 利用不同手段对样品进行表征。以罗丹明B为目标污染物, 评价了不同样品的可见光催化性能。结果表明, 层状Ti₃C₂添加量为20.0wt%时, BiOBr/Ti₃C₂复合光催化剂在60 min内对罗丹明B的降解效率为97.1%, 比BiOBr的降解效率提高了34.7%。引入层状Ti₃C₂使得BiOBr与Ti₃C₂界面形成肖特基结能垒, 产生有效的电子陷阱抑制了光生电子-空穴对的复合, 从而大大提高了BiOBr的可见光催化活性。BiOBr/Ti₃C₂复合光催化剂经5次循环实验后, 降解效率仍保持在91.0%, 表明其具有良好的稳定性。活性物种捕获实验表明, 超氧自由基为罗丹明B可见光催化降解中的主要活性物种, 并据此提出了可能的光催化机理。     

类仙人球状Ag_3PO_4/ZnO纳米棒阵列异质结的构筑及光催化性能研究

采用晶种异质外延生长法合成制备结构新颖、性能稳定的类仙人球状的Ag_3PO_4立方微晶(MC)/ZnO纳米棒阵列(NRs)异质结。利用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)表征样品形貌,X射线衍射仪(XRD)表征晶体结构。通过有机染料罗丹明B(RhB)的降解率及循环降解能力测试,研究其催化活性及稳定性。实验结果表明,制备的Ag3PO4 MC/ZnO NRs异质结表现出良好的光催化活性及稳定性;在可见光区域催化降解RhB的实验中,降解率高达98%。Ag_3PO_4 MC/ZnO NRs异质结独特的复合结构为催化反应提供大量的催化活性位点,有效提高催化反应的活性,同时降低了光生电子-空穴电荷对的复合率,从而极大地增强了光催化效率。     

含共轭结构的ZnO/聚乙烯醇复合光催化材料的制备与性能

以ZnO和NaOH为原料,采用低温水热法合成纳米ZnO 半导体材料,并与聚乙烯醇（PVA）水溶液在超声作用下混合,通过直接煅烧制备出PVA中含共轭双键碳链结构（C）的ZnO/PVA_C复合光催化材料。采用 SEM、XRD、FTIR、Raman和UV-Vis DRS对样品进行表征。结果表明:ZnO/PVA_C复合光催化材料由结晶性能良好的纳米ZnO和具有共轭结构的聚合物组成,且界面间通过化学键Zn-O-C相连接;在模拟太阳光照射下,ZnO/PVA_C复合光催化材料对光的吸收响应可扩展到整个可见光区,并产生较高光电流。光催化性能测试结果表明,ZnO/PVA_C复合光催化材料对罗丹明B的降解催化性能（30 min降解率接近于100%）明显高于纯纳米ZnO。      

钴掺杂氧化铜/可见光协同活化PMS降解罗丹明B及其机理研究

元素掺杂是提升催化剂性能的重要方法。研究采用快速沉淀法制备了钴掺杂氧化铜(Co-doped CuO)纳米催化材料, 在可见光条件下, 20 min内其活化的过氧硫酸氢钾复合盐(PMS)对罗丹明B染料的降解率达到96%以上, 远优于同等条件制备的CuO。本研究还考察了溶液pH、染料初始浓度、催化剂用量等对降解效率影响。钴掺杂后氧化铜纳米颗粒由三维针梭状结构转变为近二维薄带状结构。同时钴掺杂提高了CuO的平带电位进而提升了电荷转移效率。XPS及EPR结果表明钴掺杂能够提高CuO的氧空位含量进而提升催化活性。捕获剂实验结果表明反应过程中的主要活性物种为空穴(h⁺_VB), 且羟基自由基(•OH)、单线态氧(¹O₂)、超氧自由基(•O₂^-)、硫酸根自由基(SO₄^-•)也参与了降解反应。最后, 本文初步阐明了Co-doped CuO协同可见光活化PMS降解有机污染物的反应机理。     

Ag/ZnO复合中空材料的制备及光催化降解罗丹明B

以脱脂棉纤维为模板,二水醋酸锌和硝酸银为原料,利用模板法制备了Ag/ZnO复合材料,通过SEM、FT-IR、XRD技术对样品形貌和结构进行了分析。在紫外灯照射下,以罗丹明B染料溶液为目标降解物,探究了浸泡时间和Ag掺杂量对Ag/ZnO复合材料催化性能的影响。实验结果表明,复合材料保持了模板物的纤维形貌,呈中空结构;浸泡时间和Ag掺杂量对Ag/ZnO复合材料的催化性能影响显著。模板物浸泡2h后于700℃煅烧2h制备的Ag掺杂为1.0%(mol,摩尔百分含量)的Ag/ZnO复合材料对100mL 10mg/L罗丹明B的降解率高达99%,且具有良好的重复使性能。     

磁性MCM-41/CdS的制备及其可见光催化性能研究

采用两步沉淀法将CdS沉积在磁性MCM-41上,制备新型磁性MCM-41/CdS复合材料。通过X射线衍射光谱(XRD)、高分辨透射电镜(HRTEM)、紫外-可见吸收光谱(UV-Vis)、振动样品磁强计(VSM)等对其进行表征。以亚甲基蓝(methylene blue,简称MB)为模拟污染物,考察了磁性MCM-41/CdS复合材料的可见光催化性能。结果表明,CdS能有效地沉积在磁性MCM-41上,与CdS相比,该复合材料对MB的光催化降解效率明显提高,且可通过外加磁场进行分离。     

快速共沉淀法制备Ce掺杂ZnO及其日光催化性能研究

采用氢氧化钠快速共沉淀法制备了Ce掺杂ZnO,以模拟日光催化降解罗丹明B为指标,优化Ce掺杂比例及煅烧温度,考察催化剂套用稳定性和适用性,最后对Ce掺杂ZnO活性机理进行分析。结果表明:Ce最佳掺杂摩尔分数为3%,500℃煅烧2h,对1.0×10~(-5) mol/L罗丹明B溶液40min降解率达到93.8%,6次套用降解率达到90%以上,对仲夏自然阳光和其他染料均有良好的适用性。Ce掺杂降低了光致空穴-电子复合率,有效的提升了光催化活性。     

有序大孔-介孔Au-TiO_2复合材料的制备及其光催化性能

为提高TiO_2的光吸收和光催化能力,采用原位水热还原法将Au沉积到有序多孔TiO_2上,制备了有序大孔-介孔Au-TiO_2复合材料。材料的光催化活性以在紫外光和可见光辐射下降解罗丹明B来评价。漫反射吸收光谱显示Au-TiO_2复合材料在400~800nm有较强的吸收。在紫外光和可见光辐射下,Au-TiO_2复合材料的光催化活性优于TiO_2。在紫外光下Au-TiO_2-1.9是最高效的催化剂,3h内罗丹明B的降解率达84%,其表观速率常数K是TiO_2的2.8倍。这主要是因为沉积Au纳米粒子能有效促进电荷的分离,提高光催化效率,但过量的Au成为表面电子-空穴复合的中心,反而降低其光催化能力。在紫外光下,罗丹明B的降解反应属于准一级动力学反应,光生空穴是主要的活性物质。阻抗测试显示Au-TiO_2的圆弧半径小于TiO_2,表明电荷传递效率提高,有利于光生电子-空穴对的分离和光催化性能的提高。     

低温制备N-Fe共掺杂TiO_2-SiO_2可见光催化复合薄膜北大核心CSCD

采用溶胶-凝胶结合低温(<100℃)热水后处理法,在塑料衬底上制得N-Fe共掺杂锐钛矿TiO_2-SiO_2复合薄膜。采用多种技术手段对薄膜样品进行了表征,并考察了薄膜样品在可见光下对罗丹明B的降解能力。研究结果表明,有机衬底上形成了锐钛矿TiO_2纳米晶弥散分布的复合薄膜,薄膜具有较高的可见光催化效率,150min后对罗丹明B的降解效率达到77.4%,其中矿化率达61%。     

Au/ZnO nanocomposites: Facile fabrication and enhanced photocatalytic activity for degradation of benzene

Au nanoparticles supported on highly uniform one-dimensional ZnO nanowires (Au/ZnO hybrids) have been successfully fabricated through a simple wet chemical method, which were first used for photodegradation of gas-phase benzene. Compared with bare ZnO nanowires, the as-prepared Au/ZnO hybrids were found to possess higher photocatalytic activity for degradation of benzene under UV and visible light (degradation efficiencies reach about 56.0% and 33.7% after 24 h under UV and visible light irradiation, respectively). Depending on excitation happening on ZnO semiconductor or on the surface plasmon band of Au, the efficiency and operating mechanism are different. Under UV light irradiation, Au nanoparticles serve as an electron buffer and ZnO nanowires act as the reactive sites for benzene degradation. When visible light is used as the light irradiation source, Au nanoparticles act as the light harvesters and photocatalytic sites alongside of charge-transfer process, simultaneously.     

ZnO/CdS/Ag复合光催化剂的制备及其催化和抗菌性能

先用水热反应合成六方晶相CdS多层级花状微球并在其表面生长ZnO纳米棒形成均匀的ZnO/CdS复合结构,然后用光还原法将Ag纳米颗粒负载于ZnO纳米棒制备出ZnO/CdS/Ag三元半导体光催化剂,对其进行扫描电镜和透射电镜观察、光电性能测试、活性基团捕获实验以及光催化降解和抗菌性能测试,研究其对亚甲基蓝(MB)的降解和抗菌性能。结果表明：ZnO纳米棒均匀生长在CdS微球表面,CdS晶体没有明显裸露,Ag纳米粒子负载在ZnO纳米棒的表面;ZnO/CdS/Ag三元复合光催化剂有良好的可见光响应、较低的阻抗和较高的光电流密度;ZnO/CdS/Ag复合光催化剂能同时产生羟基和超氧自由基等活性氧基团;ZnO/CdS/Ag三元复合光催化剂对亚甲基蓝(MB)的30 min降解率高于90%;0.25 mg/mL的ZnO/CdS/Ag对革兰氏阴性菌(大肠杆菌)的灭菌率高于96%,对革兰氏阳性菌(金黄色葡萄球菌)能完全灭除。     

Extension of optical properties of ZnO/SiO2 materials induced by incorporation of Au or NiO nanoparticles

Incorporating noble metal nanoparticles (NPs) and oxides has been proved to be an effective method to tune the optical properties of silica based materials. In this paper the optical and photocatalytic properties have been studied for ZnO/SiO₂ modified with Au or NiO nanoparticles. Changes in the optical properties of semiconductor ZnO particles have been observed due to the deposition of coloured Au and NiO nanoparticles by reducing the band gap energy and thus extending light absorption to visible domain. The excellent surface characteristics of NiO/ZnO/SiO₂ and Au/ZnO/SiO₂ favour the adsorption behaviour of these materials and limit the recombination of electron–holes pairs. Crystal Violet degradation under VIS light proved to have higher efficiency in the presence of Au/ZnO/SiO₂ (97%) than for NiO/ZnO/SiO₂ (60%).     

Facile synthesis of Au/ZnO nanoparticles and their enhanced photocatalytic activity for hydroxylation of benzene

Au/ZnO nanocomposites have been prepared by a simple chemical method. For the first time, the nanocomposites were directly used as photocatalysts for hydroxylation of aromatic hydrocarbons under UV and visible light irradiation. The results show that the as-prepared photocatalysts display high photocatalytic activity for UV and visible catalytic hydroxylation of benzene. Without the assistance of any solvent or additive, high selectivity and high conversion efficiency were still obtained. Different photocatalytic mechanisms were proposed depending on whether excitation happens on ZnO semiconductor or on the surface plasmon band of Au. The former is Au nanoparticles act as electron buffer due to irradiation by UV light and ZnO nanoparticles as reactive sites for hydroxylation of benzene, the latter is that Au nanoparticles act as light harvesters and inject electrons into ZnO conduction band and as photocatalytic sites under visible light irradiation.     

Decoration of Au nanoparticles onto BiOCl sheets for enhanced photocatalytic performance under visible irradiation for the degradation of RhB dye

Plasmonic photocatalysts are promising candidates for use in the degradation of pollutants. Their ability to degrade a wide range of organic pollutants stems from key properties such as high visible light absorption, the ability to generate hot electrons and the formation of a Schottky barrier that facilitates effective separation of charge carriers. In the present work, we synthesised bismuth oxychloride sensitised with gold nanoparticles (NPs, 20–50 nm) via a two-step chemical process at low temperature. The fabricated Au/BiOCl powder was evaluated in the degradation of Rhodamine B (RhB) dye under visible light irradiation. The photocatalytic performance of the Au/BiOCl hybrid was almost double that of pristine BiOCl. This enhanced performance was attributed to electron transfer from BiOCl to Au via the formation of heterojunctions at the BiOCl/Au interface. Additionally, the surface plasmon resonance effect of the Au NPs provided high optical absorbance in the visible spectrum. TEM (transmission electron microscopy) analysis indicated the presence of polar (010) facets on the BiOCl sheets, which also contributed to dramatically improving their photocatalytic performance. The degradation time of the Au/BiOCl hybrid was 200 min compared with 320 min for pure BiOCl.     

RGO/ZnO纳米棒复合材料的合成及光催化性能

采用水热合成法制备ZnO纳米棒及RGO/ZnO纳米棒复合材料。研究不同含量的RGO对RGO/ZnO纳米棒复合材料光催化活性的影响。采用X射线衍射仪(XRD)、场发射电子显微镜(FESEM)、光电子能谱仪(XPS)及漫反射紫外-可见吸收光谱(UV-Vis)检测手段对RGO/ZnO进行表征。结果显示:RGO与ZnO纳米棒成功复合。加入GO的含量不同,获得的RGO/ZnO样品在可见光区域的吸光度值不同。以甲基橙作为模拟污染物的光催化结果表明,RGO/ZnO复合材料具有高的紫外-可见光光降解效率,加入GO与ZnO的质量比为3%时,样品紫外-可见光光催化性能最佳,120min内甲基橙基本可以完全降解;且在波长大于400nm可见光照射下,RGO/ZnO具有一定的可见光活性,180min内其降解甲基橙效率最大可达26.2%。同时,RGO/ZnO具有较好的光稳定性。     

Synthesis of Ce-doped GN/ZnO architectures with enhanced photocatalytic activity

The novel flower-like GN/ZnO architectures composed of curved cone are synthesized with hydrothermal method at 120?°C for 4?h. The GN/ZnO composite was doped with GN during preparation, the photocatalytic activity of GN/ZnO was evaluated by photodegradation of Rhodamine B (RhB) under simulated visible light. The results showed that the photocatalytic activity of α-CNTs/SnO₂ for degradation of RhB was up to 90% within 50?min, which was much higher than that of pure compound. It was significantly found that the introduction of GN, which may suppressed the recombination of photogenerated electron-hole pairs on the interface of SnO₂, leading to enhanced photocatalytic activity.     

A Simple Route to Reduced Graphene Oxide‐Draped Nanocomposites with Markedly Enhanced Visible‐Light Photocatalytic Performance

Nanocomposites (denoted RGO/ZnONRA) comprising reduced graphene oxide (RGO) draped over the surface of zinc oxide nanorod array (ZnONRA) were produced via a simple low‐temperature route, dispensing with the need for hydrothermal growth, electrochemical deposition or other complex treatments. The amount of deposited RGO can be readily tuned by controlling the concentration of graphene oxide (GO). Interestingly, the addition of Sn²⁺ not only enables the reduction of GO, but also functions as a bridge that connects the resulting RGO and ZnONRA. Remarkably, the incorporation of RGO improves the visible‐light absorption and reduces the bandgap of ZnO, thereby leading to the markedly improved visible‐light photocatalytic performance. Moreover, RGO/ZnONRA nanocomposites exhibit a superior stability as a result of the surface protection of ZnONRA by RGO. The mechanism on the improved photocatalytic performance based on the cophotosensitizations under the visible‐light irradiation has been proposed. This simple yet effective route to the RGO‐decorated semiconductor nanocomposites renders the better visible‐light utilization, which may offer great potential for use in photocatalytic degradation of organic pollutants, solar cells, and optoelectronic materials and devices.     

Photo-electrochemical and enhanced photocatalytic activity of CdS/rGO nanocomposites prepared by hydrothermal method

CdS/rGO nanocomposites with different mass ratio of rGO were fabricated via a facile one-pot hydrothermal method. The influences of different ratios on the microstructure, photo-electrochemical, and photocatalytic properties of the as-prepared samples were investigated. The experimental results show that CdS/rGO nanocomposites are hexagonal structure, one-dimensional CdS nanorods decorated on the surface of graphene. CdS/rGO nanocomposites show excellent visible light absorption and the band gap smaller than that of pure CdS and occur red shift. The photoluminescence spectra, transient photocurrent response and electrochemical impedance spectra indicate this nanostructure can accelerate the separation and migration efficiency of photogenerated electron–hole pairs, inhibit the recombination of photogenerated carries and and enhance electron transportation in the photocatalytic reactions. CdS/rGO nanocomposites display enhanced photocatalytic activity in degradation of MO under the simulated sunlight irradiation than that of pure CdS. In addition, in the photocatalytic degradation process ·O₂^? and ·OH play the key role.