Rapid preparation and photocatalytic properties of octahedral Cu2O@Cu powders

To improve the photocatalytic properties of Cu₂O, octahedral Cu₂O@Cu powders were prepared by a convenient and rapid two-step liquid phase reduction method. Glucose (C₆H₁₂O₆) and thiourea dioxide (CH₄N₂O₂S, TD for short) were used as pre-reductant and secondary-reductant separately. The microstructure and composition of the products obtained after the reduction processes were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). With the increasing of TD content, the secondary reduced products changed from solid octahedral Cu₂O to octahedral Cu₂O@Cu composites and finally hollow octahedral Cu₂O/Cu composites. The corresponding calculated mass of Cu increased from 6.2 wt% to 80.2 wt%. The photocatalytic behavior of the reduced particles were analyzed by monitoring the degradation of methyl orange solution (MO for short) and electrochemical tests. Photocatalytic performance tests showed that octahedral Cu₂O@Cu powders had an excellent photocatalytic activity. The MO degradation rate was improved from 1.4% for photocatalysts without CuNPs to 92.9% after introducing 13.4 wt% CuNPs under visible light irradiation for 60 min. This simple and rapid synthesis process allowed for the fabrication of octahedral Cu₂O@Cu material with photocatalytic performance superior to pure octahedral Cu₂O and hollow octahedral Cu₂O/Cu materials.     

Synthesis of Cu2O/T-ZnOW nanocompound and characterization of its photocatalytic activity and stability property under UV irradiation

Cu₂O/tetrapod-like ZnO whisker (T-ZnO_W) nanocompound was synthesized by a simple hydrothermal chemical method. The chemical composition, morphology, band gap and photocatalytic property of the Cu₂O/T-ZnO_W nanocompound were studied in detail. It was observed that the Cu₂O particles deposited on T-ZnO_W surface had a cubic structure and the crystallinity of T-ZnO_W did not change with the increase of Cu₂O crystals. The morphology and content of Cu₂O in the Cu₂O/T-ZnO_W nanocompound played an important role on the photocatalytic activity. In addition, the coexistence of Cu₂O and T-ZnO_W nanoparticles was propitious to the high photocatalytic activity owing to their hetero-junction effect. The Cu₂O/T-ZnO_W nanocompound prepared by 7.2% Cu/Zn MR exhibited the best photocatalytic activity on the degradation of MO solution under UV light irradiation. At the first 100 min of irradiation, the photodegradation efficiency of MO solution reached up to 99.16%, which still retained its high photocatalytic activity about 89.10% even at the end of the fourth cycle. Little change was found in their phase compositions after the photocatalytic reaction process, except partial oxidation of particles’ surface. The mechanism for UV light driven photocatalytic activity enhancement over Cu₂O/T-ZnO_W nanocompound was discussed.     

水热法制备Cu掺杂可见光催化剂BiVO4及其光催化性能研究

以Bi(NO3)3.5H2O、NH4VO3、Cu(NO3)2.3H2O为原料,采用水热法合成了Cu-BiVO4光催化剂,并利用X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、紫外漫反射(UV-Vis)等测试手段对催化剂进行了表征.结果表明,提高前驱液pH值,可得到单斜晶系白钨矿型Cu-BiVO4光催化剂,BiVO4的晶型结构并未随着Cu掺入量的增加而改变.光催化剂中的Cu元素以CuO和Cu2O的形式存在.Cu的引入使可见光吸收带发生红移,吸收强度明显提高.可见光催化降解亚甲基蓝溶液的结果表明,Cu掺杂有利于提高BiVO4的活性.其中pH值为5.0、Cu掺入量为1.0wt%的BiVO4具有最好的光催化效果,可见光照射60 min后,对初始浓度为10 mg/L的亚甲基蓝溶液的最高降解率由纯BiVO4的57.4%提高到97.8%.并对Cu掺入后光催化活性提高的机理进行了分析.     

Preparation of Fe3+-doped TiO2 catalysts by controlled hydrolysis of titanium alkoxide and study on their photocatalytic activity for methyl orange degradation

Fe3+-doped TiO2 (Fe-TiO2) porous microspheres were prepared by controlled hydrolysis of Ti(OC4H9)4 with water generated "in situ" via an esterification reaction between acetic acid and ethanol, followed by hydrothermal treatment. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic absorption flame emission spectroscopy (AAS), electron paramagnetic resonance (EPR) spectrum, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and nitrogen adsorption-desorption methods. All of the undoped TiO2 and Fe-TiO2 samples exclusively consist of primary anatase crystallites, which further form porous microspheres with diameters ranging from 150 to 500 nm. The photocatalytic activity of Fe-TiO2 catalysts was evaluated from the photodegradation of methyl orange (MO) aqueous solution both under UV and visible light irradiation. Fe3+ doping effectively improves the photocatalytic activity under both UV light irradiation and visible light irradiation with an optimal doping concentration of 0.1 and 0.2%, respectively. The photocatalytic mechanisms of Fe-TiO2 catalysts were tentatively discussed.     

Rose Bengal-Cu-TiO2的制备及可见光制氢活性研究

用光还原方法制备了负载Cu的光催化剂Cu-TiO2，并通过染料Rose bengal敏化，制备了具有可见光活性的Rose bengal-Cu-TiO2光催化剂，通过可见光下光解水制氢考察了催化剂的活性，并利用XRD、UV-Vis等手段对样品进行了表征。实验表明：载Cu增强了TiO2对可见光的吸收，Cu负载量对催化剂活性有一定的影响，Cu的最佳负载量为5％（质量分数）。Cu的负载也增加了TiO2对染料的吸附强度和吸附量，从而提高了TiO2对可见光的吸收和光催化活性。但载Cu的TiO2催化剂的活性和传统的载贵金属Pt的TiO2催化剂相比，其光催化活性较低，有待进一步提高．     

玻璃微珠-Cu/Cu_2O复合镀层的制备及其光催化降解甲基橙的研究

采用化学镀铜和水热氧化法制备了玻璃微珠-Cu/Cu2O复合镀层,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等方法对样品结构和形貌进行了分析和表征,在日光灯照射下降解一定浓度的甲基橙溶液,研究其对甲基橙溶液的降解效果。研究了催化剂用量、pH值和甲基橙初始浓度对甲基橙降解率的影响以及催化剂在重复使用中的稳定性。     

Facile preparation and enhanced photocatalytic H2-production activity of Cu(OH)2 nanospheres modified porous g-C3N4

A facile precipitation approach for the preparation of Cu(OH)₂/g-C₃N₄ composite photocatalysts with good porous structure was developed for the first time. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible light (UV–vis) absorbance spectra, photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). A photocatalytic water splitting reaction on the as-prepared photocatalysts were carried out under visible light irradiation. The results revealed that the prepared samples showed significantly enhanced photocatalytic activity. The optimal Cu(OH)₂ loading content was found to be 0.34 mol%, giving an H₂-production rate of 48.7 μmol h⁻¹ g⁻¹, which is higher 16.5 times than that of pure g-C₃N₄. This high photocatalytic H₂-production activity is attributed to the presence of Cu(OH)₂ clusters on the surface of the porous g-C₃N₄, which efficiently promotes the visible light absorption and separation of photogenerated electron–hole pairs.     

高可见光活性磁性催化剂ZnO/ZnFe_2O_4/石墨烯的制备与表征

以硝酸锌和硫酸亚铁为原料,采用水热法一步合成了ZnO/ZnFe_2O_4纳米颗粒,再通过水合肼还原氧化石墨烯合成了ZnO/ZnFe_2O_4/石墨烯磁性催化剂。采用X射线衍射(XRD),场发射扫描电子显微镜(FESEM),透射电子显微镜(TEM),傅立叶变换红外光谱仪(FT-IR)等仪器对催化剂的结构进行了表征。以亚甲基蓝作为目标降解物,考察了不同石墨烯掺量的磁性催化剂在可见光照射下的光催化性能。结果表明,当石墨烯掺量为3%时,磁性催化剂的活性最优,可见光照射60min后亚甲基蓝溶液的降解率高达98%。磁性催化剂稳定性良好,且由于ZnFe_2O_4的存在,磁性催化剂可通过外部磁场进行回收。     

Nitrogen-doped titanium dioxide photocatalysts for visible response prepared by using organic compounds

In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO₂ powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated into two different sites of the bulk phase of TiO₂. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO₂ powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system.     

Nitrogen-doped titanium dioxide photocatalysts for visible response prepared by using organic compounds

In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO₂ powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated into two different sites of the bulk phase of TiO₂. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO₂ powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system.     

熔盐法制备立方块状钛酸锶及其表面铜离子团簇修饰

采用熔盐法制备了钙钛矿结构的钛酸锶立方块。通过浸渍法对所得钛酸锶进行表面离子修饰, 得到表面负载无定形Cu(II)纳米团簇的新型可见光催化剂。利用ICP-AES、XRD、SEM、XPS、DRS等对其进行表征。通过光催化降解气相异丙醇对其可见光催化活性进行评价。研究发现, 负载无定形Cu(II)团簇后, 所得的催化剂Cu(II)-SrTiO3具有较好的可见光催化降解气相异丙醇的性能, 能够有效地将异丙醇彻底矿化成二氧化碳。     

Ru掺杂TiO2和TiO2/SiO2光催化剂的制备及可见光分解水制氢性能研究

采用溶胶-凝胶法制备了系列Ru/TiO2和Ru/TiO2/SiO2可见光活性光催化剂。通过TEM、XPS、XRD、UV-Vis漫反射和电化学对样品进行了表征。发现Ru和Si的存在可以抑制TiO2的相转变和晶粒生长;Ru掺杂使TiO2和TiO2/SiO2对可见光的吸收增强,也提高了光生电子和空穴的分离,因而,提高了催化剂可见光分解水制氢活性。当Ru在TiO2和TiO2/SiO2中的掺杂量分别为0.014%和0.021%(质量分数)时,光催化剂的可见光活性最高,且Ru/TiO2/SiO2活性为Ru/TiO2的5倍。     

纳米Ag包覆Bi_2O_3颗粒的制备及其可见光催化性能评价

本文采用两步合成工艺,通过化学共沉淀工艺制备β-Bi_2O_3纳米颗粒;经室温原位还原硝酸银,制备不同包覆量纳米Ag负载的Bi_2O_3(Ag/β-Bi_2O_3)光催化剂颗粒。对该光催化剂进行结构表征,并以甲基橙溶液模拟废水在可见光下评价其光催化性能。透射电子显微镜(TEM)测试表明纳米Ag均匀包覆于β-Bi_2O_3颗粒表面,其中β-Bi_2O_3聚集体的颗粒尺寸约30nm,而分散的纳米Ag晶体约为20nm。紫外可见光谱(UV-vis)谱图表明Ag/β-Bi_2O_3复合材料的带隙能比纯相Bi_2O_3要小,对可见光利用率相应增加,光催化性能随之增强。其中以2.0%(质量比)Ag包覆β-Bi_2O_3颗粒的光催化性能最佳。     

Sn<Superscript>4+</Superscript> and La<Superscript>3+</Superscript> co doped TiO<Subscript>2</Subscript> nanoparticles and their optical,photocatalytic and antibacterial properties under visible light

Sn⁴⁺ and La³⁺ co-doped TiO₂ photocatalytic material with nanoparticle structure have been successfully prepared using SnCl₂·2H₂O and La(NO₃)₃·6H₂O as precursors. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy and UV–visible spectroscopy have been used to for the characterization of the morphology, crystal structure, particle size and optical properties of the samples. The photocatalytic properties of sample with various amount of La doped TiO₂ have been studied by photo degradation of methyl orange (MO) in water under visible light. XRD patterns showed both rutile and anatase phases for 5 mol% of Sn and 5–10 mol% of La. But anatase phase with a little rutile phase was formed for 5 mol%Sn and 10 mol%La. The prepared Sn and La co doped TiO₂ photo-catalyst showed optical absorption edge in the visible light area and exhibited excellent photo-catalytic ability for degradation of MO solution under visible irradiation. Antibacterial behavior towards E. coli was then studied under visible irradiation. The synthesized T-5%Sn-10%La powder exhibited superior antibacterial activity under visible irradiation compared to the pure TiO₂.     

ZnO/CNTs复合材料的制备、表征及光催化性能

采用水热法制备了一系列氧化锌和碳纳米管的复合材料(ZnO/CNTs),详细考察了碳纳米管的含量对复合材料光催化性能的影响。利用X射线衍射仪、紫外-可见漫反射吸收光谱、扫描电子显微镜、X射线能谱、透射电子显微镜、X射线光电子能谱和氮气吸附-脱附等测试手段对样品的结构、形貌和光学性质进行了表征,并用亚甲基蓝溶液模拟污染物,评价了ZnO/CNTs复合材料的光催化性能。结果表明:添加CNTs提高了ZnO的比表面积,增强了ZnO的可见光吸收。ZnO/CNTs复合材料较纯ZnO具有更高的光催化活性,并且随着CNTs含量的增加,ZnO/CNTs复合材料的光催化活性呈先增加后减小的趋势。当CNTs的含量为0.3%(质量分数)时,ZnO/CNTs复合材料的光催化活性最高,经过50 min光照后,亚甲基蓝的降解率达到了96.2%。     

A facile route to synthesize ternary Cu2O quantum dot/graphene-TiO2 nanocomposites with an improved photocatalytic effect

A Cu₂O quantum dot/graphene-TiO₂ composite, a novel material, was successfully synthesized using a facile hydrothermal method. The hydrothermal reaction was used to load the Cu₂O and TiO₂ particles onto graphene sheets, and the resulting photocatalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (DRS). UV spectrophotometry was employed to measure the decrease in the concentration of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) dyes in an aqueous solution after degradation with the photocatalysts under irradiation with visible light. The results indicate that the quantum dot-sized Cu₂O is a promising material that contributes to the photocatalytic activity of Cu₂O quantum dot/graphene-TiO₂ composites.     

Zn掺杂CuO/CuAl2O4复合空心球的制备及光催化性能

以葡萄糖为模板, 硝酸锌、硝酸铜和硝酸铝为原料, 采用水热法制备高比表面Zn-CuO/CuAl₂O₄复合空心球。采用XRD、SEM、HRTEM、BET、DRS和PL等手段对样品进行表征, 结果表明: 在600℃下焙烧的Zn-CuO/CuAl₂O₄复合物呈空心球状, 球体直径约为2 μm, 比表面积高达214.97 m²/g。引入Zn有助于提高样品对紫外和可见光的吸收能力, 减少光生电子空穴对的复合, 光催化活性显著提高。在模拟太阳光照下, 以甲基橙溶液为目标降解物, 考察样品的煅烧温度和Zn加入量对光催化活性的影响。当Zn加入量为0.5wt%, 煅烧温度为600℃时, 样品的光催化活性最佳。光照60 min, 0.5 g/L光催化剂用量对25 mg/L甲基橙溶液的脱色率高达97%。     

Photo-reductive decolorization of an azo dye by natural sphalerite: Case study of a new type of visible light-sensitized photocatalyst

Natural sphalerite, which represents a new class of mineral-based catalyst, was characterized and investigated for photo-reduction of an azo dye methyl orange (MO) under visible light. After 2 h of visible light irradiation, a complete decolorization of the MO solution was achieved. The degradation rate was related to the pH conditions. Spectra from FT-IR analysis indicate an initial adsorption of MO to sphalerite via its sulfonate group. Further reduction of the adsorbed MO by sphalerite under light irradiation led to the destruction of the azo structure, as indicated by the results from UV–vis, FT-IR and ESI-MS analyses. The visible light-induced photocatalytic reductive activity of natural sphalerite was mainly attributed to the distribution of foreign metal atoms in its crystal lattice, which reduces the intrinsic bandgap of sphalerite and also broadens its spectra responding range. In addition, the high conduction band potential of natural sphalerite may also enhance the photo-reduction of MO.     

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。     

PEALD原位掺杂制备纳米TiO2-xNx光催化剂

采用等离子体增强型原子层沉积(PEALD)系统原位掺杂制备了TiO_2-xN_x光催化剂。利用光电子能谱(XPS)、高分辨率透射电镜(HRTEM)、光致发光(PL)光谱和紫外–可见光(UV-Vis)光谱对催化剂进行了表征, 并研究了TiO_2-xN_x纳米薄膜在可见光照射下水接触角的变化和催化降解亚甲基橙(MO)溶液的性能。结果表明, 等离子体功率变化可以改变掺入氮原子的结构, 在功率为50 W时主要形成替换式氮原子, 含量约为1.22at%, 晶体为锐钛矿(101)型。结构无明显缺陷, 且掺杂后TiO_2-xN_x薄膜光生电子–空穴对复合率低, 有利于光催化效率的提高。该方法解决了传统ALD工艺制备TiO_2-xN_x光催化剂时容易形成氧空位的问题, 实现了TiO2-xNx纳米材料的可见光(λ<800 nm)吸收和可见光光催化性能。