氧化锌/氧化镁纳米复合材料的制备及其光催化性能研究

采用微波辅助共沉淀法制备了纳米氧化锌/氧化镁(ZnO/MgO)光催化剂,并对催化剂样品进行了X射线衍射、透射电镜、红外光谱以及紫外-可见吸收光谱等表征。以亚甲基蓝(MB)为目标降解物对不同锌镁比的ZnO/MgO催化剂样品及相同方法下合成的ZnO及MgO进行光催化降解实验。结果表明:合成的纳米ZnO/MgO光催化剂由立方相的ZnO和非晶相的MgO组成,其尺寸均匀,在40nm左右,并在紫外区域吸收性能良好。光催化降解MB实验表明,锌镁比为2∶1时ZnO/MgO催化剂的光催化性能最佳。     

PPy/MWNTs/GO复合材料的制备与电化学性能研究

以吡咯为单体,多壁碳纳米管和氧化石墨烯为模板,过硫酸铵为氧化剂,采用原位化学聚合法制备了聚吡咯/多壁碳纳米管/氧化石墨烯(PPy/MWNTs/GO)复合材料.利用傅里叶变换红外光谱(FTIR)、X射线衍射谱(XRD)、扫描电镜(SEM)、循环伏安法(CV)和电化学交流阻抗谱(EIS)对制备复合材料的结构、微观形貌和电化学性能进行了研究,探讨了多壁碳纳米管/氧化石墨烯比例、吡咯用量对复合材料电容性能的影响.研究结果显示,PPy/MWNTs/GO复合材料具有较大的比电容和良好的循环稳定性,且具有较小的电荷转移电阻,接近于理想的超级电容器用电极材料.     

Preparation of ZnO/graphene heterojunction via high temperature and its photocatalytic property

This paper introduces a novel electrochemical route for preparing the ZnO/graphene heterojunction composite via high temperature. This process includes: (1) depositing the electrochemically reduced graphene oxide (ERGO) on ITO glass via cyclic voltammetry; (2) pulse plating a zinc (Zn) layer on the ERGO; (3) thermally treating the Zn/ERGO composite and “in situ” to obtain the ZnO/ERGO composite. SEM characterizations revealed that the Zinc Oxide (ZnO) particles were homogenously distributed on the surface of graphene sheets. XRD and Raman spectra found a ZnCO₃ phase in the ZnO/ERGO composite, which demonstrated that when the Zn film transformed into ZnO particles during thermal treatment, Zn also reacted with graphene and formed a ZnCO₃ intermediate layer at the interface between ZnO and ERGO via short-range diffusion. Compared with the heterojunction formed from regular chemical route, the present process provided a tight contact and combination between ZnO and ERGO, which eventually led to a heterojunction between ZnO and graphene sheets. This heterojunction exhibited great improvement for separation efficiency of photo-generate electron–hole pairs. Experimental results of ultraviolet–visible (UV–Vis) light catalysis demonstrated that the photocatalytic activity of the ZnO/ERGO composite had been greatly improved, and exhibited a value of three times higher than that of pure ZnO.     

Preparation, characterization and photocatalytic activity of TiO2/polyaniline core-shell nanocomposite

Polyaniline (PANI) as a promising conducting polymer has been used to prepare polyaniline/TiO₂ (PANI/TiO₂) nanocomposite with core-shell structure as photocatalyst. Titanium dioxide (TiO₂) nanoparticles with an average crystal size of 21?nm were encapsulated by PANI via the in situ polymerization of aniline on the surface of TiO₂ nanoparticles. FT?CIR, UV-Vis-NIR, XRD, SEM and TEM techniques were used to characterize the PANI/TiO₂ core-shell nanocomposite. Photocatalytic activity of PANI/TiO₂ nanocomposite was investigated under both UV and visible light irradiations and compared with unmodified TiO₂ nanoparticles. Results indicated deposition of PANI on the surface of TiO₂ nanoparticles which improved the photocatalytic activity of pristine TiO₂ nanoparticles.     

Preparation of p-n heterojunction with NiWO4 and Co-based bimetallic oxide and its photocatalytic hydrogen evolution performance

Bimetallic oxides have attracted extensive attention due to their excellent photocatalytic properties. Co₂NiO₄ has good electrical activity which can effectively regulate the distribution of charge. The scanning electron microscope and transmission electron microscope images of Co₂NiO₄ showed two-dimensional uniform lamellar morphology. This kind of morphology could provide a larger specific surface area, which was conducive to improving photocatalytic water decomposing and hydrogen evolution. In addition, we combined Co₂NiO₄ with NiWO₄ to improve the conductivity of Co₂NiO₄ and the position of Fermi energy level, forming a p-n-type heterojunction, effectively promoting the interface charge transfer through the internal electric field, and inhibiting the electron–hole pair recombination. The photocatalytic hydrogen production of CN/NW-3 in the sensitized system reached 341.83 μmol for 5 h, which was 19 times that of pure Co₂NiO₄. At the same time, UV–Vis diffuse reflection and Mott–Schottky curve were used to further determine the conduction band (CB) and valence band (VB) positions of Co₂NiO₄ and NiWO₄, which formed a charge transport path with higher separation and transfer efficiency. This work highlights the high-efficient photocatalytic hydrogen production performance of CN/NW p-n heterojunction.

Graphical abstract

Co₂NiO₄ and NiWO₄ form p-n heterojunction, and the synergy between them provides a new hydrogen-producing active center for each.

     

Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination

The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV–visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail.     

Excellent visible light photocatalytic properties of novel graphene based CdLa2S4/TiO2 heterojunction nanocomposite

This paper introduced one pot method for the synthesis of hybrid CdLa₂S₄-graphene/TiO₂ nanocomposite. The surface properties seen by SEM present a characterization of the texture on CdLa₂S₄-graphene/TiO₂ composites and showed a homogenous composition in the particles. The EDX spectra for the elemental identification showed the presence of C, O and Ti with strong Cd, La and S peaks for the CdLa₂S₄-graphene/TiO₂ nanocomposite. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the photocatalytic effect increase in the case with the modified CdLa₂S₄.From the photocatalytic results, the excellent activity of CdLa₂S₄-graphene/TiO₂ nanocompositefor degradation of methylene blue (MB) and Texbrite BA-L (TBA) undervisible irradiation could be attributed to both the effects between photocatalysis of the supported TiO₂ and charge transfer of the grapheme nanosheet, and the introduction of CdLa₂S₄ to enhance the photogenerated electrons.     

纳米CdS/壳聚糖复合粒子的制备及光催化性能研究

用原位生成法成功制备了纳米Cd S/壳聚糖复合粒子,并用于染料废水中甲基橙的可见光催化降解,研究了相关因素对甲基橙光降解率的影响。结果表明,该光催化降解反应为一级反应;酸性媒介更有利于甲基橙光催化降解;适量的复合粒子在第6次重复使用时,反应60 min甲基橙的降解率仍可达81.51%,显示出好的抗光腐蚀能力和重复使用寿命。     

原位构建P-N结复合材料及其可见光光催化性能

提高光催化过程中电子和空穴的提取和分离速率是提高光催化剂催化性能的关键技术之一。用浓硫酸剥离体相氮化碳得到石墨相g-C₃N₄,采用原位生长法制备花状g-C₃N₄/BiOBr P-N结复合材料,研究pH值对复合材料形貌的影响。利用XRD,SEM,EDS,TEM,UV-vis, BET等测试技术对所得样品的形貌、结构进行表征,讨论样品的光催化性能。结果表明:在g-C₃N₄/BiOBr复合材料内g-C₃N₄的[002]晶面和BiOBr的[001]晶面之间形成了异质结,可加速光生电子(e^-)和空穴(h⁺)的提取和分离。BiOBr和g-C₃N₄/BiOBr的禁带宽度分别为2.75,2.71 eV,复合材料的带隙减小,对可见光的吸收范围增强。BiOBr和g-C₃N₄/BiOBr复合材料的比表面积分别为1.27,6.43 m²/g,比表面积增大,增加催化反应活性位点。复合材料g-C₃N₄/BiOBr的光催化性能比纯g-C₃N₄和BiOBr更好,且重复使用效果佳。pH=8时制备的g-C₃N₄/BiOBr复合材料光催化效果最好,此时,对橙黄G、罗丹明B、甲基橙的光催化降解效率分别为91.00%,95.51%,96.72%。     

石墨烯/纳米TiO_2复合材料的制备及光催化还原性能

为探索超声辅助下利用紫外光及耦合热还原工艺制备RGO/纳米TiO_2复合材料的方法,并对其在缺氧水体中的光催化还原特性进行研究,首先,以鳞片石墨为原料,采用改进的Hummers法制备了氧化石墨烯(GO),进而通过超声/紫外光还原工艺制备了还原氧化石墨烯(RGO);然后,以钛酸丁脂和RGO为前驱物,采用溶胶-凝胶法并在氮气保护下高温加热制备了RGO/纳米TiO_2复合光催化材料;接着,利用FTIR、XRD、BET及紫外-可见光谱等对RGO/纳米TiO_2复合材料进行了结构性能表征;最后,以2,4-二氯苯氧乙酸(2,4-D)为探针物,研究了RGO/纳米TiO_2在缺氧水体中的光催化特性与2,4-D降解机制。结果表明:采用低温氧化Hummers法制备的GO六碳环上生成的活性基团较少,采用超声/紫外光还原工艺及耦合高温热还原工艺可使环状结构得到良好的修复;所制备的RGO/纳米TiO_2复合材料具有良好的2,4-D降解能力,在缺氧状态下,2,4-D主要发生光催化还原反应,脱除苯环上的氯,产生氯酚、邻苯三酚及间苯三酚等中间产物,部分2,4-D被氧化降解生成CO_2和H_2O。制备的RGO/纳米TiO_2复合材料具有良好的光催化还原性能。     

Preparation and photocatalytic activity of WO3/TiO2 nanocomposite particles

A novel photocatalyst WO₃/TiO₂ nanocomposite was prepared through a hydrothermal method by using cetyltrimethylammonium bromide (CTAB) as surfactant. The obtained WO₃/TiO₂ was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and diffused reflectance spectroscopy (DRS). Photocatalytic experiments indicate that the nanocomposites show much higher photoactivity than that of pure TiO₂ in the photodegradation reaction of Rhodamine B (RhB). The increased photoactivity of WO₃/TO₂ may be attributed to the improvement of the light absorption properties and the slow down of the recombination between the photoexcited electrons and holes during the photoreaction.     

铜修饰钒酸铋/膨润土复合材料的制备及可见光催化脱硫性能研究

采用水热法制备了铜修饰钒酸铋/膨润土(Cu-BiVO_4/BTT)复合材料,借助X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和紫外-可见漫反射吸收光谱(DRS)对其进行表征。XRD分析显示,所制备的催化剂中BiVO_4均保持单斜结构,SEM结果证实了钒酸铋负载到了膨润土上,XPS结果显示Cu元素以CuO形式存在于催化剂表面,DRS结果显示复合材料在可见光区域的吸收增强。研究表明,当Cu与Bi的摩尔比为1.2时,复合材料光催化活性最高,经可见光照射3h,对模型汽油脱硫率达91%。     

Preparation, electrocatalytic and photocatalytic performances of nanoscaled CuO/Co3O4 composite oxides

Cu-Co composite oxides with different Cu/Co atomic ratios were prepared by the calcination of the precursors synthesized via a co-precipitation method. The samples were characterized by XRD, SEM and TEM, respectively. The XRD analysis revealed that only spinel structure of Cu-Co composite oxide was confirmed with lower Cu/Co ratio (<1:2). The sizes and morphologies of samples are controlled significantly by the Cu/Co atomic ratios. The electrocatalytic activity for p-nitrophenol reduction in a basic solution with the samples decorated on glassy carbon (GC) electrodes was tested by cyclic voltammetry (CV). The results showed that the sample with Cu/Co ratio of 2:8 exhibited the highest catalytic activity for p-nitrophenol reduction. The photocatalytic performances of the samples for the degradation of methyl orange under irradiation of visible light were investigated. The samples with Cu/Co ratios from 5:5 to 10:0 all showed better photocatalytic activities for methyl orange degradation, but the sample with Cu/Co ratio of 9:1 exhibited much higher catalytic activity. The catalyst with Cu/Co ratio of 9:1 also exhibited excellent repeatability for the catalytic degradation of methyl orange.     

聚苯胺/石墨烯/金复合材料的制备及超电容性能研究

以对苯二胺( p-PDA)为单体,氯金酸(HAuCl4)为氧化剂和Au源,氧化石墨烯(GO)为基底,通过原位聚合伴随Au纳米粒子生成的方法获得了聚苯胺/石墨烯/金(PpPD/GO/Au)的纳米复合材料.FESEM、FT-IR、XRD等测试表明,聚苯胺类衍生物、氧化石墨烯以及金纳米粒子三相在整个纳米复合材料中共存.材料的...     

铒掺杂二氧化钛制备及其光催化性能研究

通过水热合成法制备了二氧化钛和稀土饵离子掺杂二氧化钛光催化剂,并通过X射线衍射仪、紫外-可见分光光度计等测试手段对产物结构和性能进行了表征,研究了不同二氧化钛质量浓度、饵离子掺杂浓度对次甲基蓝(MB)光催化性能的影响.结果表明,所制备的二氧化钛的晶型为锐钛矿型;饵离子掺杂的二氧化钛对比纯二氧化钛的光催化性能有显著提高.当二氧化钛质量浓度为3g/L时,对MB的降解效果最好;通过研究饵离子掺杂对MB光催化动力学模型,表明饵离子掺杂有较高的一级反应速率Kapp,且饵离子最佳掺杂量为5%.     

Preparation and photocatalytic property of porous CuO hollow microspheres via carbon sphere templates

Porous copper oxide (CuO) hollow microspheres have been successfully fabricated by using carbon spheres as templates. The products were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). The influences of different experimental parameters on the morphology of CuO structures have been investigated in detail and the possible formation mechanism of porous CuO hollow microspheres has also been proposed. The specific surface area of the hollow spheres with 74.805 m2/g is measured by BET method. Barrett-Joyner-Halenda (BJH) calculations for the pore size distribution, derived from desorption data, reveal that the average pore radius is 8.56 nm, and the total pore volume (r = 1686.1 A, P/P0 = 0.994296) is 0.107257 cc/g. UV-vis absorption spectrum shows quantum size effect of porous CuO hollow microspheres. Furthermore, the porous CuO hollow microspheres exhibit high efficiency for photodegradation of a sample organic dye, Rhodamine B (RhB), under UV light.     

纳米CuAl2O4/CuO的制备及其模拟太阳光催化产氢

采用共沉淀法制备了纳米结构的CuAl2O4/CuO,用草酸作牺牲剂,在150W的氙灯照射下,考查了不同焙烧温度、催化剂用量对光催化活性的影响。并用XRD、SEM、TG-DTA对样品分别进行了分析与表征,表明CuAl2O4为尖晶石型结构,平均粒径10nm左右。在相同条件下分别考察了固相法、共沉淀法与柠檬酸溶胶-凝胶法对催化剂活性的影响,实验结果表明溶胶-凝胶法产氢活性最好,产氢速率为41mL/h;共沉淀法次之,为34mL/h;固相法最差,为25mL/h。