Co掺杂TiO_2/RGO复合材料的制备及其光催化性能

首先,采用改进的Hummers法制得氧化石墨烯(GO),再以其为基体,Ti(SO4)2和Co Cl_2为前驱体,并通过修饰石墨烯的聚乙烯亚胺(PEI)为交联剂,采用一步水热法合成了三维柱状自组装的Co负载TiO_2/氧化石墨烯纳米复合材料(Co-TiO_2/RGO)。通过UV-Vis、XRD、TEM和XPS对复合材料的结构和光电性能进行了表征。在紫外和可见光照条件下,考察了复合材料的光催化降解亚甲基蓝(MB)的性能。结果表明,Co负载TiO_2/RGO纳米复合材料具有较高的光催化活性,在80 min内降解率为100%,可循环至少10次。     

镍负载二氧化钛/PEI/石墨烯纳米复合催化剂的制备与研究

首先采用改进的Hummers法制备了氧化石墨烯(GO),再以聚乙烯亚胺(PEI)修饰的氧化石墨烯为载体,并以硫酸钛和氯化镍为前驱体,利用水热法在180 ℃下以PEI为交联剂制得镍负载的TiO2/PEI/石墨烯纳米复合催化剂。通过紫外可见分光光度计(UV-vis)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)等测试手段对催化剂进行了表征。结果表明,Ni-TiO2/PEI/RGO纳米复合催化剂中镍负载TiO2纳米粒子与石墨烯能够均匀复合,并具有较小的晶粒尺寸。以对硝基苯酚(4-NP)为降解目标物,考察了该催化剂在NaBH4存在下还原4-NP的催化活性。结果表明,镍负载的TiO2/PEI/石墨烯纳米复合催化剂具有良好的重复催化活性,其降解率为98%,催化剂重复使用10次后,降解率仍能保持90%以上。     

镍负载TiO_2/聚乙烯亚胺/石墨烯纳米复合催化剂的制备及性能

首先采用改进的Hummers法制备了氧化石墨烯(GO),再以聚乙烯亚胺(PEI)修饰的氧化石墨烯为载体,并以硫酸钛和氯化镍为前驱体,利用水热法在180℃下以PEI为交联剂制得镍负载的TiO_2/PEI/石墨烯纳米复合催化剂(Ni-TiO_2/PEI/RGO)。通过紫外-可见分光光度计(UV-vis)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)等测试手段对催化剂进行了表征。结果表明,Ni-TiO_2/PEI/RGO纳米复合催化剂中镍负载TiO_2纳米粒子与石墨烯能够均匀复合,并具有较小的晶粒尺寸,孔径分布主要在4~30 nm,比表面积为241.77 m2/g,镍的负载量为2.35%(质量分数),二氧化钛的负载量为17.46%(质量分数)。考察了该催化剂在Na BH4存在下对对硝基苯酚(4-NP)还原生成对氨基苯酚(4-AP)的催化活性。结果表明,使用Ni-TiO_2/PEI/RGO催化剂4-NP降解率为98%,且催化剂重复使用9次后,4-NP降解率仍能保持90%以上。     

尖晶石铁酸锌复合材料的制备及其可见光催化性能

为提高尖晶石铁酸锌(ZnFe2O4)对环丙沙星(CIP)的光降解催化活性,采用溶剂热法制备以还原氧化石墨烯(RGO)为基底并负载氧化铋(Bi2O3)的Bi2O3/ZnFe2O4/RGO光催化剂.通过X射线衍射(XRD)、拉曼光谱(Raman)、透射电子显微镜(TEM)和紫外-可见分光光度计(UV-vis)等对催化剂的微观结构进行了表征,并将该纳米复合材料应用于光催化降解CIP中.结果表明:当Bi2O3/ZnFe2O4/RGO纳米复合物中Bi2O3的摩尔分数为20％,RGO的质量分数为10％时,可见光照射下CIP的光降解效率约92.4％,准一级动力学常数是ZnFe2O4的3.36倍,5次循环后,CIP的降解效率仍可保持在86.2％.Bi2O3/ZnFe2O4/RGO光催化性能的提高可归因于异质结的构建和RGO的负载显著增加了催化剂活性位点,提高了光生电子-空穴对的分离效率,从而有效增强了CIP降解的光催化活性.     

还原石墨烯/硫化镉纳米棒复合材料制备及其光催化性能

为调控硫化镉尺寸和形貌,采用水热法合成了还原型氧化石墨烯/硫化镉纳米棒(RGO/Cd S)复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱(FT-IR)等方法对产物进行了表征。通过调节硫化镉颗粒成核和生长速度,在乙二胺溶剂中水热合成了结构规整的硫化镉纳米棒及与石墨烯的复合材料。紫外分析表明,RGO/Cd S禁带宽度为2.81 e V。光催化降解实验表明,RGO/Cd S对甲基橙具有良好的光催化降解作用,当甲基橙溶液质量浓度为20 mg/L、RGO/Cd S用量为0.2%(质量分数)时,在可见光下反应480 min,甲基橙降解率可达96.3%。RGO/Cd S在光催化氧化处理废水领域具有潜在的应用价值。     

银负载石墨烯复合材料的制备及光催化性能研究

以石墨粉为原料,采用改进的Hummers法制取氧化石墨烯,利用化学还原法将银负载于石墨烯,并利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶红外光谱仪(IR)、紫外-可见分光光度法(UV-Vis)对其进行表征。结果表明,柠檬酸钠成功地将银离子和氧化石墨烯还原,得到银负载石墨烯复合材料,银颗粒粒径范围为(10±6)nm。以甲基橙为目标降解物,探索其在可见光下的光催化性能、稳定性和回收率。实验结果表明,银负载量为100%时复合材料光催化性能最好、稳定性好、回收率较高。     

漂浮型TiO2/石墨烯复合催化剂的制备及其性能

以空心玻璃微珠(HGM)为载体,采用水热法制备漂浮型石墨烯(RGO)-TiO_2复合光催化剂。首先将超声分散后的氧化石墨烯(GO)负载于经预处理后的HGM表面,而后以钛酸四丁酯为前驱体,在不使用还原剂条件下采用一步水热法制备出TiO_2/RGO/HGM复合光催化剂。研究了压力、GO(RGO)含量对复合光催化剂性能的影响。以罗丹明B(RhB)为降解对象分析了复合光催化剂的光催化降解效果。结果表明:GO成功负载于空心玻璃微珠表面,并通过水热过程在空心玻璃微珠表面原位还原生成RGO,二氧化钛形成RGO/HGM复合结构。此后,锐钛矿型TiO_2在RGO/HGM复合结构表面自组装成核并均匀负载从而形成TiO_2/RGO/HGM复合光催化剂。与TiO_2/HGM复合材料相比,TiO_2/RGO/HGM复合材料具有增强的光催化降解活性,再循环后具有良好的降解效果。此外,还提出了加载在HGM表面的RGO和TiO_2的可能机理和形成过程。     

CoO/CdS纳米复合材料的制备及其光催化降解亚甲基蓝的研究

采用物理气相沉积法制备CoO/CdS纳米复合材料,通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能谱仪(E DS)和紫外-可见分光光度计(UV-Vis)对其形貌、结构和光吸收性质进行表征,并以亚甲基蓝溶液的光催化降解为探针反应,在可见光下考察CoO/CdS纳米复合材料的光催化性能.结果表明,CoO/CdS纳米复合材料的光催化活性显著高于CdS纳米颗粒,100 min后亚甲基蓝降解率达到92.4％.     

NiFe_2O_4@TiO_2/RGO光催化剂的制备及催化性能研究

采用水热法成功制备了NiFe_2O_4@TiO_2/RGO纳米复合材料,考察了氧化石墨烯(GO)掺杂量对复合材料晶型、形貌、磁性能、热性能和光吸收性能的影响,并研究了复合材料对甲基橙的光催化降解性能,探讨了降解机理。结果表明,随着GO掺杂量的增加,NiFe_2O_4@TiO_2/RGO的比饱和磁化强度逐渐下降,但依然展示出超顺磁性;掺杂10%GO的NiFe_2O_4@TiO_2/RGO纳米复合材料具有优异的光吸收性能,紫外光照射90 min,其对甲基橙的脱色率达到98%。NiFe_2O_4@TiO_2/RGO纳米复合材料是性能优异的可回收光催化剂。     

微波蚀刻法制备RGO-BiOCl/Bi_2WO_6异质结型催化剂及其催化性能

采用改进的Hummers法制备氧化石墨烯,以Bi(NO_3)_3·5H_2O、KCl、Na_2WO_4为原料,采用微波蚀刻法在其基础上负载BiOCl/Bi_2WO_6。通过X射线衍射(XRD)、扫描电镜(SEM)、比表面积测定仪(BET)、紫外-可见漫反射(UV-Vis)及透射电镜(TEM)等对所制备的催化剂进行表征。以RhB作为目标降解物,考察其光催化性能。结果表明,当RGO:RGO-BiOCl(质量比)为2%、Bi_2WO_6:RGO-BiOCl/Bi_2WO_6(摩尔比)为50%,降解率可达94.6%,远高于纯BiOCl。     

Unique photocatalytic oxidation reactivity and selectivity of TiO₂-graphene nanocomposites

Mesoporous TiO(2)-graphene nanocomposites are fabricated in high yield via two successive steps: (1) hydrothermal hydrolysis of Ti(SO(4))(2) in an acidic suspension of graphene oxide to gain TiO(2)-graphene oxide nanocomposites; (2) UV-assisted photocatalytic reduction of graphene oxide to get the TiO(2)-graphene nanocomposites. The anatase TiO(2) nanocrystals with a crystallite size of 10-20 nm are densely packed and supported on meshy graphene sheets with close interfacial contacts, which is confirmed by transmission electron microscopy (TEM) together with Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Although a low graphene loading (0-2 wt%) slightly influences the textural properties (including the crystallite size, specific surface areas, and pore volume etc.), the incorporation of graphene in TiO(2)-graphene nanocomposites greatly increases the adsorption capacity towards azo dyes such as MO and MB, which is possibly associated with their unique surface properties. Significantly, the incorporated graphene exerts combined effects on the adsorption and charge transfer dynamics in TiO(2)-graphene nanocomposites, which together endow them with good photocatalytic reactivity and tunable photocatalytic selectivity in decomposing MO and MB in aqueous solution.     

Synthesis of reduced graphene oxide-anatase TiO2 nanocomposite and its improved photo-induced charge transfer properties

The construction of reduced graphene oxide or graphene oxide with semiconductor has gained more and more attention due to its unexpected optoelectronic and electronic properties. The synthesis of reduced graphene oxide (RGO) or graphene oxide-semiconductor nanocomposite with well-dispersed decorated particles is still a challenge now. Herein, we demonstrate a facile method for the synthesis of graphene oxide-amorphous TiO(2) and reduced graphene oxide-anatase TiO(2) nanocomposites with well-dispersed particles. The as-synthesized samples were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis absorption spectroscopy, Fourier transform infrared spectrometry, and thermogravimetric analysis. The photovoltaic properties of RGO-anatase TiO(2) were also compared with that of similar sized anatase TiO(2) by transient photovoltage technique, and it was interesting to find that the combination of reduced graphene oxide with anatase TiO(2) will significantly increase the photovoltaic response and retard the recombination of electron-hole pairs in the excited anatase TiO(2).     

N-TiO_2/RGO复合光催化剂的制备及其性能

用改进的Hummers法制得了氧化石墨烯,以Ti（SO4）2为钛源,氨水为氮源,在400℃煅烧下制备了锐钛矿型的氮元素掺杂的TiO2（N-TiO2）。利用溶液混合法将二者混合,再经水热处理法制备了不同质量复合比例的N-TiO2/RGO光催化剂。通过X射线衍射、Fourier变换红外光谱、扫描电子显微镜等对样品的组成与形貌进行了表征,并通过降解1×10–4mol/L亚甲基蓝溶液表征了各样品的光催化效率。结果表明：掺杂氮元素一定程度上提高了TiO2的光催化效能,与石墨烯的复合更进一步改善了N-TiO2光催化效能。     

One-pot synthesis of CdS sensitized TiO2 decorated reduced graphene oxide nanosheets for the hydrolysis of ammonia-borane and the effective removal of organic pollutant from water

A hybrid material of reduced graphene oxide (RGO) sheets decorated with CdS-TiO₂ NPs was prepared through a facile one-pot hydrothermal method. The assembly of CdS-TiO₂ nanoparticles (NPs) on RGO sheets was in-situ produced. As-synthesized nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy disperse X-ray spectrum (EDS), fourier transform infrared spectroscopy (FTIR), and photoluminescence spectroscopy (PL). The obtained nanocomposites exhibited a good photocatalytic activity for the visible-light-induced decomposition of methylene blue (MB) dye and hydrolysis of ammonia borane. The results showed that by incorporation of CdS and TiO₂ NPs on graphene oxide sheets the photocatalytic efficiency was enhanced. The significant enhancement in the photocatalytic activity of CdS-TiO₂/RGO nanocomposites under visible light irradiation can be ascribed to the effect of CdS by acting as electron traps in TiO₂ band gap. Reduced graphene oxide worked as the adsorbent, electron acceptor and a photo-sensitizer to efficiently enhance the dye photo decomposition. Such nanocomposite photocatalyst might find potential application in a wide range of fields, including hydrogen energy generation, air purification, and wastewater treatment.     

二氧化钛/氧化石墨烯复合光催化剂的合成

采用水热法,以钛酸四正丁酯及氧化石墨烯（GO）为原料,在水性体系中合成了一系列具有不同GO质量分数的TiO2/GO复合光催化剂。FE-SEM分析结果表明,分散的钛酸四正丁酯以多分子层的形式吸附到氧化石墨烯的表面,最后在水热过程中转化为锐钛型TiO2粒子。当氧化石墨烯的质量分数低于3%时,产物中含有纯TiO2微球及TiO2/GO复合物;当氧化石墨烯质量分数大于5%时,产物为单纯的TiO2/GO复合物。电化学性能测试结果表明,GO复合后,TiO2电极中载流子的传输效率提高。氧化石墨烯复合量为10%时,复合光催化剂显示了对亚甲基蓝最佳的光催化活性。当复合氧化石墨烯转化为石墨烯后,其光催化活性可得到进一步大幅度的提高。     

A facile one-step solvothermal synthesis of graphene/rod-shaped TiO₂ nanocomposite and its improved photocatalytic activity

Graphene sheets were obtained through solvothermal reduction of colloidal dispersion of graphene oxide in benzyl alcohol. The graphene/rod-shaped TiO(2) nanocomposite was synthesized by this novel and facile solvothermal method. During the solvothermal reaction, both the reduction of graphene oxide and the growth of rod-shaped TiO(2) nanocrystals as well as its deposition on graphene occur simultaneously. The photocatalytic activity of graphene/rod-shaped TiO(2) and graphene/spherical TiO(2) nanocomposites was compared. In the photocatalytic degradation of methyl orange (MO), the graphene/rod-shaped TiO(2) nanocomposite with the optimized graphene content of 0.48 wt% shows good stability and exhibits a significant enhancement of photocatalytic activity compared to the bare commercial TiO(2) (P25) and graphene/spherical TiO(2) nanocomposite with the same graphene content. Photocurrent experiments were performed, which demonstrate that the photocurrent of the graphene/rod-shaped TiO(2) nanocomposite electrode is about 1.2 times as high as that of the graphene/spherical TiO(2) nanocomposite electrode. The photocatalytic mechanism of graphene/rod-shaped TiO(2) nanocomposite was also discussed on the basis of the experimental results. This work is anticipated to open a possibility in the integration of graphene and TiO(2) with various morphologies for obtaining high-performance photocatalysts in addressing environmental protection issues.     

Blue and green luminescence of reduced graphene oxide quantum dots

We report on a new method for synthesising strongly blue and green photoluminescent graphene quantum dots (GQDs). Graphene was prepared by a new feasible method using an intensive cavitation field in a pressurised ultrasonic batch reactor. The prepared graphene was quantitatively converted to graphene oxide using our modified, safer Hummer’s method. Graphene oxide was characterised by microscopic (AFM and TEM) and spectral (infrared and Raman) methods, and the thermal stability of graphene oxide was determined using thermal analysis (DTA-TG). GQDs were prepared by a one-pot reaction, refluxing graphene oxide in different solvents (ethylene glycol, polyethylene glycol, dimethylformamide, dimethyl sulfoxide and N-methyl-2-pyrrolidone) at atmospheric pressure. The synthesised GQDs were characterised by infrared, UV–Vis absorption and photoluminescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and AFM microscopy.     

Photovoltaic and UV detector applications of ZnS/rGO nanocomposites synthesized by a green method

The effect of graphene concentration on the photovoltaic and UV detector applications of ZnS/graphene nanocomposites was investigated. The nanocomposites were synthesized by a green, cost-effective, and simple co-precipitation method with different graphene concentrations (5, 10, and 15 wt%) using L-cysteine amino acid as a surfactant and graphene oxide (GO) powder as a graphene source. Transmission electron microscopy (TEM) images showed that the ZnS NPs were decorated on GO sheets and the GO caused a significant decrease in ZnS diameter size. The results of X-ray diffraction (XRD) patterns, Raman, and Fourier transform infrared (FTIR) spectroscopy indicated that the GO sheets were changed into reduced graphene oxide (rGO) during synthesis process. Therefore, L-cysteine amino acid played its role as a reducing agent to reduce the GO. Photovoltaic measurements showed that the graphene caused to increase the efficiency of solar-cell application of ZnS/rGO nanocomposites. In addition, our observation showed that the nanocomposites were suitable as ultraviolet (UV) detectors and graphene concentration increased the responsibility of the detectors.     

纳米TiO2/C复合材料制备及其催化活性机理

用X射线衍射、透射电镜、紫外-可见光漫反射光谱等表征手段研究了纳米TiO2/C光催化剂的晶体结构和性能.结果表明:碳黑改性促使TiO2在较低温度(＜500 ℃)发生由锐钛矿相向金红石相转变,并有效抑制了纳米TiO2晶粒长大,经400 ℃热处理后,TiO2晶粒尺寸为7.3 nm.由于纳米碳黑弥散分布于纳米TiO2颗粒中,提高了该催化剂对亚甲基蓝分子的吸附性能.通过碳黑粒子的光敏化作用提高纳米TiO2的可见光光催化性能,加入5%(质量分数)纳米碳黑的TiO2/C光催化剂在400 ℃热处理后对亚甲基蓝降解率可达到93%.过多的碳黑会因其阻碍纳米TiO2与有机物接触而降低其降解效果,而过少的碳黑则会降低纳米碳黑对催化剂的敏化作用而降低其催化活性.