TiO2/石墨烯复合材料的合成及光催化分解水产氢活性

利用石墨粉根据Hummers氧化法制得氧化石墨,并进一步还原得到石墨烯。采用溶胶-凝胶法以钛酸四丁酯和石墨烯为起始材料制备了二氧化钛(TiO₂)和石墨烯的复合光催化材料。研究了该复合材料在紫外-可见光以及可见光条件下的光催化分解水制氢活性。结果表明,紫外-可见光照射下,TiO₂/石墨烯复合光催化材料的光催化分解水产氢速率为8.6 μmol·h^-1,远大于同条件下商业P25的产氢速率 (4.5 μmol·h^-1),光解水产氢活性提高了近2倍;可见光下光照3 h,TiO₂/石墨烯复合材料的光催化分解水产氢量约为0.2 μmol。     

RGO/C3N4复合材料的制备及可见光催化性能

通过半封闭一步热裂解法和改进的Hummers法分别制备了类石墨氮化碳(C₃N₄)和氧化石墨烯(GO),再利用光还原方法制得还原氧化石墨烯/氮化碳(RGO/C₃N₄)复合材料。采用X射线衍射(XRD),场发射扫描电镜(FESEM),X射线光电子能谱(XPS),紫外-可见漫反射吸收光谱(DRS),光致荧光(PL)和傅里叶变换红外光谱(FTIR)等测试技术对复合材料进行表征。以罗丹明B(RhB)为探针分子在可见光下考察RGO/C₃N₄复合材料的光催化活性,结果表明：RGO的引入显著提高了C₃N₄的光催化活性,且6.0%RGO/C₃N₄复合物的光催化活性最高,可能的原因是RGO具有优良的传导和接受电子性能,抑制了C₃N₄光生电子-空穴的复合机率,进而提高了光催化活性。     

水热合成二硫化钨/石墨烯复合材料及其氧还原性能

以六氯化钨、硫代乙酰胺、氧化石墨烯为原料,采用一步水热法合成了二维的二硫化钨/石墨烯(WS₂/RGO)复合材料。水热合成的WS₂/RGO具有薄层的二维结构,且由于石墨烯的存在,WS₂以较少的层数形成薄片状生长在石墨烯的表面。尝试将这种非Pt类材料用于电催化氧化原反应,测试结果表明,WS₂在碱性条件下氧还原活性非常低,但是复合RGO形成WS₂/RGO复合材料后,电催化氧化原性能有了极大的提高,其起始电位为-0.17 V(vs SCE),转移电子数为3.7,极限电流密度为2.5 mA·cm^-2,同时其具有较好的抗甲醇性能和循环稳定性。这是因为WS₂/RGO复合材料的二维结构具有更高的电子传输速率,同时硫化钨和石墨烯可以发挥协同催化作用。这种新型的二硫化钨/石墨烯(WS₂/RGO)复合材料作为非贵金属催化剂表现出良好的氧还原性能,在燃料电池上具有较好的应用前景。     

金红石相TiO2-石墨烯复合材料的制备及其光催化性能

以鳞片石墨为原料, 用改进的Hummers法制备氧化石墨烯(GO), 以异丙醇钛为钛源经一步水热法制备得到金红石相TiO₂-石墨烯复合材料(rGO-TiO₂), 考察了氧化石墨烯用量对复合材料光催化性能的影响. 采用X射线衍射(XRD), 比表面积(BET), 透射电镜(TEM), 扫描电镜(SEM), 拉曼光谱, 紫外-可见(UV-Vis)吸收光谱和荧光光谱(PL)等测试手段对复合材料进行表征. 结果表明: 复合材料中TiO₂为针簇状结构的金红石相, 与石墨烯能够均匀复合; 与纯金红石相TiO₂相比, 复合材料具有较大的比表面积. 研究了该复合材料在紫外光下对罗丹明B 以及可见光下对甲基橙光降解效果. 当氧化石墨烯浓度为0.5 mg·mL^-1时, 制备得到的复合材料rGO-TiO₂具有较好的光催化效果.     

Fe-CuS/还原氧化石墨烯(RGO)的制备及其光催化性能

以氯化铜（CuCl₂·2H₂O）、硫脲（（NH₂）₂CS,Tu）、1,2-丙二醇（1,2-PG）、氯化铁（FeCl₃·6H₂O）及氧化石墨烯（GO）为原料,通过溶剂热法制备了具有可见光活性的Fe-CuS/RGO复合材料。采用XRD、SEM、TEM、Raman、XPS、TG、UV-Vis等手段对产品进行了表征,并以亚甲基蓝（MB）为目标降解物对其可见光催化活性进行了研究。光催化结果表明：在汞灯（150 W）下照射140 min,CuS、CuS/RGO和Fe-CuS/RGO对MB的脱色率分别为41.2%、81.5%和90.6%。Fe-CuS/RGO对MB的降解效率较CuS/RGO和CuS有较大提升,可能原因是Fe元素有利于电荷在CuS与RGO界面间传输,降低了光生电子-空穴对的复合几率,进而提高了光催化活性。     

ZnO/RGO复合材料的结构及其光催化性能研究

本实验以ZnSO₄和氧化石墨(Graphite Oxide,GO)原料,在低温环境下(60 ℃)制备了层状ZnO/RGO(ZnO/Reduced Graphite Oxide)复合材料。通过对ZnO/RGO复合材料进行XRD、FTIR、XPS和FE-SEM等测试,表征了产物的晶相结构、界面状况及微观形貌特征。氧化石墨在与ZnO的复合反应过程中其活性基团消失或减弱,氧化石墨自身被还原为一种类石墨物质(Reduced GO,RGO);GO的预处理过程对产物的形貌有较大影响,采用稀碱溶液对石墨的剥离处理有利于产物的层状结构形成。本文还以甲基橙为目标降解物,考察了不同条件下所得催化剂的紫外光催化性能。研究表明,ZnO/RGO纳米复合材料大大提高了ZnO紫外光催化活性。光致发光谱(PL)显示,ZnO/RGO复合材料的荧光发射峰强度比纯ZnO有较大降低,说明ZnO的光激发电子在氧化石墨的还原产物RGO和ZnO纳米颗粒之间存在界面电子转移效应,因而抑制了ZnO中光生电子-空穴对的复合,从而提高了ZnO的光催化性能。     

氧化钛/氧化石墨纳米复合材料的制备、表征及性能

采用四氯化钛(TiCl₄)和氧化石墨为主要原料, 通过原位复合的方法制备了氧化钛/氧化石墨(TiO₂/GO)纳米复合材料. 采用傅里叶变换红外(FTIR)光谱仪、X射线衍射(XRD)仪、热重-差热分析(TG-DTA)仪、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)等手段研究了TiO₂/GO纳米复合材料的结构和性能. 结果表明, 石墨在氧化过程中结构层键合大量含氧官能团, 部分含氧官能团进一步与纳米TiO₂以化学键结合; 复合后氧化石墨原有衍射峰消失. 将TiO₂/GO添加到水性聚氨酯(WPU)中, 制备了TiO₂/GO-WPU复合涂膜. 紫外吸收光谱表明, 随着氧化石墨含量的增加, 复合涂膜的紫外吸收能力增强, 当GO含量达到一定数值时, 涂膜的紫外吸收最强, 随着GO含量继续增加吸收又呈下降趋势, 存在一较优浓度值. TiO₂/GO的添加显著提高了聚氨酯涂层的抗紫外线性能, 耐磨损性能和热稳定性能.     

GO/TiO2-g-C3N4纳米复合材料的制备及可见光催化性能

以水热法制备的20% g-C₃N₄/TiO₂（20%为质量分数）为基,将其与不同质量分数的氧化石墨烯（GO）复合制备出可见光催化性能优良的GO/TiO₂-g-C₃N₄三元复合材料。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）、紫外-可见漫反射光谱（UV-Vis DRS）、光致荧光光谱（PL）、瞬态光电流响应等分析测试手段对样品的结构、形貌和光电性能进行表征。研究了不同质量分数GO的加入对GO/TiO₂-g-C₃N₄在可见光下降解亚甲基蓝（MB）溶液的影响。结果表明： g-C₃N₄/TiO₂与GO复合后,锐钛矿相TiO₂颗粒形成小团簇附着在g-C₃N₄和GO片层表面,且当GO含量为15%时,TiO₂形成的团簇最小,对可见光的吸收最多且光生电子-空穴对的复合率最低。可见光照射下,15% GO/TiO₂-g-C₃N₄复合材料对MB的降解率在3 h内可达98.4%,且其降解速率常数（0.022 4 min^-1）分别是纯TiO₂（0.001 5 min^-1）和g-C₃N₄/TiO₂（0.002 5 min^-1）的15倍和9倍。     

S掺杂形式对TiO2基光催化剂结构和性能的影响

采用改进的Sol-gel法制备了S-TiO₂和TiO₂,用1 mol·L^-1的H₂SO₄对TiO₂进行表面修饰制成的SO₄^2-/TiO₂。采用XRD、IR、UV-Vis、SEM和EDS等技术对催化剂的结构进行了表征,以L酸(1-萘酚-5-磺酸)为目标物,考察了所制备的催化剂的性能．结果表明：S-TiO₂的禁带宽度明显降低,并且对400~650 nm区域的可见光都有一定的吸收,其可见光活性和紫外光活性均高于SO₄^2-/TiO₂和纯TiO₂。     

原位碳、氮共掺杂二氧化钛空心球的制备与可见光光催化性能

在H₂O₂-HF 的乙醇-水混合溶液中, 通过水热处理碳氮化钛(TiCN)制备了碳、氮共掺杂TiO₂ 空心球(CNTH). 用X 射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X 射线光电子能谱(XPS)和紫外-可见(UV-Vis)吸收光谱表征了所制备的样品. 在可见光(λ≥400 nm)照射下, 通过降解甲基蓝检测了碳、氮共掺杂TiO₂空心球的光催化活性. 结果表明, 源于TiCN中的部分碳和氮原子原位掺入了TiO₂的晶格中, 部分碳掺入TiO₂点阵的间隙中. 该材料在整个可见光区展示了增强的可见光吸收, 其带边明显红移. 光催化研究表明在强可见光吸收和独特的空心球结构的协同作用下, 碳、氮共掺杂TiO₂空心球展示了比P25更高的可见光光催化活性.     

Elaboration of nano titania-magnetic reduced graphene oxide for degradation of tartrazine dye in aqueous solution

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO₂) and magnetite (Fe₃O₄) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO₂/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO₂ nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO₂ for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).     

Photocatalytic Oxidation Based on Modified Titanium Dioxide with Reduced Graphene Oxide and CdSe/CdS as Nanohybrid Materials

Photocatalytic activity of TiO₂ nanoparticles in the visible light region was enhanced. TiO₂–CdSe and TiO₂–CdSe/CdS nanohybrids were supported on the reduced graphene oxide. These nanohybrid materials were applied as photocatalyst toward oxidation of aromatic alcohols under a mild condition and the molecular oxygen as oxidant. A plausible mechanism for the photocatalytic oxidation was also proposed. Desired nanohybrids were obtained via in situ fixation of CdSe/CdS on the surface of nanosheets of reduced graphene oxide (rGO). Finally, it was modified by TiO₂ sol nanoparticles through a hydrothermal method. The obtained nanomaterials, were characterized by SEM, TEM imaging, XRD, EDAX, DRS and XPS analyses. The size of nanohybrids materials were distributed mostly in a narrow range of 50–65 and 60–75 nm for TiO₂–rGO–CdSe and TiO₂–rGO–CdSe/CdS, respectively. These photocatalysts showed high catalytic activity under visible light irradiation in a short reaction time and even higher selectivity rather than UV irradiation. The yield of catalytic oxidation increased at least 25–30% for TiO₂–CdSe/CdS on rGO, which could be related to its higher light sensitivity and lower energy band gap. The photocatalysts were recycled and reused 8 times without significant loss of their activities due to their stability under visible light.     

CO2在纳米SiO2/TiO2悬浮体系中的光催化还原

用水热法合成了氧化硅改性的具有高比表面积、高催化活性的锐钛型二氧化钛, 并在其悬浮体系中将CO₂光催化还原合成甲醇. 采用XRD, TEM, 物理吸附, UV-Vis吸收光谱和FTIR等表征手段对催化剂结构特征进行了研究. 结果表明: 添加氧化硅后, 氧化硅和二氧化钛之间形成Si—O—Ti键, 抑制了TiO₂晶粒生长, 提高了锐钛型TiO₂的比表面积, 且随着含硅量的增加, SiO₂/TiO₂的UV吸收逐步蓝移, 禁带宽度增加. 还原反应结果表明: SiO₂/TiO₂具有光催化还原活性, 且随着含硅量的增加先增加后减小, 当SiO₂质量分数为3.5%时, SiO₂/TiO₂复合催化剂反应活性最强, 5 h内甲醇产量可达到21.0 mg/L, 并有少量甲醛生成.     

Controllable synthesis of titania/reduced graphite oxide nanocomposites with various titania phase compositions and their photocatalytic performance

A facile method is presented for preparing TiO2 /reduced graphite oxide(RGO) nanocomposites with phase-controlled TiO2 nanoparticles via redox reaction between the reductive titanium(Ⅲ) precursor and graphite oxide(GO),and a series of TiO2 /RGO composites with various TiO2 phase compositions were obtained.In all the titania/RGO composites,the TiO2 nanoparticles were uniformly distributed on the surface of the RGO.The TiO2 consisted of anatase phase particles in the form of square-plates with edges less than 10 nm and the rutile phase nanorods in diameters less than 10 nm.The performances of the as-prepared TiO2 /RGO composites were investigated on catalytically degrading phenol under visible light irradiation.The TiO2 /RGO composites can effectively degrade phenol under visible light irradiation,and the phase composition of TiO2 in the composites significantly influences the activities of these catalysts.     

Au/TiO<Subscript>2</Subscript>/Graphene Composite with Enhanced Photocatalytic Activity Under Both UV and Visible Light Irradiation

Au/TiO₂/graphene composite was synthesized by the combination of electrostatic attraction and photo-reduction method. In the composite, graphene sheets act as an adsorption site for dye molecules to provide a high concentration of dye near to the TiO₂ and Au nanoparticles (NPs), and work as an excellent electron transporter to separate photoinduced e ^?/h ⁺ pairs. Under UV irradiation, photogenerated electrons of TiO₂ are transferred effectively to Au NPs and graphene sheets, respectively, retarding the recombination of electron–hole pairs. Under visible light irradiation, the Au NPs are photo-excited due to the surface plasmon resonance effect, and charge separation is accomplished by the interfacial electron injection from the Au NPs to the conduction band of TiO₂ and then transfer further to graphene sheets. As a result, compared with pure TiO₂, Au/TiO₂/graphene composite exhibited much higher photocatalytic activity for degradation of methylene blue under both UV and visible light irradiation, based on the synergistic effect of Au, graphene in contact with TiO₂, allowing response to the visible light, effective separation of photoinduced charges, and better adsorption of the dye molecules.     

单斜与锐钛矿双晶相TiO2/MWNTs复合材料的制备及其可见光光催化活性

以超强耐酸碱的表面活性剂-丁基封端脂肪醇聚氧乙烯醚作为晶型调节剂,利用钛酸丁酯和氢氧化钠的水热反应制备了单斜相与锐钛矿相双晶相TiO₂/多壁碳纳米管(简称MWNTs)复合材料,并考察了复合材料的可见光光催化活性。结果显示:MWNTs的加入可调控TiO₂的晶相组成,增强TiO₂的光催化活性,其中含5%MWNTs的样品具有较高的催化降解效率;随煅烧温度的升高,样品的光催化活性大幅提升。其机理归因于(1)促进单斜相和锐钛矿相双晶相结构的形成;(2)碳纳米管优良的导电作用及碳纳米管/TiO₂间的异质结效应;(3)高温下碳纳米管分解产生的碳元素掺杂作用。     

单斜与锐钛矿双晶相TiO2/MWNTs复合材料的制备及其可见光光催化活性

以超强耐酸碱的表面活性剂-丁基封端脂肪醇聚氧乙烯醚作为晶型调节剂,利用钛酸丁酯和氢氧化钠的水热反应制备了单斜相与锐钛矿相双晶相TiO2/多壁碳纳米管(简称MWNTs)复合材料,并考察了复合材料的可见光光催化活性。结果显示:MWNTs的加入可调控TiO2的晶相组成,增强TiO2的光催化活性,其中含5%MWNTs的样品具有较高的催化降解效率;随煅烧温度的升高,样品的光催化活性大幅提升。其机理归因于(1)促进单斜相和锐钛矿相双晶相结构的形成;(2)碳纳米管优良的导电作用及碳纳米管/TiO2间的异质结效应;(3)高温下碳纳米管分解产生的碳元素掺杂作用。     

The Visible‐Light Photocatalytic Activity and Antibacterial Performance of Ag/AgBr/TiO2 Immobilized on Activated Carbon

Visible‐light‐driven Ag/AgBr/TiO₂/activated carbon (AC) composite was prepared by solgel method coupled with photoreduction method. For comparison, TiO₂, TiO₂/AC, and Ag/AgBr/TiO₂ were also synthesized. Their characteristics were analyzed by XRD, SEM‐EDS, TG‐DSC and UV–vis techniques. Photocatalytic activity and antibacterial performance under visible‐light irradiation were investigated by ICP‐AES, ATR‐FT‐IR and spectrophotometry methods using methylene blue and Escherichia coli as target systems, respectively. The results showed that Ag/AgBr was successfully deposited on anatase TiO₂/AC surface, and exhibited a distinct light absorption in the visible region. Ag/AgBr/TiO₂/AC displayed excellent antibacterial performance both in dark and under visible‐light illumination. The growth of E. coli cell was inhibited in the presence of Ag/AgBr/TiO₂/AC in dark. Moreover, upon visible‐light illumination, a significant damage of cell membrane was noticed. Ag/AgBr/TiO₂/AC was also shown higher photocatalytic efficiency for methylene blue degradation than those of TiO₂, TiO₂/AC, and Ag/AgBr/TiO₂. This is attributed to the synergetic effect between AC and Ag/AgBr/TiO₂, of which AC acts as the role of increasing reaction areas, continuous enriching, and transferring the adsorbed MB molecules to the surface of supported photocatalysts, and the Ag/AgBr/TiO₂ acts as a highly active photocatalyst for degrading MB molecules under visible‐light irradiation.