rGO-SnO2纳米复合物的制备及其室温下NH3气敏性能

以五水四氯化锡(Sn Cl_4·5H_2O)和氧化石墨烯(GOs)为原料,稀氨水为pH控制剂,采用沉淀-焙烧法制备了室温下对NH_3具有高灵敏度和高选择性的r GO-SnO_2纳米复合材料。利用XRD、FTIR、XPS、SEM、TEM和BET对纯SnO_2与r GO(1.0%,即r GO占SnO_2的质量分数,下同)-SnO_2纳米复合物进行了表征。与纯SnO_2相比,r GO(1.0%)-SnO_2纳米复合物中SnO_2晶体尺寸较小,为6～20 nm,比表面积更大,为33 m2/g;r GO(1.0%)-SnO_2纳米复合材料对体积分数为0.01%的NH_3灵敏度达到了49.6%,是相同NH3体积分数下纯SnO_2灵敏度的2.1倍,响应和恢复时间分别为21和204s,比纯SnO_2缩短了24和10s,具有良好的重复性、选择性与稳定性;r GO(1.0%)-SnO_2纳米复合材料优良的气敏性能是由r GO与SnO_2产生的p-n异质结以及溶解的NH3电离出的导电离子共同作用的结果。     

BiVO4/rGO复合物的制备及其 光催化还原CO2研究

采用水热法制备了颗粒状单斜相钒酸铋（BiVO4）/还原氧化石墨烯（rGO）复合催化剂。采用傅里叶红外光谱、拉曼光谱、X射线衍射和紫外-可见漫反射光谱对合成的复合材料做了表征。采用透射电镜、扫描电镜和氮吸附脱附实验对复合材料的表面形貌和表面积做了分析测试。实验结果表明,BiVO4复合物能选择性将CO2还原成甲醇,石墨烯的引入能很好地改善BiVO4光催化还原CO2的性能。当石墨烯的加入量为3%（质量分数）时,在氙灯功率为600 W的条件下,光照6 h后,BiVO4/rGO复合材料光催化还原CO2生成的甲醇产量达到513.1 μmol/L,比相同形貌的纯BiVO4的甲醇产量高73.6%。     

SnO2纳米球的制备、结构及电化学性能研究

以Na2SnO3.4H2O为原料,CO(NH2)2为表面活性剂,采用水热法制备了SnO2纳米球。利用X射线衍射（XRD)、扫描电子显微镜（SEM)、比表面积测试仪（BET）及电化学测试仪等研究材料的结构、形貌、比表面积及电化学性能。结果表明,制备的SnO2材料具有较好的球体形貌,颗粒分散均匀,形状规准,半径约为400 nm,结构呈典型的金红石相。在电压范围为0.01~3 V, 200 mA/g的电流密度下进行充放电测试,首次放电比容量为2206.6 mAh/g,50次循环后,放电比容量保持在440 mAh/g,具有较好的循环性能。     

三维有序结构聚苯胺/石墨烯纳米复合材料的制备及其在超级电容器电极中应用

用硼氢化钠(NaBH_4)还原氧化石墨烯得到还原石墨烯(rGO)分散液,rGO分散液与苯胺在酸性条件下原位聚合得到高比表面积三维有序结构的聚苯胺/石墨烯纳米复合材料。由场发射扫描电镜(FESEM)、透射电镜(TEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对其表面形貌和结构进行表征。结果表明:复合材料的比表面积高达136.9 m~2/g,高于纯聚苯胺的比表面积(32.71 m~2/g);直径10~20 nm的聚苯胺纳米棒均匀地垂直生长在石墨烯表面。在0.5 A/g的电流密度下,复合材料比电容达到358 F/g,大于石墨烯和聚苯胺的比电容;当充放电电流密度由0.5 A/g增加到10 A/g时,电容保留率达74.3%,表现出增强的倍率性能;在10 A/g高电流密度下,经过500次的充放电循环后容量保持率达到83.7%。     

SnO2掺杂对SO42-/TiO2固体酸催化剂酯化反应活性的影响

采用共沉淀与浸渍法制备了一系列不同SnO2掺杂量（1%-7%,摩尔分数）SO42-/TiO2-SnO2固体酸催化剂,利用N2-吸附脱附分析、FT-IR、XPS、NH3-TPD等手段对催化剂的结构和性质进行了表征,结果表明： SnO2掺杂可以有效改善催化剂的比表面积与孔道结构,有利于与SO42-形成配位结构,显著增加了催化剂酸性中心数量,从而增强了催化性能。SnO2掺杂量为5%的SO42-/TiO2-SnO2固体酸催催化丙烯酸与莰烯酯化反应中,莰烯的转化率为77.3%,丙烯酸异冰片酯选择性98.4%,较于SO42-/TiO2,显示出更高的反应活性与稳定性。     

MnO2/rGO复合材料的制备及电化学性能研究

采用一步水热法制备具有海胆状纳米/微米结构的MnO_2和MnO_2/rGO复合电极材料。用扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征分析其微观形貌,X射线衍射(XRD)对其成分进行分析,结果表明:rGO,MnO_2成功复合在一起。rGO包覆在海胆型MnO_2表面,有效增大了MnO_2导电率。MnO_2∶rGO=1∶1的复合材料在电流密度为0.5 A·g~(-1)时比电容可达200.13 F·g~(-1)。经过5000次循环充放电后,其比电容保持率为92%。     

SnO2/硅灰石抗静电材料的制备及性能

以硅灰石为原料,五水四氯化锡为沉淀包覆剂,采用化学沉淀法,制备了一种纳米SnO2/硅灰石复合抗静电粉体材料;采用比表面积仪、粒度仪、白度仪、扫描电子显微镜、X射线衍射仪、透射电子显微镜和红外光谱仪对复合材料进行了表征,并探讨了复合粉体的抗静电机理。结果表明：硅灰石表面均匀地包覆了一层纳米SnO2,比表面积由3.2 m2/g提高到4.7m2/g,中位径D50由7.62μm降低到7.01μm,电阻率从10.683k.cm降到了2.533k.cm。     

石墨相四氮化三碳/氧化锌复合材料的制备及其气敏性能

采用水热法制备了一系列石墨相四氮化三碳-氧化锌(g-C3N4-ZnO)复合材料,并使用X射线衍射、高分辨透射电子显微镜、Fourier变换红外光谱和X射线光电子能谱对复合材料进行了表征,研究了g-C3N4-ZnO复合材料的气敏性能。结果表明:加入9%(质量分数,下同)g-C3N4所制备的g-C3N4-ZnO复合材料在300℃对乙酸具有较好的气敏选择性和较高的气敏灵敏度,对10-3乙酸气体灵敏度达到260.4,响应和恢复时间分别为6 s和5 s,对10-6乙酸气体灵敏度可达到1.8。     

石墨相四氮化三碳/氧化锌复合材料的制备及其气敏性能EI北大核心CSCD

采用水热法制备了一系列石墨相四氮化三碳-氧化锌(g-C3N4-ZnO)复合材料,并使用X射线衍射、高分辨透射电子显微镜、Fourier变换红外光谱和X射线光电子能谱对复合材料进行了表征,研究了g-C3N4-ZnO复合材料的气敏性能。结果表明:加入9%(质量分数,下同)g-C3N4所制备的g-C3N4-ZnO复合材料在300℃对乙酸具有较好的气敏选择性和较高的气敏灵敏度,对10^–3乙酸气体灵敏度达到260.4,响应和恢复时间分别为6 s和5 s,对10^–6乙酸气体灵敏度可达到1.8。     

多孔Fe_2O_3-Ag纳米复合材料的制备及其在表面增强Raman散射光谱中应用

以多孔α-Fe_2O_3作为固相载体,通过水热合成法在α-Fe_2O_3孔道内沉积银纳米粒子。测试4种不同硝酸银用量时Fe_2O_3-Ag复合物的表面增强Raman散射光谱性能(SERS)。利用扫描电子显微镜、透射电子显微镜、X射线衍射和N_2吸附等表征手段对Fe_2O_3-Ag复合物结构及组成进行分析表征。结果表明,当银纳米粒子的负载量为6.5%时(质量分数),Fe_2O_3-Ag纳米复合物的比表面积为26.57 m~2/g,增强因子可以达到10~2～10~3,SERS活性最好。所制备的Fe_2O_3-Ag纳米复合物具有良好的SERS活性和吸附性能,可以进一步应用于其他待测物的吸附检测。     

Chemically modified graphene oxide/polybenzimidazobenzophenanthroline nanocomposites with improved electrical conductivity

Graphene/polybenzimidazobenzophenanthroline nanocomposites were prepared through the liquid-phase exfoliation of graphene oxide (GO) and reduced graphene oxide (rGO) in methanesulfonic acid with subsequent solution mixing. Various chemical and combined chemical-thermal methods were examined to be effective for producing rGO with highly graphitic structure and excellent electrical conductivity. Raman and X-ray photoelectron spectroscopy showed higher degree of reduction of the GO with the combined chemical-thermal method compared to other chemical reduction processes. Structural characterization of the nanocomposites by X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed good exfoliation and dispersion of both GO and rGO fillers in the polymer matrix. The thermogravimetric analysis found that the nanocomposites with rGO have higher onset and maximum weight loss temperatures than those with GO. Compared with the pure polymer, the electrical conductivity of the nanocomposites containing 10 wt% GO and GO reduced by the combined chemical-thermal treatment showed a remarkable increase by four and seven orders of magnitude, respectively. Long-term in-situ thermal reduction was performed to further improve the conductivities of the nanocomposites.     

Facile Preparation of LaFeO<Subscript>3</Subscript>/rGO Nanocomposites with Enhanced Visible Light Photocatalytic Activity

The present work demonstrates a facile route for preparing LaFeO₃/rGO nanocomposites comprising of metal oxide nanoparticles and graphene. Structural, morphology, optical and photocatalytic studies of the samples were characterized using powder X-ray diffraction (XRD), FT-IR, Raman, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscope (HRTEM), atomic force microscopy (AFM), thermogravimetry (TGA), X-ray photoelectron spectroscopy, UV–visible and photocatalytic. LaFeO₃/rGO nanocomposites believed as an effective photocatalyst for the degradation of methyl orange (MO) dye under visible light irradiation. The inclusion of carbon enhances the light absorption of LaFeO₃, resulting in the enhanced photocatalytic activity of the nanocomposite. The degradation of MO dye under visible light source was completely achieved using LaFeO₃/rGO as a catalyst.     

High acetic acid sensing performance of Mg-doped ZnO/rGO nanocomposites

Mg-doped ZnO/reduced graphene oxide (rGO) nanocomposites were synthesized using a facile and cost-effective sol-gel procedure to detect acetic acid vapor. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy, and photoluminescence (PL) analysis were utilized to characterize morphologies, compositions of the nanocomposites, and optical properties of the synthesized nanostructures. The gas sensing measurements of spin-coated Mg-doped ZnO/rGO thin films were carried out for a temperature range of 150–350?°C at various acetic acid vapor concentrations. It was found that the Mg-doped sample with 20?wt%/v of GO solution concentration exhibited the response/recovery time of 60?s/35?s with the best response of ~?200% for 100?ppm of acetic acid at 250?°C.     

Ag nanocrystal as a promoter for carbon nanotube-based room-temperature gas sensors

We have investigated the room-temperature sensing enhancement of Ag nanoparticles (NPs) for multiwalled carbon nanotube (MWCNT)-based gas sensors using electrical measurements, in situ infrared (IR) microspectroscopy, and density functional theory (DFT) calculations. Multiple hybrid nanosensors with structures of MWCNTs/SnO(2)/Ag and MWCNTs/Ag have been synthesized using a process that combines a simple mini-arc plasma with electrostatic force directed assembly, and characterized by electron microscopy techniques. Ag NPs were found to enhance the sensing behavior through the "electronic sensitization" mechanism. In contrast to sensors based on bare MWCNTs and MWCNTs/SnO(2), sensors with Ag NPs show not only higher sensitivity and faster response to NO(2) but also significantly enhanced sensitivity to NH(3). Our DFT calculations indicate that the increased sensitivity to NO(2) is attributed to the formation of a NO(3) complex with oxygen on the Ag surface accompanying a charge rearrangement and a net electron transfer from the hybrid to NO(2). The significant response to NH(3) is predicted to arise because NH(3) is attracted to hollow sites on the oxidized Ag surface with the H atoms pointing towards Ag atoms and electron donation from H to the hybrid sensor.     

Effect of electrolyte on the supercapacitive behaviour of copper oxide/reduced graphene oxide nanocomposite

Cupric oxide/reduced graphene oxide (CuO/rGO) nanocomposites were synthesized through a chemical reduction method using hydrazine hydrate as the reducing agent. The morphology, elemental composition, and bonding network of the CuO/rGOnanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy respectively. The XRD results reveal lattice spacing and lattice strain from 3.371 to 3.428 Å and 1.05 × 10⁻³to 5.44 × 10⁻³ respectively, with the increasing ratio of rGO: CuO from 1:1 to 1:5. The cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS)and galvanostatic charge-discharge (GCD) studyofCuO/rGOas the electrode material showed excellent super-capacitive behavior in H₂SO₄ over Na₂SO₄ electrolytes. Moreover CuO/rGO nanocomposites exhibited better capacitance retention in H₂SO₄(75.69%) compared to Na₂SO₄(12.06%).     

Electrochemical Synthesis of Reduced Graphene Oxide–Wrapped Polyaniline Nanorods for Improved Photocatalytic and Antibacterial Activities

This study depicts the electrochemical synthesis of nanocomposites based on polyaniline nanorods (NRs) wrap with reduced graphene oxide (PANI–rGO) on ITO substrates for photocurrent generation, photodegradation, and antibacterial applications. The synthesis of PANI–rGO nanocomposites was elaborated by the incorporation of rGO into PANI thin films during electropolymerization in the presence of sulfuric acid. The synthesis of rGO was done by modification on the well-known Hammer’s method. The thin film nanocomposites were characterized by X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (FESEM), UV–Visible and electrochemical photocurrent spectroscopy. FESEM revealed the formation of PANI NRs with diameters of between 50 and 150 nm. The XPS was employed to confirm the compositions of the PANI–rGO nanocomposites. From photoelectrochemical results, the generated photocurrent was improved in the presence of rGO in PANI NRs. Whereas experimental findings show that the introduction of rGO into PANI improved the photoresponse from 7 to 13 µA cm^?2. Integration of 3D rGO into PANI results in better photocatalytic performance for the degradation of Congo red (CR). The enhanced photocatalytic activity with the presence of rGO revealed the good potential of PANI-GO nanocomposites for dye degradation. The effective removal of CR of up to 90% has been observed in an acidic medium and is acceptable compared to the surface area of the substrate. At optimum conditions, also the nature of the antibacterial activities has been investigated by ITO/PANI and ITO/PANI–rGO thin films, and the results have shown exhibited antibacterial activity against the growth of E. coli gram-negative bacteria.

Graphical Abstract

     

In Situ Synthesis of Reduced Graphene Oxide and Gold Nanocomposites for Nanoelectronics and Biosensing

In this study, an in situ chemical synthesis approach has been developed to prepare graphene–Au nanocomposites from chemically reduced graphene oxide (rGO) in aqueous media. UV–Vis absorption, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were used to demonstrate the successful attachment of Au nanoparticles to graphene sheets. Configured as field-effect transistors (FETs), the as-synthesized single-layered rGO-Au nanocomposites exhibit higher hole mobility and conductance when compared to the rGO sheets, promising its applications in nanoelectronics. Furthermore, we demonstrate that the rGO-Au FETs are able to label-freely detect DNA hybridization with high sensitivity, indicating its potentials in nanoelectronic biosensing.     

石墨烯/二氧化锰复合材料的制备与电化学性能

通过改性二氧化锰和氧化石墨烯片之间的静电自组装制备了层状的rGO/MnO2复合纳米材料。通过XRD分析材料的晶体结构,用扫描电镜观察材料的微观表面形貌。这种材料用来研究其电化学电容性能,结果表明这种纳米复合材料显示出很好的电容性能(在0.2 A/g的电流密度下可达246 F/g)。此外,在2 A/g的电流密度下循环1000次后容量保持率为91%。材料的性能提升是因为复合材料中二氧化锰纳米棒和石墨烯片层很好的贴合,而石墨烯片的加入也大大提高了材料的导电性。     

Flexible rGO-SnO2 supercapacitors converted from pastes containing SnCl2 liquid precursor using atmospheric-pressure plasma jet

Reduced graphene oxide (rGO)-SnO₂ nanocomposites are fabricated on carbon cloth from screen-printed pastes containing rGO nanoflakes and SnCl₂ liquid precursor by using a nitrogen atmospheric-pressure plasma jet (APPJ). RGO-SnO₂-coated carbon cloth is then used as the electrode of gel-electrolyte supercapacitors (SCs). Experiments conducted with various APPJ processing times suggest that the optimal APPJ processing time is 300 s. Cyclic voltammetry (CV) measurements indicate that 300-s APPJ processing results in the best areal capacitance of 97.53 mF/cm². The capacitance retention rate is ~85% after a 10,000-cycle CV test. Further, capacitance increases by 11% after a 1000-cycle bending test under a bending radius of 7.5 mm, possibly owing to the better electrolyte/electrode contact and decrease in the charge transport resistance after mechanical bending. This study also characterized APPJ-processed rGO-SnO₂ nanocomposites by scanning electron microscopy with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, Raman spectroscopy, and water contact angle measurements.