实验和理论研究石墨烯氧化物的铁电性

基于独特的结构和性质, 石墨烯在很多领域都表现出了巨大的潜力. 作为制备石墨烯的主要母体材料, 石墨烯氧化物在室温条件下被观测到具有弱的铁电性. 石墨烯氧化物的表面和边界上会存在大量的羟基, 这些羟基有序重复排列而构成了一维的氢键链, 这些有序氢键链可能是石墨烯氧化物呈现铁电性能的主要原因.     

石墨烯氧化物薄膜电极的光电化学特性

采用浸渍-提拉法制备了一系列石墨烯氧化物(GO)薄膜,并通过X射线衍射(XRD),扫描电镜(SEM),傅里叶变换红外光谱,紫外-可见吸收光谱和光电化学测量等技术对样品进行了表征.在GO电极上观察到阴极光电流,且光电流密度受薄膜的厚度影响.GO薄膜电极厚度为27nm时,光电流密度为0.25μA·cm-2.此外,GO电极的光电响应还受紫外光照影响,随着紫外光照时间的延长,阴极光电流逐渐减小.该工作提供了简便的通过控制薄膜厚度或紫外光照时间来控制GO薄膜半导体光电化学性能的方法.     

Fe2O3—TiO2—K2O复合氧化物体系结构与湿敏性能

Ｆｅ２Ｏ３┐ＴｉＯ２┐Ｋ２Ｏ复合氧化物体系结构与湿敏性能储向峰刘杏芹＊王弘（中国科学技术大学材料科学与工程系合肥２３００２６）关键词Ｆｅ２Ｏ３－ＴｉＯ２－Ｋ２Ｏ，复合氧化物，湿度传感器１９９７－０４－３０收稿，１９９７－０９－２９修回Ｆｅ２Ｏ３是一种...     

基于氧化铒石墨烯氧化物复合纳米材料的葡萄糖氧化酶直接电化学性能及对葡萄糖的检测

将稀土纳米材料Er₂O₃用于构建葡萄糖生物传感器。Er₂O₃和氧化石墨烯形成复合基底,将葡萄糖氧化酶（GOD）固载在玻碳电极表面。首先利用SEM和XRD技术对所制备的Er₂O₃和氧化石墨烯纳米材料进行表征。利用EIS和CV对整个生物传感器制备过程进行表征。Er₂O₃的存在能有效地保持GOD的生物活性并加速其与电极之间的电子传递。由于Er₂O₃和氧化石墨烯之间的协同效应,使得制备的传感器在CV图中呈现一对明显的氧化还原峰,证实GOD和电极之间的直接电子传递性能。当用于对葡萄糖的电催化氧化时,传感器的CV响应随着葡萄糖浓度的增加而变弱。在葡萄糖浓度为1~10 mmol·L^-1范围内,CV响应值与葡萄糖浓度成线性关系。此外,传感器具有好的稳定性和重现性。     

基于氧化铒-石墨烯氧化物复合纳米材料的葡萄糖氧化酶直接电化学性能及对葡萄糖的检测

将稀土纳米材料Er₂O₃用于构建葡萄糖生物传感器。Er₂O₃和氧化石墨烯形成复合基底,将葡萄糖氧化酶（GOD）固载在玻碳电极表面。首先利用SEM和XRD技术对所制备的Er₂O₃和氧化石墨烯纳米材料进行表征。利用EIS和CV对整个生物传感器制备过程进行表征。Er₂O₃的存在能有效的保持GOD的生物活性并加速其电子传递速率。由于Er₂O₃和氧化石墨烯之间的协同效应,使得制备的传感器具有一对良好的氧化还原峰,证实GOD和电极之间的直接传递性能。当用于对葡萄糖的电催化氧化时,传感器的CV响应随着葡萄糖浓度的增加而变弱。在葡萄糖浓度为1~10 mmol·L^-1范围内,CV响应值与葡萄糖浓度成线性关系。此外,传感器具有好的稳定性和重现性。     

高分子型湿敏传感结构材料及器件

综述了湿敏传感器的研究进展。重点介绍了四类高分子型湿度传感器,电容型、电阻型（电子导电型和离子导电型）、声表面波（ＳＡＷ）型和光敏型。同时还简介介绍 类聚炔湿敏传感结构材料的研究结果,及今后该研究领域的发展方向。     

不同氧化程度氧化石墨烯的制备及湿敏性能研究

基于氧化石墨烯具有多种含氧官能团和极大的比表面积,研究了不同氧化程度氧化石墨烯的湿敏性能。采用改进的Hummers法制备不同氧化程度的氧化石墨,经过超声分散制备氧化石墨烯水相分散液后,制成氧化石墨烯薄膜湿敏元件。采用X射线衍射、原子力显微镜、红外光谱、拉曼光谱和X射线光电子能谱对实验样品的结构和谱学特性进行表征。结果表明:石墨经氧化后,底面间距增大为0.9 nm左右;随氧化剂用量的增加,氧化石墨中石墨的衍射峰逐渐消失,石墨相微晶尺寸逐渐减小,O/C原子比逐渐增大,氧化程度逐渐升高;氧化石墨烯在水相分散液中可达单层分散,单层氧化石墨烯厚度约为1.3 nm;氧化石墨烯表面接有-OH、C-O-C、C=O和COOH官能团,且官能团含量随氧化程度的升高而增大;氧化石墨烯薄膜元件在室温下对湿度的响应时间约3 s,灵敏度达99%;在11.3%-93.6%相对湿度范围内,元件的电阻随湿度升高显著减小,较高氧化程度的氧化石墨烯薄膜的电阻对数与相对湿度呈线性变化;氧化程度越高,元件灵敏度越高,响应时间越短。     

基于计算谱学的纳米材料结构表征及其在石墨烯氧化物中的应用

从理论上对材料结构进行表征一般是基于第一性原理电子结构计算对可能的结构模型进行能量分析, 从而得到材料的基态构型. 而经过复杂路径合成的纳米材料并不总是处于基态能量构型. 因此, 对可能的结构模型进行计算谱学模拟, 然后直接与实验谱图对比, 可以提供更为可靠的结构信息. 本文简单介绍了谱学模拟的理论背景, 以石墨烯氧化物为例展示了计算谱学在复杂纳米材料结构表征中的关键作用.     

石墨烯研究进展

石墨烯是目前发现的唯一存在的二维自由态原子晶体,它是构筑零维富勒烯、一维碳纳米管、三维体相石墨等sp²杂化碳的基本结构单元,具有很多奇异的电子及机械性能。因而吸引了化学、材料等其它他领域科学家的高度关注。本文介绍了近几年石墨烯的研究进展,包括石墨烯的合成、去氧化、化学修饰及应用前景等方面的内容。     

石墨烯的制备、功能化及在化学中的应用

石墨烯是最近发现的一种具有二维平面结构的碳纳米材料, 它的特殊单原子层结构使其具有许多独特的物理化学性质. 有关石墨烯的基础和应用研究已成为当前的前沿和热点课题之一. 本文仅就目前石墨烯的制备方法、功能化方法以及在化学领域中的应用作一综述, 重点阐述石墨烯应用于化学修饰电极、化学电源、催化剂和药物载体以及气体传感器等方面的研究进展, 并对石墨烯在相关领域的应用前景作了展望.     

氧化石墨烯薄膜的光电化学性质

用改进的Hummers法制备了氧化石墨烯(GO), 在质子化的氧化铟-氧化硒导电玻璃基片上制备了静电自组装薄膜, 通过紫外-可见光谱和扫描电镜对薄膜进行了表征并研究了薄膜的光电化学性质. 结果表明, GO薄膜是一种稳定的光电阴极材料, 在光强为100 mW/cm²的白光照射下, 偏压为－0.4 V时, 0.1 mol•L^－1的Na₂SO₄溶液中薄膜电极的光电流密度达3.72 μA/cm².     

Humidity Sensitive Properties of a Silicone-containing Polyelectrolyte Material

Humidity sensors have found wide applications in industry production, process control, environment monitoring, storage, electrical applications, etc.. Polymer electrolytes have been used in the preparation of resistive-type humidity sensors in the past ye…     

Graphene Oxide/Carbon Nanocoil Composite for High-performance Humidity Sensor

Designing a humidity sensor with high performance to quick and accurate detect relative humidity (RH) is important in various applications. Consideration must be given to both the high response and the quick reversibility. Here, based on Quartz Crystal Microbalance (QCM) sensing platform, we utilized commercial graphene oxide as a sensing material, and added commercial carbon nanocoil to block the stacking of graphene oxide layers. The fabricated novel sensor possessed super high response (4618 Hz/97 % RH) and quick reversibility (2 s). This work not only expands the application of commercial carbon materials, but also achieves the development of high-performance humidity sensor with commercial potential.     

The Effect of Temperature Conditions During Graphene Oxide Synthesis on Humidity Dependence of Conductivity in Thermally Reduced Graphene Oxide

In this work, we study the effect of temperature conditions during graphene oxide (OG) synthesis on the conductivity dependence viewed as a function of ambient humidity after thermal reduction of initial GO. GO samples obtained at various temperatures by the modified Hummers’ method were found to contain different quantitative ratios of oxide groups. The relative content of carboxyl groups in the initial GO suspension is shown to affect the humidity dependence of conductivity after GO reduction 150 °С. A humidity dependence mechanism is proposed to explain the obtained characteristics.     

Reduced Graphene Oxide Nanocomposite Modified Electrodes for Sensitive Detection of Ciprofloxacin

The synthesis of novel nanocomposites with great sensing enhancement has played an important role in analytical chemistry, especially in the electrochemical detection of drug molecules. In this work, we report a wet chemical method for the preparation of a gold nanoparticle coated β‐cyclodextrin functionalized reduced graphene oxide nanocomposite. A number of different analytical techniques including ultraviolet‐visible spectroscopy, fourier transform infrared spectroscopy, scanning electron microscope and energy dispersive X‐ray spectroscopy were employed to characterize the as‐synthesized nanocomposite. With excellent electrocatalytic properties and high supramolecular recognition ability, the as‐synthesized nanocomposite was used to modify a glassy carbon electrode surface for the sensitive determination of ciprofloxacin using voltammetric technique. The current response of ciprofloxacin on the nanocomposite modified electrode was greatly enhanced compared to that on the bare and other modified electrodes. Using differential pulse voltammetry, the oxidation peak currents increased linearly with the ciprofloxacin concentrations in the range between 0.01 to 120 μM with a detection limit of 2.7 nM. The electrochemical testing results showed good stability and reproducibility. Therefore, the nanocomposite could be a potential candidate for the development of electrochemical sensors for sensitive and selective determination of ciprofloxacin or similar drugs in the future.     

Photoluminescence Properties of Graphene Oxide in Non-Aqueous Solvents

Detailed attention to the interaction between graphene oxide (GO) and various organic fluorophores has been documented in literature as a result of which the impact of GO on the photophysical properties of the fluorophores is well known to the scientific community. However, the photoluminescence (PL) properties of GO in polar aprotic solvents are yet to be established. In this article, the PL properties of GO in polar aprotic solvents using various spectroscopic techniques have been reported. n-π* transition due to the C=O bonds in the sp³ hybrid regions and π-π* transition due to C=C bonds in the sp² hybrid are prominent in GO. The presence of quasi-molecules within sp²-sp³ domains acts as PL centers located in the sp³ matrixes of GO are responsible for the PL properties. This study showcases the presence of multiple emissive states of GO in polar aprotic solvents and conveys the fact that the PL properties of GO are very much wavelength-dependent.     

Sensitive Electrochemical Aptasensor for Thrombin Detection Based on Graphene Served as Platform and Graphene Oxide as Enhancer

A sensitive electrochemical aptasensor was developed with conductive graphene served as platform and inert graphene oxide (GO) as enhancer. An electrodeposited nano-Au layer was firstly formed on conductive graphene modified glass carbon electrode surface for further immobilizing of electrochemical redox probe hexacyanoferrates nanoparticles (NiHCFNPs). Subsequently, another nano-Au layer was formed for immobilizing of thrombin aptamer (TBA). In the presence of thrombin, the TBA on the electrode surface could bind with thrombin, which made a barrier for electrons and inhibited the electro-transfer, resulting in the decreased electrochemical signals of NiHCFNPs. Owing to the non-conductivity property of graphene oxide, further decreased electrochemical signals of NiHCFNPs could be obtained via the sandwich reaction with GO-labeled TBA. According to the signal changes before the thrombin recognition and after sandwich reaction, trace detection of thrombin could be achieved. As a result, the proposed approach showed a high sensitivity and a wider linearity to thrombin in the range from 0.005 nM to 50 nM with a detection limit of 1 pM.     

Electrochemical Sensor for Sensitive Determination of Capsaicin Using Pd Decorated Reduced Graphene Oxide

In this work, the reduced graphene oxide functionalized with poly dimethyl diallyl ammonium chloride (PDDA) modified palladium nanoparticles (PDDA‐rGO/Pd) had been facile synthesized and used as the sensing layer for sensitive determination of capsaicin. The prepared composite was characterized by transmission electron microscopy, UV‐visible absorption spectroscopy. The image demonstrated that Pd nanoparticles were uniformly distributed on the graphene surface. The electrochemical properties of the prepared sensor were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the nanocomposite exhibits attractive electrocatalytic activity towards the oxidation of capsaicin. This attributed to the synergistic action of the excellent properties of Pd nanoparticles and graphene nanosheets. Under optimized conditions, the electrochemical sensor possessed a dynamic linear range from 0.32 μM to 64 μM with a detection limit of 0.10 μM (S/N=3) for capsaicin detection. Moreover, the cost‐effective and simple fabrication procedure, good reproducibility and stability as well as acceptable accuracy for capsaicin determination in actual samples are also the main advantages of this method, which might have broad application in other amide alkaloid detection.     

氧化石墨烯水热还原前后的发光光谱

分别采用改进Hummers方法和水热还原法制备了氧化石墨烯(GO)和还原氧化石墨烯(RGO)。 GO和RGO经透射电子显微镜(TEM)、紫外-可见吸收光谱(UV-Vis)、红外光谱(IR)、荧光发射和激发光谱(PL、PLE)等技术手段进行了表征。 荧光发射光谱显示,氧化石墨烯(GO)在可见光的激发下可以得到波长在600~800 nm范围内的宽谱近红外荧光。 通过比较氧化石墨烯水热还原前后的光谱变化,发现氧化石墨烯近红外荧光起源于氧化石墨烯的表面含氧基团,如C=O、COOH。 近红外荧光穿透性好、对生物组织损坏小,非常适合于生物成像,预示着氧化石墨烯在生物成像方面的应用潜力。