A New Amperometric Hydrazine Sensor Based on Prussian Blue/Single‐walled Carbon Nanotube Nanocomposites

A slow reaction process has been successfully used to synthesize Prussian blue/single‐walled carbon nanotubes (PB/SWNTs) nanocomposites. Electrochemical and surface characterization by cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV‐vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) confirmed the presence of PB nanocrystallites on SWNTs. PB/SWNTs modified glassy carbon electrode (GCE) exhibits efficient electron transfer ability and high electrochemical response towards hydrazine. The fabricated hydrazine sensor showed a wide linear range of 2.0×10^?6–6.0×10^?3 M with a response time less than 4 s and a detection limit of 0.5 μM. PB/SWNTs modified electrochemical sensors are promising candidates for cost‐effective in the hydrazine assays.     

Amperometric Detection of Hydrogen Peroxide Using Glassy Carbon Electrodes Modified with Chromium Hexacyanoferrate/Single‐Walled Carbon Nanotube Nanocomposites

Chemical functionalization of single‐walled carbon nanotubes (SWNTs) has constructed plenty of new structures with useful properties. But the modification was often confined to organic molecules, either by covalence or noncovalence. In this report, SWNTs were successfully functionalized with one kind of electroactive inorganic compounds: chromium hexacyanoferrate (Cr hcf). The resulting Cr hcf/SWNTs nanocomposites were confirmed by Field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), UV‐vis absorption spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Cr hcf crystallites are observed to be finely attached to the SWNTs. The electrochemical properties of Cr hcf/SWNTs nanocomposites were also investigated. The nanocomposites modified glassy carbon (GC) electrode shows high electrocatalytic activity towards the reduction of H₂O₂ and the amperometric responses show a linear dependence on the concentration of H₂O₂ in a range of 0.5 μM to 10 mM (R=0.9989). In addition, the sensor has good stability and reproducibility.     

MnO2/Graphene Nanocomposites for Nonenzymatic Electrochemical Detection of Hydrogen Peroxide

MnO₂/graphene nanocomposites with different morphologies were synthesized and the petal‐shaped nanosheet MnO₂/graphene composite was developed as an electrode material for nonenzymatic hydrogen peroxide (H₂O₂) sensor. The morphology, structure, composition, and hydrophilicity of the resulting products were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and the contact angle tests. In addition, the fabricated MnO₂/graphene composites could be used as catalysts for the electrochemical oxidation of H₂O₂. Cyclic voltammogram (CV) experiments indicated that MnO₂/graphene‐modified electrode showed good electrocatalytic activity towards both the oxidation and reduction of H₂O₂ in a neutral environment. Amperometric response results illustrated that this nonenzymatic sensor had excellent anti‐interference ability and displayed two linear ranges from 10 to 90 µM and from 0.2 to 0.9 mM with a detection limit of 2 µM.     

Dual-modal Colorimetric and Fluorometric Method for Glucose Detection Using MnO2 Sheets and Carbon Quantum Dots

A novel dual-modal fluorometric and colorimetric method was developed for glucose detection using MnO2 sheets and carbon quantum dots(CQDs). The glucose could be oxidized by glucose oxidase, in accompanied witli the fbnnation of H2O2 intennediate, which resulted in the decomposition of MnO2 sheets, as well as tlie MnO2 sheets(brown) changed to Mn^2+ ions(colorless), which induced the absorption of MnO2 sheet decreased and the fluorescence of CQDs increased, consequently. The linear detection ranges of glucose are 5-1000 μmol/L by fluorescent method and 5-60 μmol/L by colorimetric method. The limits of detection of these two measurements are 2.11 and 2.18 μmol/L, respectively. This method is easy to conduct, has reasonable sensitive and selectivity, and could be applied for the glucose detection in real human senim.     

Facile Synthesis of Pd Nanoparticle Modified Carbon Black for Electroanalysis: Application to the Detection of Hydrazine

Carbon black nanoparticles modified with palladium nanoparticles (Pd/CB) were prepared using a facile methodology. Stirring CB in an aqueous solution of palladium chloride was found to result in the spontaneous formation of Pd nanoparticles on the CB surface. The Pd/CB composite demonstrated high electrocatalytic activity towards hydrazine oxidation, with good stability and reproducibility. Three linear dynamic ranges of hydrazine determination were found between 5 µM and 50 mM. The limit of detection (LOD) for hydrazine was found to be 8.8 µM (based on 3σ). The sensitivity of unmodified CB to trace metal impurities present in certain common electrolytes is also noted.     

Preparation of NiO/MWNTs Nanocomposites by a Simple Chemical Precipitation Method

NiO/MWNTs nanocomposites have been prepared by a simple and efficient chemical precipitation method with the aid of sodium dodecyl sulfate (SDS). Hybrid materials were characterized by XRD, TEM, EDX, Zeta potential and FT‐IR techniques. Experimental results show that NiO nanoparticles with the size of less than 9 nm are well‐dispersed on the outside of MWNTs functionalized with SDS. Hydrogenated NiO/MWNTs hybrid materials exhibit good catalytic performance in the benzene hydrogenation reaction.     

Preparation of Polyaniline/Au0 Nanocomposites Modified Electrode and Application for Hydrazine Detection

The PANI/Au₀ nanocomposite films were successfully prepared on glassy carbon electrode (GCE) using a simple alternate adsorption of water soluble polyaniline (PANI) and . The growth of the films was monitored by UV? Vis spectroscopy and cyclic voltammetry. was in‐situ reduced in the film due to the redox interaction between PANI and , without extra reductant. The ultrafine Au nanoparticles with the size of 2–4 nm were observed by transmission electron spectroscopy. The existence of zero‐valence Au nanocrystals (Au₀) was confirmed by X‐ray photoelectron spectroscopy, X‐ray Diffraction and FTIR. PANI in the nano‐structured PANI/Au₀ composite films displayed a good redox activity in neutral pH solution. The as‐obtained PANI/Au₀/GCE presents an excellent electrocatalytic activity to hydrazine oxidation, and the mechanism of hydrazine oxidation was studied. The calibration curve on (PANI/Au₀)₅/GCE was obtained in the concentration range of 0.01–6 mM with the detection limit of 1 µM (S/N>3). The modified electrode has a great potential for hydrazine sensor application due to its ease of fabrication, good reproducibility and high stability.     

Synthesis of Carbon Nanofibers for Mediatorless Sensitive Detection of NADH

Highly sensitive amperometric detection of dihydronicotinamide adenine dinucleotide (NADH) by using novel synthesized carbon nanofibers (CNFs) without addition of any mediator has been proposed. The CNFs were prepared by combination of electrospinning technique with thermal treatment method and were applied without any oxidation pretreatment to construct the electrochemical sensor. In amperometric detection of NADH, a linear range up to 11.45 μM with a low detection limit of 20 nM was obtained with the CNF‐modified carbon paste electrode (CNF‐CPE). Good selectivity was exhibited for the simultaneous detection of NADH and its common interferent of ascorbic acid (AA) by differential pulse voltammogram. The attractive electrochemical performance and the versatile preparation process of the CNF‐CPE made it a promising candidate for designing effective NADH sensor.     

Development of an Electrochemical Sensor Nanoarray for Hydrazine Detection Using a Combinatorial Approach

The combinatorial screening of different metallic nanoparticles as electrocatalysts was investigated and efficiently applied for the detection of hydrazine. In a first step, glassy carbon microspheres decorated with metallic nanoparticles (Au, Pd, and Ag) were abrasively attached on the surface of a basal plane pyrolytic electrode giving a ‘multi–metal’ nanoarray. In a second step, electrodes modified with only one type of metallic nanoparticles allowed the identification of Pd as the unique catalytic material. In addition, a carbon‐epoxy composite electrode loaded with the Pd nanoparticles was then constructed for a practical use. The carbon‐epoxy composite nanoarray electrode was found to have excellent characteristics as for the sensing of hydrazine with a limit of detection of 2 μM.     

MnO2/PPy/PANI三元纳米管复合材料的合成及其电化学电容性能

在聚苯胺（PANI）和二氧化锰（MnO2）存在的条件下,以FeCl3/甲基橙为模板,通过化学氧化法聚合吡咯(Py)单体,制备MnO2/PPy/PANI纳米管复合材料。 利用X射线衍射、透射电子显微镜、红外光谱和电化学测试等多种测试技术对复合材料进行物性表征和电化学电容性能测试,并讨论了不同含量的PANI对复合物材料的结构和性能的影响。 结果表明,由于PANI、MnO2与PPy三者的相互协同作用,以及材料管状结构的大比表面积,使三元复合材料具有比二元复合材料要大的电化学活性。 所合成的三元复合材料最大比容量达到458.4 F/g。     

Electrocatalytic Oxidation of Diethylaminoethanethiol and Hydrazine at Single‐walled Carbon Nanotubes Modified with Prussian Blue Nanoparticles

In this work, edged plane pyrolytic graphite electrode EPPGE was modified with functionalised single‐walled carbon nanotubes and Prussian blue nanoparticles (PB). The modified electrode was characterised by techniques such as TEM, FTIR, XPS, EDX and cyclic voltammetry. The EPPGE‐SWCNT‐PB platform exhibited enhanced electron transport and catalytic efficiency towards the oxidation of Diethylaminoethanethiol (DEAET) and hydrazine compared with the other electrodes studied. The EPPGE‐SWCNT‐PB showed good electrochemical stability in the analytical solution, showing limit of detection in the micromolar range and catalytic rate constant of 3.71×10⁶ and 7.56×10⁶ cm³ mol^?1 s^?1 for DEAET and hydrazine respectively. The adsorption properties of these analytes that impact on their detection at the SWCNT‐PB film modified electrode were evaluated and discussed.     

Synthesis of Functionalized MWCNTs Decorated with Copper Nanoparticles and Its Application as a Sensitive Sensor for Amperometric Detection of H2O2

Functionalized‐multiwall carbon nanotubes decorated with redox active copper nanoparticles have been fabricated for sensitive enzyme‐less H₂O₂ detection. The new nanocomposite was characterized by Transmission electron microscopy, energy dispersive X‐ray analysis and cyclic voltammetry. The response of the modified electrode to H₂O₂ was examined using amperometry at ?0.45 V vs. Ag/AgCl in a buffer solution at pH 10.0. The developed sensor displayed linear concentration ranges of 0.5–10.0 and 10.0–10000.0 µmol L^?1 with a detection limit of 0.3 µmol L^?1. The proposed sensor displayed good selectivity for H₂O₂ detection in the presence of common interferences such as ascorbic acid.     

Synthesis of Ag Nanoparticle Doped MnO2/GO Nanocomposites at a Gas/Liquid Interface and its Application in H2O2 Detection

Ag/MnO₂/GO nanocomposites were synthesized via the method of gas/liquid interface based on silver mirror reaction, and a non‐enzymatic H₂O₂ sensor was fabricated through immobilizing Ag/MnO₂/GO nanocomposites on GCE. The composition and morphology of the nanocomposites were studied by energy‐dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Electrochemical investigation indicated that it exhibited a favorable performance for the H₂O₂ detection. Its linear detection range was from 3 μM to 7 mM with a correlation coefficient of 0.9960; the sensitivity was 105.40 μA mM^?1 cm^?2 and the detection limit was estimated to be 0.7 μM at a signal‐to‐noise ratio of 3.     

超级电容器纳米氧化锰电极材料的合成与表征

以聚乙二醇为分散剂,利用高锰酸钾和醋酸锰溶液之间的化学共沉淀法制备纳米水合氧化锰.借助SEM,TEM,FT-IR,XRD和BET分析手段对样品结构及性能进行表征.研究结果表明,SEM和TEM显示所得粉体为纳米粉体,粒径大约为10～30nm左右,XRD分析表明该粉体为无定型a-MnO₂·nH₂O,FT-IR分析表明获得的粉体为水合物,BET测试比表面积达160.7m²/g.以氧化锰为研究电极,饱和甘汞电极(SCE)为参比电极,铂片为辅助电极的三电极体系中,以1 mol/L的Na₂SO₄溶液为电解液,通过循环伏安法研究其电化学行为.实验结果表明,纳米氧化锰是理想的超级电容器电极材料,在电位窗口为-0.2～0.9V(vs.SCE)范围内,扫描速度为4mV/s,其比电容达到203.4 F/g.     

高分子量聚苯胺/碳纳米管复合材料的合成与表征

在导电聚合物中,聚苯胺（PANI）因其导电性能优良,环境稳定性好,合成工艺简单,原料成本低廉等优点,被认为是最有可能实际应用的导电聚合物．然而用传统方法合成的聚苯胺由于其分子量小,分子链中存在缺陷而使其导电性能和力学性能大大降低,从而限制了其实际应用．而高分子量聚苯胺的导电性能和力学性能比一般聚苯胺有较大的提高．     

Microwave-assisted One-pot Synthesis of Ag NPs/C and Its Application in H2O2 and Glucose Detection

The facile preparation of Ag NPs/C via a one-pot strategy was carried out by microwave treatment of a mixed aqueous solution of AgNO₃ and glucose at 180℃ for 20 min without the presence of extra reducing agent. The as-synthesized Ag NPs/C showed high catalytic performance toward the reduction of H₂O₂. The H₂O₂ sensor constructed with as-synthesized Ag NPs/C exhibited a short amperometric response time of less than 2 s. The linear range was approximately (0.1-50) mmol/L(r=0.997), and the detection limit was approximately 3.3 μmol/L at a signal-to-noise ratio of 3. A glucose biosensor was fabricated by immobilizing glucose oxidase onto Ag NPs/C- modified glassy carbon electrode to detect glucose. The glucose sensor had a wide linear response range of 2-22 mmol/L(r=0.999) and a detection limit of 190 μmol/L.     

半晶化双螺旋介孔MnO2的合成和电化学性质

Mesoporous silica KIT-6 has novel three-dimensional gyroidal channel structure, space group of 1a-3d, and ordered tunable pores up to 10 nm. In this paper, such mesostructured silica was employed as hard template to prepare semicrystalline gyroidal mesoporous MnO2. The structure was investigated by XRD, TEM and HRTEM, and found to be of high quality 1a-3d symmetry, in good accordance with the template structure. The material has a BET surface of 118 m2·g^-1 and pore volume of 0.35 cm3·g^- 1 after eliminating template. Mesoporous MnO2 has shown good electrochemical property as supercapacitor material in 1 mol·L^-1 Na2SO4 and 1 mol·L^-1 LiClO4 solutions, but interesting pseudocapacitance behavior was observed in the case of 6 mol·L^-1 KOH. It was found that mesoporous MnO2 performed stable reversible electrochemical behavior with capacitance of 220 F·g^-1 in a potential range of -0.1-0.55 V vs. Hg/HgO in alkaline solution, demonstrating that it is a promising novel electrode material for the fabrication of electrochemical capacitors.     

MnO2/H-TiO2纳米异质阵列的调控制备及超电容特性

采用目标调控的阳极氧化工艺制备了超大比表面、管与管相互分离的有序TiO₂纳米管阵列（TiO₂ NTAs）基体,进而分别采用电化学氢化法和循环浸渍沉积法对晶化退火后的TiO₂ NTAs实施电化学氢化和高比电容MnO₂沉积的双重功能化改性,调控构筑了一种新型MnO₂/H-TiO₂纳米异质阵列电极材料。利用场发射扫描电子显微镜（FESEM）、高分辨透射电子显微镜（TRTEM）、X射线衍射仪（XRD）、X光电子能谱仪（XPS）、拉曼光谱（Raman）和电化学工作站等对样品进行综合表征与超电容特性测试,结果表明：电化学氢化改性有效提高了H-TiO₂ NTAs的导电性和电化学特性,当电流密度为0.2 mA·cm^-2时H-TiO₂ NTAs的面积电容达到7.5 mF·cm^-2,是相同电流密度下TiO₂ NTAs的75倍;经过2个浸渍循环所获得的MnO₂/H-TiO₂ NTAs-2样品在电流密度为3 mA·mg^-1时比电容可达481.26 F·g^-1,电流密度为5 mA·mg^-1时循环充放电1000圈后比电容仅下降约11%。     

纳米MnO_2粉体的固相合成及其电化学性能 (Ⅲ)固相氧化还原反应合成纳米α-MnO_2的性能

纳米材料在光、电、磁方面的特性使其在催化,磁性材料,传感器,医学,生物学等方面有特殊应用．纳米材料比常规电极在电化学性能方面有一定的优越性［１～５］．已成功地合成出多种纳米材料［６,７］．本文采用固相氧化还原反应体系直接合成出纳米αＭｎＯ２,并用Ｘ...     

Synthesis and Characterization of Novel Quinone‐Amine Polymer/Carbon Nanotubes Composite for Sensitive Electrocatalytic Detection of NADH

A novel nanocomposite of quinone‐amine polymer and multiwalled carbon nanotubes was synthesized from iodate‐oxidation/Michael addition reaction of 1,2‐dihydroxybenzene with o‐phenylenediamine, which was characterized by TEM, FTIR and UV‐vis spectra. The nanocomposite modified Au electrode with well‐defined quinone redox peaks effectively mediated the oxidation of NADH in pH 7.0 phosphate buffer, with an overpotential decrease by ca. 470 mV (vs. bare Au), a limit of detection of 6.4 nmol L^?1 and good antiinterferent ability.