基于纳米银/碳纳米纤维复合材料的增强效应电化学测定多贝斯

将银纳米粒子(AgNPs)电沉积在碳纳米纤维(CNFs)修饰玻碳电极表面制备纳米银/碳纳米纤维修饰玻碳电极(AgNPs/CNFs/GCE).采用扫描电镜考察其表面形态,在K3[Fe(CN)6]-K4[Fe(CN)6]体系中用循环伏安法和电化学阻抗法研究AgNPs/CNFs/GCE的电化学行为.采用循环伏安法和方波伏安法...     

Electrochemical capacitances of well-defined carbon surfaces

Reported is the capacitive behavior of homogeneous and well-defined surfaces of pristine carbon nanofibers (CNFs) and surface-modified CNFs. The capacitances of the well-defined CNFs were measured with cyclic voltammetry to correlate the surface structure with capacitance. Among the studied pristine CNFs, the edge surfaces of platelet CNFs (PCNF) and herringbone CNFs were more effective in capacitive charging than the basal plane surface of tubular CNF by a factor of 3-5. Graphitization of PCNF (GPCNF) changed the edge surface of PCNF into a domelike basal plane surface, and the corresponding capacitances decreased from 12.5 to 3.2 F/g. A chemical oxidation of the GPCNF, however, recovered a clear edge surface by removal of the curved basal planes to increase the capacitance to 5.6 F/g. The difference in the contribution of the edge surface and basal-plane surface to the capacitance of CNF was discussed in terms of the anisotropic conductivity of graphitic materials.     

Electrochemical Detection of Hydrazine Based on Electrospun Palladium Nanoparticle/Carbon Nanofibers

In this work, we developed an electrochemical method for the detection of hydrazine based on palladium nanoparticle/carbon nanofibers (Pd/CNFs). Pd/CNFs were prepared by electrospinning technique and subsequent thermal treatments. The electrocatalytic behaviors of Pd/CNFs modified glassy carbon electrode (Pd/CNF‐GCE) for hydrazine oxidation were evaluated by cyclic voltammetry (CV), an obvious and well‐defined oxidation peak appeared at ?0.32 V (vs. Ag/AgCl). The mechanism of the oxidation of hydrazine at Pd/CNF‐GCE was also studied, which demonstrated an irreversible diffusion‐controlled electrode process and a four‐electron transfer involved in the overall reaction. Furthermore, the wide linear range, low detection limit, good reproducibility and excellent storage stability were obtained utilizing differential pulse voltammetry (DPV).     

纳米碳纤维载铂作为质子交换膜燃料电池阳极催化剂

采用化学还原法合成了微结构不同的纳米碳纤维(板式、鱼骨式、管式)载铂催化剂(分别记为Pt/p-CNF、Pt/f-CNF、Pt/t-CNF). 通过高分辨透射电镜(HRTEM)和X射线衍射(XRD)等分析技术对催化剂的微观结构进行了表征, 并利用循环伏安(CV)法分析了催化剂的电化学比表面积(ESA). 在此基础上, 制备了膜电极(MEA), 通过单电池测试了催化剂的电催化性能. 结果表明: 铂纳米粒子在不同的纳米碳载体上表现出不同的粒径, 在板式、鱼骨式和管式纳米碳纤维上的铂纳米粒子平均粒径分别为2.4、2.7和2.8 nm. 板式纳米碳纤维载铂催化剂作单电池阳极时表现出良好的电催化性能, 其对应的最高功率密度可达0.569 W·cm^-2, 高于鱼骨式纳米碳纤维载铂催化剂和管式纳米碳纤维载铂催化剂对应的最高功率密度(分别为0.550和0.496 W·cm^-2). 同时, 也制备了碳黑(Pt/XC-72)载铂催化剂. 相比于Pt/XC-72, 纳米碳纤维载体上的铂纳米颗粒有较小的粒径、较好的分散和较高的催化活性, 说明纳米碳纤维是质子交换膜燃料电池(PEMFCs)催化剂的良好载体.     

Tin oxide (SnO2) nanoparticles/electrospun carbon nanofibers (CNFs) heterostructures: controlled fabrication and high capacitive behavior

Tin oxide (SnO(2))/carbon nanofibers (CNFs) heterostructures were fabricated by combining the versatility of the electrospinning technique and template-free solvent-thermal process. The results revealed that the SnO(2) nanostructures were successfully grown on the primary electrospun carbon nanofibers substrates. And, the coverage density of SnO(2) nanoparticles coating on the surface of the CNFs could be controlled by simply adjusting the mass ratio of CNFs to SnCl(4)·5H(2)O in the precursor during the solvent-thermal process for the fabrication of SnO(2)/CNFs heterostructures. The electrochemical performances of the SnO(2)/CNFs heterostructures as the electrode materials for supercapacitors were evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement in 1 M H(2)SO(4) solution. At different scan rates, all the samples with different coverage densities of SnO(2) showed excellent capacitance behavior. And, the sample CS2 (the mass ratio of CNFs to SnCl(4)·5H(2)O reached 1:7) exhibited a maximum specific capacitance of 187 F/g at a scan rate of 20 mV/s. Moreover, after 1000 cycles, the specific capacitance retention of this sample was over 95%. The high capacitive behavior could be ascribed to the low resistance of SnO(2)/CNFs heterostructures and rapid transport of the electrolyte ions from bulk solution to the surface of SnO(2).     

Acicular Nickel on Carbon Nanofiber as Electrochemical Sensor Electrode for the Rapid Detection of Aqueous and Gaseous Formaldehyde at Room Temperature

The rapid and straightforward detection of formaldehyde (FA) in the environment is crucial for preventing the accidental inhalation of FA and limiting skin exposure to FA. In this study, we developed a simple nickel-based electrocatalytic electrode on carbon nanofibers (CNFs−Ni), which is suitable for rapidly detecting FA at room temperature. Centrifugal electrospinning was used to obtain polyacrylonitrile (PAN) nanofibers, which was subsequently stabilized and carbonized to fabricate the CNFs. Carbonization of the CNFs occurred at various temperatures (T_c=1200, 1300, 1400, and 1500 °C). PAN CNFs served as a highly conductive template for electroless plating under a magnetic field of 500 G to grow acicular nickel. The amperometric responses of the CNFs−Ni to aqueous FA were then measured. A lab-built amperometric gas sensor (CNFs−Ni 1–8), which comprised CNFs with a reduced Ni loading, was used as the electrode for detecting gaseous FA. Scanning electron microscopy (SEM), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and chronoamperometry were used to evaluate the sensitivities of the electrodes. Within the linear range of 0.05–91.5 mM, the CNFs1400-Ni electrode was highly sensitive for detecting aqueous FA (2592 μA mM⁻¹ cm⁻²), as evidenced by the fast response time (6 s). At a low concentration of gaseous FA (0.5 ppm), the laboratory-built FA gas sensor was stable (98.3 %) and had a fast response time (5 s) after 9 h of continuous operation.     

Direct electrochemistry and electrocatalysis of reduced glutathione on CNFs-PDDA/PB nanocomposite film modified ITO electrode for biosensors

The electrochemical oxidation of reduced glutathione (GSH) catalyzed by electro generated Berlin green at carbon nanofibers-poly(diallyldimethylammonium chloride)/Prussian blue (CNFs-PDDA/PB) nanocomposite film modified ITO electrode has been studied. The CNFs-PDDA/PB nanocomposite film were fabricated by casting the composite CNFs enfolded PDDA on ITO electrode followed by electrochemical deposition of PB on the CNFs-PDDA matrix using cyclic voltammetry (CV). Electron microscopy (TEM, AFM), and Fourier transform infrared spectroscopy (FT-IR) studies were used to characterize the morphology and structure of the nanocomposite. The fabricated CNFs-PDDA/PB/ITO nanocomposite film electrode shows significant improvement of redox activity of PB due to the excellent electron transfer ability of CNFs. It was also found to possess prominent electrocatalytic activity toward the oxidation of glutathione with high sensitivity as high as 2.07 μA dm(3) mol(-1) cm(-2). A nontoxic, stable and convenient method for the detection of GSH in the concentration range of 6.0×10(-6) to 1.74×10(-5) M has been developed and it showed improved sensor performance compared to the unmodified PB electrode. The high sensitivity, wider linear range, good reproducibility, and the minimal surface fouling make this CNFs/PDDA/PB nanocomposite film a promising candidate for GSH sensors.     

All‐Polystyrene 3D‐Printed Electrochemical Device with Embedded Carbon Nanofiber‐Graphite‐Polystyrene Composite Conductor

Carbon nanofibres (CNFs) and graphite flake microparticles were added to thermoplastic polystyrene polymer with the aim of making new conductive blends suitable for 3D‐printing. Various polymer/carbon blends were evaluated for suitability as printable, electroactive material. An electrically conducting polystyrene composite was developed and used with commercially available polystyrene (HIPS) to manufacture electrodes suitable for electrochemical experiments. Electrodes were produced and evaluated for cyclic voltammetry of aqueous 1,1’‐ferrocenedimethanol and differential pulse voltammetry detection of aqueous Pb²⁺ via anodic stripping. A polystyrene/CNF/graphite (80/10/10 wt%) composite provides good conductivity and a stable electrochemical interface with well‐defined active geometric surface area. The printed electrodes form a stable interface to the polystyrene shell, give good signal to background voltammetric responses, and are reusable after polishing.     

Direct Determination of Paracetamol in Environmental Samples Using Screen‐printed Carbon/Carbon Nanofibers Sensor – Experimental and Theoretical Studies

The paper describes the first electrochemical method (differential pulse adsorptive stripping voltammetry, DPAdSV) using a screen‐printed sensor with a carbon/carbon nanofibers working electrode (SPCE/CNFs) for the direct determination of low (real) concentrations of paracetamol (PA) in environmental water samples. By applying this sensor together with DPAdSV, two linear PA concentration ranges from 2.0×10^?9 to 5.0×10^?8 mol L^?1 (r=0.9991) and 1.0×10^?7–2.0×10^?6 mol L^?1 ( r=0.9994) were obtained. For the accumulation time of 90 s, the limit of detection was 5.4×10^?10 mol L^?1. Moreover, the SPCE/CNFs sensor and the DPADSV procedure for PA determination are potentially applicable in field analysis. The process of PA adsorption at the SPCE/CNFs surface was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and theoretical studies. In the theoretical study of the interaction of CNF and PA, the first species was modelled by graphene‐like clusters containing up to 37 rings. It was found that the preferable orientation of PA is parallel to the carbon surface with the binding energy of about ?68 kJ/mol calculated by symmetry‐adapted perturbation theory (SAPT). Both the selectivity and the accuracy of the developed sensor for real sample analysis were also investigated using Polish river and sea samples.     

Supercritical CO2-driven, periodic patterning on one-dimensionals carbon nanomaterials

One-dimensional carbon nano-materials, in particular carbon nanotubes (CNTs) and carbon nanofibers (CNFs), are of scientific and technological interest due to their satisfactory properties and ability to serve as templates for directed assembly. In this work, linear high density polyethylene (PE) was periodically decorated on CNTs and CNFs using a supercritical carbon dioxide (scCO₂)antisolvent-induced polymer epitaxy (SAIPE) method, leading to nano-hybrid shish-kebab (NHSK) structures. The formation mechanism of different morphologies of PE lamellae on CNTs and CNFs has been discussed. Palladium nanoparticles were synthesized and immobilized on the PE/CNF NHSK structure with the assistance of scCO₂. The obtained hierarchical nano-hybrid architecture may find applications in microfabrication and other related fields.     

Fast preparation of PtRu catalysts supported on carbon nanofibers by the microwave-polyol method and their application to fuel cells

PtRu alloy nanoparticles (24 +/- 1 wt %, Ru/Pt atomic ratios = 0.91-0.97) supported on carbon nanofibers (CNFs) were prepared within a few minutes by using a microwave-polyol method. Three types of CNFs with very different surface structures, such as platelet, herringbone, and tubular ones, were used as new carbon supports. The dependence of particles sizes and electrochemical properties on the structures of CNFs was examined. It was found that the methanol fuel cell activities of PtRu/CNF catalysts were in the order of platelet > tubular > herringbone. The methanol fuel cell activities of PtRu/CNFs measured at 60 degrees C were 1.7-3.0 times higher than that of a standard PtRu (29 wt %, Ru/Pt atomic ratio = 0.92) catalyst loaded on carbon black (Vulcan XC72R) support. The best electrocatalytic activity was obtained for the platelet CNF, which is characterized by its edge surface and high graphitization degree.     

Electrochemical performance of Li4Ti5O12/carbon nanofibers composite prepared by an in situ route for Li-ion batteries

A Li₄Ti₅O₁₂/carbon nanofibers (LTO/CNFs) composite has been synthesized by solid-state reaction with the in situ growth of CNFs using the chemical vapor deposition method in N₂/C₂H₂. The nanocomposite is characterized by X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, Raman spectrum, and nitrogen adsorption/desorption isotherms, and is investigated as an anode material for lithium-ion (Li-ion) batteries. The underlying mechanism for the improvement is analyzed by cyclic voltammetry and electrochemical impedance spectroscopy. The in situ synthesized composite shows better electrochemical performance than the bare LTO. The in situ formation of CNFs not only supply an efficient electronic conductive network but also reduce the particle size of LTO and increase in specific surface area, leading to increased electrical conductivity and rapider Li-ion diffusion in electrode/electrolyte interface and bulk electrode.     

Carbon nanofibers decorated with platinum nanoparticles: a novel three-dimensional platform for non-enzymatic sensing of hydrogen peroxide

We have developed a 3-dimensional (3-D) electrochemical sensor for highly sensitive detection of hydrogen peroxide (H₂O₂). Porous 3-D carbon nanofibers (CNFs), prepared by electrospinning, served as scaffold on a glassy carbon electrode. The 3-D CNFs were functionalized with platinum nanoparticles (Pt-NPs) by in-situ gas-phase decomposition of platinum salts at high temperature. The Pt-NPs act as an electrocatalyst for the decomposition of H₂O₂. TEM revealed that large amounts of Pt-NPs are deposited in the electrospun CNFs electrode even without using any stabilizer or reducing reagent. The sensor was investigated by cyclic voltammetry and amperometry and displays a good response to H₂O₂ with a linear range between 10 μM and 15 mM (R?=?0.9994), a low detection limit (3.4 μM at a signal-to-noise ratio of 3), and a response time of 3 s. The sensor shows excellent stability and selectivity.

Enhanced Conductivity and mechanical properties of polyimide based nanocomposite materials with carbon nanofibers via carbonization of electrospun polyimide fibers

Carbon nanofibers (CNF) have been obtained by the thermal treatment of the electrospun polyimide fibers in our present work. The carbon structure and surface morphology of the as-received CNFs were investigated using X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Investigations of the nanocomposite materials fabricated using these CNFs as conductive fillers and polyimide as matrix show that the presence of CNFs can improve both the mechanical and electrical properties of the material. The conductivity of the nanocomposite films increases with increases in the CNF content and a percolation threshold of about 6.3 vol % (0.0785 in weight fraction) is calculated according to percolation theory.     

不同碳源催化化学气相沉积制备自支撑C/Ni-Fiber复合电极材料的电容脱盐性能

以甲烷、乙烯、乙醇和正丁醇为碳源,通过催化化学气相沉积在具有三维开放网络结构的烧结8μm-Ni金属纤维上沉积碳的方法,制备了以金属Ni纤维网络为集流极、沉积碳为离子存储库的薄层大面积自支撑C/Ni-fiber复合电极材料.用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、热重分析（TGA）、X射线衍射（XRD）、N₂-吸脱附等温线和循环伏安与电化学阻抗谱对电极材料进行了表征,并考察了其作为电极的电容脱盐性能.乙烯、甲烷、正丁醇和乙醇为碳源的沉积碳形态分别为鱼骨状碳纳米管（CNTs）、石墨烯面取向与轴平行的CNTs、棒状和蠕虫状碳纳米纤维（CNFs）.C/Ni-fiber复合电极材料对NaCl的电吸附容量顺序为:乙烯>正丁醇>甲烷>乙醇,这与复合电极的电化学特性、孔结构和碳的纳米结构相关.在1.2 V的工作电压下,以乙烯为碳源制备的C/Ni-fiber复合电极材料对水溶液中NaCl(100 mg·L^-1)的电吸附容量达159μmol·g^-1.     

热处理对富氮碳纳米纤维结构及储锂性能的影响

以聚丙烯腈(PAN)为原料,经静电纺丝、稳定化和碳化,制备了碳纳米纤维(CNFs)。系统地研究了氮的种类及含量对锂离子电池(LIBs)中Li+的储存性能和负极容量的影响。碳化过程中纤维从无定形碳向石墨化碳结构转变,含氮官能团减少,结构的变化对Li+在CNFs电极中的存储位置有很大的影响。结果表明,Li+不仅可以存储在石墨化碳层之间,还可以存储在氮功能化引起的缺陷部位,后者主要是由于碳材料的氮掺杂而使LIBs的电化学性能改善。碳化温度为600℃时,可以产生足够高的氮含量,从而提高电极的容量。在电流密度为0.1 A·g^-1时,循环200次之后比容量高达560 mAh·g^-1,即使在1 A·g^-1的高电流密度下,循环1000次比电容量仍然保持在200 mAh·g^-1。     

The study of controlling pore size on electrospun carbon nanofibers for hydrogen adsorption

Polyacrylonitrile (PAN)-based carbon nanofibers (CNFs) were prepared by using electrospinning method and heat treatment to get the media for hydrogen adsorption storage. Potassium hydroxide and zinc chloride activations were conducted to increase specific surface area and pore volume of CNFs. To investigate the relation between pore structure and the capacity of hydrogen adsorption, textural properties of activated CNFs were studied with micropore size distribution, specific surface area, and total pore volume by using BET (Brunauer-Emmett-Teller) surface analyzer apparatus and the capacity of hydrogen adsorption was evaluated by PCT (pressure-composition-temperature) hydrogen adsorption analyzer apparatus with volumetric method. The surface morphology of activated CNFs was observed by SEM (scanning electron microscope) images to investigate the surface change through activation. Even though specific surface area and total pore volume were important factors for increasing the capacity of hydrogen adsorption, the pore volume which has pore width (0.6-0.7 nm) was a much more effective factor than specific surface area and pore volume in PAN-based electrospun activated CNFs.     

Disordered carbon nanofibers/LiCoPO<Subscript>4</Subscript> composites as cathode materials for lithium ion batteries

LiCoPO₄-coated disordered carbon nanofibers (CNFs/LiCoPO₄) were obtained by a sol–gel method, using triethyl phosphite or triethyl phosphate as the phosphorous source. The crystal structure of the products was analyzed by X-ray powder diffraction, while morphology was studied using scanning electron microscopy, transmission electron microscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. Optimal synthesis conditions for the CNFs/LiCoPO₄ in light of the best electrochemical performance are discussed. The best discharge capacity 105 mAh/g (or ca. 63% of the theoretical capacity) shows the material with 40% CNFs/LiCoPO₄ and addition coating by carbon black. This composition has a best purity of active materials and point coverage of CNFs. The X-ray photoelectron C1s spectra of the CNFs surface without and with sputter erosion show enhancement of C–O bonds at the fiber surface, which does not influence significantly electrochemical behavior of the composite materials.     

碳纳米纤维负载铁钴镍硼化物可控制备及其电催化析氢性能研究

通过乙醇催化燃烧法制备了碳纳米纤维（CNFs），采用化学沉积法在CNFs载体上负载铁钴镍硼化物（FeCoNiB），并以多种测试手段对其表征，研究了化学沉积工艺条件对FeCoNiB粒径、分散、成分及结构的影响，建立了碳纳米纤维负载的铁钴镍硼化物（FeCoNiB/CNFs）可控制备方法。采用电化学测试手段研究了FeCoNiB/CNFs在碱性环境下的氢气析出反应（HER）催化性能。结果表明，在100 mA/cm²的电流密度下，FeCoNiB/CNFs的过电位仅为366 mV，塔菲尔斜率低至41 mV/dec；在持续10 h的稳定性测试中电位衰减幅度很小，基本保持不变。这说明FeCoNiB/CNFs制备成本低，但其高稳定性可媲美贵金属的高催化活性HER催化剂；该研究可为非贵金属HER催化剂的研制及低成本电解水制氢技术的规模化应用提供参考。     

Electrochemical determination of L-Tryptophan, L-Tyrosine and L-Cysteine using electrospun carbon nanofibers modified electrode

A novel and simple method for the direct and quantitative determination of L-tryptophan (Trp), L-tyrosine (Tyr) and L-cysteine (Cys) was proposed in this work. Carbon nanofibers (CNFs), made by electrospinning technique, were used to modify carbon paste electrode (CPE) without any treatment to study the electrochemical behaviors of the three amino acids using cyclic voltammetry (CV) and constant potential amperometric method. The results demonstrated that the CNFs modified carbon paste electrode (CNF-CPE) exhibited high electrocatalytic activity and good analytical performance towards the oxidation of the three amino acids. The linear ranges of Trp, Tyr and Cys were 0.1-119, 0.2-107 and 0.15-64 μM with correlation coefficients of 0.9994, 0.9985 and 0.9996, respectively. All the detection limits of the analytes were 0.1 μM (S/N = 3). In addition, the CNF-CPE displayed good reproducibility, high sensitivity and good selectivity towards the determination of the amino acids, making it suitable for the determination of Trp, Tyr and Cys in clinical and medicine.