New Forms of Carbon

A number of novel carbon materials whose unique properties fit them for many uses have recently been developed. Pyrolytic graphites are excellent conductors of heat and electricity parallel to the surface, whereas they are semiconductors perpendicular to the surface. A similar anisotropy is found in graphite foils, which are impermeable, but also very flexible. Glasslike carbon, which is also impermeable, is, however, completely isotropic. Carbon foams and felts are extremely light and exhibit very good thermal insulation up to high temperatures. In addition to very high strength, carbon fibers have values of Young's modulus greater than that of any other fibers or wires. Carbon fiber/resin composites are therefore more rigid than any other known materials; their specific Young's modulus is five times that of steel.     

《碳纳米材料电化学》专辑序言 ——方兴未艾的电化学能量转换和存储先进材料和技术

可以预见,在相当一段时期内,能源和环境将是全球发展的两大主题. 其实,人类对能源的获取方式将对地球的生态环境和人类未来的生存状态和生活方式产生重要影响. 正因为如此,世界各国正在大力发展可再生能源和清洁能源. 电化学能源是将化学能高效转变为电能的一种能量转换方式,它历史悠久,但不断被改进和创新,尤其是近年来得到了较快的发展. 目前,电化学能源转换和存储器件主要包括一次电池（如锌锰电池等）、二次电池（如铅酸电池、镍氢电池、锂离子电池等）、燃料电池、金属-空气电池以及超级电容器等. 电化学能源和其它可再生能源相互补充、交叉利用将是未来清洁能源的主要发展方向.     

Functionalized Carbon Black Nanospheres Hybrid with MoS2 Nanoclusters for the Effective Electrocatalytic Reduction of Chloramphenicol

Synthesis of nanomaterials using cheap and highly efficient material is an important aspect of nanotechnology. In this present work, we have used the carbon black (CB) as a highly conductive and inexpensive carbonaceous material for the fabrication of the electrochemical sensor. However, the poor dispersion in water obstructs the usage of CB in electrochemical sensor and biosensor applications. Hence, the CB was functionalized by simple reflux method and the functionalized CB (f‐CB) nanospheres hybrids with hydrothermally synthesized MoS₂ nanoclusters by simple ultrasonication process. In addition, the various suitable spectrometric techniques used to probe the surface morphology and chemical modification of the prepared materials. The prepared MoS₂ and f‐CB nanohybrids (f‐CB/MoS₂) applied for the electrocatalytic reduction of toxic chloramphenicol (CAP). Fascinatingly, the f‐CB/MoS₂ modified electrode showed a competitive electrocatalytic performance comparing with other modified electrodes. At the optimized condition, the sensor exhibited the LOD about 0.002 μM, wider linear range 0.015 to 1370 μM with the sensitivity of 3400 μA μM⁻¹ cm⁻² for the determination of CAP. Moreover, the practical viability of the sensor was exploited in milk powder and honey samples.     

纳米碳管作为氧扩散电极催化层第二相碳载体的电极特性

A novel gas diffusion electrode using binary carbon supports (carbon nanotubes and active carbon) as the catalyst layer was prepared. The electrochemical properties for oxygen reduction reaction (ORR) in alkaline electrolyte were investigated by polarization curves and electrochemical impedance spectroscopy. The results show that the binary-support electrode exhibits higher electrocatalytic activity than the single-support electrode, and the best performance is obtained when the mass ratio of carbon nanotubes and activated carbon is 50 ∶50. The results from their electrode kinetic parameters indicate that the introduction of carbon nanotubes as a secondary support provides high accessible surface area, good electronic conductivity and fast ORR kinetics. The electrocatalytic activity of binary-support electrodes is obviously improved by the deposition of Pt nanoparticles on carbon nanotubes, even at very low Pt loading (45.7 μg/cm2). In addition, the EIS analysis results show that the process of ORR may be controlled by diffusion of oxygen in the thin film for binary-support electrodes with or without Pt catalyst.     

Diffusion Mechanism of Carbon Dioxide in Zeolite 4A and CaX Pellets

The adsorption kinetics and equilibria of CO₂ in commercial zeolite 4A and CaX pellets were theoretically and experimentally studied by a gravimetric method in the range of 273–313 K and 0.0–0.8 atm. The diffusion mechanism of an adsorbate into a pellet is composed of micropore and macropore diffusion due to the bidisperse structure of the pellet. When one diffusion mechanism played a more important role than the other in determining the overall diffusion rate, the diffusion rate was estimated by the nonisothermal monodisperse diffusion model (NMDM). However, when the combined effects of both mechanisms controlled the overall adsorption kinetics, the experimental uptake was analyzed by the nonisothermal bidisperse diffusion model (NBDM). The CO₂ diffusion in zeolite 4A pellets was controlled by micropore diffusion within the experimental pressure and temperature ranges. However, both macropore and micropore diffusion contributed to CO₂ diffusion in the zeolite CaX pellet. The overall CO₂ diffusion rate in zeolite CaX became faster as pressure increased mainly due to its highly favorable isotherm in the zeolite CaX. The micropore diffusion time constant of CO₂ in the zeolite CaX pellet was approximately one hundred times greater than that in the zeolite 4A pellet. In addition, the activation energy of micropore diffusion of CO₂ diffusion in the zeolite CaX pellet was smaller than that in the zeolite 4A pellet. In this study, the dimensionless parameter, , indicating the relative importance of macropore and micropore diffusion, was modified to consider non-zero coverage as an initial condition for each step in the gravimetric method. When is greater than 100, the overall adsorption rate is controlled by macropore diffusion. However, in cases where is less than 0.1, micropore diffusion is the dominant mechanism in the overall adsorption rate. In the case of a system with between these values, both macropore and micropore diffusion contributed to the overall diffusion rate.     

Quantification methods of Black Carbon: comparison of Rock-Eval analysis with traditional methods

Black Carbon (BC) quantification methods are reviewed, including new Rock-Eval 6 data on BC reference materials. BC has been reported to have major impacts on climate, human health and environmental quality. Especially for risk assessment of persistent organic pollutants (POPs) it is important to account for risk reduction caused by BC, as suggested for POP safety assessment in the framework of the new European Community Regulation on Registration, Evaluation, Authorization and Restriction of Chemicals (REACH). Four major classes of BC quantification methods are reviewed including application to BC reference materials. Methods include chemical oxidation, thermal oxidation, molecular marker, optical methods and Rock-Eval analyses. Residual carbon from Rock-Eval 6 analysis correlated well with BC data from 'gentle' methods like optical and molecular marker methods, which capture a major part of the BC continuum including labile fractions (e.g. char). In contrast, the temperature at which 50% of the organic matter was oxidized (T(50%)) in an oxidation-only Rock-Eval analysis, correlated well with data from chemothermal oxidation (CTO), which captures only refractory BC fractions (e.g. soot). Rock-Eval analysis can further be used for BC characterization through deconvolution of the dominant peaks of the thermogram and appears to be a powerful tool in BC analysis.     

A Film-Pore-Surface Diffusion Model for the Adsorption of Acid Dyes on Activated Carbon

The sorption of acid dyes from aqueous effluents onto activated carbon has been studied. The effects of initial dye concentration and activated carbon mass on the rate of Acid Blue 80, Acid Red 114 and Acid Yellow 117 removal have been investigated. A three-resistance mass transport model based on film, pore and surface diffusion control has been applied to model the concentration decay curves. The model incorporates an effective diffusion coefficient D _eff, which is dependant on the equilibrium solid phase concentration or fractional surface coverage. The results of the film-pore-surface diffusion model are compared with the data obtained from the basic film-pore diffusion model. It has been found that the film-pore-surface diffusion model provides a major improvement over the data correlated by the film-pore diffusion model. Also, the relationship between surface diffusion and fractional surface coverage has been investigated for the adsorption of acid dyes on activated carbon.     

A Film-Pore-Surface Diffusion Model for the Adsorption of Acid Dyes on Activated Carbon

The sorption of acid dyes from aqueous effluents onto activated carbon has been studied. The effects of initial dye concentration and activated carbon mass on the rate of Acid Blue 80, Acid Red 114 and Acid Yellow 117 removal have been investigated. A three-resistance mass transport model based on film, pore and surface diffusion control has been applied to model the concentration decay curves. The model incorporates an effective diffusion coefficient D _eff, which is dependant on the equilibrium solid phase concentration or fractional surface coverage. The results of the film-pore-surface diffusion model are compared with the data obtained from the basic film-pore diffusion model. It has been found that the film-pore-surface diffusion model provides a major improvement over the data correlated by the film-pore diffusion model. Also, the relationship between surface diffusion and fractional surface coverage has been investigated for the adsorption of acid dyes on activated carbon.     

Diffusion Converter of a Hydrodynamic Flow Velocity to Electric Current: A Theory

Non-steady-state distributions of the velocity and concentration of electroactive ions in the vicinity of a gauze electrode system of an electrochemical diffusion converter are computed using a numerical method of finite volumes. Dependence of the diffusion frequency and coefficient of nonlinear distortions of the signal current on geometrical parameters of the electrode system are investigated. Regularities of the behavior of the frequency response, nonlinear distortion factor, and dynamic range of the converter are established.     

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.     

Multi‐Wall Carbon Nanotube Paste Electrode for Adsorptive Stripping Determination of Quercetin: A Comparison with Graphite Paste Electrode via Voltammetry and Chronopotentiometry

Adsorptive‐stripping voltammetry and chronopotentiometry were used to study the adsorption and oxidation of quercetin at both graphite‐nujol paste electrode (GPE) and carbon nanotubes‐nujol paste electrode (CNTPE) for the potential application of carbon nanotube to flavonoids determination. As compared with GPE, CNTPE showed very great power to adsorb quercetin and resulted in a considerable signals enhancement. The adsorption isotherm of quercetin on CNTPE was of Langmuir type, and the stripping of quercetin adsorbed on CNTs showed a quasi‐reversible oxidation reaction involving two‐electron and two‐proton. The high adsorbtive activity of CNTPE was contributed to the high specific surface area and the special surface characteristics of carbon nanotubes. The peak current response of differential pulse voltammetry depended linearly on quercetin concentration. A linear equation I_p(μA)=0.987c(μmol L^?1)+0.023 with a correlation coefficient of 0.994 was obtained over the concentration range 0.1–1.0 μmol L^?1.     

分子动力学模拟苯和萘在超临界二氧化碳中的无限稀释扩散系数

采用球型模型和点位-点位模型对超临界二氧化碳的自扩散系数及苯或萘在超临界二氧化碳中的无限稀释扩散系数进行了分子动力学模拟。结果表明,球型模型及点位-点位模型均可较准确地预测二氧化碳的自扩散系数,球型模型因形式简单,准确度相对较差;点位-点位模型准确度虽高,但需较长的模拟机时。两种位能模型所获得的准确度相当,但点位-点位模型可以更精细地反映体系的微观结构。     

碳纳米管可控制备的过去、现在和未来

碳纳米管独特的几何和电子结构使其具有丰富优异的性质,因此在过去的二十余年备受研究者的关注。然而,碳纳米管结构的多样性成为其从实验室走到产业化的最大阻碍,结构决定性质,制备决定未来,完善的结构控制制备技术将成为碳纳米管基础研究和产业化应用中至关重要的一环。本文首先对碳纳米管的结构进行描述,然后综述了碳纳米管的结构可控制备方法和溶液纯化分离技术,提出未来理想的碳纳米管制备之路是将碳纳米管精细结构控制方法与宏量制备技术相结合,在降低碳纳米管生产成本的同时,提高其纯度,并建立碳纳米管产品的标准。最后,展望了碳纳米管的杀手锏级应用和该领域的机遇和挑战。     

Development of Bio-inspired Composite Materials for the Detection of Traces of Silver Present in Water: Use of Taguchi Methodology to Design Low-cost Carbon Paste Electrodes

Carbon Paste Electrodes (CPE) modified with Grapefruit-Peels (GP) functionalized with Urea (GPU) and, Melamine (GPM) were designed for the detection of Ag⁺ in water. Taguchi L₉ methodology was used to determine the optimal graphite-Active material ratio. The best electrochemical response was for CPE-GPU with an 80 : 20 ratio. The results obtained showed a linear detection range between 0.5 to 28 μg L⁻¹, with a detection limit of 0.73 μg L⁻¹ and a limit of quantification of 1.04 μg L⁻¹. Attributable to CPE-GPU characteristics: electroactive surface area 0.175 cm², roughness factor 3.87, resistance 0.09 Ω and, mostly −NH₂ groups on its surface. The composite material offers a viable option to be used for the determination of silver traces in situ in industrial processes.     

A Novel Electrochemical Glassy Carbon Electrode Modified with Carbon Black and Glyceline Deep Eutectic Solvent within a Crosslinked Chitosan Film for Simultaneous Determination of Acetaminophen and Diclofenac

Glyceline, reline, or ethaline deep eutectic solvents and carbon black nanoparticles within a crosslinked chitosan film are investigated as glassy carbon electrode modifiers for the first time. The selected 5 mg mL⁻¹ glyceline modified GCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. Simultaneous determination of acetaminophen and diclofenac by differential pulse adsorptive stripping voltammetry (DPAdSV) presented limits of detection of 2.6×10⁻⁸ and 5.2×10⁻⁸ mol L⁻¹ for acetaminophen and diclofenac, respectively, in pharmaceutical and biological samples. The obtained results were compared with those obtained by HPLC at a confidence level of 95 %.     

A Novel Carbon Nitride Nanosheets-based Electrochemical Sensor for Determination of Hydroxychloroquine in Pharmaceutical Formulation and Synthetic Urine Samples

This study introduces modified carbon paste electrodes with carbon nitride nanosheets (CNNS) and outlines their application for the determination of hydroxychloroquine sulfate (HCQ) in tablets and synthetic urine samples. CNNS were synthesized by hydrothermal route (200 °C, 10 h) using melamine and citric acid as their precursors. The carbon nitride nanosheets-based electrode (CNNS/E) presented a linear dynamic range for HCQ (LDR), ranging from 10.0 nmol l⁻¹ to 6.92 μmol l⁻¹, and detection (LOD) and quantification limits (LOQ) of 0.16 nmol l⁻¹ and 0.52 nmol l⁻¹, respectively. LOD and LOQ were calculated by the equations: LOD=3(S_d/b), and LOQ=10(S_d/b). The modified sensor presented excellent relative standard deviations for parameters such as repeatability (2.39 % and 1.87 %) and reproducibility (3.22 % and 2.32 %) in HCQ oxidation peaks (1 and 2). The CNNS/E has not shown significant variations in its anodic signal intensity in the presence of some organic and inorganic substances. It is worth bearing in mind that CNNS/E can be easily manufactured and the sensor has the lowest HCQ detection limits reported so far. The proposed sensor was successfully applied for HCQ determination in tablets and synthetic urine, showing good recovery values and an error of 0.60 % about comparative method in tablet samples, assuring the quality of the method.     

Voltammetric Determination of Nifedipine on Carbon Nanotubes‐Modified Glassy Carbon Electrode: A new Application to Dissolution Test Studies

We report the adsorptive voltammetric determination of nifedipine on multiwalled carbon nanotubes (MWCNT)‐modified glassy carbon electrode (GCE). Nifedipine was adsorbed on the MWCNT and then reduced using linear sweep and cyclic voltammetry (LSV and CV). Parameters such as pH and accumulation time were tested. The MWCNT‐modified GCE showed enhanced currents and good signal‐to‐noise characteristics in comparison with the bare GCE. Consecutive measurements with the modified electrode were highly repeatable and reproducible. The MWCNT/GCE was used for the determination of nifedipine and is recommended for quantitation in dissolution test studies. In this study we have tested normal and extended‐release pharmaceutical formulations of nifedipine using USP apparatus 2 and tracking the released drug in solution by the proposed voltammetric method. The main advantage of the voltammetric determination is the feasibility to detect the drug in‐situ avoiding tedious intermediate steps such as filtration, collection and replenishment of sample solutions. This work seeks to demonstrate the feasibility of applying voltammetric techniques in dissolution test studies.     

Surface Diffusion of Hydrocarbons in Activated Carbon: Comparison Between Constant Molar Flow, Differential Permeation and Differential Adsorption Bed Methods

This paper presents the comparison of surface diffusivities of hydrocarbons in activated carbon. The surface diffusivities are obtained from the analysis of kinetic data collected using three different kinetics methods- the constant molar flow, the differential adsorption bed and the differential permeation methods. In general the values of surface diffusivity obtained by these methods agree with each other, and it is found that the surface diffusivity increases very fast with loading. Such a fast increase can not be accounted for by a thermodynamic Darken factor, and the surface heterogeneity only partially accounts for the fast rise of surface diffusivity versus loading. Surface diffusivities of methane, ethane, propane, n-butane, n-hexane, benzene and ethanol on activated carbon are reported in this paper.