Highly conductive graphite/carbon fiber/cellulose composite papers

Papermaking techniques were used to produce graphite/carbon fiber/cellulose fiber composite papers with tunable electrical conductivity and good mechanical properties.     

Gold nanoparticles/graphene oxide composite for electrochemical sensing of hydroxylamine and hydrogen peroxide

It has been discovered that the complex formed by cetyltrimethyl ammonium bromide (CTAB) and graphene oxide (GO) is highly stable in aqueous solution and adhesive to the glassy carbon electrode (GCE) surface in our previous research. In this work, the film of CTAB/GO complex was directly formed on GCE and gold nanoparticles were facilely incorporated into the matrix of CTAB/GO complex at the same time. Scanning electron microscopic (SEM) investigation shows that gold nanoparticles were distributed uniformly on the sheets of graphene. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry were used to investigate the electrochemical behaviors of AuNP/CTAB/GO. The obtained AuNP/CTAB/GO presents excellent catalytic capabilities towards the oxidation of hydroxylamine (HA) and the reduction of H₂O₂. The oxidation current of HA and the reduction current of H₂O₂ are linear with their concentrations in the range of 10～1000 μM and 1.0～5000 μM, respectively. The detection limits for HA and H₂O₂ are 3.5 μM and 0.67 μM, respectively. The mechanism of the oxidation of HA on AuNP/CTAB/GO modified GCE was also studied.     

水处理用多孔悬浮陶粒表面磁/炭改性的应用研究

在多孔陶粒表面覆盖磁性Fe3O4/活性炭复合涂层进行改性,以增强其吸附性能,对各种工艺参数如浸渍比、炭化温度、活化温度、活化时间、磁性粉体添加量进行了研究,结果表明,活性炭原料中KOH/葡萄糖浸渍比为4、炭化温度400℃、活化温度850℃,活化时间1h、磁性粉体添加量为10%为最佳,改性后陶粒的亚甲基蓝吸附去除率(88.1%)是改性前的3.15倍,效果显著。     

Fabrication of multiwalled carbon nanotubes/polypyrrole/Prussian blue ternary composite nanofibers and their application for enzymeless hydrogen peroxide detection

In this article, Prussian blue (PB) covered multiwalled carbon nanotubes (MWCNTs)/polypyrrole (PPy) ternary composite nanofibers with good dispersibility in water and ethanol have been prepared by directly mixing ferric-(III) chloride and potassium ferricyanide in the presence of MWCNT/PPy coaxial nanofibers under ambient conditions. Transmission electron microscopy shows that the as-synthesized PB nanoparticles covered on the surface of MWCNT/PPy nanofibers. Fourier-transform infrared spectroscopy, UV–Visible spectroscopy, and X-ray diffraction patterns have been used to characterize the obtained MWCNT/PPy/PB ternary composite nanofibers. The MWCNT/PPy/PB ternary composite nanofibers exhibit good electrocatalytic response to detection of H₂O₂ and provide a new material to modify electrode for amperometric biosensors.     

三维石墨烯/氧化锌纳米结构复合材料的制备及其在双氧水检测中的应用

通过化学气相沉积法制备出孔洞为300~500μm骨架完好的三维石墨烯,并采用晶种诱导法在三维石墨烯表面原位生长直径为100nm左右、长度达2.80μm的ZnO纳米棒,从而制备出高度结晶的三维石墨烯/氧化锌纳米结构的复合材料。复合材料用XRD、SEM进行表征,并通过循环伏安曲线(CV曲线)及时间电流曲线(I-t曲线)电化学测试方法,测试三维石墨烯/氧化锌纳米结构复合材料对双氧水的检测情况。结果显示,采用新方法制备的三维石墨烯/氧化锌纳米结构复合材料作为电极对双氧水表现出优异的检测性能,检测限为1μmol/L,且线性检测范围为10~120μmol/L。     

Advances and issues in developing intercalation graphite cathodes for aqueous batteries

Aqueous rechargeable batteries offer a safe alternative for electrochemical energy storage, integrating cost-efficiency and energy density to meet the demand for stationary applications. Recent efforts have focused on the improvement of electrode materials in aqueous electrolytes, particularly the cycle life and energy reliability of batteries. The anion intercalation chemistry in graphite could be an alternative cathode candidate, often requiring an upper cut-off potential above 4.5 V vs. Li⁺/Li. Such a potential readily exceeds the electrochemical stability windows of water-based electrolytes. Herein, we provide a progress report and critical comment on the reversible intercalation chemistry in graphite compounds, i.e., anion and halogen intercalations, for the development of economical, high-energy aqueous rechargeable batteries. In addition, this review focuses on the charge carrier species, their charge storage mechanisms and battery configurations, aiming to provide solutions to solve the remaining key challenges for aqueous batteries.     

Fabrication of a novel hydrogen peroxide biosensor based on C@Au composite

A promising hydrogen peroxide (H2O2) biosensor was fabricated by the immobilization of hemoglobin (Hb) on C@Au composite surface. The composite with carbon spheres and gold shell (C@Au) was synthesized via the seed-growth assembly technique. The assembly of the gold shell on carbon sphere surfaces was characterized by scanning electron miscroscopy (SEM). Owing to the unique structure and large surface area of the gold shell, the composite offered an effective interface for the immobilization of hemoglobin to fabricate a H2O2 biosensor. The obtained biosensor showed a wide linear range from 5.0 microM to 135 microM with a detection limit of 1.67 microM at 3sigma, and the apparent Michaelis-Menten constant (Km(app)) of the immobilized Hb was calculated to be 88.6 microM. Moreover, the biosensor also exhibited good reproducibility and long-term stability. Therefore, this kind of composite can provide an ideal matrix for protein immobilization and biosensor fabrication.     

Interface property of carbon fibers/epoxy resin composite improved by hydrogen peroxide in supercritical water

Carbon fibers were treated by hydrogen peroxide in supercritical water and the surface morphologies of treated carbon fibers were observed by atomic force microscopy. It was found that surface roughness of the treated carbon fiber was improved obviously. Furthermore, X-ray photoelectron spectroscopy (XPS) was used to analyze surface functional groups of carbon fibers. It was found that functional groups containing oxygen were significantly increased compared with untreated carbon fibers. The maximal interlaminar shear strength (ILSS) of treated carbon fibers/epoxy resin composite was 110.5 MPa, which was higher than 63.5 MPa for untreated carbon fibers/epoxy resin composite. It also indicated that interface property of carbon fibers/epoxy resin composite was improved by hydrogen peroxide in supercritical water.     

In-situ formation of Ni-Al intermetallics-coated graphite/Al composite in a cold-sprayed coating and its high temperature tribological behaviors

In this study, cold spraying(CS) was used to deposit a mixture of nickel-coated graphite and 40 vol.% Al powder(Ni-Gr/Al) on a steel substrate aiming to effectively preserve a certain volume fraction of graphite in the deposited Ni-Gr/Al composite coating. The microstructure of the as-sprayed coating and the effect of post-spray heat-treatment(PSHT) temperatures on the in-situ formation of Ni-Al intermetallic phases in coating were studied. The tribological behaviors of the as-sprayed coating and the PSHTed coating under 450?C were tested at 25?C, while the as-sprayed coating was tested at 450?C for comparison.As a result, the Ni-Gr particles showed a homogenous distribution in the coating. The multilayer Ni-Al intermetallics-coated graphite/Al composite coating was achieved in situ after the PSHT of 450?C, where the graphite did decompose at 550?C leaving big pores in the coating. The coefficients of friction(COF)of the CSed coating and the PSHTed coating were measured at 450?C as well as 25?C, which showed a similar tendency, much higher than that of the CSed coating tested at 25?C. The lubrication phase(graphite) improved the formation of a graphite film during sliding friction and decreased the COF, while the hard Ni-Al intermetallic phases contributed to the increase of COF.     

Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor

A novel nonenzymatic sensor for H₂O₂ was developed based on an Ag@TiO₂ nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO₂ nanocomposite were examined by UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO₂ nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO₂ nanocomposite modified GCE (Ag@TiO₂/GCE) displayed excellent performance towards H₂O₂ sensing at ? 0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ~ 65.2328 ± 0.01 μAμM^? 1 cm^? 2, respectively. In addition, Ag@TiO₂/GCE exhibited good operational reproducibility and long term stability.     

SiO2/聚四氟乙烯复合薄膜的制备及力学性能

采用空气辅助干法共混、冷压烧结并车削成膜的方法制备了SiO₂填充量为35wt%、厚度为50 μm的聚四氟乙烯（PTFE）基复合薄膜。系统研究了SiO₂颗粒粒径对SiO₂/PTFE薄膜复合材料的孔洞缺陷和力学性能等的影响,并研究了SiO₂在PTFE中的分散情况及分子间相互作用对其性能变化的影响机制。结果表明,随SiO₂粒径的逐渐增大,其在PTFE中的分散趋于均匀,同时PTFE能更好地包覆粒子,因此SiO₂/PTFE薄膜孔洞缺陷逐渐减少,力学性能逐渐增强;当SiO₂的粒径D₅₀为12 μm时,其在PTFE中的分散均匀性最佳,SiO₂/PTFE复合薄膜孔洞缺陷最少,具有较好的力学性能,断裂伸长率达19.5%,拉伸强度达9.2 MPa。      

石墨/环氧树脂高填充复合材料的制备和性能研究

通过溶液共混法和“真空处理-预固化-破碎-模压-加热固化”的方式制备了石墨/环氧树脂高填充复合材料.使用光学显微镜对其形貌进行了分析,研究了石墨含量对复合材料导电性能和力学性能的影响规律,确定了一种制备石墨/环氧树脂高填充复合材料可行的方法.结果表明,所制备的复合材料中石墨含量达80％,体积电阻率为10-2Ω·cm.逾...     

Solid electrolyte/graphite composite particle for an all-solid-state lithium-ion battery

A great issue in the development of an all-solid-state lithium-ion battery (ASSLIB) is the fabrication of a composite electrode with good contact between active materials (AMs) and solid electrolytes (SEs). To overcome this challenge, it is important to develop a powder processing technology that produces composite particles of AMs and SEs. In this study, we investigated a dry impact blending process for producing graphite composite particles (typical anode AM) and sulfide SEs. First, by controlling the rotating speed of the rotor in the dry impact blending process, two types of composite particles, namely surface-coated (SC) composite particles with no graphite breakage and matrix-type (MT) composite particles with graphite breakage, were produced. The SC composite particles showed higher electrochemical performance than the MT composite particles due to less change in the graphite crystallinity. Second, the longer the processing times for the preparation of SC composite particles, the higher the SE coating on graphite, resulting in higher electrochemical performance. Third, we demonstrated that the SC composite particles exhibited higher electrochemical performance than those prepared using a conventional lab-scale mixing technique. We demonstrated the effectiveness of the dry impact blending process for the preparation of an anode composite electrode for ASSLIBs.     

埃洛石-玻纤/聚四氟乙烯复合材料的摩擦磨损热膨胀及力学性能

采用冷压成型烧结工艺制备出玻璃纤维（GF）和埃洛石（HNTs）填充的聚四氟乙烯（PTFE）复合材料。研究了填料类型及不同配比的填料对PTFE复合材料的界面、摩擦学性能、线膨胀系数及力学性能的影响。结果表明:适量填充HNTs可以提升GF/PTFE复合材料的摩擦磨损、热膨胀及力学性能。填充2.0%HNTs时的HNTs-GF/PTFE复合材料比GF/PTFE复合材料的磨损率降低32.7%,高温时HNTs-GF/PTFE复合材料的线膨胀系数（CTE）比纯PTFE降低近2个数量级,断裂伸长率、拉伸强度和弯曲强度分别提高40.0%、2.3%和7.1%。      

Preparation of nitrogen-doped three-dimensional hierarchical porous carbon/sulfur composite cathodes for high-performance aluminum-sulfur batteries

Abstract

Aluminum-ion batteries, as a feasible substitute for lithium-ion batteries, have the advantages of high safety, high capacity, low cost and environmental friendliness. However, the cathode material is one of the key factors restricting the performance and practical application of aluminum-ion batteries. Sulfur is becoming a promising cathode material for aluminum-ion batteries due to its considerable theoretical specific capacity. However, the poor conductivity of elemental sulfur seriously limits the development of aluminum-sulfur batteries. In this work, nitrogen doped three-dimensional multi-stage porous carbon materials (N-C/S) were prepared, which were compounded with sulfur to prepare carbon sulfur composite cathode materials. The microstructure, phase morphology, element composition and electrochemical performance were analyzed by various characterization methods. Then, N-C/S composite was used as a positive electrode to assemble a new type of aluminum-sulfur batteries, and its performance was evaluated. This novel high-performance N-C/S composite cathode holds great potential in future high-performance aluminum-sulfur batteries.     

Rate sensitivity of mode II interlaminar fracture toughness in graphite/epoxy and graphite/PEEK composite materials

This paper presents results from an experimental study of the effect of rate on the Mode II interlaminar fracture toughness, G_IIC, in graphite/PEEK (APC-2) and graphite/epoxy (AS4/3501-6) laminates. The end notched flexure test geometry was employed for Mode II experiments which were performed at room temperature over a range of crosshead speeds from 4·2 × 10⁻⁶ to 9¢2 × 10⁻² mc⁻¹. The APC-2 material exhibited ductile crack growth at low rates and brittle crack growth at high rates. The change in fracture mechanism resulted in a decrease in G_IIC from 1·0 to 0·40 kJ m⁻² at the upper range of test rates. The AS4/3501-6 material exhibited brittle crack growth at all rates. The G_IIC values also decreased at higher test rates from 0·46 to 0·06 kJ m⁻².     

Electrophoretic deposition of HA/MWNTs composite coating for biomaterial applications

A composite coating of hydroxyapatite (HA)/multi-walled carbon nanotubes (MWNTs) has been fabricated by electrophoretic deposition (EPD). The nano powders of HA and MWNTs were dispersed in ethanol with total concentration of 0.005 g/mL and MWNTs 20% and 30% contents (wt). And the pH value of suspension was adjusted in a range from 4 to 5. After stabilization the mixture was ultrasonically treated for 3 h to form a stable suspension. Prior to the electrophoretic deposition, the titanium substrate was hydrothermally treated at 140 in NaOH (10 mol/L) solution for 6 h. A titanium sheet and circinal net of stainless steel were used as a cathode and an anode respectively, and a constant deposition voltage of 30 V was applied for 50-60 s in the EPD process. The thickness of the coatings was controlled from 10 mum to 20 mum. The samples of composite coating were then sintered in a resistance tube furnace in flowing argon at 700 for 2 h. The structure of the as prepared coating was characterized by SEM and XRD, and the bonding force of the coating/substrate was measured by an interfacial shear strength test. It is shown that the bonding strengths between the coating and the titanium substrate is as high as 35 MPa. The cell culture experiments indicate that the prepared composite coating of HA/MWNTs possesses good biocompatibility.