Constructing a hollow core-shell structure of RuO_(2) wrapped by hierarchical porous carbon shell with Ru NPs loading for supercapacitor

Hollow core-shell structure nanomaterials have been broadly used in energy storage, catalysis, reactor,and other fields due to their unique characteristics, including the synergy between different materials,a large specific surface area, small density, large charge carrying capacity and so on. However, their synthesis processes were mostly complicated, and few researches reported one-step encapsulation of different valence states of precious metals in carbon-based materials. Hence, a novel hollow core-shell nanostructure electrode material, RuO_(2)@Ru/HCs, with a lower mass of ruthenium to reduce costs was constructed by one-step hydrothermal method with hard template and co-assembled strategy, consisting of RuO_(2) core and ruthenium nanoparticles(Ru NPs) in carbon shell. The Ru NPs were uniformly assembled in the carbon layer, which not only improved the electronic conductivity but also provided more active centers to enhance the pseudocapacitance. The RuO_(2) core further enhanced the material’s energy storage capacity. Excellent capacitance storage(318.5 F·g^(-1)at 0.5 A·g^(-1)), rate performance(64.4%) from 0.5 A·g^(-1)to 20 A·g^(-1), and cycling stability(92.3% retention after 5000 cycles) were obtained by adjusting Ru loading to 0.92%(mass). It could be attributed to the wider pore size distribution in the micropores which increased the transfer of electrons and protons. The symmetrical supercapacitor device based on RuO_(2)@Ru/HCs could successfully light up the LED lamp. Therefore, our work verified that interfacial modification of RuO_(2) and carbon could bring attractive insights into energy density for nextgeneration supercapacitors.

Removal of Methyl Violet in Aqueous Solution on Activated Carbon Based on Saba senegalensis Shell Residues

Adsorption on activated carbon is one of the most widely used methods for the removal of dyes. The objective of this study is to valorize the shells of Saba senegalensis from local product in Senegal in the form of activated carbon and to test its effectiveness for the removal of methyl violet. The study was carried out in batch mode for a maximum duration of one hour with 100 mL of solution treated at 600 rpm. The results reveal that the granulometry 500 μm gives the best yield with an adsorption rate of 95%, a mass of adsorbent of 0.2 g gives an adsorption capacity of 20 mg/g, the contact time of one hour with a capacity of 5 mg/g. The study also showed that the adsorption process of methyl violet is described by the pseudo-second order kinetic model with correlation coefficient of 0.99. Two adsorption isotherms were studied, and the results revealed that the Freundlich model better describes the adsorption of methyl violet on Saba senegalensis shell residue-based activated carbon (SSSRAC). The results indicate that SSSRAC could be used as a low-cost alternative for the removal of textile dyes such as methyl violet.

Chemical Analysis of Activated Carbon from Bull and Cow Horns Pyrolysis to Be Used as Antidotes

The purpose of this study is to compare the results of chemical analysis of two types of activated from the pyrolysis of bull horn and that of cow. Six samples were used to measure pH, carbon, calcium and to determine adsorbent power. The pH was measured at a temperature of 20˚C using an “ANION 7010 ionomer” pH meter, the carbon (C) content was analyzed using a “EURO EA 3000” analyzer. and the electronic balance: “Sartorius CP-2P”, calcium (Ca) was analyzed using a DFS-8 spectrograph. For the adsorbency test, the 0.15% methylene blue R solution was used. At the end of this study, we found that the activated carbon from the bull horn demonstrated a carbon content that is higher than that of the cow horn (20.79% against 15.63%), activated carbon of cow horn is richer in calcium than that of bull horn (16.27% against 3.69%) and then the pH. The cow horn is higher than that of the bull horn (7.43 versus 6.5). For the adsorbent power, the sample (75% bull horn and 25% cow horn) was recorded with the greatest adsorbent power. Thus, from this study, it can be recommended as an activated carbon antidote to be used for poisonings treatment.

Yolk-shell Si/C composites with multiple Si nanoparticles encapsulated into double carbon shells as lithium-ion battery anodes

The conceptual design of yolk-shell structured Si/C composites is considered to be an effective way to improve the recyclability and conductivity of Si-based anode materials. Herein, a new type of yolk-shell structured Si/C composite (denoted as TSC-PDA-B) has been intelligently designed by rational engineering and precise control. In the novel structure, the multiple Si nanoparticles with small size are successfully encapsulated into the porous carbon shells with double layers benefiting from the strong etching effect of HF. The TSC-PDA-B product prepared is evaluated as anode materials for lithium-ion batteries (LIBs). The TSC-PDA-B product exhibits an excellent lithium storage performance with a high initial capacity of 2108 mAh g^-1 at a current density of 100 mA g^-1 and superior cycling performance of 1113 mAh g^-1 over 200 cycles. The enhancement of lithium storage performance may be attributed to the construction of hybrid structure including small Si nanoparticles, high surface area, and double carbon shells, which can not only increase electrical conductiv让y and intimate electrical contact with Si nanoparticles, but also provide built-in buffer voids for Si nanoparticles to expand freely without damaging the carbon layer. The present findings can provide some scientific insights into the design and the application of advanced Si-based anode materials in energy storage fields.

Characterization of Metal Oxide-modified Walnut-shell Activated Carbon and Its Application for Phosphine Adsorption: Equilibrium, Regeneration, and Mechanism Studies

We prepared a kind of metal oxide-modified walnut-shell activated carbon(MWAC) by KOH chemical activation method and used for PH_3 adsorption removal. Meanwhile, the PH_3 adsorption equilibrium was investigated experimentally and fitted by the Toth equation, and the isosteric heat of PH_3 adsorption was calculated by the Clausius-Clapeyron Equation. The exhausted MWAC was regenerated by water washing and air drying. Moreover, the properties of five different samples were characterized by N_2 adsorption isotherm, SEM/EDS, XPS, and FTIR. The results showed that the maximum PH_3 equilibrium adsorption capacity was 595.56 mg/g. The MWAC had an energetically heterogeneous surface due to values of isosteric heat of adsorption ranging from 43 to 90 kJ/mol. The regeneration method provided an effective way for both adsorption species recycling and exhausted carbon regeneration. The high removal efficiency and big equilibrium adsorption capacity for PH_3 adsorption on the MWAC were related to its large surface area and high oxidation activity in PH_3 adsorption-oxidation to H_3 PO_4 and P_2 O_5. Furthermore, a possible PH_3 adsorption mechanism was proposed.

High performance columnar-like Fe2O3@carbon composite anode via yolk@shell structural design

Conversion-type reaction anode materials with high specific capacity are attractive candidates to improve lithium ion batteries(LIBs), yet the rapid capacity fading and poor rate capability caused by drastic volume change and low electronic conductivity greatly hinder their practical applications. To circumvent these issues, the successful design of yolk@shell Fe2 O3@C hybrid composed of a columnar-like Fe2O3 core within a hollow cavity completely surrounded by a thin, self-supported carbon(C) shell is presented as an anode for high-performance LIBs. This yolk@shell structure allows each Fe2O3 core to swell upon lithiation without deforming the carbon shell. This preserves the structural and electrical integrity against pulverization, as revealed by in situ transmission electron microscopy(TEM) measurement. Benefiting from these structural advantages, the resulting electrode exhibits a high reversible capacity(1013 m Ah g-1 after80 cycles at 0.2 A g-1), outstanding rate capability(710 m Ah g-1 at 8 A g-1) and superior cycling stability(800 m Ah g-1 after 300 cycles at 4 A g-1). A Li-ion full cell using prelithiated yolk@shell Fe2 O3@C hybrid as the anode and commercial Li CoO2(LCO) as the cathode demonstrates impressive cycling stability with a capacity retention of 84.5% after 100 cycles at 1 C rate, holding great promise for future practical applications.

Adsorption of Tartrazine onto Activated Carbon Based Cola Nuts Shells: Equilibrium, Kinetics, and Thermodynamics Studies

The uptake of tartrazine from its aqueous solution by powdered activated carbon prepared from cola nut shells chemically activated with potassium hydroxide (ACK) and phosphoric acid (ACP) has been investigated using kinetics models. Batch isotherm data were analysed with the pseudo-first order, pseudo-second order model as well as the intraparticle diffusion model. For structural elucidation, the materials were characterized using FTIR, XRD and SEM. These analyses revealed that the activated carbons (ACK and ACP) were predominantly mesoporous with several oxygen-containing functional groups dispersed on their surface. The reaction was systematically investigated under various experimental conditions such as contact time, adsorbent dose and pH. For the two adsorbents, the quantity adsorbed of 19.256 mg/g and 18.196 mg/g respectively for ACP and ACK at respective contact times of 5 and 10 min were obtained. The adsorption data were tested with the Langmuir, Freundlich models. Langmuir model was found to best describe the adsorption of tartrate ions with maximum monolayer adsorption capacities of 24.57 and 21.59 mg/g for ACP and ACK, respectively. Results analysis indicated clearly that the pseudo-second order kinetic rate model best fitted the experimental data and therefore was the adsorption controlling mechanism for both adsorbents. Thermodynamic studies revealed that the adsorption process was spontaneous and exothermic for ACP with increased randomness at the solid solution interface, then exothermic but non-spontaneous for ACK. The results show that these activated carbons could be an alternative for more costly adsorbents for the purpose of tartrate ions elimination.

Core-shell meso/microporous carbon host for sulfur loading toward applications in lithium-sulfur batteries

Lithium-sulfur（Li-S） batteries belong to one of the promising technologies for high-energy-density rechargeable batteries.However,sulfur cathodes suffer from inherent problems of its poor electronic conductivity and the shuttling of highly dissoluble lithium polysulfides generated during the cycles.Loading sulfur into porous carbons has been proved to be an effective approach to alleviate these issues.Mesoporous and microporous carbons have been widely used for sulfur accommodation,but mesoporous carbons have poor sulfur confinement,whereas microporous carbons are impeded by low sulfur loading rates.Here,a core-shell carbon,combining both the merits of mesoporous carbon with large pore volume and microporous carbon with effective sulfur confinement,was prepared by coating the mesoporous CMK-3 with a microporous carbon（MPC） shell and served as the carbon host（CMK-3 @MPC） to accommodate sulfur.After sulfur infusion,the as-obtained S/（CMK-3@MPC） cathode delivered a high initial capacity of up to 1422 mAh·g-1 and sustained 654 mAh·g-1 reversible specific capacity after 36 cycles at 0.1 C.The good performance is ascribed to the unique core-shell structure of the CMK-3@MPC matrix,in which sulfur can be effectively confined within the meso/microporous carbon host,thus achieving simultaneously high electrochemical utilization.

Preparation and SO2 Adsorption Behavior of Coconut Shell-Based Activated Carbon via Microwave-Assisted Oxidant Activation

A series of oxidants supported on coconut shell-based activated carbon(CAC) through microwave irradiation were prepared and characterized using scanning electron microscopy(SEM), N_2 adsorption/desorption analysis, and X-ray photoelectron spectroscopy(XPS). The SO_2 adsorption capacities and rates were evaluated by adsorption tests performed in a fixed bed reactor with a simulated flue gas, and the adsorption isotherm models were validated against the experimental results. The findings revealed that the SO_2 adsorption capacity decreased in the following order: MW-K_2Cr_2O_7-CAC > MWKMnO_4-CAC > MW-H_2O_2-CAC > MW-CAC. The SO_2 adsorption capacities and adsorption rates of the samples increased with an increasing oxidizability of the oxidants owing to the increment of mean pore size and oxygen-containing functional groups. In addition, a high initial SO_2 concentration and a low bed temperature could positively affect the SO2 adsorption. Finally, the Langmuir model validated that SO_2 was mainly adsorbed through chemical adsorption on the sample surfaces.

Optimization Conditions of the Preparation of Activated Carbon Based Egusi (<i>Cucumeropsis mannii</i>Naudin) Seed Shells for Nitrate Ions Removal from Wastewater

Egusi seed shells (ESS) were used as precursor for the preparation of two activated carbons (ACs) following H3PO4 and ZnCl2 activation. The effect of factors controlling the preparation of ACs such as chemical activating agent concentration (2 - 10 M), activation temperature (400°C - 700°C) and residence time (30 - 120 min) were optimized using the Box-Behnken Design (BBD). The optimized activated carbons based H3PO4 (ACP) and ZnCl2 (ACZ) were characterized by N2 adsorption, elemental analysis, atomic force microscopy (AFM), Boehm titration and Fourier transformed infrared (FTIR) techniques. The specific surface area was found to be 1053.91 and 1009.89 m2·g-1 for ACP and ACZ respectively. The adsorbents had similar surface functionalities and were both microporous. The effect of various parameters such as initial pH, concentration, and contact time on the adsorption of nitrate ions on ACP and ACZ in aqueous solution was studied. ACZ demonstrated better adsorption capacity (8.26 mg·g-1) compared to ACP (5.65 mg·g-1) at the same equilibrium time of 20 min. The adsorption process was governed by a “physical interactions” phenomenon for both adsorbents.

Characterization and Methanol Adsorption of Walnutshell Activated Carbon Prepared by KOH Activation

Walnut-shellactivated carbons（WSACs）were prepared by the KOH chemicalactivation.The effects of carbonization temperature,activation temperature,and ratio of KOH to chars on the pore development of WSACs were investigated.Fourier transform infrared spectroscopy（FTIR）,X-ray powder diffraction（XRD）,and scanning electron microscopy（SEM）were employed to characterize the microstructure and morphology of WSACs.Methanoladsorption performance onto the optimalWSAC and the coal-based AC were also investigated.The results show that the optimalpreparation conditions are a carbonization temperature of 700 ℃,an activation temperature of 700 ℃,and a mass ratio of 3.The BET surface area,the micropore volume,and the micropore volume percentage of the optimalWASC are 1636 m^2/g,0.641 cm^3/g and 81.97%,respectively.There are a lot of micropores and a certain amount of meso-and macropores.The characteristics of the amorphous state are identified.The results show that the optimalWSAC is favorable for methanoladsorption.The equilibrium adsorption capacity of the optimalWSAC is 248.02mg/g.It is shown that the equilibrium adsorption capacity of the optimalWSAC is almost equivalent to that of the common activated carbon.Therefore the optimalWSAC could be a potentialadsorbent for the solar energy adsorption refrigeration cycle.

Electrocatalysts based on metal@carbon core@shell nanocomposites:An overview

Developing low-cost, high-performance catalysts is of fundamental significance for electrochemical energy conversion and storage. In recent years, metal@carbon core@shell nanocomposites have emerged as a unique class of functional nanomaterials that show apparent electrocatalytic activity towards a range of reactions, such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and CO2 reduction reaction, that are important in water splitting, fuel cells and metal-air batteries. The activity is primarily attributed to interfacial charge transfer from the metal core to the carbon shell that manipulate the electronic interactions between the catalyst surface and reaction intermediates, and varies with the structures and morphologies of the metal core(elemental composition, core size, etc.) and carbon shell(doping,layer thickness, etc.). Further manipulation can be achieved by the incorporation of a third structural component. A perspective is also included highlighting the current gap between theoretical modeling and experimental results, and technical challenges for future research.

Dissolution-regrowth synthesis of SiO_2 nanoplates and embedment into two carbon shells for enhanced lithium-ion storage

In this work, SiO2 nanoplates with opened macroporous structure on carbon layer （C-mSiO2） have been obtained by dissolving and subsequent ingrowing the outer solid SiO2 layer of the aerosol-based C-SiO2 double-shell hollow spheres. Subsequently, triple-shell C-mSiO2-C hollow spheres were successfully prepared after coating the C- mSiO2 templates by the carbon layer from the carbonization of sucrose. When being applied as the anode material fur lithium-ion batteries, the C-mSiO2-C triple-shell hollow spheres deliver a high capacity of 501 mA. h.g- 1 after 100 cycles at 500 mA.g-1 （based on the total mass of silica and the two carbon shells）, which is higher than those of C-mSiO2 （391 mA.h.g 1） spheres with an outer porous SiO2 layer, C-SiO2-C （370 mA-h.g-1） hollow spheres with a middle solid Si02 layer, and C-SiO2 （319.8 mA·h-g-1） spheres with an outer solid SiO2 layer. In addition, the battery still delivers a high capacity of 403 mA· h· g- 1 at a current density of 1000 mA· g- 1 after 400 cycles. The good electrochemical performance can be attributed to the high surface area （246.7 m2·g- 1 ） and pore volume （0.441 cm3· g-1） of the anode materials, as well as the unique structure of the outer and inner carbon layer which not only enhances electrical conductivity, structural stability, but buffers volume change of the intermediate SiO2 layer during repeated charge-discharge processes. Furthermore, the SiO2 nanoplates with opened macroporous structure facilitate the electrolyte transport and electrochemical reaction.

Semisolid forging electronic packaging shell with silicon carbon-reinforced copper composites

To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed： temperature 1,025 ℃and holding time 5 min.

An Efficient Activated Carbon for the Wastewater Treatment, Prepared from Peanut Shell

My group is actively involved in the research “Preparation of activated carbon from peanut shell, characterization and its use as adsorbent and as a support for catalyst. The paper published in the MRC entitle “An Efficient Activated Carbon for the Wastewater Treatment, Prepared from Peanut Shell” Modern Research in Catalysis, 2013, 2, 148-156, was submitted in the earlier stage of research, at present stage I am fully convinced that the kinetic section of the paper is totally incorrect. Therefore I appeal that remove the paper from the Journal site to avoid the citation of incorrect literature.

Short Review on the Use of Oil Palm Shell in Concrete and Activated Carbon

Oil palm is known as Elaeis guineensis, found in Africa, South East Asia and China. Oil palm shell is used to prepare activated carbon because of high carbon content, high surface area, highly developed porosity and low price. During the physical activation, carbonization occurs in order to create porosity in the raw material. Literature review indicated that carbon material was impregnated with chemical agents such as phosphoric acid, potassium hydroxide, sulphuric acid, sodium hydroxide and zinc chloride in chemical activation process. Experimental results showed that the obtained activated carbon was used in hydrogen storage purpose, supercapacitor, gases and liquid phase adsorption process. On the other hand, oil palm shell was used in manufacturing lightweight concrete because of lighter and will not produce toxic substance. The bulk density and compressive strength of oil palm shell-based concrete were 500 - 600 kg/m3 and more than 25 MPa, respectively.

Hard carbons derived from pine nut shells as anode materials for Na-ion batteries

Hard carbons as promising anode materials for Na-ion batteries(NIBs) have captured extensive attention because of their low operation voltage, easy synthesis process, and competitive specific capacity. However, there are still several disadvantages, such as high cost and low initial coulombic efficiency, which limit their large-scale commercial applications.Herein, pine nut shells(PNSs), a low-cost biomass waste, are used as precursors to prepare hard carbon materials. Via a series of washing and heat treatment procedures, a pine nut shell hard carbon(PNSHC)-1400 sample has been obtained and delivers a reversible capacity of around 300 mAh/g, a high initial coulombic efficiency of 84%, and good cycling performance. These excellent Na storage properties indicate that PNSHC is one of the most promising candidates of hard carbon anodes for NIBs.

Coating Multi-walled Carbon Nanotubes with Uniform Silica Shells:Independent of Surface Chemistry

A facile and general method was described to coat six types of multi-walled carbon nanotubes, functionalized by either noncovalent or covalent way, with smooth silica shells. 3-Aminopropyltriethoxysilane（APTES） and pH value play important roles in the coating process and the thickness of silica shell could be controlled by the added amount of silicon alkoxides. After the removal of multi-walled carbon nanotubes by calcination, the silica nanotubes were successfully prepared.