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.

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.

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

In this work, SiO_2 nanoplates with opened macroporous structure on carbon layer(C-mSiO_2) have been obtained by dissolving and subsequent regrowing the outer solid SiO_2 layer of the aerosol-based C-SiO_2 double-shell hollow spheres. Subsequently, triple-shell C-mSiO_2-C hollow spheres were successfully prepared after coating the Cm SiO_2 templates by the carbon layer from the carbonization of sucrose. When being applied as the anode material for lithium-ion batteries, the C-mSiO_2-C triple-shell hollow spheres deliver a high capacity of 501 mA ·h·g^(-1) after100 cycles at 500 m A·g^(-1)(based on the total mass of silica and the two carbon shells), which is higher than those of C-mSiO-12(391 m A·h·g^(-1)) spheres with an outer porous SiO_2 layer, C-SiO_2-C(370 m A·h·g) hollow spheres with a middle solid SiO_2 layer, and C-SiO_2(319.8 m A·h·g^(-1)) spheres with an outer solid SiO_2 layer. In addition,the battery still delivers a high capacity of 403 m A·h·g^(-1) at a current density of 1000 m A·g^(-1) after 400 cycles.The good electrochemical performance can be attributed to the high surface area(246.7 m^2·g^(-1)) and pore volume(0.441 cm^3·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 SiO_2 layer during repeated charge–discharge processes. Furthermore, the SiO_2 nanoplates with opened macroporous structure facilitate the electrolyte transport and electrochemical reaction.

Fe-N co-doped coral-like hollow carbon shell toward boosting peroxymonosulfate activation for efficient degradation of tetracycline: Singlet oxygen-dominated non-radical pathway

Fe-N co-doped coral-like hollow carbon shell (Fe-N-CS) was synthesized via a simply impregnation-pyrolysis method.The Fe-N-CS showed an excellent ability for activating peroxymonosulfate (PMS),which could degrade about 93.74%tetracycline (20 mg/L) in 12 min.The Fe-N-CS/PMS system exhibited a good anti-interference capacity of various pH,inorganic anions,HA and different water qualities.More importantly,the Fe nanoparticles were anchored uniformly in the carbon layer,effectively limiting the metal leaching.The quenching tests and electron spin resonance (ESR) manifested that non-radical singlet oxygen (1O_(2))was the main reactive oxygen species (ROS) for TC degradation.The mechanism study showed that Fe nanoparticles,defect and graphite N played a key role in activating PMS to produce ROS.Moreover,three probable degradation pathways were proposed by using LC-MS measurements.Generally,this work had a new insight for the synthesis of heterogeneous Fe-N-C catalysts in the advanced oxidation process based on PMS.

Plasma-enabled synthesis of ordered PtFe alloy nanoparticles encapsulated with ultrathin N-doped carbon shells for efficient methanol electrooxidation

Methanol oxidation reaction(MOR),the key reaction for clean energy generation in fuel cells,is kinetically sluggish and short-lasting because of insufficient catalytic activity and stability of the common Pt-based electrocatalysts.Ordered Pt alloy structures which promise to surmount these issues,are challenging and impractical to fabricate using common high-temperature annealing.To address the urgent need for simple and rapid synthesis methods for such alloys,here we report the versatile plasma-assisted thermal annealing synthesis of a robust electrocatalyst with PtFe alloys supported on N-doped carbon nanotubes(denoted as PtFe@NCNT-P).Benefiting from the reactive plasma-specific effects,the PtFe@NCNT-P electrocatalyst features ultrafine PtFe alloy nanoparticles(mean size~2.88 nm,ordered degree~87.07%)and ultrathin N-doped carbon(NC)shells(0.3–0.7 nm),leading to the excellent catalytic activity and stability toward MOR.The catalyst shows the specific and mass activities of 3.99 mA/cm^(2)and 2,148.5 mA/mg,which are 7.82 and 7.41 times higher than those for commercial Pt/C(0.51 mA/cm^(2),290 mA/mg),and 2.18 and 2.59 times higher compared to the plasma-untreated PtFe@NCNT(1.83 mA/cm2,829.5 mA/mg),respectively.The PtFe@NCNT-P further exhibits extraordinary stability during the long-term chronoamperometry test and 1,000-cycle cyclic voltammetry scanning,much better compared to PtFe@NCNT samples even after the longer thermal annealing.These findings show great potential of the plasma-enabled synthesis of high-performance carbon-supported metallic electrocatalysts for the emerging clean energy technologies.

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.

Adsorption of rare earth ions using carbonized polydopamine nano carbon shells

Herein we reported the structure effects of carbon nano-shells prepared by the carbonization of polydopamine for the ad- sorption of rare earth elements （REEs） for the first time. Solid carbon spheres, 60 nm carbon shells and 500 nm carbon shells were prepared and evaluated for adsorption and desorption of REEs. The adsorption performance of carbon nano-shells for REEs was far superior to the solid carbon spheres. In addition, the effect of acidity on the adsorption and desorption properties was discussed. The good adsorption performance of the carbon nano-shells could be attributed to their pore structure, specific surface area, and the pres- ence of both amine and carbonyl groups from the grafted dopamine.

Rational synthesis of carbon shell coated polyaniline/ MoS2 monolayer composites for high-performance supercapacitors

Conducting polymers generally show high specific capacitance but suffer from poor rate capability and rapid capacitance decary which greatly limits their practical applications in supercapacitor electrodes. To this end, many studies have focused on improving the overall capacitive performance by synthesizing nanostructured conducting polymers or by depositing a range of coatings to increase the active surface area exposed to the electrolyte and enhance the charge transport efficiency and structural stability. Despite this, simultaneously achieving high specific capacitance, good rate performance, and long cycle life remains a considerable challenge. Among the various two-dimensional （2D） layered materials, octahedral （1T） phase molybdenum disulfide （MoS2） nano- sheets have high electrical conductivity, large specific surface areas, and unique surface chemical characteristics, making them an interesting substrate for the controlled growth of nanostructured conducting polymers. This paper reports the rational synthesis of carbon shell-coated polyaniline （PANI） grown on 1T MoS2 monolayers （MoS2/PANI@C）. The composite electrode comprised of MoS2/ PANI@C with a -3 nm carbon shell exhibited a remarkable specific capacitance of up to 678 F-g-1 （1 mV.s-1）, superior capacity retention of 80% after 10,000 cycles and good rate performance （81% at 10 mV.s-1） due to the multiple synergic effects between the PANI nanostructure and 1T MoS2 substrates as well as protection by the uniform thin carbon shell. These properties are comparable to the best overall capacitive performance achieved for conducting polymers-based supercapacitor electrodes reported thus far.

Carbon shell coated hollow NiCoSe_(x)composite as high-performance anode for lithium storage

Hollow NiCoSe_(x)(H-NiCoSe_(x)) nanospheres encapsulated with carbon shell were prepared via one-step easy solvothermal method followed by the carbon coating process.H-NiCoSe_(x)@C has large interior void with the uniform dimension around 350 nm and the thickness of carbon shell around 20-30 nm.Coupling with the large interior void as well as robust protective carbon shell,H-NiCoSe_(x)@C can retain the reversible capacity of 805.6 mAh·g^(-1) after 100 cycles at 200 mA·g^(-1).In particular,H-NiCoSe_(x)@C delivers large reversible capacity of 1532.2 mAh·g^(-1) upon cycling for 1000 loops at 1000 mA·g^(-1)with the capacity retention as high as 128.2% upon long period of activation.Even at the high rate of 3000 mA·g^(-1),its specific capacity still retains up to 659.3 mAh·g^(-1).The superior lithium storage performances for H-NiCoSe_(x)@C profit from its robust hollow core-shell structure as well as enhanced electrical conductivity and ion transport.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Synthesis and Characterization of Cobalt-Carbon Core-Shell Microspheres in Supercritical Carbon Dioxide System

在 supercritical 二氧化碳系统的钴碳核心壳 microspheres 的合成被调查。有大约 1 m 的直径的钴碳核心壳 microspheres 在 350 耀被准备吗？？

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.