Controllable fabrication of FeCoS_(4) nanoparticles/S-doped bowl-shaped hollow carbon as efficient lithium storage anode

To address the low conductivity and easy agglomeration of transition metal sulfide nanoparticles,FeCoS_(4) nanoparticles embedded in S-doped hollow carbon(FeCoS_(4)@S-HC)composites were successfully fabricated through a combination of hydrothermal processes and sulfidation treatment.The unique bowlshaped FeCoS_(4)/S-HC composites exhibit excellent structural stability with a high specific surface area of 303.7 m^(2)·g^(-1) and a pore volume of 0.93 cm^(3)·g^(-1).When applied as anode material for lithium-ion batteries,the FeCoS_(4)@S-HC anode exhibits efficient lithium storage with high reversible specific capacity(970.2 mA·h·g^(-1) at 100 mA·g^(-1))and enhanced cycling stability(574 mA·h·g^(-1) at 0.2 A·g^(-1) after 350 cycles,a capacity retention of 84%).The excellent lithium storage is attributed to the fact that the bimetallic FeCoS_(4) nanoparticles with abundant active sites can accelerate the electrochemical reaction kinetics,and the bowl-shaped S-HC structure can provide a stable mechanical structure to suppress volume expansion.

Waste to wealth: Oxygen-nitrogen-sulfur codoped lignin-derived carbon microspheres from hazardous black liquors for high-performance DSSCs

Carbon materials are effective substitutes for Pt counter electrodes(CEs) in dye-sensitized solar cells(DSSCs). However, many of these materials, such as carbon nanotubes and graphene, are expensive and require complex preparation process. Herein, waste lignin, recycled from hazardous black liquors,is used to create oxygen-nitrogen-sulfur codoped carbon microspheres for use in DSSC CEs through the facile process of low-temperature preoxidation and high-temperature self-activation. The large number of ester bonds formed by preoxidation increase the degree of cross-linking of the lignin chains, leading to the formation of highly disordered carbon with ample defect sites during pyrolysis. The presence of organic O/N/S components in the waste lignin results in high O/N/S doping of the pyrolysed carbon,which increases the electrolyte ion adsorption and accelerates the electron transfer at the CE/electrolyte interface, as confirmed by density functional theory(DFT) calculations. The presence of inorganic impurities enables the construction of a hierarchical micropore-rich carbon structure through the etching effect during self-activation, which can provide abundant catalytically active sites for the reversible adsorption/desorption of electrolyte ions. Under these synergistic effects, the DSSCs that use this novel carbon CE achieve a quite high power-conversion efficiency of 9.22%. To the best of our knowledge, the value is a new record reported so far for biomass-carbon-based DSSCs.

Novel Bilayer-Shelled N,O-Doped Hollow Porous Carbon Microspheres as High Performance Anode for Potassium-Ion Hybrid Capacitors

With the advantages of high energy/power density,long cycling life and low cost,dual-carbon potassium ion hybrid capacitors(PIHCs)have great potential in the field of energy storage.Here,a novel bilayer-shelled N,O-doped hollow porous carbon microspheres(NOHPC)anode has been prepared by a self-template method,which is consisted of a dense thin shell and a hollow porous spherical core.Excitingly,the NOHPC anode possesses a high K-storage capacity of 325.9 mA h g^(−1)at 0.1 A g^(−1)and a capacity of 201.1 mAh g^(−1)at 5 A g^(−1)after 6000 cycles.In combination with ex situ characterizations and density functional theory calculations,the high reversible capacity has been demonstrated to be attributed to the co-doping of N/O heteroatoms and porous structure improved K+adsorption and intercalation capabilities,and the stable long-cycling performance originating from the bilayer-shelled hollow porous carbon sphere structure.Meanwhile,the hollow porous activated carbon microspheres(HPAC)cathode with a high specific surface area(1472.65 m^(2)g^(−1))deriving from etching NOHPC with KOH,contributing to a high electrochemical adsorption capacity of 71.2 mAh g^(−1)at 1 A g^(−1).Notably,the NOHPC//HPAC PIHC delivers a high energy density of 90.1 Wh kg^(−1)at a power density of 939.6 W kg^(−1)after 6000 consecutive charge-discharge cycles.

Platanus orientalis leaves based hierarchical porous carbon microspheres as high efficiency adsorbents for organic dyes removal

Water contamination caused by hazardous organic dyes has drawn considerable attention, among all of the techniques released, adsorption has been widely used, which however to a large degree is dependent on the development of high efficiency adsorbents. Waste biomass based porous carbon is becoming the new star class of adsorbents, and thus contribute more to the sustainable development of the society. In this work, for the first time to the best of our knowledge, abundant waste fallen Platanus orientalis leaves are employed as the raw material for hierarchical activated porous carbon(APC) microspheres via a mild hydrothermal carbonization(210 ℃,12.0 h) followed by one-step calcination(750 ℃, 1.0 h). The APC microspheres exhibit a specific surface area of 1355.53 m^2·g^-1 and abundant functional groups such as O—H and C=O. Furthermore, the APC microspheres are used as the adsorbents for removal of Rh B and MO, with the maximum adsorption capabilities of 557.06 mg·g^-1 and 327.49 mg·g^-1, respectively, higher than those of the most porous carbon originated from biomass. The adsorption rates rapidly approach to 98.2%(RhB) and 95.4%(MO) within 10 min. The adsorption data can be well fitted by Langmuir isotherm model and the pseudo-second-order kinetic model, meanwhile the intra-particle diffusion and Boyd models simultaneously indicate that the diffusion within the pores is the main rate-limiting step. Besides, the APC microspheres also demonstrate good recyclability, and may also be applied to other areas such as heterogeneous catalysis and energy storage.

Hollow Carbon Microspheres/MnO_2 Nanosheets Composites:Hydrothermal Synthesis and Electrochemical Behaviors

This article reported the electrochemical behaviors of a novel hollow carbon microspheres/manganese dioxide nanosheets(micro-HC/nano-MnO2) composite prepared by an in situ self-limiting deposition method under hydrothermal condition. The results of scanning electron microscopy reveal that MnO2 nanosheets homogeneously grow onto the surface of micro-HC to form a loose-packed microstructure. The quantity of MnO2 required in the electrode layer has thereby been reduced significantly, and higher specific capacitances have been achieved. The micro-HC/nano-MnO2 electrode presents a high capacitance of 239.0 F g-1 at a current density of 5 m A cm-2, which is a strong promise for high-rate electrochemical capacitive energy storage applications.

ZnIn_2S_4 flowerlike microspheres embedded with carbon quantum dots for efficient photocatalytic reduction of Cr(Ⅵ)

Development of efficient heterostructured photocatalysts that respond to visible light remains a considerable challenge.We herein show the synthesis of ZnIn2S4/carbon quantum dot hybrid photocatalysts with flowerlike microspheres via a facile solvothermal method.The ZnIn2S4/carbon quantum dot flowerlike microspheres display enhanced photocatalytic and photoelectrochemical activity compared with that of pure ZnIn2S4.With a content of only 0.5 wt%carbon quantum dots,93%of Cr(VI)is reduced under visible‐light irradiation at 40 min.As a co‐catalyst,the carbon quantum dots improve the light absorption and lengthen the lifetime of charge carriers,consequently enhancing the photocatalytic and photoelectrochemical activity.

Insights into the thermochemical evolution of maleic anhydride-initiated esterified starch to construct hard carbon microspheres for lithium-ion batteries

Starch,as a typical polysaccharide with natural spherical morphology,is not only a preferred precursor for preparing carbon materials but also a model polymer for investigating thermochemical evolution mechanisms.However,starch usually suffers from severe foaming and low carbon yield during direct pyrolysis.Herein,we report a simple and eco-friendly dry strategy,by maleic anhydride initiating the esterification of starch,to design carbon microspheres against the starch foaming.Moreover,the infuence of ester grafting on the pyrolytic behavior of starch is also focused.The formation of ester groups in precursor guarantees the structural stability of starch-based intermediate because it can promote the accumulation of unsaturated species and accelerate the water elimination during pyrolysis.Meanwhile,the esterification and dehydration reactions greatly deplete the primary hydroxyl groups in the starch molecules and thus the rapid levoglucosan release is inhibited,which well keeps the spherical morphology of starch and ensures the high carbon yield.In further exploration as anode materials for Lithium-ion batteries,the obtained carbon microspheres exhibit good cyclability and rate performance with a reversible capacity of 444 m Ah g^(-1)at 50 m A g^(-1).This work provides theoretical fundamentals for the controllable thermal transformation of biomass towards wide applications.

Preparation and Characterization of Carbon Microspheres From Waste Cotton Textiles By Hydrothermal Carbonization

Carbon microspheres were prepared from waste cotton fibers by hydrothermal carbonization(HTC)with the addition of copper sulphate in this work.The important influence factors,temperature,concentration of copper sulphate,resident time were explored here.The smooth and regular carbon microspheres could be formed at 330°C with 0.15 wt%copper sulphate after 6 h from waste cotton fibers.The crystal structures of cotton fibers were destructed in a short resident time with 0.15 wt%copper sulphate from SEM images and XRD patterns of solid products.This strategy provides a new,mild and efficient method to prepare carbon microspheres from waste cotton fibers by HTC.FTIR spectra verified that the abundant functional groups existed on the surface of synthesized carbon microspheres.From XPS and element analysis results,the copper sulphate participated in the forming process of carbon microspheres indeed.The presence of copper sulphate in the carbon microspheres provided a possibility for the application in antibacterial field.Besides,the catalytic mechanism of copper sulphate on the hydrolysis and carbonization of waste cotton fibers were also discussed.In conclusion,the copper sulphate is an efficient agent for preparing carbon microspheres by HTC from waste cotton fibers.

Nitrogen-doped lignin based carbon microspheres as anode material for high performance sodium ion batteries

Nitrogen-doped lignin-based carbon microspheres are synthesized using 3-aminophenol as a nitrogen source by the hydrothermal method.The structural change and the effect on the electrochemical properties are systematically investigated. Nitrogen-doped lignin-based carbon microspheres represent well-developed spherical morphology with many active sites, ultramicroporous(< 0.7 nm) structure, and large interlayer spacing. Consistent with the obtained physical structures and properties, the nitrogen-doped carbon microspheres exhibit fast sodium ion adsorption/intercalation kinetic process and excellent electrochemical performance. For example, a reversible specific capacity of 374 m Ah g^(-1) at 25 m A g^(-1) with high initial coulombic efficiency of 85% and high capacitance retention of 90% after 300 cycles at 100 m A g^(-1) and stable charge/discharge behavior at different current density is obtained. The additional defects and abundant ultramicroporous structure can enhance sloping capacity, and large interlayer spacing is considered to be the reason for improving plateau capacity.

Understanding the improved performance of sulfur-doped interconnected carbon microspheres for Na-ion storage

As one of the low-cost energy storage systems,Na-ion batteries(NIBs)have received tremendous attention.However,the performance of current anode materials still cannot meet the requirements of NIBs.In our work,we obtain sulfur-doped interconnected carbon microspheres(S-CSs)via a simple hydrothermal method and subsequent sulfurizing treatment.Our S-CSs exhibit an ultrahigh reversible capacity of 520 mAh g^(-1) at 100 mA g^(-1) after 50 cycles and an excellent rate capability of 257 mAh g^(-1),even at a high current density of 2 A g^(-1).The density functional theory calculations demonstrate that sulfur doping in carbon favors the adsorption of Na atom during the sodiation process,which is accountable for the performance enhancement.Furthermore,we also utilize operando Raman spectroscopy to analyze the electrochemical reaction of our S-CSs,which further highlights the sulfur doping in improving Na-ion storage performance.

Structural evolution of carbon aerogel microspheres by thermal treatment for high–power supercapacitors

In this work, a series of carbon aerogel microspheres（CAMs） with tailored pore structures were successfully prepared via a sol-gel method and subsequent heat-treatment at various temperatures from 600 to 1600 ℃. The effects of heat-treatment temperature（HTT） on the CAM microstructure were systematically investigated by physical and chemical characterization. The electrical conductivity increased by up to 250 S/cm and mesopores with high electrolyte accessibility developed in the CAM with increasing HTT. However, the specific surface area（SSA） decreased for HTTs from 1000 to 1600 ℃. The results show that these two factors should be finely balanced for further applications in high power supercapacitors.The CAMs carbonized at 1000 ℃ had the highest SSA（1454 m^2/g）, large mesoporous content（20%） and favorable conductivity（71 S/cm）. They delivered a high energy density of 38.4 Wh/kg at a power density of 0.17 kW/kg. They retained an energy density of 25.5 Wh/kg even at a high power density of 10.2 kW/kg,and a good rate capability of 84% after 10,000 cycles. This performance is superior to, or at least comparable to, those of most reported carbon materials.

VN nanoparticle-assembled hollow microspheres/N-doped carbon nanofibers:An anode material for superior potassium storage

Thanks to inexpensive and bountiful potassium resources,potassium ion batteries(PIBs)have come into the spotlight as viable alternatives for next-generation battery systems.However,poor electrochemical kinetics due to the large size of the K^(+) is a major challenge for PIB anodes.In this paper,an ingenious design of VN nanoparticleassembled hollow microspheres within N-containing intertwined carbon nanofibers(VN-NPs/N-CNFs)via an electrospinning process is reported.Employed as PIB anodes,VN-NPs/N-CNFs exhibit a superb rate property and prolonged cyclability,surpassing that of other reported metal nitride-based anodes.This is ascribed to:(i)the VN NP-assembled hollow microspheres,which shorten the K^(+) diffusion distance,and mitigate volume expansion;and(ii)the interconnected N-CNFs,which supply numerous active sites for K^(+) adsorption and facilitate rapid electron/ion transport.

Selective Hydrogenation of Maleic Anhydride to Succinic Anhydride over Nickel Catalyst Supported on Carbon Microspheres

The colloidal carbon microspheres(CMS)were prepared by the hydrothermal method.The nickel catalysts supported on carbon microspheres(Ni/CMS)were further prepared and were characterized by the Fourier transform infrared spectroscopy(FTIR),the X-ray diffraction(XRD),the scanning electron microscopy(SEM),the transmission electron microscopy(TEM),and the N_(2)adsorption technique.The selective hydrogenation of maleic anhydride(MA)to succinic anhydride(SA)over the Ni/CMS catalysts was investigated.The results indicated that the Ni/CMS catalyst,which was prepared with glucose as carbon source and calcined at 500℃,exhibited the best performance.The hydrogen pressure,reaction temperature,and reaction time could significantly affect the conversion of maleic anhydride during the hydrogenation reaction.A 98.4%conversion of MA and an 100%selectivity to SA were achieved over the Ni/CMS catalyst in acetic anhydride solvent under mild conditions covering a temperature of 90℃,a H2 pressure of 1.0 MPa,and a reaction time of 3 h.

Effect of Ultrasonication on the Properties of Multi-walled Carbon Nanotubes/Hollow Glass Microspheres/Epoxy Syntactic Foam

Multi-walled carbon nanotubes（MWCNTs） reinforced hollow glass microspheres（HGMs）/epoxy syntactic foam was fabricated. The effects of ultrasonication on the density, compression strength, and water absorption properties were studied. Better dispersed MWCNTs can be obtained after ultrasonication treatment, but an increasing viscosity will lead to a larger amount of voids during syntactic foam preparation especially when the content of HGMs is more than 70 vol%. The existing voids will decrease the density of epoxy syntactic foam. However, the ultrasonication does not change the compression strength much. Ultrasonication treatment will decrease the water absorption content due to the better dispersion and hydrophobic properties of MWCNTs. But a significant increase of water absorption content occurs when HGMs is more than 70 vol%, which is attributed to the higher viscosity and larger amount of voids.

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

The synthesis of cobalt-carbon core-shell microspheres in supercritical carbon dioxide system was investi- gated. Cobalt-carbon core-shell microspheres with diameter of about 1μm were prepared at 350 ℃ for 12 h in a closed vessel containing an appropriate amount of bis（cyclopentadienyl）cobalt powder and dry ice. Characterization by a variety of techniques, including X-ray powder diffraction, X-ray photoelectron spectroscopy, TransmissiOn electron microscope, Fourier transform infrared spectrum and Raman spectroscopy analysis reveals that each cobalt-carbon core-shell microsphere is made up of an amorphous cobalt core with diameter less than 1 μm and an amorphous carbon shell with thickness of about 200 nm. The possible growth mechanism of cobalt-carbon core-shell microspheres is discussed, based on the pyrolysis of bis（cyclopentadienyl）cobalt in supercritical carbon dioxide and the deposition of carbon or carbon clusters with odd electrons on the surface of magnetic cobalt cores due to magnetic attraction. Magnetic measurements show 141.41 emu/g of saturation magnetization of a typical sample, which is lower than the 168 emu/g of the corresponding metal cobalt bulk material. This is attributed to the considerable mass of the carbon shell and amorphous nature of the magnetic core. Control of magnetism in the cobalt-carbon core-shell microspheres was achieved by annealing treatments.

Low temperature molten salt synthesis of porous La_(1-x)Sr_xMn_(0.8)Fe_(0.2)O_3(0≤x≤0.6) microspheres with high catalytic activity for CO oxidation

A molten salt method was developed to prepare porous La1‐xSrxMn0.8Fe0.2O3 （0≤ x ≤ 0.6） micro‐spheres using hierarchical porous δ‐MnO2 microspheres as a template in eutectic NaNO3‐KNO3. X‐ray diffraction patterns showed that single phase LaMn0.8Fe0.2O3 with good crystallinity was syn‐thesized at 450℃ after 4 h. Transmission electron microscope images exhibited that the LaMn0.8Fe0.2O3 sample obtained at 450？？ after 4 h possessed a porous spherical morphology com‐posed of aggregated nanocrystallites. Field emission scanning electron microscope images indicated that the growth of the porous LaMn0.8Fe0.2O3 microspheres has two stages. SEM pictures showed that a higher calcination temperature than 450？？ had an adverse effect on the formation of a po‐rous spherical structure. The LaMn0.8Fe0.2O3 sample obtained at 450？？ after 4 h displayed a high BET surface area of 55.73 m2/g with a pore size of 9.38 nm. Fourier transform infrared spectra suggested that Sr2＋ions entered the A sites and induced a decrease of the binding energy between Mn and O. The CO conversion with the La1‐xSrxMn0.8Fe0.2O3 （0≤x≤0.6） samples indicated that the La0.4Sr0.6Mn0.8Fe0.2O3 sample had the best catalytic activity and stability. Further analysis by X‐ray photoelectron spectroscopy demonstrated that Sr2＋doping altered the content of Mn4＋ions, oxygen vacancies and adsorbed oxygen species on the surface, which affected the catalytic performance for CO oxidation.

Facile preparation of coal-based ultramicroporous carbon microspheres for selective CO_(2)capture

The basic structure of aromatic compounds that are abundant in coal is the carbonaceous precursor derived from carbon microspheres.However,it remains to be a huge challenge to prepare carbon microspheres using coal due to the complex construction and composition of coal.Herein,a simple and viable way to obtain coal-based microporous carbon microspheres was developed by means of ethanol pyrolysis and a sequential extraction strategy.The as-prepared carbon microsphere featured aspherical micron particles of a uniform size(0.6-1.6㎛),abundant O-functional groups,excellent thermal stability,high SBET(415.5-983.2 m^(2)/g),and plentiful ultra-micropores(63.15-72.72%).The coal-based carbon microsphere exhibited a noteworthy CO_(2)uptake(3.19-4.97 mmol/g at 273 K and 1.0 bar),acceptable CO_(2)/N_(2)selectivity(IAST:23-46)and moderate isosteric heats(20-32 kJ/mol).This synthetic strategy is important for the preparation of ultramicroporous carbon microspheres using coal,and the synthetic carbon microspheres have promising prospects for highly efficient CO_(2)capture.

KHCO_3 activated carbon microsphere as excellent electrocatalyst for VO^(2+)/VO_2^+ redox couple for vanadium redox flow battery

In this paper,carbon microsphere prepared by hydrothermal treatment was activated by KHCO_3 at high temperature,and employed as the catalyst for VO^(2+)/VO_2^+redox reaction for vanadium redox flow battery(VRFB).Carbon microsphere can be etched by KHCO_3 due to the reaction between the pyrolysis products of KHCO_3 and carbon atoms.Moreover,KHCO_3 activation can bring many oxygen functional groups on carbon microsphere,further improving the wettability of catalyst and increasing the active sites.The electrocatalytic properties of carbon microsphere from hydrothermal treatment are improved by high temperature carbonization,and can further be enhanced by KHCO_3 activation.Among carbon microsphere samples,the VO^(2+)/VO_2^+redox reaction exhibits the highest electrochemical kinetics on KHCO_3 activated sample.The cell using KHCO_3 activated carbon microsphere as the positive catalyst demonstrates higher energy efficiency and larger discharge capacity,especially at high current density.The results reveal that KHCO_3 activated carbon microsphere is an efficient,low-cost carbon-based catalyst for VO^(2+)/VO_2^+redox reaction for VRFB system.

Porous Microspheres Comprising CoSe2 Nanorods Coated with N-Doped Graphitic C and Polydopamine-Derived C as Anodes for Long-Lived Na-Ion Batteries

Metal–organic framework-templated nitrogen-doped graphitic carbon(NGC)and polydopaminederived carbon(PDA-derived C)-double coated one-dimensional CoSe_(2) nanorods supported highly porous threedimensional microspheres are introduced as anodes for excellent Na-ion batteries,particularly with long-lived cycle under carbonate-based electrolyte system.The microspheres uniformly composed of ZIF-67 polyhedrons and polystyrene nanobeads(φ=40 nm)are synthesized using the facile spray pyrolysis technique,followed by the selenization process(P-CoSe_(2)@NGC NR).Further,the PDA-derived C-coated microspheres are obtained using a solution-based coating approach and the subsequent carbonization process(P-CoSe_(2)@PDA-C NR).The rational synthesis approach benefited from the synergistic effects of dual carbon coating,resulting in a highly conductive and porous nanostructure that could facilitate rapid diffusion of charge species along with efficient electrolyte infiltration and effectively channelize the volume stress.Consequently,the prepared nanostructure exhibits extraordinary electrochemical performance,particularly the ultra-long cycle life stability.For instance,the advanced anode has a discharge capacity of 291(1000th cycle,average capacity decay of 0.017%)and 142 mAh g^(-1)(5000th cycle,average capacity decay of 0.011%)at a current density of 0.5 and 2.0 A g^(-1),respectively.

Assisting Bi_(2)MoO_(6) microspheres with phenolic resin-based ACSs as attractive tailor-made supporter for highly-efficient photocatalytic CO_(2) reduction

It is rather essential to design glorious system with high CO_(2) adsorption capacity and electron migration efficiency for improving selective and effective CO_(2) reduction into solar fuels.Here,as-synthesized phenolic resin spheres via suspension polymerization were carbonized and activated by water vapor to obtain activated carbon spheres(ACSs).Subsequently,Bi_(2)MoO_(6)/ACSs were prepared via hydrothermal-impregnated method.The systematical characterizations of samples,including XRD,XPS,SEM,EDX,DRS,BET,PL,CO_(2) adsorption isotherm,EIS and transient photocurrent,were analyzed.The results clearly demonstrated that Bi_(2)MoO_(6) with suitable oxidation reduction potentials and bandgap and ACSs with admirable CO_(2) adsorption and electrical conductivity not only enhanced separation efficiency of photoindued electron-hole pair,but also displayed as 1.8 times CO_(2) reduction activity to CO as single Bi_(2)MoO_(6) sample under Xe-lamp irradiation.Finally,a concerned photocatalytic CO_(2) reduction mechanism was proposed and investigated.Our findings should provide innovative guidance for designing a series of photocatalytic CO_(2) reduction materials with highly efficient and selective ability.