Electrochemical Performance of Core-Sheath Dip-Coated Lignin Derived Carbon/Wet-Spun Graphene Electrodes for Fiber-Shaped Supercapacitors

One-dimensional graphene fibers(GFs)possess excellent properties,including high electrical conductivity,good physical and chemical stability,high thermal conductivity,flexibility,etc.GFs are ideal electrode materials for fiber-shaped supercapacitors.However,due to the lack of an effective method to manufacture GFs with high specific capacitance,their low energy density hinders their practical application.Herein,we decorated wet-spun graphene oxide fibers(GOFs)by dip-coating them with graphene oxide(GO)solutions containing different contents of lignin to obtain a core-sheath lignin/GO composite fibers.After carbonization and activation,we successfully prepared lignin derived carbon/GF electrodes.The assembled fiber-shaped supercapacitors(FSSCs)exhibit a specific capacitance of 9.98 mF/cm^(2)and an energy density of 0.89μW·h/cm^(2),about 6 times of those of pure GFs(1.57 mF/cm^(2)and 0.14μW·h/cm^(2),respectively),long cycling life and cycling stability.This suggests that the introduction of lignin derived carbon into GFs can effectively increase the specific capacitance and the energy density of FSSCs.

Carbide derived carbon electrode with natural graphite addition in magnesium electrolyte based cell for supercapacitor enhancements

Herein,we have presented a supercapacitor based on carbide derived carbon（CDC） electrode with natural graphite（NG） addition.The capacitor was analyzed at 22°C by cyclic voltammetry,galvanostatic charge-discharge and impedance techniques using a 0.5 mol/L of magnesium（II）bis（trifluoro methanesulfonyl） imide（Mg TFSI） in ethylene carbonate-propylene carbonate（EC ：PC = 1 ：1,v/v） as electrolyte.The results conclude that the CDC cell enhancements have been proven by the composite electrode（5%–30% NG to CDC） especially on the cell efficiency and voltage i.e.,the CDC cell around 2.5 V limit was improved.An obtainable specific capacitance,real power and energy density are 15 F g-1,1.2 k W kg-1and 15 Wh kg-1,respectively.

An innovative wood derived carbon-carbon nanotubes-pyrolytic carbon composites with excellent electrical conductivity and thermal stability

The functionality of wood has evolved with time to adapt to the emerging needs of society.Carbonized wood-based composites have attracted tremendous interest in the fields of aerospace,military power,electric power,and system electronic devices,especially at high temperatures.Nevertheless,their electrical conductivity and thermal stability characteristics are still far from satisfactory.Herein,an innova-tive wood-derived carbon-carbon nanotubes-pyrolytic carbon composites(WDC-CNTs-PyCs)is successfully fabricated by chemical vapor deposition and chemical vapor infiltration.The combination of wood-derived carbon(WDC),carbon nanotubes(CNTs),and pyrolytic carbon(PyC)has never been reported in any previous work.We have innovatively introduced PyC into the WDC by chemical vapor infiltration.CNTs promote the continuous deposition of PyC to form dense structures.WDC-CNTs-PyC demonstrates significant compressive strength(85.4 MPa)and excellent electrical conductivity(632 S cm^(-1)).The weight loss rate of WDC-CNTs-PyC is 6%after heating at 500℃ for 10 min in the air atmosphere.Furthermore,WDC-CNTs-PyC could resist oxyacetylene ablation above 2300℃ for 15 s.With excellent electrical conductivity,outstanding thermal stability,and mechanical properties,WDC-CNTs-PyC opens up a surprising strategy for efficiently fabricating various high-performance electronic device composites that could be used in high-temperature fields.

The synthesis of MOF derived carbon and its application in water treatment

In recent years,since water pollution has aroused great public concern,various carbon materials have already been widely applied for water treatment.In this respect,tremendous effort has been made to provide different synthesis methods of carbon materials.Among all carbon materials,metal-organic framework(MOF)derived carbon has always been favored as it possesses several appealing merits such as high specific surface area,large pore volume,and outstanding chemical stability.This review presents the latest development of MOFs as templates and precursors for the fabrication of various carbon materials,including porous carbon,nanocarbon,and graphene,which are pyrolyzed at different temperatures.The article also emphasizes on their future trends and perspectives on the application of water treatment.

Atomic regulations of single atom from metal-organic framework derived carbon for advanced water treatment

Single atom(SA)-embedded nitrogen-doped carbon has shown great potential in environmental remediation.Nowadays,engineered nanomaterials(ENMs)have attracted great research interests in recent years.Metal-organic framework(MOF)derived SAs show the advantages of tunable topology and averaged separated active sites.SAs bridge the gap between homogeneous and heterogeneous catalysts.The reaction efficiency can be significantly improved by designing the MOFs derived from carbon and SAs.In this review,the research advanced in MOFs-derived carbon and SAs in advanced oxidation process(AOP)in water were summarized.Major strategies to fabricate the SAs derived from MOFs were discussed,including the mixed/single metal strategy,metal-containing linker strategy,pore confinement strategy,thermal diffusion strategy,and pyrolysis MOFs with bulk metals.Advanced characterization technologies have been introduced,including electron microscopy and spectroscopic methods.To explain the catalytic mechanism for various applications,the relationship between the performance and the atomic configuration was systematically discussed.Recent applications of the MOFs derived from carbon and SAs have been summarized.A series of the latest work on effectively removing pollutants by SAs are also listed.Based on the fundamental knowledge and recent practical application of MOFs-derived carbon and SAs,some perspectives on the further directions were presented.This review offers guidance for applying novel engineered nanomaterials in the water treatment field.

Amperometric Ascorbic Acid Sensor Based on Disposable Facial Tissues Derived Carbon Aerogels

In this study,the disposable facial tissues derived carbon aerogels(DFTs-CAs)were synthesized using disposable facial tissues as the raw material for fabricating a sensitive amperometric ascorbic acid(AA)sensor.The experimental results indicated that compared to glassy carbon electrode(GCE)and the popular carbon nanotubes modified GCE(CNTs/GCE),DFTs-CAs modified GCE(DFTs-CAs/GCE)exhibited better electrocatalytic activity(i.e.,lower peak potential and higher peak current)for AA electrooxidation and higher analytical performance for AA determination(i.e.,wider linear range,higher sensitivity and lower detection limit),which could be most likely due to the high density of defective sites and large specific surface area of DFTs-CAs.Especially,the DFTs-CAs/GCE was used for evaluating the AA level in real samples(i.e.,medical injection dose,vitamin C tablets,fresh orange juice and human urine)and the results are satisfactory.

MOF(ZM)/Potassium Citrate-Derived Composite Porous Carbon and Its Electrochemical Properties

Metal-organic frameworks are compounds with a reticulated skeletal structure formed by chemically bonding inorganic and organic units that are widely used in many fields, such as photocatalysis, gas separation and energy storage, because of their unique structures. In this paper, we prepared a metal-organic framework [(μ2-2-methylimidazolyl)12-Zn(ii)6-H18O10]n(ZM) with well-developed pores and high specific surface area of MOFs by the solution method. And MOF-derived porous carbon was prepared by the direct charring method in an argon atmosphere using a mixture of ZM, ZM and potassium citrate as carbon precursors. Characterization analysis revealed that the maximum specific surface area of ZMPC-800-1:15 was 2014.97 m2⋅g−1, and the pore size structure was mainly mesoporous. At a current density of 1.0 A⋅g−1 the specific capacitance of ZMC-800 and ZMPC-800-1:15 was 121.3 F⋅g−1 and 226.6 F⋅g−1, respectively, with a substantial increase of 86.8%. The specific capacitance of ZMPC-800-1:15 decays to 168.8 F⋅g−1, with a decay rate of 25.5%, when the current density increases to 10.0 A⋅g−1. After 5000 constant current charge/ discharge cycles, the capacitance retention rate was still 96.41%. These results prove that the application of MOF-derived carbon materials in future supercapacitors is very promising.

Two-dimensional porous carbon derived from pollen with enlarged interlayer distance enhanced electrocatalytic oxidation of n-valeraldehyde to octane

Electrocatalytic n-valeraldehyde oxidation reaction was an inexpensive and eco-friendly method to control n-valeraldehyde contamination and produce high value-added octane.However,low-cost and readily available electrocatalysts with high current efficiency were urgently needed.Herein,two-dimensional porous carbon derived from pollen with enlarged interlayer distance was built by alkali activation method,applying in electrocatalytic n-valeraldehyde oxidation reaction.The enlarged interlayer distance was verified by X-ray diffraction(XRD)and high-angle annular dark-field scanning transmission electron microscope(HAADF-STEM).Electrocatalytic experiments consequences showed activated biomass derived carbon possessed a higher electrocatalytic activity and octane selectivity than unactivated catalyst.Systematic tests and in situ infrared experiments demonstrated that enlarged interlayer distance was positively correlated with specific surface area of catalysts,large specific surface area provided abundant absorption sites,facilitated the adsorption for n-valeraldehyde,and further promoted the transformation of n-valeraldehyde to octane.This work also provides a new avenue for creating high-performance electrocatalysts in terms of lattice engineering.

Effective dielectric attenuation for excellent microwave absorption with broadband response of carbon hollow microspheres derived from resin

Carbon hollow microspheres as microwave absorption materials(MAMs)are of great significance in the research focuses owing to their lightweight,good impedance matching,and modifiable dielectric proper-ties.However,it is still a huge challenge to distinguish the contribution of dielectric attenuation between carbon intrinsic feature and hollow structure due to the lack of appropriate model materials.Then,the inadequate analysis of effective dielectric attenuation resulted in the construction of carbon hollow mi-crospheres semiempirical and often lacked precise modification of microstructure.Herein,a series of car-bon hollow microspheres with controllable graphitization and thickness of shell derived from phenolic resin coated on polystyrene microspheres that fully decomposed were synthesized,which is free of the impact of template residue.The carbon fragments ground from hollow microspheres exhibit the same broadband response as hollow microspheres,with effective bandwidth(RL<-10 dB)of 7.6 GHz,while their electromagnetic wave loss mechanisms are distinct.The high dielectric loss of carbon fragments with the same intrinsic characteristics as carbon hollow microspheres is mainly caused by dipole po-larization relaxation and enhancement of electrical conductivity ascribed to overlapping between carbon sheets.For the hollow structure,in addition to dipole polarization relaxation attributed to carbon intrin-sic feature,the effective dielectric loss is also comprised of the interfacial polarization in advantage due to the effective heterogeneous interface between air and carbon shell.This work provides a simplified model to clarify the effect of carbon intrinsic feature and microstructure on the dielectric loss of carbon hollow microspheres.

Phase changes and electromagnetic wave absorption performance of XZnC(X=Fe/Co/Cu)loaded on melamine sponge hollow carbon composites

Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melamine sponge(MS)carbon composites were investigated through vacuum filtration followed by calcination.The FeZnC/CoZnC/CuZnC with carbon nanotubes(CNTs)were uniformly dispersed on the surface of melamine sponge carbon skeleton and Co-containing sample exhibits the highest CNTs concentration.The minimum reflection loss(RL_(min))of the CoZnC/MS composite(m_(composite):m_(paraffin)=1:1,m represents mass)reached-33.60 dB,and the effective absorption bandwidth(EAB)reached 9.60 GHz.The outstanding electromagnetic wave absorption(EMWA)properties of the CoZnC/MS composite can be attributed to its unique hollow structure,which leads to multiple reflections and scattering.The formed conductive network improves dielectric and conductive loss.The incorporation of Co enhances the magnetic loss capability and optimizes interfacial polarization and dipole polarization.By simultaneously improving dielectric and magnetic losses,ex-cellent impedance matching performance is achieved.The clarification of element replacement in XZnC/MS composites provides an effi-cient design perspective for high-performance non-stoichiometric carbide EMW absorbers.

Petroleum coke derived porous carbon/NiCoP with efficient reviving catalytic and adsorptive activity as sulfur host for high performance lithium-sulfur batteries

Sulfur-host material with abundant pore structure and high catalysis plays an important role in development of high-energy-density lithium-sulfur(Li-S)batteries.Herein,we implanted NiCoP nanoparticles into the N,S co-doped porous carbon derived from petroleum coke(PCPC)to fabricate the sulfur-host of PCPC/NiCoP composites.The high specific surface area of PCPC provides abundant adsorption sites for capturing LiPSs and the NiCoP nanoparticles to improve the polarity and boost the LiPSs conversion kinetics of PCPC.The Li-S cells fabricated with PCPC/NiCoP as sulfur-host deliver high discharge capacity of 1,462.7 mAh·g^(-1)under the current density of 0.1 C and exhibit ultralong lifespan over 800 cycles under the current density of 1,2,and even 5 C.Additionally,the prepared composites cathodes deliver an outstanding discharge capacity of 932.5 and 826.4 mAh·g^(-1)at 0.5 and 1 C with a high sulfur loading of over 3.90 mg·cm^(-2),and remain stable about 60 cycles.Furthermore,the promoted adsorption-conversion process of polysulfides by introducing NiCoP nanoparticles into PCPC was investigated by experimental and theoretical calculation studies.This work offers a new light for tacking the obstacles of porous carbon-based sulfur-host and propelling the development of petroleum coke-based porous carbon for high performance Li-S batteries.

Fabrication of LiOH-metal organic framework derived hierarchical porous host carbon matrix composites for seasonal thermochemical energy storage

By virtue of its long lifespan and outstanding storage intensity with near-zero heat loss,salt hydrate thermochemical energy storage(TES)materials provide a feasible option for the effective use of renewable energy and overcoming its unsynchronized supply and demand.Here,an activated porous carbon originating from the zeolite imidazolate framework(ZHCM)is fabricated and served as the carbon matrix for the LiOH TES material.The as-synthesized Li/ZHCM2-40 not only has excellent storage intensity(maximum 2414.2 kJ·kg^(−1))with low charging temperature,but also shows great hydration properties stemming from the ultrahigh surface area and hierarchical porous structure of ZHCM2.Besides,this composite material exhibits superior thermal conductivity,while its storage intensity is only attenuated by 10.2%after 15 times of consecutive charge-discharge process,revealing its outstanding cycle stability.And the numerical simulation results also demonstrate its superior heat transfer performance.The developed LiOH TES composite may afford a new avenue for efficient low-grade thermochemical energy storage and liberate the possibility of further exploration of metal organic frameworks derived porous carbon matrix in the future.

Infrared Photodissociation Spectroscopic and Theoretical Study of the HC2nO+（n=3-6） Cations

The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged”[HC2nO·CO]+ cation complexes in 1600-3500 cm-1 frequency range. The geometric and electronic structures of the [HC2nO·CO]+ complexes and the core HC2nO+(n=3-6) cations are determined with the aid of density functional theory calculations. These HC2nO+(n=3-6) ions are identified to be linear carbon chain derivatives terminally capped by hydrogen and oxygen. The triplet ground states are 10-15 kcal/mol lower in energy than the singlet states, indicating cumulene-like carbon chain structures.

Fine decoration of carbon nanotubes with metal organic frameworks for enhanced performance in supercapacitance and oxygen reduction reaction

Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （ZIFs, e.g., ZIF-8） via an in situ pyrolysis process. The resultant materials are completely new carbon composites with desirable hierarchical porosity and nitrogen-doped features. Electron microscopy images show that CNTs with small external diameters enable more uniform dispersion of ZlF-8-derived carbons, subsequently yielding a unique hierarchically porous structure. Such carbon shows superior activity in oxygen reduction reaction （ORR） and high performance of supercapacitance, making it a valu- able metal-flee electrode material and a competent alternative to the state-of-the-art Pt/C catalyst. The electrocatalytic performance of CNTs can be dramatically improved by the incorporation of ZIF-8-derived carbons, which is attributed to the combination of good conductivity, abundant accessible dopant species, as well as proper porosity. Our method offers a new avenue for constructing electrocatalysts by effective integration of ZlF-8-derived carbon and the CNTs skeleton.

Cu@Cu_(2)O/carbon for efficient desalination in capacitive deionization

Electrode materials with strong desalting ability is an important research direction of capacitive deionization.In this study,HKUST-1 was successfully synthesized by the solvothermal method,and MOFsderived porous carbon/Cu@Cu_(2)O composites were prepared by simple pyrolysis as cathode materials for CDI.After high-temperature pyrolysis,the Cu^(+) site with unsaturated coordination is generated,and the structure changes from micropores to the coexistence of mesoporous and micropores.The complex pore structure is conducive to strengthening ion migration and diffusion.The results show that the porous carbon/Cu@Cu_(2)O materials derived from MOFs depend on the pseudocapacitance behavior for capacitive deionization and desalination.At a voltage window of-1.2V~1.2V,a current density of 40mA/g.and 5 mmol/L NaCl,the HDC-1100 exhibited the best desalting capacity of 30.9 mg/g.HDC-1100 also has good cycle stability.After 20 cycles of adsorption and desorption,the desalting capacity almost does not decrease.Therefore,MOFs derived porous carbon/Cu@Cu_(2)O composites are expected to be an excellent choice for CDI cathode materials.

Behaviour of 4-(4-chlorophenyl)-6-(4-tolyl)-4,5-dihydro pyrimidine-2(1H)thione and 2-hydrazino derivative toward carbon electrophiles

The reaction of thiourea with p-methyl-β-p-chlorophenyl acrylophenone(1)is,in princi- ple,an attractive[3+ 3]-fragment approach to the synthesis of dihydropyrimidine bearing aryl groups.

Synthesis and comparative study of reactivities of δ-lactone,estor group and oxazinone ring in coumarin derivatives towards carbon or nitrogen nucleophiles

Condensation of methyl 7-methylcoumarin-4-acetate(2)with primary amines and with an- thranilic acid gave 7-methyl-2-oxo-N-aryl-2H-[1]-benzopyran-4--acetamide(4a—d)and(7),respectively. Compound 7 underwent cyclization to give 2-(7-methyl-2-oxo-2H-[1]-benzopyran-4-yl)-methyl-4H-3,1- benzoxazin-4-one(3).The reaction of 3 with aromatic amines gave the corresponding quinazolone derivatives 5 which tautomerises to the thermodynamically more stable isomer 6,whereas its reaction with Grignard reagents and aromatic aldehydes gave 8a,8b,and 9a,9b,respectively.

An angle-insensitive electromagnetic absorber enabling a wideband absorption

Electromagnetic(EM)wave absorbers with wideband absorption capability are proposed as a strategy to mitigate environmental pollution by EM waves.However,designing an EM absorber with its performance capacity independent of the EM wave incident angle remains elusive to date.Resolving this challenge requires development of EM absorbers whose EM absorption performance is insensitive to the EM wave incident angle.Herein,we synthesized EM absorbers with a variety of structures with different symme-tries(including micro-/nanospheres,nanoflakes and nanotubes)to study the effect of the EM absorbers’structure and the EM wave incident angle on the EM absorption performance.Our analysis reveals that non-magnetic EM absorbers with spatially symmetric nanostructures exhibit excellent EM wave incident angle-insensitivity.Finally,we demonstrate that a class of non-magnetic EM absorbers made from bam-boo derived-carbon nanospheres exhibit EM incident angle-insensitivity and wideband EM absorption performance with an effective absorption band up to 3.5 GHz when the thickness is 1.4 mm,a signif-icant improvement from prior studies which used thicknesses as high as 3-4 mm for comparable EM absorption performance.

Nature-inspired Three-dimensional Au/Spinach as a Binder-free and Self-standing Cathode for High-performance Li-O_(2) Batteries

Design and fabrication of functional porous air cathode materials with superior catalytic activity is still the key point for non-aqueous lithium-oxygen(Li-O2) batteries. Herein, inspired by the self-standing three-dimensional(3D) structure of the natural spinach leaves, a unique binder-free and self-standing porous Au/spinach cathode for high-performance Li-O2 batteries has been developed. The carbonized spinach leaves serve as a superconductive current collector and an ideal porous host for accommodating catalysts. The Au/spinach cathode could offer enough spaces for accommodating the discharge products, shorten the distance of the oxygen and electrolyte diffusion, and promote the oxygen reduction reaction(ORR) and oxygen evolution reaction (OER) processes. This optimized Au/spinach cathode achieved a high specific area capacity of 7.23 mA‧h/cm2 at a current density of 0.05 mA/cm2 and exhibited excellent stability(280 cycles at 0.05 mA/cm2 with a fixed capacity of 0.2 mA‧h/cm2). The superior performance encourages the construction of more advanced cathode architectures by the use of bio-composites for Li-O2 batteries.

N-methylation of quinolines with CO2 and H2 catalyzed by Ru-triphos complexes

N-methyl-tetrahydroquinolines(MTHQs) are a kind of very useful chemicals, which can be obtained from N-methylation of amines.However, the methylation of quinolines which is a kind of highly unsaturated nitrogen-containing heterocyclic aromatic compounds has not been reported. In this work, we report the first work for the synthesis of MTHQs by methylation of quinolines using CO_2 and H_2. It was found that Ru(acac)_3-triphos [triphos: 1,1,1-tris(diphenylphosphinomethyl)ethanl] complex was very active and selective for the N-methylation reaction of quinolines, and the yield of the desired product could reach 99%.