The(TiNbTaZrHf)C high entropy carbide(HEC)was successfully synthesized by complete commercial transition metal powders,obtained fine sintered bulks without additives by in-situ reaction element synthesis method.(TiNbT...
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The(TiNbTaZrHf)C high entropy carbide(HEC)was successfully synthesized by complete commercial transition metal powders,obtained fine sintered bulks without additives by in-situ reaction element synthesis method.(TiNbTaZrHf)C bulk shows a face centered cubic rock salt structure with homogeneous single-phase FCC structure in composition and *** optimum sintering temperature is about 1900℃at which the best mechanical properties are *** mechanical properties of(TiNbTaZrHf)C ceramic block are better than those of binary transition metal carbides,and it has obvious high entropy *** a small amount of Al as sintering additive,the mechanical properties of(TiNbTaZrHf)C ceramics continue to improve,the bending strength of the samples at each temperature is increased by at least 38%,and the highest is 486 *** elastic modulus and hardness of the sample at 1900℃are also slightly increased by 4%and 14%,*** above conclusions illustrate that the properties of high entropy ceramics are greatly improved by in-situ reaction sintering.
Hollow nitrogen-doped porous carbon materials covered with different thicknesses of carbon layers were synthesized to assist evaluation of the influence of nitrogen atom on the surrounding carbon *** designed carbon-b...
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Hollow nitrogen-doped porous carbon materials covered with different thicknesses of carbon layers were synthesized to assist evaluation of the influence of nitrogen atom on the surrounding carbon *** designed carbon-based materials were synthesized through pyrolysis of surface-attached block copolymer layers on silica nanoparticles with different thicknesses of the second block of grafted polymer chains,followed by removal of silica *** experimental results reveal that coverage a carbon layer with proper thickness can improve the oxygen reaction reduction activity of nitrogen-doped carbon materials as evidenced by the positive shift of half-wave potential in linear scanning voltammetry response *** conclusions may provide a reference work on understanding the active sites and designing materials with superior electrochemical performance.
Porous carbon spheres represent an ideal family of electrode materials forsupercapacitors because of the high surface area,ideal conductivity,negligible aggregation,and ability to achieve space efficient ***,the devel...
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Porous carbon spheres represent an ideal family of electrode materials forsupercapacitors because of the high surface area,ideal conductivity,negligible aggregation,and ability to achieve space efficient ***,the development of new synthetic methods towards porous carbon spheres still remains a great ***,N-doped hollow carbon spheres with an ultrahigh surface area of2044 m^(2)/g have been designed based on the phenylenediamine-formaldehyde *** applied in symmetric supercapacitors with ionic electrolyte(EMIBF_4),the obtained N-doped hollow carbon spheres demonstrate a high capacitance of 234 F/g,affording an ultrahigh energy density of 114.8 Wh/*** cycling stability has also been *** impressive capacitive performances make the phenylenediamine-formaldehyde resin derived N-doped carbon a promising candidate electrode material for supercapacitors.
We reported the synthesis of nitrogen-doped carbon using surface-attached polyelectrolyte layers as precursors. The synthesized material has a large surface area of 800 m^2·g^-1 with uniformed pore distribution. ...
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We reported the synthesis of nitrogen-doped carbon using surface-attached polyelectrolyte layers as precursors. The synthesized material has a large surface area of 800 m^2·g^-1 with uniformed pore distribution. Benefitfed from the high pyridinic nitrogen content, the synthesized nitrogen-doped porous carbon material exhibits promising electrocatalytic activity toward oxygen reduction reactions in acidic medium and very high stability against continuous cyclic voltammetry scans. The experimental results demonstrate that surface-attached polyelectrolyte layers are promising carbon and nitrogen sources for the formation of heteroatom-doped porous carbon materials.
A recombinant protein ChiSifiCa,which was originally designed for regulation of calcium carbonate,was utilized to direct the mineralization of PbI_(2).By the regulation of ChiSifiCa protein,PbI_(2)nanoparticles compos...
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A recombinant protein ChiSifiCa,which was originally designed for regulation of calcium carbonate,was utilized to direct the mineralization of PbI_(2).By the regulation of ChiSifiCa protein,PbI_(2)nanoparticles composed of crystalline nanoflakes and amorphous nanorods were fabricated under environmental benign *** PbI_(2)was successfully applied for preparation of perovskite precursors to fabricate solar *** regulation of ChiSifiCa on PbI_(2)improves the power conversion efficiency of corresponding perovskite solar cells to 16%.The present study may open a new avenue in the design and synthesis of materials with novel structures and functions.
Two isomeric fluorene-based heteroundecenes of bis(thienocyclopenthieno[3,2-b]thieno)fluorene(BT2T-F)and bis(dithieno[3,2-b:2’,3’-d]thiophene)cyclopentafluorene(B3T-F)have been designed and *** side chains of 4-hexy...
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Two isomeric fluorene-based heteroundecenes of bis(thienocyclopenthieno[3,2-b]thieno)fluorene(BT2T-F)and bis(dithieno[3,2-b:2’,3’-d]thiophene)cyclopentafluorene(B3T-F)have been designed and *** side chains of 4-hexylphenyl anchor on the 5th and 8th positions in B3T-F while on the 4th and 9th positions in BT2T-F,in which the former is closer to the center of the fused *** corresponding acceptor-donor-acceptor(A-D-A)type small molecule acceptors(SMAs)of BT2T-FIC and B3T-FIC were prepared by linking BT2T-F and B3T-F as fused ring donor units with the acceptor unit of 2-(5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene)malononitrile(IC-2F),respectively.B3T-FIC presents a superior crystallinity with intense face-on π-π stacking in its neat film while BT2T-FIC is more *** blended with PBDB-T-2Cl as a polymer donor,the optimized PBDB-T-2Cl:BT2T-FIC device exhibits an averaged power conversion efficiency(PCE)of 10.56%while only 7.53%in the PBDB-T-2Cl:B3T-FIC *** improved short-circuit current(J_(sc))and fill factor(FF)of the PBDB-T-2Cl:BT2T-FIC device are the main contribution of its higher performance,which is attributed to its more efficient and balanced charge transport and better carrier recombination *** that BT2T-FIC blend and B3T-FIC blend films both take a preferential face-on orientatedπ-πstacking with comparable distances,the suitable SMA domain size obtained in the BT2T-FIC blend could account for its more efficient photovoltaic *** results highlight the importance of side-chain strategy in developing efficient SMAs with huge fused ring cores.
A high-pressure hot-pressing process was applied to densify a commercial boron carbide-titanium diboride (B4C-TiB2) powder *** fully dense (98.6%) materials were obtained at 1700℃ under a pressure of *** to the sinte...
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A high-pressure hot-pressing process was applied to densify a commercial boron carbide-titanium diboride (B4C-TiB2) powder *** fully dense (98.6%) materials were obtained at 1700℃ under a pressure of *** to the sintering temperature required to achieve similar results when a pressure of only 30MPa was applied,the sintering temperature was found to decrease by about 200℃ under pressure of 100 *** of the thermodynamics and microstructure showed that the plastic deformation of the B4C grains induced by high pressure dominated the densification mechanism when high pressure was ***,higher pressure resulted in remarkably improved mechanical properties of the composites,which could be traced back to the generation of stacking faults in the B4C grains and aggregation of TiB2.
The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB_(2)-ZrO_(2) composite via the ZrO_(2)-coated ZrB_(2) powder(ZrB_(2)@ZrO_(2))prepared by in situ passivation method were *...
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The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB_(2)-ZrO_(2) composite via the ZrO_(2)-coated ZrB_(2) powder(ZrB_(2)@ZrO_(2))prepared by in situ passivation method were *** composition and microstructure were characterized by XRD,Raman,SEM,and EDS *** coated powder has excellent sintering *** relative density of the composite reaches above 90%at 1200℃,and the main sintering process occurs between ZrO_(2) *** at above 1500℃,the relative density reaches above 95%and the main sintering process occurs between ZrB_(2) and ZrO_(2) *** the increase of ZrO_(2) coating content,the structure of the sintered body changes from ZrB_(2) continuous network structure to island *** the content is 20%,an island structure is *** the ZrO_(2) content further causes the overheating of ZrO_(2).Thus,the best sintering performance reaches when the coating content is 20wt%.
Titanium diboride ceramic was produced via spark plasma sintering(SPS)using finer TiB_(2)powder made by high-speed planetary ball *** effects of ball milling parameters on the composites and particle size of TiB_(2)po...
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Titanium diboride ceramic was produced via spark plasma sintering(SPS)using finer TiB_(2)powder made by high-speed planetary ball *** effects of ball milling parameters on the composites and particle size of TiB_(2)powder were *** was shown that the average particle size of TiB_(2)powder decreased from 5.8 to 1.59μm and the wear rate of WC balls was 1.58 wt%,when the ball-to-powder weight ratio(BPR),the rotary speed and milling time and were 10:1,600 rpm and 20 min,*** content of WC in TiB_(2)powder can be limited below 4.58 vol%by optimizing the milling *** sintering temperature of TiB_(2)powder milled can be decreased obviously,and the mechanical properties are evidently improved and the microstructure becomes more homogeneous when the powder of TiB_(2)becomes *** relative density,hardness,bending strength,and fracture toughness of the TiB_(2)ceramic fabricated at 1700℃reach the optimal values,which are 98.13%,19.14 GPa,756 MPa,and 5.71 MPa·m~(1/2),*** decrease of TiB_(2)particle size and the introduction of WC are the potential reasons for the improvement of TiB_(2)ceramic performance.
A novel fused nonacyclic monomer of dithieno[6,5-b：10,11-b＇]-8 H-cyclopentyl[1,2-b：4,3-b＇]diphenanthrene（DTCPDP） was synthesized by combining the structural features of ladder-type and multiple fused multi-cycli...
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A novel fused nonacyclic monomer of dithieno[6,5-b：10,11-b＇]-8 H-cyclopentyl[1,2-b：4,3-b＇]diphenanthrene（DTCPDP） was synthesized by combining the structural features of ladder-type and multiple fused multi-cyclic aromatics. DTCPDP has a single sp3-hybridized carbon bridge between fused multi-cyclic aromatics. The copolymerization of DTCPDT with the electron accepting unit of 4,7-di（thiophen-2-yl）benzo[c][1,2,5]thiadiazole（DTBT） via Stille coupling afforded a novel donor-acceptor（D-A） alternating copolymer PDTCPDT-DTBT. The copolymer exhibited good chemical and thermal stabilities, with an optical band gap of 1.82 eV and a low-lying highest occupied molecular orbital（HOMO） energy level of-5.32 eV. When the copolymer was incorporated into polymer： fullerene（PC_（71）BM） blends to fabricate bulk heterojunction polymer solar cell devices, the devices exhibited a moderate maximum power conversion efficiency（PCE） of 5.90%.
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