Hexagonal BN-coated powders have been widely used in various engineering sectors,however,their pro-ductions are restricted by the complexity of gas-solid *** this study,guided by thermodynamics,a novel approach to syn...
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Hexagonal BN-coated powders have been widely used in various engineering sectors,however,their pro-ductions are restricted by the complexity of gas-solid *** this study,guided by thermodynamics,a novel approach to synthesize Layer-structured hexagonal BN(hBN)-coated high entropy diboride pow-ders in vacuum was developed,using metal salt Zr(NO_(3))4·5H_(2)O,HfCl_(4),NbC_(15),TaC_(15),C_(16)H_(36)O_(4)Ti,boric acid,and sucrose as raw *** adjusting the ratio of carbon to metal source(C/M),powders only consisting of two boride solid solutions and hBN were finally obtained,under an optimal process-ing condition of C/M=5.5 and synthesis temperature of 1400 ℃.Parts of hBN were found to coat on high-entropy metal diborides ceramic(HEB)particles,corresponding formation mechanism for core-shell structured powders was investigated,together with the liquid precursor assisted boro/carbothermal re-duction *** from as-synthesized core-shell powders,(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B2-11 vol%hBN ceramics were densified at 1900 ℃ under 50 MPa without holding,with a high relative density of 97.3%.
The doping process and thermoelectric properties of donor-acceptor(D-A)type copolymers are investigated with the representative poly([2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]3-fluoro-2-[(2-ethylhe...
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The doping process and thermoelectric properties of donor-acceptor(D-A)type copolymers are investigated with the representative poly([2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl))(PTB7-Th).The PTB7-Th is doped by Fe Cl;and only polarons are induced in its doped *** results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping *** energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping ***,the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved,which is one of the main reasons for the decrease of electrical conductivity at the later stage of *** best electrical conductivity and power factor are obtained to be 42.3 S·cm^(-1);and 33.9μW·mK^(-1),respectively,in the doped PTB7-Th film at room *** power factor is further improved to 38.3μW·mK^(-1);at 75℃.This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.
Owing to the high spatiotemporal resolution,the second near-infrared(NIR-II)imaging window can provide high imaging contrast with diminished tissue autofluorescence and suppressed photon scattering to pinpoint the loc...
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Owing to the high spatiotemporal resolution,the second near-infrared(NIR-II)imaging window can provide high imaging contrast with diminished tissue autofluorescence and suppressed photon scattering to pinpoint the locations for tumor *** to the unique optical properties and excellent fluorescence performance,quantum dots(QDs)are regarded as ideal nanoprobes for fluorescence-guided surgery(FGS).Moreover,QDs can be excited by a variety of light sources owing to the continuous and wide absorption ***,light-emitting diode(LED)was used as the excitation source of QDs-based nanoprobes to realize FGS of tumor with high *** the LED light could irradiate a large region with consistent light intensity,signal distortion at the edge of imaging field was *** signal intensity of the view edges under LED excitation can be improved by about 5 times compared to laser ***,more micro-vessels and smaller tumors(Vtumor<5 mm^(2))could be detected,thus providing more precise guidance for tumor resection surgery.
Perovskite solar cells(PSCs)emerge as the most promising photovoltaics(PV)for their high performance and potential convenient cost-effective production routes comparing to the sophomore PV *** printed PSCs with simpli...
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Perovskite solar cells(PSCs)emerge as the most promising photovoltaics(PV)for their high performance and potential convenient cost-effective production routes comparing to the sophomore PV *** printed PSCs with simplified device architecture and fabrication procedures could further enhance the competitive strength of PSC *** this work,we present an in-situ defect passivation(ISDP)assisted full-printing of high performance formamidine-lead bromide(FAPbBr_(3))*** three rapid printing steps are involved for electron transporting layer(ETL),perovskite and carbon to form a complete solar cell on the low-cost fluorine-doped tin oxide(FTO)***-chain polymer monomethyl ether polyethylene glycol is particularly utilized as the ISDP passivator,leading to conformal coating on the rough FTO and defect passivation for both ETL and perovskite during printing.A high efficiency of 10.85%(certified 10.14%)and a high V_(oc)up to 1.57 V are achieved for the printed *** unencapsulated PSCs maintain above 90%of the initial efficiency after continuously heating at 85℃for 1000 h and over 80%of the efficiency after the maximum power point tracking for 3500 *** fully printed semitransparent PSCs with carbon grids(CGs)show average visible light transmittance over 33%and an efficiency of 8.81%.
The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development,thus garnering significant *** perovskite solar cells,t...
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The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development,thus garnering significant *** perovskite solar cells,the hole transport layer plays a crucial *** the commonly employed organic small molecule hole transport material Spiro-OMeTAD,a certain period of oxidation treatment is required to achieve complete transport ***,this posttreatment oxidation processes typically rely on ambient oxidation,which poses challenges in terms of precise control and leads to degradation of the perovskite light absorption *** approach fails to meet the demands for high efficiency and stability in practical ***,the mechanism of ultrafast laser on Spiro-OMeTAD and the reaction process for laser-induced oxidation of it are ***2at Perovskite/Spiro-OMeTAD interface breaks down to produce I2upon ultrafast laser irradiation and I2promote the oxidation *** the laser irradiation oxidation processing,a higher stability of perovskite solar cells is *** work establishes a new approach toward oxidation treatment of Spiro-OMeTAD.
Seawater electrolysis is a highly promising method to produce high energy density hydrogen,especially in dry areas that have scarce freshwater ***,application of seawater electrolysis is confronted by two major proble...
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Seawater electrolysis is a highly promising method to produce high energy density hydrogen,especially in dry areas that have scarce freshwater ***,application of seawater electrolysis is confronted by two major problems associated with catalysts employed for the anodic oxygen evolution reaction(OER) including the competitive hypochlorite evolution reaction(HCER) and strong chloridion(Cl-) triggered *** studies aimed at overcoming these problems,a facile method has been developed to synthesize a homologous CoS2heterojunction as an OER *** to a difference in work functions at the interface and increased electron density,this material has directed electron transfer and strong chloridion repulsion properties,*** have shown that CoS2achieves low overpotentials of 289 and 322 mV at 10 mA cm-2current density in respective alkaline(1 M KOH) and alkaline simulated seawater ***,the outstanding stability of CoS2is reflected in a negligible decline in activity during promotion of the OER for 100 *** of density functional theory calculations reveal that the homologous CoS2heterojunction promotes directed electron transport for optimizing adsorption/desorption of reactive species and heightens the Cl-adsorption energy for strongly repulsing Cl-,phenomena that enhance OER performance in alkaline simulated seawater.
Photocatalytic reduction of CO_(2)has attracted considerable interest owing to its potential to resolve the energy and environmental ***,the lack of proficient photocatalysts has restricted the application of solar-dr...
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Photocatalytic reduction of CO_(2)has attracted considerable interest owing to its potential to resolve the energy and environmental ***,the lack of proficient photocatalysts has restricted the application of solar-driven photocatalytic CO_(2)***,we reported an S-scheme heterojunction by combining g-C_(3)N_(4)with La^(3+)and Rh^(3+)co-doped SrTiO_(3)through the electrostatic self-assembly method for the efficient photocatalytic CO_(2)*** comparison with g-C_(3)N_(4),the asprepared CN/LRSTO-30 wt%S-scheme heterojunction not only possesses a broadened visible-light response due to the defect states in La,Rh co-doped SrTiO_(3)induced by codoped La^(3+)and Rh^(3+)but also has more adsorption sites for the capture and activation of CO_(2)***,separation and transfer efficiency of the photoinduced charge carriers is much enhanced in the CN/LRSTO-30wt%S-scheme heterojunction via its robust internal electric field,which is firmly demonstrated by in situ irradiation X-ray photoelectron spectroscopy ***,the prepared S-scheme heterojunction achieves impressive photocatalytic CO_(2)reduction performance with an average CO and CH4 evolution rate of4.1-1.8μmol·g^(-1)·h^(-1),respectively,which are~1.9 and~22.5-fold higher than those of pure g-C_(3)N_(4).This study provides innovative perspectives on the design of creative S-scheme heterojunctions for applications in photocatalytic CO_(2)reduction.
A high-quality tin oxide electron transport layer(ETL) is a key common factor to achieve high-performance perovskite solar cells(PSCs). However, the conventional annealing technique to prepare high-quality ETLs by con...
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A high-quality tin oxide electron transport layer(ETL) is a key common factor to achieve high-performance perovskite solar cells(PSCs). However, the conventional annealing technique to prepare high-quality ETLs by continuous heating under near-equilibrium conditions requires high temperatures and a long fabrication time. Alternatively, we present a non-equilibrium, photoexcitation-induced passivation technique that uses multiple ultrashort laser pulses. The ultrafast photoexcitation and following electron–electron and electron–phonon scattering processes induce ultrafast annealing to efficiently passivate surface and bulk defects, and improve the crystallinity of Sn O2, resulting in suppressing the carrier recombination and facilitating the charge transport between the ETL and perovskite interface. By rapidly scanning the laser beam, the annealing time is reduced to several minutes, which is much more efficient compared with conventional thermal annealing. To demonstrate the university and scalability of this technique, typical antisolvent and antisolvent-free processed hybrid organic–inorganic metal halide PSCs have been fabricated and achieved the power conversion efficiency(PCE) of 24.14% and 22.75% respectively, and a12-square-centimeter module antisolvent-free processed perovskite solar module achieves a PCE of 20.26%,with significantly enhanced performance both in PCE and stability. This study establishes a new approach towards the commercialization of efficient low-temperature manufacturing of PSCs.
We studied a method to prepare a novel titanium dioxide(TiO_(2))composite photocatalyst,starting from improving the separation efficiency of photogenerated electrons and *** TiO_(2)microspheres were prepared by sol-ge...
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We studied a method to prepare a novel titanium dioxide(TiO_(2))composite photocatalyst,starting from improving the separation efficiency of photogenerated electrons and *** TiO_(2)microspheres were prepared by sol-gel method and loaded onto Ti3C2Tx(Mxene).The high electrical conductivity of Mxene was utilized to transfer photogenerated electrons quickly and effectively prevent their *** adjusting the addition amount of Mxene,the hydrogen production efficiency of the sample was greatly improved,and the maximum efficiency reached 135.2μmol·g^(-1)·h^(-1),which was twice that of pure TiO_(2).The nanocomposites were characterized by XRD,PL,TEM and SEM analysis and electrochemical methods,and the test proved that the improvement of hydrogen production efficiency was caused by the improvement of the separation efficiency of photogenerated electrons and *** work demonstrates the application of Mxene as a catalyst to improve efficiency and broadens the application prospects of Mxene.
A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed *** method can evaluate the longitudinal stress evolution of each composite layer as impregnated filaments ...
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A numerical method to predict the bursting strength of filament wound composite rocket motor case is proposed *** method can evaluate the longitudinal stress evolution of each composite layer as impregnated filaments with fiber tension are wound layer by layer,and consider the effects of accumulated stress and deformation during filament winding on the bursting strength of composite ***∅520 mm composite cases as a case study,the filament-winding-process-induced stress and deformation as well as progressive damage behavior are numerically predicted,followed by a comparison with experimental *** numerical results show that the predicted bursting pressures for composite cases manufactured on the mandrels with and without a flexible component are 14.20 MPa and 21.40 MPa,*** values exhibit slight deviation from the measured pressures of 13.50 MPa and 21.57 ***,the predicted damage locations,situated respectively in the dome and cylinder,agree well with the experimental *** observations indicate that use of flexible component reduces the load-bearing capacity of the ***,it validates the reliability and accuracy of the proposed numerical method in predicting the bursting strength of composite cases.
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