Room-temperature phosphorescence(RTP)materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption,anti-counterfeiting,and sensing.However,most polym...Room-temperature phosphorescence(RTP)materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption,anti-counterfeiting,and sensing.However,most polymers exhibit a short RTP lifetime(<1 s)because of their unstable triplet excitons.Herein,a new strategy of polymer chain stabilized phosphorescence(PCSP),which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response,has been reported.The rigid polymer chains of poly(methyl mathacrylate)(PMMA)immobilize the emitter molecules through multiple interactions between them,giving rise to efficient RTP.Meanwhile,the loosely-packed amorphous polymer chains allow oxygen to diffuse inside,endowing the doped polymers with oxygen sensitivity.Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum,which was among the best performance of PMMA.Intriguingly,their RTP was rapidly quenched in the presence of oxygen.Furthermore,RTP microparticles with a diameter of 1.63μm were synthesized using in situ dispersion polymerization technique.Finally,oxygen sensors for quick,visual,and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis.With distinctive advantages such as an ultralong lifetime,oxygen sensitivity,ease of fabrication,and cost-effectiveness,PCSP opens a new avenue to sensitive materials for oxygen detection.展开更多
Germanium(Ge)-air battery,a new type of semiconductor-air battery,has garnered increasing attention owing to its environmental friendliness,safety,and excellent dynamic performance.However,the flat Ge anode is prone t...Germanium(Ge)-air battery,a new type of semiconductor-air battery,has garnered increasing attention owing to its environmental friendliness,safety,and excellent dynamic performance.However,the flat Ge anode is prone to passivation,owing to GeO_(2) accumulation on its surface,resulting in premature discharge termination.In this study,various nano-Ge pyramid structures(GePS)were prepared using chemical etching(CE)and metal-assisted chemical etching(MACE)methods to enhance the specific surface area of the Ge anode,thereby facilitating the dissolution of the passivation layer.This study revealed that the MACE method significantly accelerated the etching rate of the Ge surface,producing exceptional GePS.Furthermore,Ge-air batteries employing Ge anodes prepared using MACE demonstrated an exceptional discharge life of up to 9240 h(385 days).The peak power density reached 3.03mW/cm^(2),representing improvements of more than 2 times and 1.8 times,respectively,compared with batteries using flat Ge anodes.This study presents a straightforward approach to enhance Ge anode performance,thereby expanding the potential applications of Ge-air batteries.展开更多
Lithium-ion batteries(LIBs)with high energy and power densities are extensively applied in various fields,such as portable electronic devices and electric vehicles.Compared with traditional inorganic electrode materia...Lithium-ion batteries(LIBs)with high energy and power densities are extensively applied in various fields,such as portable electronic devices and electric vehicles.Compared with traditional inorganic electrode materials,which confront the challenges of resource scarcity and restrained energy density,covalent organic frameworks(COFs)are attractive candidates as electrode materials for the next-generation LIBs.Herein,rational Schiff-base condensation of tetraphenyl-pphenylenediamine(TPPDA)and 5,12-bis(4-(5,5-dimethyl-1,3-dioxan-2-yl)phenyl)-5,12-dihydroquinolino[2,3-b]acridine-7,14-dione(QA-PCHO)yields a two-dimensional(2D)QT-COF as the cathode.2D QT-COF features a high crystalline nature with kgm topology and hierarchically micro-/meso-porous structure,which can strengthen the stability of the chemical structure and promote the fast Li^(+)diffusion under large current densities.These merits make the QT-COF cathode exhibit 110,000 ultralong cycling stability with~100%retention at 10,000 mA g^(-1)upon running for 150 days,exceeding all the thus far reported COF-based electrodes.Additionally,the combination of ex situ X-ray photoelectron spectroscopy,in-situ Raman investigation,and theoretical calculation exhaustively unveils the ion storage mechanism and the rationale underlying the exceptional property of QT-COF.The present result offers an advanced COF with enormous potential as organic electrodes for LIBs,hopefully solving the challenges of ultrahigh cycling stability with superb capacity preservation at high current densities.展开更多
Single negatively charged nitrogen vacancy(NV-)centers in diamond have emerged as promising platforms for quantum information science,where long coherence times are essential for advancing quantum technologies.However...Single negatively charged nitrogen vacancy(NV-)centers in diamond have emerged as promising platforms for quantum information science,where long coherence times are essential for advancing quantum technologies.However,traditional fabrication methods often introduce lattice damage during the irradiation process used to create vacancies,significantly impairing the spin coherence properties of NV-centers.展开更多
Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life ...Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life Zn2+storage based on a pseudocapacitive storage mechanism.In the RuO2·H2O||Zn zinc-ion hybrid capacitors with Zn(CF3SO3)2 aqueous electrolyte,the RuO2·H2O cathode can reversibly store Zn2+in a voltage window of 0.4-1.6 V(vs.Zn/Zn2+),delivering a high discharge capacity of 122 mAh g?1.In particular,the zinc-ion hybrid capacitors can be rapidly charged/discharged within 36 s with a very high power density of 16.74 kW kg?1 and a high energy density of 82 Wh kg?1.Besides,the zinc-ion hybrid capacitors demonstrate an ultralong cycle life(over 10,000 charge/discharge cycles).The kinetic analysis elucidates that the ultrafast Zn2+storage in the RuO2·H2O cathode originates from redox pseudocapacitive reactions.This work could greatly facilitate the development of high-power and safe electrochemical energy storage.展开更多
The main challenges in development of traditional liquid lithium-sulfur batteries are the shuttle effect at the cathode caused by the polysulfide and the safety concern at the Li metal anode arose from the dendrite fo...The main challenges in development of traditional liquid lithium-sulfur batteries are the shuttle effect at the cathode caused by the polysulfide and the safety concern at the Li metal anode arose from the dendrite formation.All-solid-state lithium-sulfur batteries have been proposed to solve the shuttle effect and prevent short circuits.However,solid-solid contacts between the electrodes and the electrolyte increase the interface resistance and stress/strain,which could result in the limited electrochemical performances.In this work,the cathode of all-solid-state lithium-sulfur batteries is prepared by depositing sulfur on the surface of the carbon nanotubes(CNTs@S)and further mixing with Li10GeP2S12 electrolyte and acetylene black agents.At 60℃,CNTs@S electrode exhibits superior electrochemical performance,delivering the reversible discharge capacities of 1193.3,959.5,813.1,569.6 and 395.5 mAhg^-1 at the rate of 0.1,0.5,1,2 and 5 C,respectively.Moreover,the CNTs@S is able to demonstrate superior high-rate capability of 660.3 mAhg^-1 and cycling stability of 400 cycles at a high rate of 1.0 C.Such uniform distribution of the CNTs,S and Li10GeP2S12 electrolyte increase the electronic and ionic conductivity between the cathode and the electrolyte hence improves the rate performance and capacity retention.展开更多
The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution rea...The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is currently an urgent issue.Herein,an efficient bifunctional electrocatalyst featured by ultralong N,S-doped carbon nano-hollow-sphere chains about 1300 nm with encapsulated Co nanoparticles(Co-CNHSCs)is developed.The multifunctional catalytic properties of Co together with the heteroatom-induced charge redistribution(i.e.,modulating the electronic structure of the active site)result in superior catalytic activities toward OER and ORR in alkaline media.The optimized catalyst Co-CNHSC-3 displays an outstanding electrocatalytic ability for ORR and OER,a high specific capacity of 1023.6 mAh gZn^(-1),and excellent reversibility after 80 h at 10mA cm^(-2)in a Zn-air battery system.This work presents a new strategy for the design and synthesis of efficient multifunctional carbon-based catalysts for energy storage and conversion devices.展开更多
Largescale vaporsolid synthesis of ultralong silicon nitride （Si3N4） nanowires was achieved by using simple thermal evaporation of mixture powders of active carbon and monoxide silicon. The products were charac teri...Largescale vaporsolid synthesis of ultralong silicon nitride （Si3N4） nanowires was achieved by using simple thermal evaporation of mixture powders of active carbon and monoxide silicon. The products were charac terized by Xray diffraction, scanning electron microscopy, energydispersive Xray spectroscopy, and transmission electron microscopy. The results suggest that the silicon nitride nanowires have a smooth surface, with lengths of up to several hundreds of microns and diameters of 100300 nm. A detailed study of both the chemical and structural composition was performed. Such ultralong sil icon nitride nanowires demonstrate potential applications as materials for constructing nanoscale devices and as reinforcement in advanced composites.展开更多
Organic phosphorescence materials demonstrate potential optoelectronic applications due to their remarkably ultralong organic phosphorescence(UOP)lifetime and abundant optical characteristics prior to the fluorescence...Organic phosphorescence materials demonstrate potential optoelectronic applications due to their remarkably ultralong organic phosphorescence(UOP)lifetime and abundant optical characteristics prior to the fluorescence materials.For a better insight into the intrinsic relationship among regioisomeric molecules,crystalline interactions,and phosphorescence properties,three crystalline dicarbazol-9-yl pyrazine-based regioisomers with para-,meta-and ortho-convergent substitutions(p-DCzP,m-DCzP,and o-DCzP)were designed and presented gradually increased UOP lifetimes prolonging from 63.14,127.93 to 350.46 ms,respectively,due to the regioisomerism effect(RIE)which would be an effective strategy for better understanding of structure-property of UOP materials.展开更多
The high specific capacity and low negative electrochemical potential of lithium metal anodes(LMAs),may allow the energy density threshold of Li metal batteries(LMBs)to be pushed higher.However,the existing detrimenta...The high specific capacity and low negative electrochemical potential of lithium metal anodes(LMAs),may allow the energy density threshold of Li metal batteries(LMBs)to be pushed higher.However,the existing detrimental issues,such as dendritic growth and volume expansion,have hindered the practical implementation of LMBs.Introducing three-dimensional frameworks(e.g.,copper and nickel foam),have been regarded as one of the fundamental strategies to reduce the local current density,aiming to extend the Sand'time.Nevertheless,the local environment far from the skeleton is almost the same as the typical plane Li,due to macroporous space of metal foam.Herein,we built a double-layered 3D current collector of Li alloy anchored on the metal foam,with micropores interconnected macropores,via a viable thermal infiltration and cooling strategy.Due to the excellent electronic and ionic conductivity coupled with favorable lithiophilicity,the Li alloy can effectively reduce the nucleation barrier and enhance the Li^(+)transportation rate,while the metal foam can role as the primary promotor to enlarge the surface area and buffer the dimensional variation.Synergistically,the Li composite anode with hierarchical structure of primary and secondary scaffolds realized the even deposition behavior and minimum volume expansion,outputting preeminent prolonged cycling performances under high rate.展开更多
Ultralong organic phosphorescent materials have invoked considerable attention for their great potential in sensing,data encryption,information anti-counterfeiting and so forth.However,effective ways to achieve highly...Ultralong organic phosphorescent materials have invoked considerable attention for their great potential in sensing,data encryption,information anti-counterfeiting and so forth.However,effective ways to achieve highly efficient ultralong organic phosphorescence(UOP)in metal-free organic materials remain a great challenge.Herein,we designed three isomers based on asymmetric triazines with various bromine substituted positions.Impressively,phosphorescence efficiency of p-BrAT in solid state can reach up to 9.7%with a long lifetime of 386 ms,which was one of the highest efficient UOP materials reported so far.Theoretical calculations further demonstrated that para-substitution exhibited the most effective radiative transition for triplet excitons.These results will provide an effective approach to achieving highly efficient UOP materials.展开更多
Ultra-long room temperature phosphorescence(URTP) has been increasingly recognized in pure organic luminophor in recent years. Through a simpler molecular design and charge separation-recombination pathway, organic lu...Ultra-long room temperature phosphorescence(URTP) has been increasingly recognized in pure organic luminophor in recent years. Through a simpler molecular design and charge separation-recombination pathway, organic luminophor can achieve even better URTP properties. In this work, we achieved URTP in a system of host-vip doped benzophenone derivatives whose phosphorescence is visible to the naked eye. The differences in the wavelength lifetimes of luminescent emission correspond to different photophysical mechanisms. Through a combination of theoretical calculations and experiments, the host acts as a powerful substrate that restricts the motion of the vip and inhibits the non-radiative transitions of the vip, accompanied by a charge transfer separation-recombination process between the host and the vip, resulting in an URTP phenomenon. Transient absorption results demonstrate the existence of a charge-separated state. The design strategy via charge separation is generic and easy to implement,providing a direction for the future design of doped URTP.展开更多
Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the exp...Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the explanation of the luminescent properties of(R)-5-(9H-carbazol-9-yl)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)isoindoline-1,3-dione((R)-ImNCz),which was recently reported[Chemical Engineering Journal 418129167(2021)].The polarizable continuum model(PCM)and the combined quantum mechanics and molecular mechanics(QM/MM)method are adopted in simulation of the property of the molecule in the gas phase,solvated in acetonitrile and in aggregation states.It is found that large spin–orbit coupling(SOC)constants and a smaller energy gap between the first singlet excited state and the first triplet excited state(△E_(st))in prism-like single crystals(SC_(p)-form)are responsible for the TADF of(R)-lmNCz,while no TADF is found in block-like single crystals(SC_(b)-form)with a larger △E_(st).The multiple ultralong phosphorescence(UOP)peaks in the spectrum are of complex origins,and they are related not only to ImNCz but also to a minor amount of impurities(ImNBd)in the crystal prepared in the laboratory.The dimer has similar phosphorescence emission wavelengths to the(R)-lmNCz-SC_(p) monomers.The complex composed of(R)-lmNCz and(R)-lmNBd contributes to the phosphorescent emission peak at about 600 nm,and the phosphorescent emission peak at about 650 nm is generated by(R)-lmNBd.This indicates that the impurity could also contribute to emission in molecular crystals.The present calculations clarify the relationship between the molecular aggregation and the light-emitting properties of the TADF emitters and will therefore be helpful for the design of potentially more useful TADF emitters.展开更多
Constructing heterostructure is considered as an effective strategy to address the sluggish electronic and ionic kinetics of anode materials for sodium ion batteries(SIBs).However,realizing the orientated growth and u...Constructing heterostructure is considered as an effective strategy to address the sluggish electronic and ionic kinetics of anode materials for sodium ion batteries(SIBs).However,realizing the orientated growth and uniform distribution of the heterostructure is still a great challenge.Herein,the regulated novel CoSe_(2)/NiSe_(2)heterostructure confined in N-doped carbon nanofibers(CoSe_(2)/NiSe_(2)@N-C)are prepared by using Co/Ni-ZIF template,in which,the CoSe_(2)/NiSe_(2)heterostructures realize uniform distribution on a micro level.Benefiting from the unique heterostructure and N-doped carbon nanofibers,the CoSe_(2)/NiSe_(2)@N-C deliveries superior rate capability and durable cycle lifespan with a reversible capacity of 400.5 mA h g^(-1)after 5000 cycles at 2 A g^(-1).The Na-ion full battery with CoSe_(2)/NiSe_(2)@N-C anode and layered oxide cathode displays a remarkable energy density of 563 W h kg^(-1)with 241.1 W kg^(-1)at 0.1 A g^(-1).The theoretical calculations disclose that the periodic and directional built-in electric-field along with the heterointerfaces of CoSe_(2)/NiSe_(2)@N-C can accelerate electrochemical reaction kinetics.The in(ex)situ experimental measurements reveal the reversible conversion reaction and stable structure of CoSe_(2)/NiSe_(2)@N-C during Na+insertion/extraction.The study highlights the potential ability of precisely controlled heterostructure to stimulate the electrochemical performances of advanced anode for SIBs.展开更多
Ultralong organic afterglow materials are being actively explored as attractive candidates for a wide range of applications such as data storage,security inks,emergency lighting,etc.,due to their unique long-lived exc...Ultralong organic afterglow materials are being actively explored as attractive candidates for a wide range of applications such as data storage,security inks,emergency lighting,etc.,due to their unique long-lived excited state properties and inherent advantages of low cost,appreciable functionality and ease of preparation.In the last three years,much effort has been devoted to achieving efficient ultralong afterglow from organic small molecules,which possess controllable intermolecular interactions and defined energy levels,making them a good platform to suppress the non-radiative decays,hence stabilizing the excitons for efficient afterglow emissions at room temperature.Nevertheless,there has been a lack of reviews on how efficient ultralong organic afterglow can be systematically achieved from small molecular host-vip materials,which is not conducive to the development of the field.In this review,we have outlined and summarized small-molecule ultralong organic afterglow materials based on different emission mechanisms.We have included emission mechanisms involving ultralong room-temperature phosphorescence(URTP),ultralong thermally activated delayed fluorescence(UTADF)and organic long persistent luminescence(OLPL),where the latter two mechanisms have rarely been reported.In addition,challenges and future perspectives are discussed to emphasize the future directions.展开更多
Carbon nanotubes have attracted extensive interest owing to their extraordinary properties and wide applications in many fields.Among various types of carbon nanotubes,only ultralong carbon nanotubes with macroscale l...Carbon nanotubes have attracted extensive interest owing to their extraordinary properties and wide applications in many fields.Among various types of carbon nanotubes,only ultralong carbon nanotubes with macroscale lengths,low defect concentrations,and high degrees of alignment can fully demonstrate their intrinsic performance.These attributes make ultralong carbon nanotubes highly promising for applications in cutting-edge fields,such as carbon-based integrated circuits,ultra-strong fibers,and transparent conductive films.However,the mass production of ultralong carbon nanotubes with precise structural control remains a major challenge,limiting their widespread applications.In the past decades,great progress has been achieved in the study of ultralong carbon nanotubes.In this review,we summarized the growth mechanisms and the controlled synthesis strategies of ultralong carbon nanotubes.Then,we introduced the advanced applications of ultralong carbon nanotubes in many areas,such as field-effect transistors,sensors,and photodetectors.Finally,we discussed the remaining challenges and offered our perspectives on the future directions of this field.展开更多
Room-temperature phosphorescence(RTP)materials play a vital role in security domain due to their unique optical properties.However,most average lifetimes of available RTP materials remain less than 1 s in aqueous-phas...Room-temperature phosphorescence(RTP)materials play a vital role in security domain due to their unique optical properties.However,most average lifetimes of available RTP materials remain less than 1 s in aqueous-phase media,which is unfavorable to practical applications.Herein,an ex-situ covalent coupling strategy is proposed to fabricate liquid-phase long-lived RTP materials by combining SiO_(2)microspheres with the feather-derived carbon dots(CDs).Astonishingly,the aqueous dispersion of the resulting CDs@SiO_(2)microspheres exhibits a lifetime of up to 2.38 s with an absolute quantum yield of 22%.Moreover,the average lifetime of the solid CDs@SiO_(2)is as long as 3.04 s,which is superior to that of existing RTP carbon-based materials.The striking enhancements in the RTP of the CDs@SiO_(2)composites are mainly attributed to the immobilization of the formed Si–O–C covalent bonds and Si–O–Si rigid networks.The CDs@SiO_(2)composites were subsequently applied in the fields of information encryption and anti-fake.Interestingly,the CDs@SiO_(2)composites possess intriguing,reversible and stable optical properties,including water-responsive structural colors,blue fluorescence and cyan RTP,exhibiting excellent covert performance in applications of information encryption and decryption,and high-level anticounterfeiting.These findings provide not only a straightforward strategy for developing multiresponsive optical materials but also a more secure anticounterfeiting technology.展开更多
Ultralong thermally activated delayed fluorescence(UTADF)materials play an important role in realizing time-dependent color-tunable afterglow.Some typical carbazole(Cz)derivatives have been reported to exhibit UTADF p...Ultralong thermally activated delayed fluorescence(UTADF)materials play an important role in realizing time-dependent color-tunable afterglow.Some typical carbazole(Cz)derivatives have been reported to exhibit UTADF properties.However,a 10-fold difference in TADF lifetime was found between commercial Cz derivatives and the corresponding lab-synthesized ones,which indicated that UTADF may not be derived from the single Cz derivatives as reported.To reveal the real mechanism,we synthesized three Cz derivatives and one isomer to form three host-vip pairs for optical studies.The photophysical properties revealed that UTADF originated from the intermolecular charge transfer between host and vip,while the ultralong organic phosphorescence was from the vip.Thanks to the rich color variations in luminescence displayed by 4-(1H-benzo[f]indol-1-yl)−4′-(9H-carbazol-9-yl)-[1,1′-biphenyl]−3,3′-dicarbonitrile/4,4′-di(9H-carbazol-9-yl)-[1,1′-biphenyl]−3,3′-dicarbonitrile(CBP-2CN)at different delay times,it can be applied to realize multi-dimensional encryption in both delay time and luminescent color.展开更多
The high power density and intelligence of next-generation flexible electronic devices bring many challenges to fabricate flexible composite films with electromagnetic interference(EMI)shielding effectiveness(SE)prope...The high power density and intelligence of next-generation flexible electronic devices bring many challenges to fabricate flexible composite films with electromagnetic interference(EMI)shielding effectiveness(SE)property and excellent toughness via a simple method.Herein,inspired by the layered structure and biopolymer matrix networks in natural nacre,nacre-like layered Ti_(3)C2TX(MXene)/aramid nanofiber(ANF)films were fabricated through sol-gel,vacuum-assisted filtration,and hot-pressing.Three-dimensional(3D)interconnected aramid nanofibers networks between adjacent layered MXene result in an ultralong strain-to-failure of the film.Even though the functional filler MXene contents are as high as 60 wt.%and 70 wt.%,the strain-to-failure of the films could reach astonishing values of 18.34%±1.86%and 14.43%±1.26%,respectively.And the tensile strength could maintain about 85 MPa.Excitingly,with such a high filler,the film can also withstand double folding and vigorous rubbing without damage,which could better adapt to a harsh application environment.The result means that this work provides a convenient way to prepare other high functional filler composite films with excellent mechanical performance.The EMI SE values could reach 45 and 52.15 dB at 60 wt.%and 70 wt.%MXene in 8.2–12.4 GHz.Meanwhile,the films have prominent Joule heating properties,high sensitivity(<15 s),small voltage operation(0.5 V),and high operation constancy(1300 s).Therefore,nacre-inspired MXene/ANF composite films in this work have ability to apply in many areas including communication technology,military,and aerospace.展开更多
We experimentally demonstrated a type of tunable and switchable harmonic h-shaped pulse generation in a thulium-doped fiber(TDF) laser passively mode locked by using an ultralong nonlinear optical loop mirror.The tota...We experimentally demonstrated a type of tunable and switchable harmonic h-shaped pulse generation in a thulium-doped fiber(TDF) laser passively mode locked by using an ultralong nonlinear optical loop mirror.The total cavity length was ～3.03 km, the longest ever built for a TDF laser to our best knowledge, which resulted in an ultralarge anomalous dispersion over -200 ps^2 around the emission wavelength. The produced h-shaped pulse can operate either in a fundamental or in a high-order harmonic mode-locking(HML) state depending on pump power and intra-cavity polarization state(PS). The pulse duration, no matter of the operation state, was tunable with pump power. However, pulse breaking and self-organizing occurred, resulting in high-order HML,when the pump power increased above a threshold. At a fixed pump power, the order of HML was switchable from one to another by manipulating the PS. Switching from the 8 th up to the 48 th order of HML was achieved with a fixed pump power of ～4.15 W. Our results revealed the detailed evolution and switching characteristics of the HML and individual pulse envelope with respect to both the pump power and PS. We have also discussed in detail the mechanisms of both the h-shaped pulse generation and the switching of its HML. This contribution would be helpful for further in-depth study on the underlying dynamics of long-duration particular-envelope pulses with ultralarge anomalous dispersion and ultralong roundtrip time.展开更多
基金National Natural Science Foundation of China(No.22475241)Guangdong Basic and Applied Basic Research Foundation(Nos.2022A1515010826 and 2023A1515012696)the Fundamental Research Funds for the Central Universities(Nos.17lgjc03 and 18lgpy04).
文摘Room-temperature phosphorescence(RTP)materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption,anti-counterfeiting,and sensing.However,most polymers exhibit a short RTP lifetime(<1 s)because of their unstable triplet excitons.Herein,a new strategy of polymer chain stabilized phosphorescence(PCSP),which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response,has been reported.The rigid polymer chains of poly(methyl mathacrylate)(PMMA)immobilize the emitter molecules through multiple interactions between them,giving rise to efficient RTP.Meanwhile,the loosely-packed amorphous polymer chains allow oxygen to diffuse inside,endowing the doped polymers with oxygen sensitivity.Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum,which was among the best performance of PMMA.Intriguingly,their RTP was rapidly quenched in the presence of oxygen.Furthermore,RTP microparticles with a diameter of 1.63μm were synthesized using in situ dispersion polymerization technique.Finally,oxygen sensors for quick,visual,and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis.With distinctive advantages such as an ultralong lifetime,oxygen sensitivity,ease of fabrication,and cost-effectiveness,PCSP opens a new avenue to sensitive materials for oxygen detection.
基金financially supported by the National Natural Science Foundation of China(No.61904073)Spring City Plan-Special Program for Young Talents(No.K202005007)+2 种基金Yunnan Talents Support Plan for Yong Talents(No.XDYC-QNRC-2022-0482)Yunnan Local Colleges Applied Basic Research Projects(No.202101BA070001-138)Frontier Research Team of Kunming University 2023.
文摘Germanium(Ge)-air battery,a new type of semiconductor-air battery,has garnered increasing attention owing to its environmental friendliness,safety,and excellent dynamic performance.However,the flat Ge anode is prone to passivation,owing to GeO_(2) accumulation on its surface,resulting in premature discharge termination.In this study,various nano-Ge pyramid structures(GePS)were prepared using chemical etching(CE)and metal-assisted chemical etching(MACE)methods to enhance the specific surface area of the Ge anode,thereby facilitating the dissolution of the passivation layer.This study revealed that the MACE method significantly accelerated the etching rate of the Ge surface,producing exceptional GePS.Furthermore,Ge-air batteries employing Ge anodes prepared using MACE demonstrated an exceptional discharge life of up to 9240 h(385 days).The peak power density reached 3.03mW/cm^(2),representing improvements of more than 2 times and 1.8 times,respectively,compared with batteries using flat Ge anodes.This study presents a straightforward approach to enhance Ge anode performance,thereby expanding the potential applications of Ge-air batteries.
基金financially supported by the Natural Science Foundation of China(22235001,22175020 and 22001015)the Fundamental Research Funds for the Central Universities(No.2050205)+2 种基金the Guizhou Provincial Key Laboratory Platform Project(ZSYS[2025]008)the Talent Program of Guizhou University(No.[2024]11)the Science and Technology Project of Jiangsu Province(BZ2022056)。
文摘Lithium-ion batteries(LIBs)with high energy and power densities are extensively applied in various fields,such as portable electronic devices and electric vehicles.Compared with traditional inorganic electrode materials,which confront the challenges of resource scarcity and restrained energy density,covalent organic frameworks(COFs)are attractive candidates as electrode materials for the next-generation LIBs.Herein,rational Schiff-base condensation of tetraphenyl-pphenylenediamine(TPPDA)and 5,12-bis(4-(5,5-dimethyl-1,3-dioxan-2-yl)phenyl)-5,12-dihydroquinolino[2,3-b]acridine-7,14-dione(QA-PCHO)yields a two-dimensional(2D)QT-COF as the cathode.2D QT-COF features a high crystalline nature with kgm topology and hierarchically micro-/meso-porous structure,which can strengthen the stability of the chemical structure and promote the fast Li^(+)diffusion under large current densities.These merits make the QT-COF cathode exhibit 110,000 ultralong cycling stability with~100%retention at 10,000 mA g^(-1)upon running for 150 days,exceeding all the thus far reported COF-based electrodes.Additionally,the combination of ex situ X-ray photoelectron spectroscopy,in-situ Raman investigation,and theoretical calculation exhaustively unveils the ion storage mechanism and the rationale underlying the exceptional property of QT-COF.The present result offers an advanced COF with enormous potential as organic electrodes for LIBs,hopefully solving the challenges of ultrahigh cycling stability with superb capacity preservation at high current densities.
基金supported by the National Natural Science Foundation of China(Grant Nos.112374012 and 11974208)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2023JQ001 and tsqn202211128)。
文摘Single negatively charged nitrogen vacancy(NV-)centers in diamond have emerged as promising platforms for quantum information science,where long coherence times are essential for advancing quantum technologies.However,traditional fabrication methods often introduce lattice damage during the irradiation process used to create vacancies,significantly impairing the spin coherence properties of NV-centers.
基金the financial support by the Australian Research Council through the ARC Discovery projects(DP160104340 and DP170100436)Rail Manufacturing Cooperative Research Centre(RMCRC 1.1.1 and RMCRC 1.1.2 projects)+1 种基金financially supported by the International Science&Technology Cooperation Program of China(No.2016YFE0102200)Shenzhen Technical Plan Project(No.JCYJ20160301154114273).
文摘Rechargeable aqueous zinc-ion hybrid capacitors and zincion batteries are promising safe energy storage systems.In this study,amorphous RuO2·H2O for the first time was employed to achieve fast and ultralong-life Zn2+storage based on a pseudocapacitive storage mechanism.In the RuO2·H2O||Zn zinc-ion hybrid capacitors with Zn(CF3SO3)2 aqueous electrolyte,the RuO2·H2O cathode can reversibly store Zn2+in a voltage window of 0.4-1.6 V(vs.Zn/Zn2+),delivering a high discharge capacity of 122 mAh g?1.In particular,the zinc-ion hybrid capacitors can be rapidly charged/discharged within 36 s with a very high power density of 16.74 kW kg?1 and a high energy density of 82 Wh kg?1.Besides,the zinc-ion hybrid capacitors demonstrate an ultralong cycle life(over 10,000 charge/discharge cycles).The kinetic analysis elucidates that the ultrafast Zn2+storage in the RuO2·H2O cathode originates from redox pseudocapacitive reactions.This work could greatly facilitate the development of high-power and safe electrochemical energy storage.
基金supported by the National Key R&D Program of China (Grant no. 2016YFB0100105)the National Natural Science Foundation of China (Grant no. 51872303)+1 种基金Zhejiang Provincial Natural Science Foundation of China (Grant no. LD18E020004, LQ16E020003, LY18E020018, LY18E030011)Youth Innovation Promotion Association CAS (2017342)
文摘The main challenges in development of traditional liquid lithium-sulfur batteries are the shuttle effect at the cathode caused by the polysulfide and the safety concern at the Li metal anode arose from the dendrite formation.All-solid-state lithium-sulfur batteries have been proposed to solve the shuttle effect and prevent short circuits.However,solid-solid contacts between the electrodes and the electrolyte increase the interface resistance and stress/strain,which could result in the limited electrochemical performances.In this work,the cathode of all-solid-state lithium-sulfur batteries is prepared by depositing sulfur on the surface of the carbon nanotubes(CNTs@S)and further mixing with Li10GeP2S12 electrolyte and acetylene black agents.At 60℃,CNTs@S electrode exhibits superior electrochemical performance,delivering the reversible discharge capacities of 1193.3,959.5,813.1,569.6 and 395.5 mAhg^-1 at the rate of 0.1,0.5,1,2 and 5 C,respectively.Moreover,the CNTs@S is able to demonstrate superior high-rate capability of 660.3 mAhg^-1 and cycling stability of 400 cycles at a high rate of 1.0 C.Such uniform distribution of the CNTs,S and Li10GeP2S12 electrolyte increase the electronic and ionic conductivity between the cathode and the electrolyte hence improves the rate performance and capacity retention.
基金Collaborative Innovation Center of Suzhou Nano Science and TechnologyNational Natural Science Foundation of China,Grant/Award Numbers:21773163,22271203+3 种基金EPSRC for an Overseas Travel Grant,Grant/Award Number:EP/R023816/1State Key Laboratory of Organometallic Chemistry of Shanghai Institute of Organic Chemistry,Grant/Award Number:KF2021005Priority Academic Program Development of Jiangsu Higher Education InstitutionsProject of Scientific and Technologic Infrastructure of Suzhou,Grant/Award Number:SZS201905。
文摘The development of simple and effective strategies to prepare electrocatalysts,which possess unique and stable structures comprised of metal/nonmetallic atoms for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is currently an urgent issue.Herein,an efficient bifunctional electrocatalyst featured by ultralong N,S-doped carbon nano-hollow-sphere chains about 1300 nm with encapsulated Co nanoparticles(Co-CNHSCs)is developed.The multifunctional catalytic properties of Co together with the heteroatom-induced charge redistribution(i.e.,modulating the electronic structure of the active site)result in superior catalytic activities toward OER and ORR in alkaline media.The optimized catalyst Co-CNHSC-3 displays an outstanding electrocatalytic ability for ORR and OER,a high specific capacity of 1023.6 mAh gZn^(-1),and excellent reversibility after 80 h at 10mA cm^(-2)in a Zn-air battery system.This work presents a new strategy for the design and synthesis of efficient multifunctional carbon-based catalysts for energy storage and conversion devices.
基金supported by the Key Program of the National Natural Science Foundation of China(No.19934003)the Grand Program of Natural Science Research of Anhui Education Department(No.ZD2007003-1)+1 种基金the Natural Science Research Program of Universities and Colleges of Anhui Province(No.KJ2008A19ZC)the Opening Program of Cultivating Baseof Anhui Key Laboratory of Spintronics and Nano-materials(No.2012YKF10)
文摘Largescale vaporsolid synthesis of ultralong silicon nitride （Si3N4） nanowires was achieved by using simple thermal evaporation of mixture powders of active carbon and monoxide silicon. The products were charac terized by Xray diffraction, scanning electron microscopy, energydispersive Xray spectroscopy, and transmission electron microscopy. The results suggest that the silicon nitride nanowires have a smooth surface, with lengths of up to several hundreds of microns and diameters of 100300 nm. A detailed study of both the chemical and structural composition was performed. Such ultralong sil icon nitride nanowires demonstrate potential applications as materials for constructing nanoscale devices and as reinforcement in advanced composites.
基金supported by the National Natural Science Foundation of China(Nos.21975126,51673095,21875104,21875191,21603104)the Natural Science Foundation of Jiangsu Province(Nos.BK20171470,BK20160991,BK20150064,BK20130912)+1 种基金973 Program(No.2015CB932200)Ministry of Education and Synergetic Innovation Center for Organic Electronics and Information Displays for financial support
文摘Organic phosphorescence materials demonstrate potential optoelectronic applications due to their remarkably ultralong organic phosphorescence(UOP)lifetime and abundant optical characteristics prior to the fluorescence materials.For a better insight into the intrinsic relationship among regioisomeric molecules,crystalline interactions,and phosphorescence properties,three crystalline dicarbazol-9-yl pyrazine-based regioisomers with para-,meta-and ortho-convergent substitutions(p-DCzP,m-DCzP,and o-DCzP)were designed and presented gradually increased UOP lifetimes prolonging from 63.14,127.93 to 350.46 ms,respectively,due to the regioisomerism effect(RIE)which would be an effective strategy for better understanding of structure-property of UOP materials.
基金supported by Huzhou Natural Science Foundation Project(Nos.2022YZ04 and 2022YZ21)S&T Special Program of Huzhou(No.2023GZ03)National Natural Science Foundation of China(No.52172184)。
文摘The high specific capacity and low negative electrochemical potential of lithium metal anodes(LMAs),may allow the energy density threshold of Li metal batteries(LMBs)to be pushed higher.However,the existing detrimental issues,such as dendritic growth and volume expansion,have hindered the practical implementation of LMBs.Introducing three-dimensional frameworks(e.g.,copper and nickel foam),have been regarded as one of the fundamental strategies to reduce the local current density,aiming to extend the Sand'time.Nevertheless,the local environment far from the skeleton is almost the same as the typical plane Li,due to macroporous space of metal foam.Herein,we built a double-layered 3D current collector of Li alloy anchored on the metal foam,with micropores interconnected macropores,via a viable thermal infiltration and cooling strategy.Due to the excellent electronic and ionic conductivity coupled with favorable lithiophilicity,the Li alloy can effectively reduce the nucleation barrier and enhance the Li^(+)transportation rate,while the metal foam can role as the primary promotor to enlarge the surface area and buffer the dimensional variation.Synergistically,the Li composite anode with hierarchical structure of primary and secondary scaffolds realized the even deposition behavior and minimum volume expansion,outputting preeminent prolonged cycling performances under high rate.
基金supported by the National Natural Science Foundation of China(Nos.21875104 and 51673095)National Basic Research Program of China(973 Program,No.2015CB932200)+4 种基金Natural Science Fund for Distinguished Young Scholars(No.BK20180037)the Natural Science Fund for Colleges and Universities(No.17KJB430020)"High-Level Talents in Six Industries"(No.XCL-025)of Jiangsu ProvinceNanjing Tech Start-up Grant(Nos.3983500158 and 3983500169)the High Performance Computing Centre of Nanjing Tech University for supporting the computational resources
文摘Ultralong organic phosphorescent materials have invoked considerable attention for their great potential in sensing,data encryption,information anti-counterfeiting and so forth.However,effective ways to achieve highly efficient ultralong organic phosphorescence(UOP)in metal-free organic materials remain a great challenge.Herein,we designed three isomers based on asymmetric triazines with various bromine substituted positions.Impressively,phosphorescence efficiency of p-BrAT in solid state can reach up to 9.7%with a long lifetime of 386 ms,which was one of the highest efficient UOP materials reported so far.Theoretical calculations further demonstrated that para-substitution exhibited the most effective radiative transition for triplet excitons.These results will provide an effective approach to achieving highly efficient UOP materials.
基金supported by the National Natural Science Foundation of China (Nos. 21873068, 21573229 and 21422309)the financial support from Double FirstRate and Peiyang Scholar Projects (Tianjin University)+1 种基金the Open Research Funds of State Key Laboratory of Bioelectronics (Southeast University)the Frontier Science Project of the Knowledge Innovation Program of Chinese Academy of Sciences (CAS)。
文摘Ultra-long room temperature phosphorescence(URTP) has been increasingly recognized in pure organic luminophor in recent years. Through a simpler molecular design and charge separation-recombination pathway, organic luminophor can achieve even better URTP properties. In this work, we achieved URTP in a system of host-vip doped benzophenone derivatives whose phosphorescence is visible to the naked eye. The differences in the wavelength lifetimes of luminescent emission correspond to different photophysical mechanisms. Through a combination of theoretical calculations and experiments, the host acts as a powerful substrate that restricts the motion of the vip and inhibits the non-radiative transitions of the vip, accompanied by a charge transfer separation-recombination process between the host and the vip, resulting in an URTP phenomenon. Transient absorption results demonstrate the existence of a charge-separated state. The design strategy via charge separation is generic and easy to implement,providing a direction for the future design of doped URTP.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974216,11874242,21933002 and 11904210)Shandong Provincial Natural Science Foundation,China(Grant No.ZR2019MA056)+1 种基金the support of the Taishan Scholar Project of Shandong Provincethe project funded by China Postdoctoral Science Foundation(Grant No.2018M642689)。
文摘Aggregation-induced thermally activated delayed fluorescence(TADF)phenomena have attracted extensive attention recently.In this paper,several theoretical models including monomer,dimer,and complex are used for the explanation of the luminescent properties of(R)-5-(9H-carbazol-9-yl)-2-(1,2,3,4-tetrahydronaphthalen-1-yl)isoindoline-1,3-dione((R)-ImNCz),which was recently reported[Chemical Engineering Journal 418129167(2021)].The polarizable continuum model(PCM)and the combined quantum mechanics and molecular mechanics(QM/MM)method are adopted in simulation of the property of the molecule in the gas phase,solvated in acetonitrile and in aggregation states.It is found that large spin–orbit coupling(SOC)constants and a smaller energy gap between the first singlet excited state and the first triplet excited state(△E_(st))in prism-like single crystals(SC_(p)-form)are responsible for the TADF of(R)-lmNCz,while no TADF is found in block-like single crystals(SC_(b)-form)with a larger △E_(st).The multiple ultralong phosphorescence(UOP)peaks in the spectrum are of complex origins,and they are related not only to ImNCz but also to a minor amount of impurities(ImNBd)in the crystal prepared in the laboratory.The dimer has similar phosphorescence emission wavelengths to the(R)-lmNCz-SC_(p) monomers.The complex composed of(R)-lmNCz and(R)-lmNBd contributes to the phosphorescent emission peak at about 600 nm,and the phosphorescent emission peak at about 650 nm is generated by(R)-lmNBd.This indicates that the impurity could also contribute to emission in molecular crystals.The present calculations clarify the relationship between the molecular aggregation and the light-emitting properties of the TADF emitters and will therefore be helpful for the design of potentially more useful TADF emitters.
基金financially supported by the Natural Science Foundation of Shandong Province(ZR2021QB055,ZR2023MB017,ZR2022JQ10)the National Natural Science Foundation of China(21901146,220781792,22274083)。
文摘Constructing heterostructure is considered as an effective strategy to address the sluggish electronic and ionic kinetics of anode materials for sodium ion batteries(SIBs).However,realizing the orientated growth and uniform distribution of the heterostructure is still a great challenge.Herein,the regulated novel CoSe_(2)/NiSe_(2)heterostructure confined in N-doped carbon nanofibers(CoSe_(2)/NiSe_(2)@N-C)are prepared by using Co/Ni-ZIF template,in which,the CoSe_(2)/NiSe_(2)heterostructures realize uniform distribution on a micro level.Benefiting from the unique heterostructure and N-doped carbon nanofibers,the CoSe_(2)/NiSe_(2)@N-C deliveries superior rate capability and durable cycle lifespan with a reversible capacity of 400.5 mA h g^(-1)after 5000 cycles at 2 A g^(-1).The Na-ion full battery with CoSe_(2)/NiSe_(2)@N-C anode and layered oxide cathode displays a remarkable energy density of 563 W h kg^(-1)with 241.1 W kg^(-1)at 0.1 A g^(-1).The theoretical calculations disclose that the periodic and directional built-in electric-field along with the heterointerfaces of CoSe_(2)/NiSe_(2)@N-C can accelerate electrochemical reaction kinetics.The in(ex)situ experimental measurements reveal the reversible conversion reaction and stable structure of CoSe_(2)/NiSe_(2)@N-C during Na+insertion/extraction.The study highlights the potential ability of precisely controlled heterostructure to stimulate the electrochemical performances of advanced anode for SIBs.
基金financial support from the NSF of China(62275217,T.Y.)Natural Science Basic Research Programme of Shaanxi(2024JC-JCQN-51,T.Y.)a start-up grant from City University of Hong Kong(9610637,C.-Y.C.).
文摘Ultralong organic afterglow materials are being actively explored as attractive candidates for a wide range of applications such as data storage,security inks,emergency lighting,etc.,due to their unique long-lived excited state properties and inherent advantages of low cost,appreciable functionality and ease of preparation.In the last three years,much effort has been devoted to achieving efficient ultralong afterglow from organic small molecules,which possess controllable intermolecular interactions and defined energy levels,making them a good platform to suppress the non-radiative decays,hence stabilizing the excitons for efficient afterglow emissions at room temperature.Nevertheless,there has been a lack of reviews on how efficient ultralong organic afterglow can be systematically achieved from small molecular host-vip materials,which is not conducive to the development of the field.In this review,we have outlined and summarized small-molecule ultralong organic afterglow materials based on different emission mechanisms.We have included emission mechanisms involving ultralong room-temperature phosphorescence(URTP),ultralong thermally activated delayed fluorescence(UTADF)and organic long persistent luminescence(OLPL),where the latter two mechanisms have rarely been reported.In addition,challenges and future perspectives are discussed to emphasize the future directions.
基金supported by the National Key Research and Development Program(Grant Nos.2020YFC2201103 and 2020YFA0210702)the National Natural Science Foundation of China(Grant No.22075163).
文摘Carbon nanotubes have attracted extensive interest owing to their extraordinary properties and wide applications in many fields.Among various types of carbon nanotubes,only ultralong carbon nanotubes with macroscale lengths,low defect concentrations,and high degrees of alignment can fully demonstrate their intrinsic performance.These attributes make ultralong carbon nanotubes highly promising for applications in cutting-edge fields,such as carbon-based integrated circuits,ultra-strong fibers,and transparent conductive films.However,the mass production of ultralong carbon nanotubes with precise structural control remains a major challenge,limiting their widespread applications.In the past decades,great progress has been achieved in the study of ultralong carbon nanotubes.In this review,we summarized the growth mechanisms and the controlled synthesis strategies of ultralong carbon nanotubes.Then,we introduced the advanced applications of ultralong carbon nanotubes in many areas,such as field-effect transistors,sensors,and photodetectors.Finally,we discussed the remaining challenges and offered our perspectives on the future directions of this field.
基金the National Natural Science Foundation of China(52173206)the Applied Foundation Frontier Project from Wuhan Science and Technology Bureau(2022013988065202)。
文摘Room-temperature phosphorescence(RTP)materials play a vital role in security domain due to their unique optical properties.However,most average lifetimes of available RTP materials remain less than 1 s in aqueous-phase media,which is unfavorable to practical applications.Herein,an ex-situ covalent coupling strategy is proposed to fabricate liquid-phase long-lived RTP materials by combining SiO_(2)microspheres with the feather-derived carbon dots(CDs).Astonishingly,the aqueous dispersion of the resulting CDs@SiO_(2)microspheres exhibits a lifetime of up to 2.38 s with an absolute quantum yield of 22%.Moreover,the average lifetime of the solid CDs@SiO_(2)is as long as 3.04 s,which is superior to that of existing RTP carbon-based materials.The striking enhancements in the RTP of the CDs@SiO_(2)composites are mainly attributed to the immobilization of the formed Si–O–C covalent bonds and Si–O–Si rigid networks.The CDs@SiO_(2)composites were subsequently applied in the fields of information encryption and anti-fake.Interestingly,the CDs@SiO_(2)composites possess intriguing,reversible and stable optical properties,including water-responsive structural colors,blue fluorescence and cyan RTP,exhibiting excellent covert performance in applications of information encryption and decryption,and high-level anticounterfeiting.These findings provide not only a straightforward strategy for developing multiresponsive optical materials but also a more secure anticounterfeiting technology.
基金National University of Singapore,Grant/Award Number:A-0001423-06-00The Singapore National Research Foundation,Grant/Award Number:A-0009163-01-00。
文摘Ultralong thermally activated delayed fluorescence(UTADF)materials play an important role in realizing time-dependent color-tunable afterglow.Some typical carbazole(Cz)derivatives have been reported to exhibit UTADF properties.However,a 10-fold difference in TADF lifetime was found between commercial Cz derivatives and the corresponding lab-synthesized ones,which indicated that UTADF may not be derived from the single Cz derivatives as reported.To reveal the real mechanism,we synthesized three Cz derivatives and one isomer to form three host-vip pairs for optical studies.The photophysical properties revealed that UTADF originated from the intermolecular charge transfer between host and vip,while the ultralong organic phosphorescence was from the vip.Thanks to the rich color variations in luminescence displayed by 4-(1H-benzo[f]indol-1-yl)−4′-(9H-carbazol-9-yl)-[1,1′-biphenyl]−3,3′-dicarbonitrile/4,4′-di(9H-carbazol-9-yl)-[1,1′-biphenyl]−3,3′-dicarbonitrile(CBP-2CN)at different delay times,it can be applied to realize multi-dimensional encryption in both delay time and luminescent color.
基金Financial support from the Talent Fund of Beijing Jiaotong University(No,2023XKRC015)the National Natural Science Foundation of China(No.52172081)is gratefully acknowledged.
文摘The high power density and intelligence of next-generation flexible electronic devices bring many challenges to fabricate flexible composite films with electromagnetic interference(EMI)shielding effectiveness(SE)property and excellent toughness via a simple method.Herein,inspired by the layered structure and biopolymer matrix networks in natural nacre,nacre-like layered Ti_(3)C2TX(MXene)/aramid nanofiber(ANF)films were fabricated through sol-gel,vacuum-assisted filtration,and hot-pressing.Three-dimensional(3D)interconnected aramid nanofibers networks between adjacent layered MXene result in an ultralong strain-to-failure of the film.Even though the functional filler MXene contents are as high as 60 wt.%and 70 wt.%,the strain-to-failure of the films could reach astonishing values of 18.34%±1.86%and 14.43%±1.26%,respectively.And the tensile strength could maintain about 85 MPa.Excitingly,with such a high filler,the film can also withstand double folding and vigorous rubbing without damage,which could better adapt to a harsh application environment.The result means that this work provides a convenient way to prepare other high functional filler composite films with excellent mechanical performance.The EMI SE values could reach 45 and 52.15 dB at 60 wt.%and 70 wt.%MXene in 8.2–12.4 GHz.Meanwhile,the films have prominent Joule heating properties,high sensitivity(<15 s),small voltage operation(0.5 V),and high operation constancy(1300 s).Therefore,nacre-inspired MXene/ANF composite films in this work have ability to apply in many areas including communication technology,military,and aerospace.
基金Natural Science Foundation of Jiangsu Province,China(BK20170243)National Natural Science Foundation of China(NSFC)(61705094,11674133,11711530208,61575089)+5 种基金Key Research Program of Natural Science of Jiangsu Higher Education Institutions(17KJA416004)Royal Society(IE161214)Protocol of the 37th Session of China-Poland Scientific and Technological Cooperation Committee(37-17)H2020 Marie Sk?odowska-Curie Actions(MSCA)(790666)Jiangsu Overseas Visiting Scholar Program for University Prominent Young and Middle-aged Teachers and PresidentsPriority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘We experimentally demonstrated a type of tunable and switchable harmonic h-shaped pulse generation in a thulium-doped fiber(TDF) laser passively mode locked by using an ultralong nonlinear optical loop mirror.The total cavity length was ～3.03 km, the longest ever built for a TDF laser to our best knowledge, which resulted in an ultralarge anomalous dispersion over -200 ps^2 around the emission wavelength. The produced h-shaped pulse can operate either in a fundamental or in a high-order harmonic mode-locking(HML) state depending on pump power and intra-cavity polarization state(PS). The pulse duration, no matter of the operation state, was tunable with pump power. However, pulse breaking and self-organizing occurred, resulting in high-order HML,when the pump power increased above a threshold. At a fixed pump power, the order of HML was switchable from one to another by manipulating the PS. Switching from the 8 th up to the 48 th order of HML was achieved with a fixed pump power of ～4.15 W. Our results revealed the detailed evolution and switching characteristics of the HML and individual pulse envelope with respect to both the pump power and PS. We have also discussed in detail the mechanisms of both the h-shaped pulse generation and the switching of its HML. This contribution would be helpful for further in-depth study on the underlying dynamics of long-duration particular-envelope pulses with ultralarge anomalous dispersion and ultralong roundtrip time.
