Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the develop...Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the development of electrochemicallydriven technologies for efficient hydrogen production and avoid CO_(2) emission. Herein, the hetero-nanocrystals between monodispersed Pt(~ 2 nm) and Ni_(3)S_(2)(~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H_(2) generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni_(3)S_(2) could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH_(3)OH to formate is accomplished at very low potentials(1.45 V) to attain 100 m A cm^(-2) with high electronic utilization rate(~ 98%) and without CO_(2) emission. Meanwhile, the Pt–Ni_(3)S_(2) can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction(HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction(MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 m A cm^(-2) with good reusability.展开更多
Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution ...Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution reactions(OER).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(CD)based metal-organic framework as the precursor.With the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional ORR/OER overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to date.Synchrotron X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER,resulting in an enhanced bifunctional electrocatalytic performance.The Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+RuO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))catalysts.During the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.展开更多
Co-N-C is a promising oxygen electrochemical catalyst due to its high stability and good durability.However,due to the limited adsorption ability improvement for oxygen-containing intermediates,it usually exhibits ina...Co-N-C is a promising oxygen electrochemical catalyst due to its high stability and good durability.However,due to the limited adsorption ability improvement for oxygen-containing intermediates,it usually exhibits inadequate catalytic activity with 2-electron pathway and high selectivity of hydrogen peroxide.Herein,the adsorption of Co-N-C to these intermediates is modulated by constructing heterostructures using transition metals and their derivatives based on d-band theory.The heterostructured nanobelts with MoC core and pomegranate-like carbon shell consisting of Co nanoparticles and N dopant(MoC/Co-N-C)are engineered to successfully modulate the d band center of active Co-N-C sites,resulting in a remarkably enhanced electrocatalysis performance.The optimally performing MoC/Co-N-C exhibits outstanding bi-catalytic activity and stability for the oxygen electrochemistry,featuring a high wave-half potential of 0.865 V for the oxygen reduction reaction(ORR)and low overpotential of 370 mV for the oxygen evolution reaction(OER)at 10 mA cm^(-2).The zinc air batteries with the MoC/Co-N-C catalyst demonstrate a large power density of 180 mW cm^(-2)and a long cycling lifespan(2000 cycles).The density functional theory calculations with Hubbard correction(DFT+U)reveal the electron transferring from Co to Mo atoms that effectively modulate the d band center of the active Co sites and achieve optimum adsorption ability with"single site double adsorption"mode.展开更多
Thermoelectric generators have attracted a wide research interest owing to their ability to directly convert heat into electrical power.Moreover,the thermoelectric properties of traditional inorganic and organic mater...Thermoelectric generators have attracted a wide research interest owing to their ability to directly convert heat into electrical power.Moreover,the thermoelectric properties of traditional inorganic and organic materials have been significantly improved over the past few decades.Among these compounds,layered two-dimensional(2D)materials,such as graphene,black phosphorus,transition metal dichalcogenides,IVA–VIA compounds,and MXenes,have generated a large research attention as a group of potentially high-performance thermoelectric materials.Due to their unique electronic,mechanical,thermal,and optoelectronic properties,thermoelectric devices based on such materials can be applied in a variety of applications.Herein,a comprehensive review on the development of 2D materials for thermoelectric applications,as well as theoretical simulations and experimental preparation,is presented.In addition,nanodevice and new applications of 2D thermoelectric materials are also introduced.At last,current challenges are discussed and several prospects in this field are proposed.展开更多
Graphene foam is becoming a material of choice for magnetoelectronic devices due to its large,linear and unsaturated room temperature magnetoresistance.However,the magnetoresistance of graphene foam is not as large as...Graphene foam is becoming a material of choice for magnetoelectronic devices due to its large,linear and unsaturated room temperature magnetoresistance.However,the magnetoresistance of graphene foam is not as large as that of monolayer graphene.Herein,we describe how magnetoresistance^100%was detected at room temperature under a magnetic field of 5 T that is comparable to the magnetoresistance in monolayer graphene;the highest magnetoresistance of^158%was detected at 5 K under a magnetic field of 5 T.Unlike monolayer graphene,graphene foam is far more comfortable with producing in gram scale and utilizing in magnetoelectronic devices.展开更多
Electrochemical reduction of CO_(2)to formate is economically attractive but improving the reaction selectivity and activity remains challenging.Herein,we introduce boron(B)atoms to modify the local electronic structu...Electrochemical reduction of CO_(2)to formate is economically attractive but improving the reaction selectivity and activity remains challenging.Herein,we introduce boron(B)atoms to modify the local electronic structure of bismuth with positive valence sites for boosting conversion of CO_(2)into formate with high activity and selectivity in a wide potential window.By combining experimental and computational investigations,our study indicates that B dopant differentiates the proton participations of rate-determining steps in CO_(2)reduction and in the competing hydrogen evolution.By comparing the experimental observations with the density functional theory,the dominant mechanistic pathway of B promoted formate generation and the B concentration modulated effects on the catalytic property of Bi are unravelled.This comprehensive study offers deep mechanistic insights into the reaction pathway at an atomic and molecular level and provides an effective strategy for the rational design of highly active and selective electrocatalysts for efficient CO_(2)conversion.展开更多
Electrochemical reduction of CO_(2) to fuels and chemicals is a viable strategy for CO_(2) utilization and renewable energy storage.Developing free-standing electrodes from robust and scalable electrocatalysts becomes...Electrochemical reduction of CO_(2) to fuels and chemicals is a viable strategy for CO_(2) utilization and renewable energy storage.Developing free-standing electrodes from robust and scalable electrocatalysts becomes highly desirable.Here,dense SnO_(2) nanoparticles are uniformly grown on three-dimensional(3D)fiber network of carbon cloth(CC)by a facile dip-coating and calcination method.Importantly,Zn modification strategy is employed to restrain the growth of long-range order of SnO_(2) lattices and to produce rich grain boundaries.The hybrid architecture can act as a flexible electrode for CO_(2)-to-formate conversion,which delivers a high partial current of 18.8 m A cm-2 with a formate selectivity of 80%at a moderate cathodic potential of-0.947 V vs.RHE.The electrode exhibits remarkable stability over a 16 h continuous operation.The superior performance is attributed to the synergistic effect of ultrafine SnO_(2) nanoparticles with abundant active sites and 3D fiber network of the electrode for efficient mass transport and electron transfer.The sizeable electrodes hold promise for industrial applications.展开更多
Efficient and robust single-atom catalysts(SACs)based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia(NRR)under ambient conditions.Herein,for the first ti...Efficient and robust single-atom catalysts(SACs)based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia(NRR)under ambient conditions.Herein,for the first time,a Mn-N-C SAC consisting of isolated manganese atomic sites on ultrathin carbon nanosheets is developed via a template-free folic acid self-assembly strategy.The spontaneous molecular partial dissociation enables a facile fabrication process without being plagued by metal atom aggregation.Thanks to well-exposed atomic Mn active sites anchored on two-dimensional conductive carbon matrix,the catalyst exhibits excellent activity for NRR with high activity and selectivity,achieving a high Faradaic efficiency of 32.02%for ammonia synthesis at−0.45 V versus reversible hydrogen electrode.Density functional theory calculations unveil the crucial role of atomic Mn sites in promoting N_(2) adsorption,activation and selective reduction to NH_(3) by the distal mechanism.This work provides a simple synthesis process for Mn-N-C SAC and a good platform for understanding the structure-activity relationship of atomic Mn sites.展开更多
Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions(OER).Small molecule oxidation reactions with lower working poten...Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions(OER).Small molecule oxidation reactions with lower working potentials,such as methanol oxidation reactions,are good alternatives to OER with faster kinetics.However,the typically employed Ni-based electrocatalysts have poor activity and stability.Herein,a novel three-dimensional(3D)-networking Modoped Ni(OH)_(2) with ultralow Ni-Ni coordination is synthesized,which exhibits a high MOR activity of 100 mA cm^(−2) at 1.39 V,delivering 28 mV dec^(−1) for the Tafel slope.Meanwhile,hydrogen evolution with value-added formate co-generation is boosted with a current density of more than 500 mA cm^(−2) at a cell voltage of 2.00 V for 50 h,showing excellent stability in an industrial alkaline concentration(6 M KOH).Mechanistic studies based on density functional the-ory and X-ray absorption spectroscopy showed that the improved performance is mainly attributed to the ultralow Ni-Ni coordination,3D-networking structures and Mo dopants,which improve the catalytic activity,increase the active site density and strengthen the Ni(OH)_(2)3D-networking structures,respectively.This study paves a new way for designing electrocatalysts with enhanced activity and durability for industrial energy-saving hydrogen production.展开更多
Gallium oxide(Ga_2O_3) thin films were deposited on a-Al2O3(1120) substrates by pulsed laser deposition(PLD) with different oxygen pressures at 650?C. By reducing the oxygen pressure, mixed-phase Ga_2O_3 films with α...Gallium oxide(Ga_2O_3) thin films were deposited on a-Al2O3(1120) substrates by pulsed laser deposition(PLD) with different oxygen pressures at 650?C. By reducing the oxygen pressure, mixed-phase Ga_2O_3 films with α and β phases can be obtained, and on the basis of this, mixed-phase Ga_2O_3 thin film solar-blind photodetectors(SBPDs) were prepared.Comparing the responsivities of the mixed-phase Ga_2O_3 SBPDs and the single β-Ga_2O_3 SBPDs at a bias voltage of 25 V,it is found that the former has a maximum responsivity of approximately 12 A/W, which is approximately two orders of magnitude larger than that of the latter. This result shows that the mixed-phase structure of Ga_2O_3 thin films can be used to prepare high-responsivity SBPDs. Moreover, the cause of this phenomenon was investigated, which will provide a feasible way to improve the responsivity of Ga_2O_3 thin film SBPDs.展开更多
Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap e...Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al_(1-x)In_(x)N on a free-standing GaN substrate through direct radio-frequency magnetron sputtering.The optical properties of Al_(1-x)In_(x)N will be enhanced by the polarization effect of a heterostructure composed of Al_(1-x)In_(x)N and other Ⅲ-nitride materials. An Al_(1-x)In_(x)N/Ga N visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A·W^(-1)under 365 nm wavelength illumination and the photodetector was determined to have the composition Al0.75In0.25N/GaN.A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_(1-x)In_(x)N visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method,this study expands the application of ternary alloy Al_(1-x)In_(x)N visible-light photodetectors in optical communication.展开更多
Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further de...Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further development.In the last few years,metal–organic frameworks(MOFs)have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry,tunable morphologies,high porosity,and chemical/thermal stability.From this perspective,this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based(MOF-derived-supported and MOF-supported)SACs.Then,MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments,local electronic structures,spatial distributions,and catalytic/electrochemical reaction mechanisms.This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage,including hydrogen evolution reactions,oxygen evolution reactions,O_(2)/CO_(2)/N_(2) reduction reactions,fuel cells,and rechargeable batteries.Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.展开更多
Seeking for composite electrolytes reinforced all-solid-state sodium ion batteries with superior long lifespan and rate performance remains a great challenge.Here,a unique strategy to tailor the architecture of compos...Seeking for composite electrolytes reinforced all-solid-state sodium ion batteries with superior long lifespan and rate performance remains a great challenge.Here,a unique strategy to tailor the architecture of composite electrolyte via inserting polymer chains into a small quantity of sulfate sodium grafted C_(48)0H_(28)O_(32)Zr_(6)(UIOSNa)is proposed.The intimate contact between polymer segments and UIOSNa with limited pore size facilitates the anion immobilization of sodium salts and reduction of polymer crystallinity,thereby providing rapid ion conduction and reducing the adverse effect caused by the immigration of anions.The tNa+grafting of-SO_(3)Na groups on fillers allows the free movement of more sodium ions to further improve and ionic conductivity.Consequently,even with the low content of UIOSNa fillers,a high ionic conductivity of 6.62×10^(-4) S·cm^(-1) at 60℃ and a transference number of 0.67 for the special designed composite electrolyte are achieved.The assembled all-solid-state sodium cell exhibits a remarkable rate performance for 500 cycles with 95.96%capacity retention at a high current rate of 4 C.The corresponding pouch cell can stably work for 1000 cycles with 97.03%capacity retention at 1 C,which is superior to most of the reported composite electrolytes in the literature.展开更多
otentiometric oxygen sensors have been widely used in internal combustion engines,industrial boilers,and metallurgical heat treatment furnaces.However,traditional oxygen sensors based on yttria-stabilized zirconia(YSZ...otentiometric oxygen sensors have been widely used in internal combustion engines,industrial boilers,and metallurgical heat treatment furnaces.However,traditional oxygen sensors based on yttria-stabilized zirconia(YSZ)electrolyte can only be operated at elevated temperatures(>750℃)due to their rela-tively low ionic conductivity.In this study,we present a highly efficient micro-oxygen sensor that can be operated at a temperature as low as 300℃.This micro-oxygen sensor incorporates a composite solid electrolyte,i.e.,well-aligned gadolinium-doped cerium oxide(CGO)nanofibers embedded within a YSZ matrix(YSZ/CGO_(f)).The arrays of CGO nanofibers in the YSZ matrix are parallel to the conduction direc-tion,providing rapid conducting channels for oxygen ions.Benefitting from this design,the composite electrolyte leads to a conductivity of four times higher than that of traditional YSZ solid electrolytes at low temperatures.This enhancement in conductivity is attributed to the presence of a defective interfacial region between CGO_(f)and YSZ,which promotes the mobility of oxygen ions.The strategy of constructing fast ionic conduction in the composite electrolyte by using well-aligned nanofibers may be considered for the design and optimization of other micro/nano-devices including sensors,batteries,and fuel cells.展开更多
The topology of conjugated macrocycles had significant impacts on their photo-physical and photochemical properties.Herein,a series ofπ-conjugated macrocycles with diverse topology were synthesized via intramolecular...The topology of conjugated macrocycles had significant impacts on their photo-physical and photochemical properties.Herein,a series ofπ-conjugated macrocycles with diverse topology were synthesized via intramolecular McMurry coupling.Their chemical structure and macrocyclic topology were unambiguously confirmed via NMR,MALDI-TOF mass spectra,crystal analysis and scanning tunneling microscopy(STM).Depending on the structural topology and structural rigidity,these cyclic compounds display obviously distinctive emission behavior and photochemical reactions in the solution and in the solid state.Monocyclic phenylene vinylene macrocycle(denoted as MST)exhibiting aggregation-induced emission behavior,was more vulnerable to photo-cyclization in solution and triplet sensitizer promoted photodimerization due to lower strain and more flourishing intramolecular motions.After UV light irradiation,relatively more flexible MST could yield the anti-dimer via triplet excimer on the HOPG surface confirmed by STM investigation.By contrast,highly constrained bicyclic analogue(named as DMTPE)with central tetraphenylethene core,displayed high emission quantum yields of 68%both in solution and in the solid state,and was relatively inert to photochemical reactions and yield syn-dimer on the surface via singlet excimer involved[2+2]photo-dimerization.Based on the solution-mediated photo-polymerization of MST moiety,multicyclic porous carbon-rich ribbon connected with four-membered ring was successfully constructed and validated via STM imaging.展开更多
Exploration of single molecular species synchronously featured by long excitation/emission wavelength, accurate diagnosis, and effective therapy, remains supremely appealing to implement high-performance cancer photot...Exploration of single molecular species synchronously featured by long excitation/emission wavelength, accurate diagnosis, and effective therapy, remains supremely appealing to implement high-performance cancer phototheranostics. However, those previously established phototheranostic agents are undiversified and stereotyped in terms of structural skeleton, and generally exhibit insufficient phototheranostic outcomes. Herein, we innovatively utilized indanone-condensed thiadiazolo[3,4-g]quinoxaline(ITQ) as electron acceptor to construct novel photosensitizer with second near-infrared(NIR-II) emission. Experimental study and theoretical calculation demonstrated that comparing with the counterparts constituting by widely employed NIR-II building block benzobisthiadiazole(BBTD) and 6,7-diphenylthiadiazoloquinoxaline(DPTQ), ITQ-based photosensitizer(TITQ) showed superior aggregation-induced emission(AIE) characteristics, much stronger type-I reactive oxygen species(ROS) production, and prominent photothermal conversion capacity. Furthermore, TITQ nanoparticles with excellent biocompatibility were capable of effectively accumulating in the tumor site and visualizing tumor through fluorescence-photoacoustic-photothermal trimodal imaging with highly spatiotemporal resolution, and completely eliminating tumor by type-I photodynamic-photothermal therapy.展开更多
In this study,a galliumnitride(GaN)substrate and its 15μmepitaxial layer were entirely grown by adopting the hydride vapor phase epitaxy(HVPE)technique.To enhance the breakdown voltage(VBR)of vertical GaN-on-GaN Scho...In this study,a galliumnitride(GaN)substrate and its 15μmepitaxial layer were entirely grown by adopting the hydride vapor phase epitaxy(HVPE)technique.To enhance the breakdown voltage(VBR)of vertical GaN-on-GaN Schottky barrier diodes(SBDs),a dual ion coimplantation of carbon and heliumwas employed to create the edge termination.The resulting devices exhibited a low turn-on voltage of 0.55 V,a high Ion/Ioff ratio of approximately 109,and a lowspecific onresistance of 1.93 mU cm^(2).When the ion implantation edge was terminated,the maximumVBR of the devices reached 1575 V,with an average improvement of 126%.These devices demonstrated a high figure of merit(FOM)of 1.28 GW cm^(-2) and showed excellent reliability during pulse stress testing.展开更多
Semiconducting polymers(SPs)have shown great feasibility as candidates for near-infrared-II(NIR-Ⅱ)fluorescence imaging-navigated photothermal therapy due to their strong light-harvesting ability and flexible tunabili...Semiconducting polymers(SPs)have shown great feasibility as candidates for near-infrared-II(NIR-Ⅱ)fluorescence imaging-navigated photothermal therapy due to their strong light-harvesting ability and flexible tunability.However,the fluorescence signal of traditional SPs tends to quench in their aggregate states owing to the strongπ-πstacking,which can lead to the radiative decay pathway shutting down.To address this issue,aggregation-induced emission effect has been used as a rational tactic to boost the aggregate-state fluorescence of NIR-Ⅱemitters.In this contribution,we developed a precise molecular engineering tactic based on the block copolymerizations that integrate planar and twisted segments into one conjugated polymer backbone,providing great flexibility in tuning the photophysical properties and photothermal conversion capacity of SPs.Two monomers featured with twisted and planar architectures,respectively,were tactfully incorporated via a ternary copolymerization approach to produce a series of new SPs.The optimal copolymer(SP2)synchronously shows desirable absorption ability and good NIR-Ⅱquantum yield on the premise of maintaining typical aggregation-induced emission characteristics,resulting in balanced NIR-Ⅱfluorescence brightness and photothermal property.Water-dispersible nanoparticles fabricated from the optimal SP2 show efficient photothermal therapeutic effects both in vitro and in vivo.The in vivo investigation reveals the distinguished NIR-Ⅱfluorescence imaging performance of SP2 nanoparticles and their photothermal ablation toward tumor with prominent tumor accumulation ability and excellent biocompatibility.展开更多
The widespread applications of thermoelectric(TE)materials in power generation and solid-state cooling require improving their TE figure of merit(ZT)significantly.Recently,GeTe-based alloys have shown great promise as...The widespread applications of thermoelectric(TE)materials in power generation and solid-state cooling require improving their TE figure of merit(ZT)significantly.Recently,GeTe-based alloys have shown great promise as mid-temperature TE materials with superhigh TE performance,mostly due to their relatively high-degeneracy band structures and low lattice thermal conductivity.In this perspective,we review the most recent progress of the GeTe-based TE alloys from the view of phase and defect engineering.These two strategies are the most widely-used and efficient approaches in GeTe-based alloys to optimize the transport properties of electrons and phonons for high ZT.The phase transition from rhombohedral to cubic structure is believed to improve the band convergence of GeTe-based alloys for higher electrical performance.Typical defects in GeTe-based alloys include the point defects from Ge vacancies and substitutional dopants,linear and planar defects from Ge vacancies.The defect engineering of GeTe-based alloys is important not only for optimizing the carrier density but also for tuning the band structure and phonon-scattering processes.The summarized strategies in this review can also be used as a reference for guiding the further development of GeTe-based alloys and also other TE materials.展开更多
Micromanipulation and biological,material science,and medical applications often require to control or measure the forces asserted on small objects.Here,we demonstrate for the first time the microprinting of a novel f...Micromanipulation and biological,material science,and medical applications often require to control or measure the forces asserted on small objects.Here,we demonstrate for the first time the microprinting of a novel fiber-tip-polymer clamped-beam probe micro-force sensor for the examination of biological samples.The proposed sensor consists of two bases,a clamped beam,and a force-sensing probe,which were developed using a femtosecond-laser-induced two-photon polymerization(TPP)technique.Based on the finite element method(FEM),the static performance of the structure was simulated to provide the basis for the structural design.A miniature all-fiber micro-force sensor of this type exhibited an ultrahigh force sensitivity of 1.51 nmμN−1,a detection limit of 54.9 nN,and an unambiguous sensor measurement range of~2.9 mN.The Young’s modulus of polydimethylsiloxane,a butterfly feeler,and human hair were successfully measured with the proposed sensor.To the best of our knowledge,this fiber sensor has the smallest force-detection limit in direct contact mode reported to date,comparable to that of an atomic force microscope(AFM).This approach opens new avenues towards the realization of small-footprint AFMs that could be easily adapted for use in outside specialized laboratories.As such,we believe that this device will be beneficial for high-precision biomedical and material science examination,and the proposed fabrication method provides a new route for the next generation of research on complex fiber-integrated polymer devices.展开更多
基金the financial support of Guangdong Basic and Applied Basic Research Foundation (No. 2023A1515010940)Shenzhen Natural Science Fund (the Stable Support Plan Program No. 20220809160022001)the Shenzhen Science and Technology Programs (No. ZDSYS20220527171401003, KQTD20190929173914967)。
文摘Constructing the efficacious and applicable bifunctional electrocatalysts and establishing out the mechanisms of organic electro-oxidation by replacing anodic oxygen evolution reaction(OER) are critical to the development of electrochemicallydriven technologies for efficient hydrogen production and avoid CO_(2) emission. Herein, the hetero-nanocrystals between monodispersed Pt(~ 2 nm) and Ni_(3)S_(2)(~ 9.6 nm) are constructed as active electrocatalysts through interfacial electronic modulation, which exhibit superior bi-functional activities for methanol selective oxidation and H_(2) generation. The experimental and theoretical studies reveal that the asymmetrical charge distribution at Pt–Ni_(3)S_(2) could be modulated by the electronic interaction at the interface of dual-monodispersed heterojunctions, which thus promote the adsorption/desorption of the chemical intermediates at the interface. As a result, the selective conversion from CH_(3)OH to formate is accomplished at very low potentials(1.45 V) to attain 100 m A cm^(-2) with high electronic utilization rate(~ 98%) and without CO_(2) emission. Meanwhile, the Pt–Ni_(3)S_(2) can simultaneously exhibit a broad potential window with outstanding stability and large current densities for hydrogen evolution reaction(HER) at the cathode. Further, the excellent bi-functional performance is also indicated in the coupled methanol oxidation reaction(MOR)//HER reactor by only requiring a cell voltage of 1.60 V to achieve a current density of 50 m A cm^(-2) with good reusability.
基金supported by the Shenzhen Government’s Plan of Science and Technology(JCYJ20190808121407676 and 20200813142301001)National Natural Science Foundation of China(22178223 and 22262010)+1 种基金Guangxi Science and Technology Fund for Distinguished High-Talent Introduction Program(No.RZ2200002233AC22035091).
文摘Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution reactions(OER).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(CD)based metal-organic framework as the precursor.With the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional ORR/OER overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to date.Synchrotron X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER,resulting in an enhanced bifunctional electrocatalytic performance.The Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+RuO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))catalysts.During the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.
基金financially supported by the National Natural Science Foundation of China(No.21975163)the Shenzhen Innovative Research Team Program(KQTD20190929173914967)the Senior Talent Research Start-up Fund of Shenzhen University(000265)。
文摘Co-N-C is a promising oxygen electrochemical catalyst due to its high stability and good durability.However,due to the limited adsorption ability improvement for oxygen-containing intermediates,it usually exhibits inadequate catalytic activity with 2-electron pathway and high selectivity of hydrogen peroxide.Herein,the adsorption of Co-N-C to these intermediates is modulated by constructing heterostructures using transition metals and their derivatives based on d-band theory.The heterostructured nanobelts with MoC core and pomegranate-like carbon shell consisting of Co nanoparticles and N dopant(MoC/Co-N-C)are engineered to successfully modulate the d band center of active Co-N-C sites,resulting in a remarkably enhanced electrocatalysis performance.The optimally performing MoC/Co-N-C exhibits outstanding bi-catalytic activity and stability for the oxygen electrochemistry,featuring a high wave-half potential of 0.865 V for the oxygen reduction reaction(ORR)and low overpotential of 370 mV for the oxygen evolution reaction(OER)at 10 mA cm^(-2).The zinc air batteries with the MoC/Co-N-C catalyst demonstrate a large power density of 180 mW cm^(-2)and a long cycling lifespan(2000 cycles).The density functional theory calculations with Hubbard correction(DFT+U)reveal the electron transferring from Co to Mo atoms that effectively modulate the d band center of the active Co sites and achieve optimum adsorption ability with"single site double adsorption"mode.
基金supported by National Science Foundation for Young Scientists of China (No.61905161 and 51702219)the National Natural Science Foundation of China (No.61975134,61875138 and 61775147)+1 种基金the Science and Technology Innovation Commission of Shenzhen (No. JCYJ20180206121837007)the Shenzhen Nanshan District Pilotage Team Program (LHTD20170006)
文摘Thermoelectric generators have attracted a wide research interest owing to their ability to directly convert heat into electrical power.Moreover,the thermoelectric properties of traditional inorganic and organic materials have been significantly improved over the past few decades.Among these compounds,layered two-dimensional(2D)materials,such as graphene,black phosphorus,transition metal dichalcogenides,IVA–VIA compounds,and MXenes,have generated a large research attention as a group of potentially high-performance thermoelectric materials.Due to their unique electronic,mechanical,thermal,and optoelectronic properties,thermoelectric devices based on such materials can be applied in a variety of applications.Herein,a comprehensive review on the development of 2D materials for thermoelectric applications,as well as theoretical simulations and experimental preparation,is presented.In addition,nanodevice and new applications of 2D thermoelectric materials are also introduced.At last,current challenges are discussed and several prospects in this field are proposed.
基金The authors would like to thank the National High Technology Research and Development Plan of China(2015AA043505)the National Science Foundation of China(21574086)+5 种基金Shenzhen Sci&Tech(research grant ZDSYS201507141105130)the Shenzhen City Science,Technology Plan Project(JCYJ20160520171103239)Equipment Advanced Research Funds(61402100401)Equipment Advanced Research Key Laboratory Funds(6142804180106)Shenzhen Fundamental Research Funds(JCYJ20180508151910775)the National Natural Science Foundation of China(11850410427)for financial support.
文摘Graphene foam is becoming a material of choice for magnetoelectronic devices due to its large,linear and unsaturated room temperature magnetoresistance.However,the magnetoresistance of graphene foam is not as large as that of monolayer graphene.Herein,we describe how magnetoresistance^100%was detected at room temperature under a magnetic field of 5 T that is comparable to the magnetoresistance in monolayer graphene;the highest magnetoresistance of^158%was detected at 5 K under a magnetic field of 5 T.Unlike monolayer graphene,graphene foam is far more comfortable with producing in gram scale and utilizing in magnetoelectronic devices.
基金This work was supported by the Shenzhen Science and Technology Program(KQTD20190929173914967)。
文摘Electrochemical reduction of CO_(2)to formate is economically attractive but improving the reaction selectivity and activity remains challenging.Herein,we introduce boron(B)atoms to modify the local electronic structure of bismuth with positive valence sites for boosting conversion of CO_(2)into formate with high activity and selectivity in a wide potential window.By combining experimental and computational investigations,our study indicates that B dopant differentiates the proton participations of rate-determining steps in CO_(2)reduction and in the competing hydrogen evolution.By comparing the experimental observations with the density functional theory,the dominant mechanistic pathway of B promoted formate generation and the B concentration modulated effects on the catalytic property of Bi are unravelled.This comprehensive study offers deep mechanistic insights into the reaction pathway at an atomic and molecular level and provides an effective strategy for the rational design of highly active and selective electrocatalysts for efficient CO_(2)conversion.
基金supported by the National Natural Science Foundation of China(51902204,22003041,21975163)Bureau of Industry and Information Technology of Shenzhen(201901171518)Shenzhen Science and Technology Program(KQTD20190929173914967)。
文摘Electrochemical reduction of CO_(2) to fuels and chemicals is a viable strategy for CO_(2) utilization and renewable energy storage.Developing free-standing electrodes from robust and scalable electrocatalysts becomes highly desirable.Here,dense SnO_(2) nanoparticles are uniformly grown on three-dimensional(3D)fiber network of carbon cloth(CC)by a facile dip-coating and calcination method.Importantly,Zn modification strategy is employed to restrain the growth of long-range order of SnO_(2) lattices and to produce rich grain boundaries.The hybrid architecture can act as a flexible electrode for CO_(2)-to-formate conversion,which delivers a high partial current of 18.8 m A cm-2 with a formate selectivity of 80%at a moderate cathodic potential of-0.947 V vs.RHE.The electrode exhibits remarkable stability over a 16 h continuous operation.The superior performance is attributed to the synergistic effect of ultrafine SnO_(2) nanoparticles with abundant active sites and 3D fiber network of the electrode for efficient mass transport and electron transfer.The sizeable electrodes hold promise for industrial applications.
基金The authors thank the financial support from the National Natural Science Foundation of China(No.51902204,52001214,21975163)Bureau of Industry and Information Technology of Shenzhen(No.201901171518)Shenzhen Science and Technology Program(KQTD20190929173914967).
文摘Efficient and robust single-atom catalysts(SACs)based on cheap and earth-abundant elements are highly desirable for electrochemical reduction of nitrogen to ammonia(NRR)under ambient conditions.Herein,for the first time,a Mn-N-C SAC consisting of isolated manganese atomic sites on ultrathin carbon nanosheets is developed via a template-free folic acid self-assembly strategy.The spontaneous molecular partial dissociation enables a facile fabrication process without being plagued by metal atom aggregation.Thanks to well-exposed atomic Mn active sites anchored on two-dimensional conductive carbon matrix,the catalyst exhibits excellent activity for NRR with high activity and selectivity,achieving a high Faradaic efficiency of 32.02%for ammonia synthesis at−0.45 V versus reversible hydrogen electrode.Density functional theory calculations unveil the crucial role of atomic Mn sites in promoting N_(2) adsorption,activation and selective reduction to NH_(3) by the distal mechanism.This work provides a simple synthesis process for Mn-N-C SAC and a good platform for understanding the structure-activity relationship of atomic Mn sites.
基金We gratefully thank the financial support from the National Natural Science Foundation of China(22272108,21975163 and 22003041)Shenzhen Science and Technology Program(No.KQTD20190929173914967,JCYJ20200109110416441)the Senior Talent Research Start-up Fund of Shenzhen University(000263 and 000265).
文摘Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions(OER).Small molecule oxidation reactions with lower working potentials,such as methanol oxidation reactions,are good alternatives to OER with faster kinetics.However,the typically employed Ni-based electrocatalysts have poor activity and stability.Herein,a novel three-dimensional(3D)-networking Modoped Ni(OH)_(2) with ultralow Ni-Ni coordination is synthesized,which exhibits a high MOR activity of 100 mA cm^(−2) at 1.39 V,delivering 28 mV dec^(−1) for the Tafel slope.Meanwhile,hydrogen evolution with value-added formate co-generation is boosted with a current density of more than 500 mA cm^(−2) at a cell voltage of 2.00 V for 50 h,showing excellent stability in an industrial alkaline concentration(6 M KOH).Mechanistic studies based on density functional the-ory and X-ray absorption spectroscopy showed that the improved performance is mainly attributed to the ultralow Ni-Ni coordination,3D-networking structures and Mo dopants,which improve the catalytic activity,increase the active site density and strengthen the Ni(OH)_(2)3D-networking structures,respectively.This study paves a new way for designing electrocatalysts with enhanced activity and durability for industrial energy-saving hydrogen production.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51872187,51302174,11774241,and 61704111)the National Key Research and Development Program of China(Grant No.2017YFB0400304)+3 种基金the Natural Science Foundation of Guangdong Province,China(Grant Nos.2016A030313060 and 2017A030310524)the Project of Department of Education of Guangdong Province,China(Grant No.2014KTSCX110)the Fundamental Research Project of Shenzhen,China(Grant No.JCYJ20180206162132006)the Science and Technology Foundation of Shenzhen,China(Grant No.JCYJ2015-2018)
文摘Gallium oxide(Ga_2O_3) thin films were deposited on a-Al2O3(1120) substrates by pulsed laser deposition(PLD) with different oxygen pressures at 650?C. By reducing the oxygen pressure, mixed-phase Ga_2O_3 films with α and β phases can be obtained, and on the basis of this, mixed-phase Ga_2O_3 thin film solar-blind photodetectors(SBPDs) were prepared.Comparing the responsivities of the mixed-phase Ga_2O_3 SBPDs and the single β-Ga_2O_3 SBPDs at a bias voltage of 25 V,it is found that the former has a maximum responsivity of approximately 12 A/W, which is approximately two orders of magnitude larger than that of the latter. This result shows that the mixed-phase structure of Ga_2O_3 thin films can be used to prepare high-responsivity SBPDs. Moreover, the cause of this phenomenon was investigated, which will provide a feasible way to improve the responsivity of Ga_2O_3 thin film SBPDs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61974144, 62004127, and 12074263)Key-Area Research and Development Program of Guangdong Province (Grant Nos. 2020B010174003 and 2020B010169001)+2 种基金Guangdong Science Foundation for Distinguished Young Scholars (Grant No. 2022B1515020073)the Science and Technology Foundation of Shenzhen (Grant No. JSGG20191129114216474)the Open Project of State Key Laboratory of Functional Materials for Informatics。
文摘Al_(1-x)In_(x)N, a Ⅲ-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al_(1-x)In_(x)N on a free-standing GaN substrate through direct radio-frequency magnetron sputtering.The optical properties of Al_(1-x)In_(x)N will be enhanced by the polarization effect of a heterostructure composed of Al_(1-x)In_(x)N and other Ⅲ-nitride materials. An Al_(1-x)In_(x)N/Ga N visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A·W^(-1)under 365 nm wavelength illumination and the photodetector was determined to have the composition Al0.75In0.25N/GaN.A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_(1-x)In_(x)N visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method,this study expands the application of ternary alloy Al_(1-x)In_(x)N visible-light photodetectors in optical communication.
基金support from the Shenzhen Science and Technology Program(No.KQTD20190929173914967,ZDSYS20220527171401003,and JCYJ20200109110416441).
文摘Single-atom catalysts(SACs)have gained substantial attention because of their exceptional catalytic properties.However,the high surface energy limits their synthesis,thus creating significant challenges for further development.In the last few years,metal–organic frameworks(MOFs)have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry,tunable morphologies,high porosity,and chemical/thermal stability.From this perspective,this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based(MOF-derived-supported and MOF-supported)SACs.Then,MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments,local electronic structures,spatial distributions,and catalytic/electrochemical reaction mechanisms.This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage,including hydrogen evolution reactions,oxygen evolution reactions,O_(2)/CO_(2)/N_(2) reduction reactions,fuel cells,and rechargeable batteries.Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.
基金supported by Basic and Applied Basic Research Project of Guangdong Province(Nos.2022A1515011438 ,2023A1515011055)Basic Research Project of the Science and Technology Innovation Commission of Shenzhen(No.JCYJ20220531101013028)Key Project of Shenzhen Basic Research(No.JCYJ2022081800003006).
文摘Seeking for composite electrolytes reinforced all-solid-state sodium ion batteries with superior long lifespan and rate performance remains a great challenge.Here,a unique strategy to tailor the architecture of composite electrolyte via inserting polymer chains into a small quantity of sulfate sodium grafted C_(48)0H_(28)O_(32)Zr_(6)(UIOSNa)is proposed.The intimate contact between polymer segments and UIOSNa with limited pore size facilitates the anion immobilization of sodium salts and reduction of polymer crystallinity,thereby providing rapid ion conduction and reducing the adverse effect caused by the immigration of anions.The tNa+grafting of-SO_(3)Na groups on fillers allows the free movement of more sodium ions to further improve and ionic conductivity.Consequently,even with the low content of UIOSNa fillers,a high ionic conductivity of 6.62×10^(-4) S·cm^(-1) at 60℃ and a transference number of 0.67 for the special designed composite electrolyte are achieved.The assembled all-solid-state sodium cell exhibits a remarkable rate performance for 500 cycles with 95.96%capacity retention at a high current rate of 4 C.The corresponding pouch cell can stably work for 1000 cycles with 97.03%capacity retention at 1 C,which is superior to most of the reported composite electrolytes in the literature.
基金supported by the Fundamental Research Funds for the Central Universities(Nos.2023MS093,JB2023106)the National Natural Science Foundation of China(Nos.52073156,52202234,91960104).
文摘otentiometric oxygen sensors have been widely used in internal combustion engines,industrial boilers,and metallurgical heat treatment furnaces.However,traditional oxygen sensors based on yttria-stabilized zirconia(YSZ)electrolyte can only be operated at elevated temperatures(>750℃)due to their rela-tively low ionic conductivity.In this study,we present a highly efficient micro-oxygen sensor that can be operated at a temperature as low as 300℃.This micro-oxygen sensor incorporates a composite solid electrolyte,i.e.,well-aligned gadolinium-doped cerium oxide(CGO)nanofibers embedded within a YSZ matrix(YSZ/CGO_(f)).The arrays of CGO nanofibers in the YSZ matrix are parallel to the conduction direc-tion,providing rapid conducting channels for oxygen ions.Benefitting from this design,the composite electrolyte leads to a conductivity of four times higher than that of traditional YSZ solid electrolytes at low temperatures.This enhancement in conductivity is attributed to the presence of a defective interfacial region between CGO_(f)and YSZ,which promotes the mobility of oxygen ions.The strategy of constructing fast ionic conduction in the composite electrolyte by using well-aligned nanofibers may be considered for the design and optimization of other micro/nano-devices including sensors,batteries,and fuel cells.
基金supported by the National Natural Science Foundation of China(Nos.21704065,22272039)National Key Basic Research Program of China(No.2016YFA0200700)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030228)。
文摘The topology of conjugated macrocycles had significant impacts on their photo-physical and photochemical properties.Herein,a series ofπ-conjugated macrocycles with diverse topology were synthesized via intramolecular McMurry coupling.Their chemical structure and macrocyclic topology were unambiguously confirmed via NMR,MALDI-TOF mass spectra,crystal analysis and scanning tunneling microscopy(STM).Depending on the structural topology and structural rigidity,these cyclic compounds display obviously distinctive emission behavior and photochemical reactions in the solution and in the solid state.Monocyclic phenylene vinylene macrocycle(denoted as MST)exhibiting aggregation-induced emission behavior,was more vulnerable to photo-cyclization in solution and triplet sensitizer promoted photodimerization due to lower strain and more flourishing intramolecular motions.After UV light irradiation,relatively more flexible MST could yield the anti-dimer via triplet excimer on the HOPG surface confirmed by STM investigation.By contrast,highly constrained bicyclic analogue(named as DMTPE)with central tetraphenylethene core,displayed high emission quantum yields of 68%both in solution and in the solid state,and was relatively inert to photochemical reactions and yield syn-dimer on the surface via singlet excimer involved[2+2]photo-dimerization.Based on the solution-mediated photo-polymerization of MST moiety,multicyclic porous carbon-rich ribbon connected with four-membered ring was successfully constructed and validated via STM imaging.
基金supported by the Natural Science Foundation of China (52122317, 22175120, 22101183, 22305049)Shenzhen Science and Technology Program (JCYJ20190808153415062,RCYX20200714114525101, 20220809130438001, JSGG20220606-141800001)the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province (2020B1515020011)。
文摘Exploration of single molecular species synchronously featured by long excitation/emission wavelength, accurate diagnosis, and effective therapy, remains supremely appealing to implement high-performance cancer phototheranostics. However, those previously established phototheranostic agents are undiversified and stereotyped in terms of structural skeleton, and generally exhibit insufficient phototheranostic outcomes. Herein, we innovatively utilized indanone-condensed thiadiazolo[3,4-g]quinoxaline(ITQ) as electron acceptor to construct novel photosensitizer with second near-infrared(NIR-II) emission. Experimental study and theoretical calculation demonstrated that comparing with the counterparts constituting by widely employed NIR-II building block benzobisthiadiazole(BBTD) and 6,7-diphenylthiadiazoloquinoxaline(DPTQ), ITQ-based photosensitizer(TITQ) showed superior aggregation-induced emission(AIE) characteristics, much stronger type-I reactive oxygen species(ROS) production, and prominent photothermal conversion capacity. Furthermore, TITQ nanoparticles with excellent biocompatibility were capable of effectively accumulating in the tumor site and visualizing tumor through fluorescence-photoacoustic-photothermal trimodal imaging with highly spatiotemporal resolution, and completely eliminating tumor by type-I photodynamic-photothermal therapy.
基金supported by the GuangdongMajor Project of Basic and Applied Basic Research(2023B0303000012)Guangdong Science Foundation for Distinguished Young Scholars(2022B1515020073)Shenzhen Science and Technology Program(JCYJ20220818102809020).
文摘In this study,a galliumnitride(GaN)substrate and its 15μmepitaxial layer were entirely grown by adopting the hydride vapor phase epitaxy(HVPE)technique.To enhance the breakdown voltage(VBR)of vertical GaN-on-GaN Schottky barrier diodes(SBDs),a dual ion coimplantation of carbon and heliumwas employed to create the edge termination.The resulting devices exhibited a low turn-on voltage of 0.55 V,a high Ion/Ioff ratio of approximately 109,and a lowspecific onresistance of 1.93 mU cm^(2).When the ion implantation edge was terminated,the maximumVBR of the devices reached 1575 V,with an average improvement of 126%.These devices demonstrated a high figure of merit(FOM)of 1.28 GW cm^(-2) and showed excellent reliability during pulse stress testing.
基金supported by the funding from the National Natural Science Foundation of China(22271197 and 22225506)the Guangdong Basic and Applied Basic Research Foundation(2023A1515011578 and 2022A1515110146)+2 种基金the Natural Science Foundation for Distinguished Young Scholars of Guangdong Province(2020B1515020011)Shenzhen Key Laboratory of Functional Aggregate Materials(ZDSYS20211021111400001)the Shenzhen Science and Technology Program(RCYX20221008092924059,JCYJ20220531102601003,JCYJ20190808142403590,KQTD20210811090142053,and JCYJ20220818103007014).
文摘Semiconducting polymers(SPs)have shown great feasibility as candidates for near-infrared-II(NIR-Ⅱ)fluorescence imaging-navigated photothermal therapy due to their strong light-harvesting ability and flexible tunability.However,the fluorescence signal of traditional SPs tends to quench in their aggregate states owing to the strongπ-πstacking,which can lead to the radiative decay pathway shutting down.To address this issue,aggregation-induced emission effect has been used as a rational tactic to boost the aggregate-state fluorescence of NIR-Ⅱemitters.In this contribution,we developed a precise molecular engineering tactic based on the block copolymerizations that integrate planar and twisted segments into one conjugated polymer backbone,providing great flexibility in tuning the photophysical properties and photothermal conversion capacity of SPs.Two monomers featured with twisted and planar architectures,respectively,were tactfully incorporated via a ternary copolymerization approach to produce a series of new SPs.The optimal copolymer(SP2)synchronously shows desirable absorption ability and good NIR-Ⅱquantum yield on the premise of maintaining typical aggregation-induced emission characteristics,resulting in balanced NIR-Ⅱfluorescence brightness and photothermal property.Water-dispersible nanoparticles fabricated from the optimal SP2 show efficient photothermal therapeutic effects both in vitro and in vivo.The in vivo investigation reveals the distinguished NIR-Ⅱfluorescence imaging performance of SP2 nanoparticles and their photothermal ablation toward tumor with prominent tumor accumulation ability and excellent biocompatibility.
基金supported by the National Natural Science Foundation of China(21805196)Natural Science Foundation of Guangdong Province,China(2018A030310416,2019A1515010832)。
文摘The widespread applications of thermoelectric(TE)materials in power generation and solid-state cooling require improving their TE figure of merit(ZT)significantly.Recently,GeTe-based alloys have shown great promise as mid-temperature TE materials with superhigh TE performance,mostly due to their relatively high-degeneracy band structures and low lattice thermal conductivity.In this perspective,we review the most recent progress of the GeTe-based TE alloys from the view of phase and defect engineering.These two strategies are the most widely-used and efficient approaches in GeTe-based alloys to optimize the transport properties of electrons and phonons for high ZT.The phase transition from rhombohedral to cubic structure is believed to improve the band convergence of GeTe-based alloys for higher electrical performance.Typical defects in GeTe-based alloys include the point defects from Ge vacancies and substitutional dopants,linear and planar defects from Ge vacancies.The defect engineering of GeTe-based alloys is important not only for optimizing the carrier density but also for tuning the band structure and phonon-scattering processes.The summarized strategies in this review can also be used as a reference for guiding the further development of GeTe-based alloys and also other TE materials.
基金This study was supported by the National Natural Science Foundation of China(NSFC)(62075136 and 62005173)Natural Science Foundation of Guangdong Province(2018B030306003 and 2020A0505100066)+1 种基金Science and Technology Innovation Commission of Shenzhen(JCYJ20200109114001806 and RCYX20200714114524139)China Postdoctoral Science Foundation(2020TQ0201).
文摘Micromanipulation and biological,material science,and medical applications often require to control or measure the forces asserted on small objects.Here,we demonstrate for the first time the microprinting of a novel fiber-tip-polymer clamped-beam probe micro-force sensor for the examination of biological samples.The proposed sensor consists of two bases,a clamped beam,and a force-sensing probe,which were developed using a femtosecond-laser-induced two-photon polymerization(TPP)technique.Based on the finite element method(FEM),the static performance of the structure was simulated to provide the basis for the structural design.A miniature all-fiber micro-force sensor of this type exhibited an ultrahigh force sensitivity of 1.51 nmμN−1,a detection limit of 54.9 nN,and an unambiguous sensor measurement range of~2.9 mN.The Young’s modulus of polydimethylsiloxane,a butterfly feeler,and human hair were successfully measured with the proposed sensor.To the best of our knowledge,this fiber sensor has the smallest force-detection limit in direct contact mode reported to date,comparable to that of an atomic force microscope(AFM).This approach opens new avenues towards the realization of small-footprint AFMs that could be easily adapted for use in outside specialized laboratories.As such,we believe that this device will be beneficial for high-precision biomedical and material science examination,and the proposed fabrication method provides a new route for the next generation of research on complex fiber-integrated polymer devices.
