Catalytic anode surface enabling in situ polymerization of gel polymer electrolyte for stable Li metal batteries

Employing quasi-solid-state gel polymer electrolyte(GPE)instead of the liquid counterpart has been regarded as a promising strategy for improving the electrochemical performance of Li metal batteries.However,the poor and uneven interfacial contact between Li metal anode and GPE could cause large interfacial resistance and electrochemical Li stripping/plating inhomogeneity,deteriorating the electrochemical performance.Herein,we proposed that the functional component of composite anode could work as the catalyst to promote the in situ polymerization reaction,and we experimentally realized the integration of polymerized-dioxolane electrolyte and Li/Li_(22)Sn_(5)/LiF composite electrode with low interfacial resistance and good stability by in situ catalyzation polymerization.Thus,the reaction kinetics and stability of metallic Li anode were significantly enhanced.As a demonstration,symmetric cell using such a GPE-Li/Li_(22)Sn_(5)/LiF integration achieved stable cycling beyond 250 cycles with small potential hysteresis of 25 mV at 1 mA·cm^(−2)and 1 mAh·cm^(−2),far outperforming the counterpart regular GPE on pure Li.Paired with LiNi0.5Co0.3Mn0.2O2,the full cell with the GPE-Li/Li_(22)Sn_(5)/LiF integration maintained 85.7%of the original capacity after 100 cycles at 0.5 C(1 C=200 mA·g^(−1)).Our research provides a promising strategy for reducing the resistance between GPE and Li metal anode,and realizes Li metal batteries with enhance electrochemical performance.

Integrating 2D layered materials with 3D bulk materials as van der Waals heterostructures for photodetections:Current status and perspectives

In the last decade,two-dimensional layered materials(2DLMs)have been drawing extensive attentions due to their unique properties,such as absence of surface dangling bonds,thickness-dependent bandgap,high absorption coeffi-cient,large specific surface area,and so on.But the high-quality growth and transfer of wafer-scale 2DLMs films is still a great challenge for the commerciali-zation of pure 2DLMs-based photodetectors.Conversely,the material growth and device fabrication technologies of three-dimensional(3D)semiconductors photodetectors tend to be gradually matured.However,the further improvement of the photodetection performance is limited by the difficult heterogeneous inte-gration or the inferior crystal quality via heteroepitaxy.Fortunately,2D/3D van der Waals heterostructures(vdWH)combine the advantages of the two types of materials simultaneously,which may provide a new platform for developing high-performance optoelectronic devices.Here,we first discuss the unique advantages of 2D/3D vdWH for the future development of photodetection field and simply introduce the structure categories,working mechanisms,and the typical fabrication methods of 2D/3D vdWH photodetector.Then,we outline the recent progress on 2D/3D vdWH-based photodetection devices integrating 2DLMs with the traditional 3D semiconductor materials,including Si,Ge,GaAs,AlGaN,SiC,and so on.Finally,we highlight the current challenges and pros-pects of heterointegrating 2DLMs with traditional 3D semiconductors toward photodetection applications.

高纵横比单层MoS_(2)纳米-微米带的可控合成及其在高性能光电晶体管中的应用

本文报道了一种快速、可控合成单层MoS_(2)纳米-微米带的方法:通过在蓝宝石衬底上旋涂Na_(2)MoO_(4)和NaOH的混合溶液后一步化学气相沉积硫化的方式进行生长.其中,通过改变NaOH的浓度,对气-液-固生长过程中的反应物液滴流动性进行调控,我们实现了对所获得的MoS_(2)的形貌和取向的调控;同时,通过改变生长时间,可以实现对MoS_(2)层数的调控.利用这种方法,我们获得了最窄宽度仅为200 nm,纵横比超过100的单层MoS_(2)纳米-微米带,且表征证明其具有很高的晶体质量.同时,我们还用该MoS_(2)纳米带作为沟道材料,制备了光电晶体管,测试表明其具有高达9×10^(5)的电流开/关比、超过10^(5)的光暗电流比以及高达8.6 A W^(-1)的响应度,展现了其在电子和光电子器件中的应用潜力.

Directly accessing octave-spanning dissipative Kerr soliton frequency combs in an AlN microresonator

Self-referenced dissipative Kerr solitons (DKSs) based on optical microresonators offer prominent characteristics allowing for various applications from precision measurement to astronomical spectrometer calibration. To date,direct octave-spanning DKS generation has been achieved only in ultrahigh-Q silicon nitride microresonators under optimized laser tuning speed or bi-directional tuning. Here we propose a simple method to easily access the octave-spanning DKS in an aluminum nitride (AlN) microresonator. In the design,two modes that belong to different families but with the same polarization are nearly degenerate and act as a pump and an auxiliary resonance,respectively. The presence of the auxiliary resonance can balance the thermal dragging effect,crucially simplifying the DKS generation with a single pump and leading to an enhanced soliton access window. We experimentally demonstrate the long-lived DKS operation with a record single-soliton step (10.4 GHz or83 pm) and an octave-spanning bandwidth (1100–2300 nm) through adiabatic pump tuning. Our scheme also allows for direct creation of the DKS state with high probability and without elaborate wavelength or power schemes being required to stabilize the soliton behavior.

Cascaded deep ultraviolet light-emitting diode via tunnel junction

The Al Ga N-based deep ultraviolet(DUV)light-emitting diode(LED)is an alternative DUV light source to replace traditional mercury-based lamps.However,the state-of-the-art DUV LEDs currently exhibit poor wall-plug efficiency and low light output power,which seriously hinder their commercialization.In this work,we design and report a tunnel-junctioncascaded(TJC)DUV LED,which enables multiple radiative recombinations within the active regions.Therefore,the light output power of the TJC-DUV LEDs is more than doubled compared to the conventional DUV LED.Correspondingly,the wall-plug efficiency of the TJC-DUV LED is also significantly boosted by 25%at 60 m A.

Selective growth and characterization of ZnO nanorods assembled a hexagonal pattern on H2-decomposed GaN epilayer

This paper reported a simple and effective method for fabricating and patterning highly ordered ZnO nanorod arrays on H2-decomposed GaN epilayer via hydrothermal route. The edge of pattern, which has been decomposed by H2 flow, provides appropriate nucleation sites for the selective-growth of aligned ZnO nanorods. The density of ZnO nanorod arrays assembled the hexagonal pattern can be tuned by varying the solution concentrations, growth time and reaction temperatures. The results have demonstrated that the ZnO nanorods are highly uniform in diameter and height with perfect alignment and are epitaxially grown along [0001] direc- tion. This work provides a novel and accessible route to prepare oriented and aligned ZnO nanorod arrays pattern. And the aligned ZnO nanorods form an ideal hexagonal pattern that might be used in many potential applications of ZnO nanomaterials.

Diluted magnetic characteristics of Ni-doped AIN films via ion implantation

The structural and magnetic properties, as well as the mechanism of magnetization, of Ni-implanted A1N films were studied. A1N was deposited on A1203 substrates by metalorganic chemical vapor deposition （MOCVD）, and subsequently Ni ions were implanted into the A1N films by Metal Vapor Arc （MEVVA） sources at an energy of 100 keV for 3 h. The films were annealed at 900~C for 1 h in the furnace in order to transfer the Ni ions from interstitial sites to substitutional sites in A1N, thus activating the Ni3＋ ions. Characterizations were performed in situ using X-ray diffraction （XRD）, X-ray photoemis- sion spectroscopy （XPS）, and vibrating sample magneto- metry （VSM）, which showed that the films have a wurtzite structure without the formation of a secondary phase after implanting and annealing. Ni ions were successfully implanted into substitutional sites of AlN films, and the chemical bonding states are Ni-N. The apparent hysteresis loops prove that the films exhibited magnetism at 300 K. The room temperature （RT） saturation magnetization moment （Ms） and eoercivity （He） values were about 0.36 emu/g and 35.29 Oe, respectively. From the first-principles calculation, a total magnetic moment of 2.99 ~tB per supercell is expected, and the local magnetic moment of a NiN4 tetrahedron, 2.45 gB, makes the primary contribu- tion. The doped Ni atom hybridizes with four nearby N atoms in a NiN4 tetrahedron; then the electrons of the N atoms are spin-polarized and couple with the electrons of the Ni atom with strong magnetization, which results in magnetism. Therefore, the p-d exchange mechanism between Ni-3d and N-2p can be the origin of the magnetism. It is expected that these room temperature, ferromagnetic, Ni-doped A1N films will have many potential applications as diluted magnetic semiconductors.

Controlled Synthesis of NaV_6O_(15) Nanorods with High Reversible Capacity and Excellent Cycling Stability

In this work, we demonstrate an effective method to improve capacitive performance of NaV6O（15） intrinsically by annealing. NaV6O（15） nanorods（NRs） prepared by a simple annealing treatment exhibit significantly improved electrochemical performance compared with the untreated NaV6O（15） electrode, and yield a high specific capacitance（402.8 F/g at 300 mA/g）. Furthermore, the annealing treated nanorods show excellent rate capability and cycling stability（ca. 80% capacitance retention after 1000 cycles at a scan rate of100 mV/s）. Our results have confirmed that the annealing treatment has great influence on the capacitive performance of NaV6O（15）, which may be attributed to the intrinsic three dimensional（3D） tunneled structures of NaV6O（15）, and NR morphology. These findings may further broaden the application of NaV6O（15）-based materials for high performance supercapacitors（SCs）, aqueous rechargeable lithium batteries and Li-ion capacitors.

Ripening-resistance of Pd on TiO_(2)(110)from first-principles kinetics

Suppressing sintering of supported particles is of importance for the study and application of metal-TiO_(2)system.Theoretical study of Ostwald ripening of TiO_(2)(110)-supported Pd particles would be helpful to extend the understanding of the sintering.In this paper,based on density functional theory(DFT),the surface energy of Pd and the total activation energy(the sum of formation energy and diffusion barrier)of TiO2-supported Pd were calculated.Since the total activation energy is mainly contributed from the formation energy,it is indicated that the ripening of Pd particles would be in the interface control limit.Subsequently,the calculated surface energy and total activation energy were used to simulate Ostwald ripening of TiO_(2)(l 10)-supported Pd particles.As a result,in comparison with larger particles,smaller particles would worsen the performance of ripening-resistance according to its lower onset temperature and shorter half-life time.The differences on ripeningresistance among different size particles could be mitigated along with the increase of temperature.Moreover,it is verified that the monodispersity can improve ripening resistance especially for the smaller particles.However,the different performances of the ripening originating from difference of the relative standard deviation are more obvious at higher temperature than lower temperature.This temperature effect for the relative standard deviation is the inverse of that for the initial main particle size.It is indicated that the influence of dispersity of TiO_(2)(l 10)-supported Pd particles on ripening may be more sensitive at higher temperature.In this contribution,we extend the first principle kinetics to elaborate the ripening of Pd on TiO_(2)(l 10).It is expected that the information from first principle kinetics would be helpful to the study in experiments.

Growth of InGaN-based blue-LED on AlN/sapphire sputtered with different oxygen flow rate

Indium gallium nitride(InGaN)based blue light-emitting diodes(LEDs)suffer from insufficient crystal quality and serious efficiency droop in large forward current.In this paper,the InGaN-based blue LEDs are grown on sputtered aluminum nitride(AlN)films to improve the device light power and weaken the efficiency droop.The effects of oxygen flow rate on the sputtering of AlN films on sapphire and device performance of blue LEDs are studied in detail.The mechanism of external quantum efficiency improvement is related to the change of V-pits density in multiple quantum wells.The external quantum efficiency of 66%and 3-V operating voltage are measured at a 40-mA forward current of with the optimal oxygen flow rate of 4 SCCM.

Building one-dimensional Bi2S3 nanorods as enhanced photoresponding materials for photodetectors

In this paper, Bi2S3 nanorods were successfully synthesized via a facile one-pot hydrothermal method and characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Then the Bi2S3 nanorods were deposited on Au interdigital electrodes by dip-coating to fabricate photodetectors. The photoresponse properties using Bi2S3 nanorods as a representative system showed a significantly enhanced conductivity and the current-voltage （I-V） characteristic exhibited about ca. 2 orders of magnitude larger response and decay time was than the dark current. The estimated to be -371.66 and 386 ms, respectively, indicating Bi2S3 may be an excellent candidate for high speed and high-sensitivity photoelectrical switches and light sensitive devices.