Anti-aging performance improvement and enhanced combustion efficiency of boron via the coating of PDA

Boron is an ambitious fuel in energetic materials since its high heat release values,but its application is prohibited by low combustion efficiency and oxidization during storage.The polydopamine(PDA)was introduced into boron particles,investigating the impact of PDA content on the energetic behavior of boron.The results indicated that the PDA coating formed a fishing net structure on the surface of boron particles.The heat release results showed that the combustion calorific value of B@PDA was higher than that of the raw boron.Specifically,the actual combustion heat of boron powder in B@10%PDA increased by 38.08%.Meanwhile,the DSC peak temperature decreased by 100.65℃under similar oxidation rate compared to raw boron.Simultaneously,the B@PDA@AP and B@AP composites were prepared,and their combustion properties were evaluated.It was demonstrated that B@10%PDA@AP exhibited superior performance in terms of peak pressure and burning time,respectively.The peak pressure is 12.43 kPa more than B@AP and burning time is 2.22 times higher than B@AP.Therefore,the coating of PDA effectively inhibits the oxidization of boron during storage and enhances the energetic behavior of boron and corresponding composites.

Single-Molecule Confinement Induced Intrinsic Multi-Electron Redox-Activity to Enhance Supercapacitor Performance

Aggregation of polyoxometalates(POM)is largely responsible for the reduced performance of POM-based energy-storage systems.To address this challenge,here,the precise confinement of single Keggin-type POM molecule in a porous carbon(PC)of unimodal super-micropore(micro-PC)is realized.Such precise single-molecule confinement enables sufficient activity center exposure and maximum electron-transfer from micro-PC to POM,which well stabilizes the electron-accepting molecules and thoroughly activates its inherent multi-electron redox-activity.In particular,the redox-activities and electron-accepting properties of the confined POM molecule are revealed to be super-micropore pore size-dependent by experiment and spectroscopy as well as theoretical calculation.Meanwhile,the molecularly dispersed POM molecules confined steadily in the“cage”of micro-PC exhibit unprecedented large-negative-potential stability and multiple-peak redox-activity at an ultra-low loading of~11.4 wt%.As a result,the fabricated solid-state supercapacitor achieves a remarkable areal capacitance,ultrahigh energy and power density of 443 mF cm^(-2),0.12 mWh cm^(-2)and 21.1 mW cm^(-2),respectively.This work establishes a novel strategy for the precise confinement of single POM molecule,providing a versatile approach to inducing the intrinsic activity of POMs for advanced energy-storage systems.

Scaling laws governing the elastic properties of 3D graphenes

In this study,we comprehensively investigated the scaling law for elastic properties of three-dimensional honeycomb-like graphenes(3D graphenes)using hybrid neural network potential-based molecular dynamics simulations and theoretical analyses.The elastic constants were obtained as functions of honeycomb hole size,denoted by the graphene wall length L.All five independent elastic constants in the large-L limit are proportional to L^(-1).The associated coefficients are combinations of elastic constants of two-dimensional graphene.High-order terms including L^(-2)and L^(-3)emerge for finite L values.They have three origins,the distorted areas close to the joint lines of 3D graphenes,the variation in solid angles between graphene plates,and the bending distortion of graphene plates.Significantly,the chirality becomes essential with decreasing L because the joint line structures are different between the armchair and zigzag-type 3D graphenes.Our findings provide insights into the elastic properties of graphene-based superstructures and can be used for further studies on graphene-based materials.

Tunable optical topological transitions of plasmon polaritons in WTe_(2) van der Waals films

Naturally existing in-plane hyperbolic polaritons and the associated optical topological transitions,which avoid the nano-structuring to achieve hyperbolicity,can outperform their counterparts in artificial metasurfaces.Such plasmon polaritons are rare,but experimentally revealed recently in WTe_(2)van der Waals thin films.Different from phonon polaritons,hyperbolic plasmon polaritons originate from the interplay of free carrier Drude response and interband transitions,which promise good intrinsic tunability.However,tunable in-plane hyperbolic plasmon polariton and its optical topological transition of the isofrequency contours to the elliptic topology in a natural material have not been realized.Here we demonstrate the tuning of the optical topological transition through Mo doping and temperature.The optical topological transition energy is tuned over a wide range,with frequencies ranging from 429 cm^(−1)(23.3 microns)for pure WTe_(2)to 270 cm^(−1)(37.0 microns)at the 50%Mo-doping level at 10 K.Moreover,the temperature-induced blueshift of the optical topological transition energy is also revealed,enabling active and reversible tuning.Surprisingly,the localized surface plasmon resonance in skew ribbons shows unusual polarization dependence,accurately manifesting its topology,which renders a reliable means to track the topology with far-field techniques.Our results open an avenue for reconfigurable photonic devices capable of plasmon polariton steering,such as canaling,focusing,and routing,and pave the way for low-symmetry plasmonic nanophotonics based on anisotropic natural materials.

Kirigami/origami:unfolding the new regime of advanced 3D microfabrication/nanofabrication with“folding”

Advanced kirigami/origami provides an automated technique for modulating the mechanical,electrical,magnetic and optical properties of existing materials,with remarkable flexibility,diversity,functionality,generality,and reconfigurability.In this paper,we review the latest progress in kirigami/origami on the microscale/nanoscale as a new platform for advanced 3D microfabrication/nanofabrication.Various stimuli of kirigami/origami,including capillary forces,residual stress,mechanical stress,responsive forces,and focussed-ion-beam irradiation-induced stress,are introduced in the microscale/nanoscale region.These stimuli enable direct 2D-to-3D transformations through folding,bending,and twisting of microstructures/nanostructures,with which the occupied spatial volume can vary by several orders of magnitude compared to the 2D precursors.As an instant and direct method,ion-beam irradiation-based tree-type and close-loop nano-kirigami is highlighted in particular.The progress in microscale/nanoscale kirigami/origami for reshaping the emerging 2D materials,as well as the potential for biological,optical and reconfigurable applications,is briefly discussed.With the unprecedented physical characteristics and applicable functionalities generated by kirigami/origami,a wide range of applications in the fields of optics,physics,biology,chemistry and engineering can be envisioned.

Sign-reversible valley-dependent Berry phase effects in 2D valley-half-semiconductors

Manipulating valley-dependent Berry phase effects provides remarkable opportunities for both fundamental research and practical applications.Here,by referring to effective model analysis,we propose a general scheme for realizing topological magneto-valley phase transitions.More importantly,by using valley-half-semiconducting VSi2N4 as an outstanding example,we investigate sign change of valley-dependent Berry phase effects which drive the change-in-sign valley anomalous transport characteristics via external means such as biaxial strain,electric field,and correlation effects.As a result,this gives rise to quantized versions of valley anomalous transport phenomena.Our findings not only uncover a general framework to control valley degree of freedom,but also motivate further research in the direction of multifunctional quantum devices in valleytronics and spintronics.