A triboelectric nanogenerator based on a spiral rotating shaft for efficient marine energy harvesting of the hydrostatic pressure differential

Equipment used in underwater sensing and exploration typically relies on cables or batteries for energy supply,resulting in a limited and inconvenient energy supply and marine environmental pollution that hinder the sustainable development of distributed ocean sensing networks.Here,we design a deep-sea differential-pressure triboelectric nanogenerator(DP-TENG)based on a spiral shaft drive using modified polymer materials to harness the hydrostatic pressure gradient energy at varying ocean depths to power underwater equipment.The spiral shaft structure converts a single compression into multiple rotations of the TENG rotor,achieving efficient conversion of differential pressure energy.The multi-pair electrode design enables the DP-TENG to generate a peak current of 61.7μA,the instantaneous current density can reach 0.69μA cm^(-2),and the output performance can be improved by optimizing the spiral angle of the shaft.The DP-TENG can charge a 33μF capacitor to 17.5 V within five working cycles.It can also power a digital calculator and light up 116 commercial power light-emitting diodes,demonstrating excellent output capability.With its simple structure,low production cost,and small form factor,the DP-TENG can be seamlessly integrated with underwater vehicles.The results hold broad prospects for underwater blue energy harvesting and are expected to contribute to the development of self-powered equipment toward emerging“smart ocean”and blue economy applications.

Hierarchical grain size and nanotwin gradient microstructure for improved mechanical properties of a non-equiatomic CoCrFeMnNi high-entropy alloy

This study explored a multi-mechanism approach to improving the mechanical properties of a Co CrFe Mn Ni high-entropy alloy through non-equiatomic alloy design and processing.The alloy design ensures a single-phase face-centered cubic structure while lowering the stacking fault energy to encourage the formation of deformation twins and stacking faults by altering the equiatomic composition of the alloy.The processing strategy applied helped create a hierarchical grain size gradient microstructure with a high nanotwins population.This was achieved by means of rotationally accelerated shot peening(RASP).The non-equiatomic Co Cr Fe Mn Ni high-entropy alloy achieved a yield strength of 750 MPa,a tensile strength of 1050 MPa,and tensile uniform elongation of 27.5%.The toughness of the alloy was 2.53×10^(10)k J/m^(3),which is about 2 times that of the same alloy without the RASP treatment.The strength increase is attributed to the effects of grain boundary strengthening,dislocation strengthening,twin strengthening,and hetero-deformation strengthening associated with the heterogeneous microstructure of the alloy.The concurrent occurrence of the multiple deformation mechanisms,i.e.,dislocation deformation,twining deformation and microband deformation,contributes to achieving a suitable strain hardening of the alloy that helps to prevent early necking and to assure steady plastic deformation for high toughness.

Understanding the structural evolution of Au/WO_(2.7) compounds in hydrogen atmosphere by atomic scale in situ environmental TEM

Hydrogen energy is a resuscitated clean energy source and its sensitive detection in air is crucial due to its very low explosive limit.Metal oxide decorated with noble metal nanoparticles has been used for the enhancement of gas detection and exhibits superior sensitivity.Understanding the intrinsic mechanism of the detection and the enhancement mechanism is thus becoming a fundamental issue for the further development of novel metal/oxide compound gas-sensing materials.However,the correlation between the microstructural evolution,the charge transport and the complex sensing process has not yet been directly revealed and its atomic mechanism is still debatable.In this study,an Au/WO_(2.7) compound was synthesized and exhibited a strongly enhanced gas sensitivity to many reductive gases,especially H2.Aberration-corrected environmental transmission electron microscopy was used to investigate the atomic-scale microstructural evolution in situ during the reaction between H_(2) and Au/WO_(2.7) compound.Swing and sintering processes of the Au particles on the WO_(2.7) surface were observed under heating and gaseous environments,and no injection of hydrogen atoms was suggested.First principle calculations verified the swing and sintering processes,and they can be explained by the enhancement of H2 sensitivity.

Colloidal synthesis and phase transformation of all-inorganic bismuth halide perovskite nanoplates

Lead-free bismuth-based halide perovskites and their analogues have attracted research interest for their high stability and optoelectronic properties.However,the morphology-controlled synthesis of bismuth-based perovskite nanocrystals has been rarely demonstrated.Herein,we report the colloidal synthesis of zero-dimensional(0D)Cs3BiCl6 nanosheets(NSs),Cs3Bi2Cl9 NSs/nanoplates(NPs)and Cs4MnBi2Cl12 NPs through a hot-injection method.We demonstrate that the Cs3BiCl6 NSs,as an initial product of Cs3Bi2Cl9 and Cs4MnBi2Cl12 NPs,can transform into Cs3Bi2Cl9 NSs or Cs4MnBi2Cl12 NPs via Cl-induced metal ion insertion reactions under the templating effect of Cs3BiCl6.This growth mechanism is also applicable for the synthesis of Cs4CdBi2Cl12 nanoplates.Furthermore,the alloying of Cd2+into Cs4MnBi2Cl12 lattice could weaken the strong coupling effect between Mn and Mn,which leads to a prolonged photoluminescence lifetime and an enhanced photoluminescence quantum yield(PLQY).As a proof of concept,the alloyed Cs4MnxCd1–xBi2Cl12 NPs are used as a scintillator,which show a lowest detection limit of 134.5 nGy/s.The X-ray imaging results display a high spatial resolution of over 20 line pairs per millimeter(lp/mm).These results provide new insights in the synthesis of anisotropic bismuth-based perovskite nanocrystals and their applications in radiation detection.

Sonochemical synthesis of photocatalysts and their applications

Sonochemical synthesis has flourished significantly in the last few decades for the preparation of photocatalysts.A large number of photocatalysts have been prepared through sonochemical techniques.This review highlights the scope of sonochemistry in the preparation of photocatalysts,and their applications in energy production and environmental remediation.Beside,the sonochemical degradation of pollutants is discussed in detail.The progress made in sonochemical synthesis and the future perspective for this technique are summarized here.This review may create more enthusiasm among researchers to pay extra attention to the sonochemical synthesis of materials and add their useful contribution to the investigation of new materials for photocatalytic and other applications.This will propel this technique toward commercial sonosynthesis of nanomaterials.

Anisotropies of the g-factor tensor and diamagnetic coefficient in crystal-phase quantum dots in InP nanowires

Crystal-phase low-dimensional structures offer great potential for the implementation of photonic devices of interest for quantum information processing.In this context,unveiling the fundamental parameters of the crystal phase structure is of much relevance for several applications.Here,we report on the anisotropy of the g-factor tensor and diamagnetic coefficient in wurtzite/zincblende(WZ/ZB)crystal-phase quantum dots(QDs)realized in single InP nanowires.The WZ and ZB alternating axial sections in the NWs are identified by high-angle annular dark-field scanning transmission electron microscopy.The electron(hole)g-factor tensor and the exciton diamagnetic coefficients in WZ/ZB crystal-phase QDs are determined through micro-photoluminescence measurements at low temperature(4.2 K)with different magnetic field configurations,and rationalized by invoking the spin-correlated orbital current model.Our work provides key parameters for band gap engineering and spin states control in crystal-phase low-dimensional structures in nanowires.

A novel HfNbTaTiV high-entropy alloy of superior mechanical properties designed on the principle of maximum lattice distortion

This paper reports a synergistic design of high-performance BCC high-entropy alloy based on the combined consideration of the principles of intrinsic ductility of elements,maximum atomic size difference for solid solution strengthening and the valence electron concentration criterion for ductility.The single-phase BCC HfNbTaTiV alloy thus designed exhibited a high compressive yield strength of 1350 MPa and a high compressive ductility of>45%at the room temperature.This represents a 50%increase in yield strength relative to a HfNbTaTiZr alloy.This is attributed to the maximized solid solution strengthening effect caused by lattice distortion,which is estimated to be 1094 MPa.The alloy was also able to retain 53%of its yield strength and 77%of its ductility at 700℃.These properties are superior to those of most refractory BCC high-entropy alloys reported in the literature.

Origin of high elastic strain in amorphous silica nanowires

An understanding of the origin of elastic strain is extremely important for both crystalline materials and amorphous materials. Owing to the lack of a long range order in their structure, it is arduous to dynamically study the elastic mechanism of amorphous materials experimentally at atomic scale compared with their crystalline counterparts. Here, the elastic deformation mechanism of amorphous silica nanowires(NWs) has been studied for the first time via in situ elastic tensile tests in a transmission electron microscope. Radial distribution functions(RDFs) calculated from the corresponding selected area electron diffraction patterns(SAEDPs) at different strains were used to reconstruct a structural model based on the reverse Monte-Carlo(RMC) method. The result interestingly indicates that the elastic strain of silica glass NWs can be mainly attributed to the elastic elongation of the bond length accompanied by a change in the bond angle distribution. This work is useful for understanding the high strength of amorphous materials.

In situ atomic-scale observation of dislocation behaviors in twin-structured Pt nanocrystals

The deformation mechanisms of twin-structured metallic materials have attracted great interest.Though previous theoretical predictions have suggested that the repulsive force of the twin boundary(TB)can significantly affect the deformation of twinstructured metals,it remains unclear whether this prediction applies to experimental conditions.In this paper,the atomic-scaled deformation process of twin-structured Pt nanocrystals was in situ observed using our home-made device in a high-resolution transmission electron microscope.We have shown that the plastic deformation of the twin-structured Pt nanocrystals was governed by full dislocation generation as well as Lomer dislocation(LD)lock formation and destruction.After LD locks were destructed,these full dislocations tended to move towards the surface of the nanocrystals.The findings revealed that due to the ultra-high repulsive force of TB on dislocation,there was no dislocation-TB reaction during the deformation.These findings can enrich our understanding of the dislocation behaviors of twin-structured nanocrystals.

In-situ revealing the degradation mechanisms of Pt film over 1000℃

Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions determines its service temperature and lifetime.In this work,the self-heating degradation behaviors of Pt thin films above 1000℃were studied in situ by TEM at the nanoscale.The Pt films degraded mainly through void nucleation and growth on the Pt-SiN_(x)interface.Voids preferentially formed at the grain boundary and triple junction intersections with the interface.At temperatures above 1040℃,the voids nucleated at both the grain boundaries and inside the Pt grains.A stress simulation of the suspended membrane suggests the existence of local tensile stress in the Pt film,which promotes the nucleation of voids at the Pt-Si Nxinterface.The grain-boundary-dominated mass transportation renders the voids grow preferentially at GBs and triple junctions in a Pt film.Additionally,under the influence of an applied current,the voids that nucleated inside Pt grains grew to a large size and accelerated the degradation of the Pt film.

Near-unity broadband emissive hybrid manganese bromides as highly-efficient radiation scintillators

Zero-dimensional(0D)hybrid manganese halides have gained wide attention for the various crystal structures,excellent optical performance and scintillation properties compared with 3D lead halide perovskite nanocrystals.In this work,a new family of 0D hybrid manganese halides of A_(2)MnBr_(4)(A=BzTPP,Br-BzTPP,and F-BzTPP)based on discrete[MnBr_(4)]^(2-) tetrahedral units is reported as highly efficient lead-free scintillators.Excited by UV or blue light,these hybrids emit bright green light originating from the d–d transition of Mn^(2+) with near-unity PLQY(99.5%).Signif-icantly,high PLQY and low self-absorption render extraordinary radioluminescence properties with the highest light yield of 80,100 photons MeV-1,which reached the climax of present hybrid manganese halides and surpassed most commercial scin-tillators.The radioluminescence intensity features a linear response to X-ray doses with a detection limit of 30 nGyair s^(-1),far lower than the requirement of medical diagnostic(5.5µGyair s^(-1)).X-ray imaging demonstrates ultrahigh spatial resolution of 14.06 lp mm^(-1) and short afterglow of 0.3 ms showcasing promising application prospects in radiography.Overall,we demonstrated new hybrid manganese halides as promising scintillators for advanced applications in X-ray imaging with multi-ple superiorities of nontoxicity,facile-assembly process,high irradiation light yield,excellent resolution,and stability.

Simultaneously enhanced oxidation resistance and mechanical properties in a novel lightweight Ti_(2)VZrNb_(0.5)-Al_(0.5)high-entropy alloy

Enhanced oxidation resistance is a primary demand for the application of refractory high-entropy alloys(RHEAs)at elevated temperatures.In this study,Al was added to a Ti_(2)VZrNb RHEA to partially substitute Nb to improve its oxidation resistance and mechanical properties.The alloy was found to have an increased oxidation resistance by forming a continuous Al_(2)O_(3)+ZrO_(2)oxide protective surface.At the same time,the room-temperature yield strength was also increased by 66%to 1273 MPa via solid solution strengthening.The low atomic mass of Al also helped to reduce the density of the alloy by 8.2%to 5.44 g cm^(−3).This resulted in a high specific yield strength of 234 MPa cm3 g^(−1) for the alloy.Meanwhile,the Ti_(2)VZrNb_(0.5)-Al_(0.5)alloy also exhibited a high compressive plasticity of>50%.These values are among the best reported so far for RHEAs.