Strain engineering and hydrogen effect for two-dimensional ferroelectricity in monolayer group-Ⅳmonochalcogenides MX(M=Sn,Ge;X=Se,Te,S)

Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of monolayer group-IV monochalcogenides MX(M=Sn,Ge;X=Se,Te,S)via strain engineering,and their effects with contaminated hydrogen are also discussed.GeSe,GeTe,and GeS do not go through transition up to the compressive strain of-5%,and consequently have good ferroelectric parameters for device applications that can be further improved by applying strain.According to the calculated ferroelectric properties and the band gaps of these materials,we find that their band gap can be adjusted by strain for excellent photovoltaic applications.In addition,we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe.It reveals that H prefers to absorb on SnS and SnTe monolayers as molecules rather than atomic H.As a result,hydrogen molecules have little effect on the polarization and electronic structure of monolayer SnTe and SnS.

Synergistic defect passivation and strain compensation toward efficient and stable perovskite solar cells

Rational interface engineering is essential for minimizing interfacial nonradiative recombination losses and enhancing device performance.Herein,we report the use of bidentate diphenoxybenzene(DPOB)isomers as surface modifiers for perovskite films.The DPOB molecules,which contain two oxygen(O)atoms,chemically bond with undercoordinated Pb^(2+) on the surface of perovskite films,resulting in compression of the perovskite lattice.This chemical interaction,along with physical regulations,leads to the formation of high-quality perovskite films with compressive strain and fewer defects.This compressive strain-induced band bending promotes hole extraction and transport,while inhibiting charge recombination at the interfaces.Furthermore,the addition of DPOB will reduce the zero-dimensional(OD) Cs_4PbBr_6 phase and produce the two-dimensional(2D) CsPb_(2)Br_5 phase,which is also conducive to the improvement of device performance.Ultimately,the resulting perovskite films,which are strain-released and defect-passivated,exhibit exceptional device efficiency,reaching 10.87% for carbon-based CsPbBr_(3) device,14.86% for carbon-based CsPbI_(2)Br device,22,02% for FA_(0.97)Cs_(0.03)PbI_(3) device,respectively.Moreover,the unencapsulated CsPbBr_(3) PSC exhibits excellent stability under persistent exposure to humidity(80%) and heat(80℃) for over 50 days.

Diamond semiconductor and elastic strain engineering

Diamond,as an ultra-wide bandgap semiconductor,has become a promising candidate for next-generation microelec-tronics and optoelectronics due to its numerous advantages over conventional semiconductors,including ultrahigh carrier mo-bility and thermal conductivity,low thermal expansion coefficient,and ultra-high breakdown voltage,etc.Despite these ex-traordinary properties,diamond also faces various challenges before being practically used in the semiconductor industry.This review begins with a brief summary of previous efforts to model and construct diamond-based high-voltage switching diodes,high-power/high-frequency field-effect transistors,MEMS/NEMS,and devices operating at high temperatures.Following that,we will discuss recent developments to address scalable diamond device applications,emphasizing the synthesis of large-area,high-quality CVD diamond films and difficulties in diamond doping.Lastly,we show potential solutions to modulate diamond’s electronic properties by the“elastic strain engineering”strategy,which sheds light on the future development of diamond-based electronics,photonics and quantum systems.

Strain Engineering for Germanium-on-Insulator Mobility Enhancement with Phase Change Liner Stressors

We investigate the strain in various Ge-on-insulator （GeOI） micro-structures induced by three phase-change maferials （PCMs） （Ge2Sb2Te5, Sb2Te3, GeTe） deposited. The PCMs could change the phase from amorphous state to polycrystalline state with a low temperature thermal annealing, resulting in an intrinsic contraction in the PCM films. Raman spectroscopy analysis is performed to compare the strain induced in the GeOI micro- structures by various PCMs. By comparison, Sb2 Tea could induce the largest amount of tensile strain in the GeOI micro-structures after the low temperature annealing. Based on the strain calculated from the Raman peak shifts, finite element numerical simulation is performed to calculate the strain-induced electron mobility enhancement for Ge n-MOSFETs with PCM liner stressors. With the adoption of Sb2 Te3 liner stressor, 22% electron mobility enhancement at Xinv=1×10^13cm^-2 could be achieved, suggesting that PCM especially Sb2 Te3 liner stressor is a promising technique for the performance enhancement of Ge MOSFETs.

Control of surface wettability via strain engineering

Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sam- ple material and molecular dynamic simulations, we demon- strate that strain engineering can serve as an effective way to control the surface wettability. The contact angles 0 of water droplets on a graphene vary from 72.5° to 106° under biaxial strains ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface （at zero strain）, the variation of 0 upon the applied strains is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the strains. In light of the inherent dependence of the contact an- gle on liquid-solid interfacial energy, we develop an analytic model to show the cos 0 as a linear function of the adsorption energy Eads of a single water molecule over the substrate sur- face. This model agrees with our molecular dynamic results very well. Together with the linear dependence of Eads on bi- axial strains, we can thus understand the effect of strains on the surface wettability. Thanks to the ease of reversibly ap- plying mechanical strains in micro/nano-electromechanical systems, we believe that strain engineering can be a promis- ing means to achieve the reversibly control of surface wetta- bility.

Raman Scattering Modification in Monolayer ReS_2 Controlled by Strain Engineering

Regulation of optical properties and electronic structure of two-dimensionM layered ReS2 materials has attracted much attention due to their potential in electronic devices. However, the identification of structure transformation of monolayer ReS2 induced by strain is greatly lacking. In this work, the Raman spectra of monolayer ReS2 with external strain are determined theoretically based on the density function theory. Due to the lower structural symmetry, deformation induced by external strain can only regulate the Raman mode intensity but cannot lead to Raman mode shifts. Our calculations suggest that structural deformation induced by external strain can be identified by Raman scattering.

Research on the Construction and Function of a Chlorophyll Degradation Recombinant Engineering Strain

In order to effectively reduce the chlorophyll content in flue-cured tobacco, improve the overall quality of tobacco leaves, chlorophyllase gene was cloned from Arabidopsis thaliana. After the expression of the expression vector in E. coil, the recombinant engineering strain was obtained. Afterwards, IPTG （isopropy-β-D-thiogalactopyranoside）was used to induce the goal protein, and the chlorophyllase activity of the recombinant engineering strain was measured, so as to investigate its degradation effect on the chlorophyll in the extracts of tobacco leaves. The results were as follows： （1） the amplified chlorophyllase gene At- CLH1 constructed the expression vector pET28a-AtCLH1 successfully, obtaining the recombinant engineering strain; （2） induced under 30 ℃ for 22 h, the strain could well express the recombinant protein AtCLH1 with 0.5 mmol/L IPTG, and the molecular weight was about 35 kDa; （3） the strain showed good chlorophyllase producing capability, and the activity of the produced chlorophyllase could reach up to 24.9 U/mL, which could degrade the chlorophyll in tobacco extract and had a good application prospect in improving the quality of low quality tobacco; （4） based on the results of orthogonal test, the enzyme extract from the strain was added to the tobacco leaf surface, which could make the degradation rate of chlorophyll in the tobacco leaf reach 17.06% under the temperature of 37 ℃ at the humidity of 75% for 48 h; （5） after treated by the enzyme liquid, the test tobacco showed increase in the content of aromatic substances, enhancement of tobacco fragrance quality and amount, significant decrease of offensive odor and irritation, significant improvement of agreeable aftertaste, making the overall sensory quality of the tobacco leaf significantly improved.

Valley-dependent transport in strain engineering graphene heterojunctions

We study the effect of strain on band structure and valley-dependent transport properties of graphene heterojunctions.It is found that valley-dependent separation of electrons can be achieved by utilizing strain and on-site energies.In the presence of strain,the values of transmission can be effectively adjusted by changing the strengths of the strain,while the transport angle basically keeps unchanged.When an extra on-site energy is simultaneously applied to the central scattering region,not only are the electrons of valleys K and K'separated into two distinct transmission lobes in opposite transverse directions,but the transport angles of two valleys can be significantly changed.Therefore,one can realize an effective modulation of valley-dependent transport by changing the strength and stretch angle of the strain and on-site energies,which can be exploited for graphene-based valleytronics devices.

Response of rice to inoculation with genetic engineered strains of associative diazotrophs

Enhancement of nitrogen fixation in the rhizo-sphere of cereals has attracted a wide interestin biological and agricultural research,insteadof chemicals,for supplying higher plants withcombined nitrogen.Bacteria in association withrice plant.s were sensitive to the surroundingfactors in the soil,such as NH~+ or O,whichrepressed associative nitrogen fixation between

Monodispersed ultrathin twisty PdBi alloys nanowires assemblies with tensile strain enhance C_(2+)alcohols electrooxidation

Direct alcohol fuel cells(DAFCs)are powered by the alcohol electro-oxidation reaction(AOR),where an electrocatalyst with an optimal electronic structure can accelerate the sluggish AOR.Interestingly,strain engineering in hetero-catalysis offers a promising route to boost their catalytic activity.Herein,we report on a class of monodispersed ultrathin twisty PdBi alloy nanowires(TNWs)assemblies with face-centered structures that drive AORs.These thin nanowire structures expose a large number of reactive sites.Strikingly,Pd_(6)Bi_(1)TNWs show an excellent current density of 2066,3047,and 1231 mA mg_(Pd)^(-1)for oxidation of ethanol,ethylene glycol,and glycerol,respectively.The“volcano-like”behaviors observed on PdBi TNWs for AORs indicate that the maximum catalytic mass activity is a well balance between active intermediates and blocking species at the interface.This study offers an effective and universal method to build novel nanocatalysts in various applications by rationally designing highly efficient catalysts with specific strain.

Bismuth doping enhanced tunability of strain-controlled magnetic anisotropy in epitaxial Y_(3)Fe_(5)O_(12)(111) films

Y_(3)Fe_(5)O_(12)(YIG) and Bi Y_(3)Fe_(5)O_(12)(Bi:YIG) films were epitaxially grown on a series of(111)-oriented garnet substrates using pulsed laser deposition. Structural and ferromagnetic resonance characterizations demonstrated the high epitaxial quality, extremely low magnetic loss and coherent strain state in these films. Using these epitaxial films as model systems, we systematically investigated the evolution of magnetic anisotropy(MA) with epitaxial strain and chemical doping. For both the YIG and Bi:YIG films, the compressive strain tends to align the magnetic moment in the film plane while the tensile strain can compete with the demagnetization effect and stabilize perpendicular MA. We found that the strain-induced lattice elongation/compression along the out-of-plane [111] axis is the key parameter that determines the MA. More importantly, the strain-induced tunability of MA can be enhanced significantly by Bi doping;meanwhile, the ultralow damping feature persists. We clarified that the cooperation between strain and chemical doping could realize an effective control of MA in garnet-type ferrites, which is essential for spintronic applications.

Interface strain engineering of Ir clusters on ultrathin NiO nanosheets for electrochemical water splitting over 1800 hours

Strain engineering of two-dimensional(2D)material interfaces represents a powerful strategy for enhanc-ing the electrocatalytic activity of water splitting.However,maintaining catalytic stability under various harsh conditions by introducing interface strain remains a great challenge.The catalyst developed and evaluated herein comprised Ir clusters dispersed on 2D NiO nanosheets(NSs)derived from metal organic frameworks(lr@NiO/C_(BDc)),which displays a high activity and stability under all pH conditions,and even a change of only 1%in the applied voltage is observed after continuous electrocatalytic operation for over 1800 h under alkaline conditions.Through combined experimental and computational studies,we found that the introduced interfacial strain contributes to the outstanding structural stability of the Ir@NiO/CBDC catalyst,arising from its increased Ir and Ni vacancy formation energies,and hence suppressing its leach-ing.Moreover,strain also enhances the kinetically sluggish electrocatalytic water splitting reaction by op-timizing its electronic structure and coordination environment.This work highlights the effects of strain on catalyst stability and provides new insights for designing widely applicable electrocatalysts.

Enhancing energy storage efficiency in lead-free dielectric ceramics through relaxor and lattice strain engineering

Dielectric capacitors with high power density and fast charge-discharge speed play an essential role in the development of pulsed power systems.The increased demands for miniaturization and practicality of pulsed power equipment also necessitate the development of dielectric materials that possess high energy density while maintaining ultrahigh efficiency(η).In particular,ultrahigh efficiency signifies minimal energy loss,which is essential for practical applications but challenging to effectively mitigate.Here,we demonstrate a strategy of incorporating heterovalent elements into Ba(Zr_(0.1)Ti_(0.9))O_(3),which contributes to achieving relaxor ferroelectric ceramics and reducing lattice strain,thereby improving the comprehensive energy storage performance.Finally,optimal energy storage performance is attained in 0.85Ba(Zr_(0.1)Ti_(0.9))O_(3)-0.15Bi(Zn_(2/3)Ta_(1/3))O_(3)(BZT-0.15BiZnTa),with an ultrahighηof 97.37%at 440 kV/cm(an advanced level in the lead-free ceramics)and an excellent recoverable energy storage density(Wrec)of 3.74 J/cm^(3).Notably,the BZT-0.15BiZnTa ceramics also exhibit exceptional temperature stability,maintaining fluctuations in Wrec within∼10%andηconsistently exceeding 90% across the wide temperature range of−55℃ to 160℃,and under a high electric field of 250 kV/cm.All these features demonstrate that the relaxor and lattice strain engineering strategies have been successful in achieving high-performance lead-free ceramics,paving the way for designing high-efficiency dielectric capacitors with a wide temperature range.

Strain engineering of Pt-based electrocatalysts for oxygen reaction reduction

Proton exchange membrane fuel cells(PEMFCs)are playing irreplaceable roles in the construction of the future sustainable energy system.However,the insufficient performance of platinum(Pt)-based electrocatalysts for oxygen reduction reaction(ORR)hinders the overall efficiency of PEMFCs.Engineering the surface strain of catalysts is considered an effective way to tune their electronic structures and therefore optimize catalytic behavior.In this paper,insights into strain engineering for improving Pt-based catalysts toward ORR are elaborated in detail.First,recent advances in understanding the strain effects on ORR catalysts are comprehensively discussed.Then,strain engineering methodologies for adjusting Ptbased catalysts are comprehensively discussed.Finally,further information on the various challenges and potential prospects for strain modulation of Pt-based catalysts is provided.

Effect of Elastic Strains on Adsorption Energies of C,H and O on Transition Metal Oxides

Platinum(Pt)-based noble metal catalysts(PGMs)are the most widely used commercial catalysts,but they have the problems of high cost,low reserves,and susceptibility to small-molecule toxicity.Transition metal oxides(TMOs)are regarded as potential substitutes for PGMs because of their stability in oxidizing environments and excellent catalytic performance.In this study,comprehensive investigation into the influence of elastic strains on the adsorption energies of carbon(C),hydrogen(H)and oxygen(O)on TMOs was conducted.Based on density functional theory(DFT)calculations,these effects in both tetragonal structures(PtO_(2),PdO_(2))and hexagonal structures(ZnO,CdO),along with their respective transition metals were systematically explored.It was identified that the optimal adsorption sites on metal oxides pinpointed the top of oxygen or the top of metal atom,while face-centered cubic(FCC)and hexagonal close-packed(HCP)holes were preferred for the transition metals.Furthermore,under the influence of elastic strains,the results demonstrated significant disparities in the adsorption energies of H and O between oxides and transition metals.Despite these differences,the effect of elastic strains on the adsorption energies of C,H and O on TMOs mirrored those on transition metals:adsorption energies increased under compressive strains,indicating weaker adsorption,and decreased under tension strains,indicating stronger adsorption.This behavior was rationalized based on the d-band model for adsorption atop a metallic atom or the p-band model for adsorption atop an oxygen atom.Consequently,elastic strains present a promising avenue for tailoring the catalytic properties of TMOs.

Electric potential and energy band in ZnO nanofiber tuned by local mechanical loading

Recent success in strain engineering has triggered tremendous interest in its study and potential applications in nanodevice design. In this paper, we establish a coupled piezoelectric/semiconducting model for a wurtzite structure ZnO nanofiber under the local mechanical loading. The energy band structure tuned by the local mechanical loading and local length is calculated via an eight-band k·p method, which includes the coupling of valance and conduction bands. Poisson's effect on the distribution of electric potential inversely depends on the local mechanical loading. Numerical results reveal that both the applied local mechanical loading and the local length exhibit obvious tuning effects on the electric potential and energy band. The band gap at band edges varies linearly with the applied loading. Changing the local length shifts the energy band which is far away from the band edges. This study will be useful in the electronic and optical enhancement of semiconductor devices.

Lipopeptide Antibiotics Produced by the Engineered Strain Bacillus subtilis GEB3 and Detection of Its Bioactivity

MALDI-TOF-MS technology was used for identification of lipopeptide antibiotics producedby GEB3 strain, a derivative of Bacillus subtilis 168 which was transformed by lpaB3gene. The result showed GEB3 only produced lipopeptide antibiotic surfactin. The analysisby LC-MS demonstrated that GEB3 produced standard surfactin isoforms with side chainlengths of 13,14 and 15 carbon atoms. The bioactivity detection of surfactin indicatedthat the surfactin produced by GEB3 had inhibition effect on plant pathogens Rhizoctoniasolani and Pyricularia oryzae.

Parallel Nanoimprint Forming of One-Dimensional Chiral Semiconductor for Strain-Engineered Optical Properties

The low-dimensional,highly anisotropic geometries,and superior mechanical properties of one-dimensional(1D) nanomaterials allow the exquisite strain engineering with a broad tunability inaccessible to bulk or thin-film materials.Such capability enables unprecedented possibilities for probing intriguing physics and materials science in the 1-D limit.Among the techniques for introducing controlled strains in 1D materials,nanoimprinting with embossed substrates attracts increased attention due to its capability to parallelly form nanomaterials into wrinkled structures with controlled periodicities,amplitudes,orientations at large scale with nanoscale resolutions.Here,we systematically investigated the strain-engineered anisotropic optical properties in Te nanowires through introducing a controlled strain field using a resist-free thermally assisted nanoimprinting process.The magnitude of induced strains can be tuned by adjusting the imprinting pressure,the nanowire diameter,and the patterns on the substrates.The observed Raman spectra from the chiral-chain lattice of 1D Te reveal the strong lattice vibration response under the strain.Our results suggest the potential of 1D Te as a promising candidate for flexible electronics,deformable optoelectronics,and wearable sensors.The experimental platform can also enable the exquisite mechanical control in other nanomaterials using substrate-induced,on-demand,and controlled strains.

One-dimensional ZnO nanostructure-based optoelectronic

Semiconductor nanowires, with their unique capability to bridge the nanoscopic and macroscopic worlds, have been demonstrated to have potential applications in energy conversion, electronics, optoelectronics, and biosensing devices. Onedimensional（1D） ZnO nanostructures, with coupled semiconducting and piezoelectric properties, have been extensively investigated and widely used to fabricate nanoscale optoelectronic devices. In this article, we review recent developments in 1D ZnO nanostructure based photodetectors and device performance enhancement by strain engineering piezoelectric polarization and interface modulation. The emphasis is on a fundamental understanding of electrical and optical phenomena, interfacial and contact behaviors, and device characteristics. Finally, the prospects of 1D ZnO nanostructure devices and new challenges are proposed.

Opportunities and challenges of strain engineering for advanced electrocatalyst design

Electrocatalysis is becoming more and more important in energy conversion and storage due to rising energy demands,increasing carbon dioxide emissions,and impending climate change.The design and synthesis of high-performance electrocatalysts are the spotlights of electrocatalysis.Among many design methodologies reported,strain engineering has gained growing attention because it can change the atomic arrangement and lattice structure of electrocatalysts.However,strain engineering remains to be problematic in regulating the properties of electrocatalysts.This review discusses the strain effect tactics to regulate metal and non-metal electrocatalysts,including three sections focusing on strain categorization,strain regulation mechanism,and applications in electrocatalysis,respectively.Finally,the current challenges and an outlook of strain engineering are discussed.