oscale devices.In the present work,we investigate the electronic structures of germanane/antimonene vdW heterostructure in response to normal strain and an external electric field by using the first-principles calcul...oscale devices.In the present work,we investigate the electronic structures of germanane/antimonene vdW heterostructure in response to normal strain and an external electric field by using the first-principles calculations based on density functional theory(DFT).The results demonstrate that the germanane/antimonene vdW heterostructure behaves as a metal in a[1,,0.6]V/A range,while it is a direct semiconductor in a[0.5,0.2]V/A range,and it is an indirect semiconduc-tor in a[0.3,1.0]V/A range.Interestingly,the band alignment of germanane/antimonene vdW heterostructure appears astype-II feature both in a[0.5,0.1]range and in a[0.3,1]V/A range,while it shows the type-I character at 0.2 V/A.In ad-dition,we find that the germanane/antimonene vdW heterostructure is an indirect semiconductor both in an in-plane biaxial strain range of[[5%,,3%]and in an in-plane biaxial strain range of[3%,5%],while it exhibits a direct semiconductor character in an in-plane biaxial strain range of[2%,2%].Furthermore,the band alignment of the germanane/antimonene vdW heterostructure changes from type-II to type-I at an in-plane biaxial strain of 3%.The adjustable electronic structure of this germanane/antimonene vdW heterostructure will pave the way for developing the nanoscale devices.展开更多
Using first-principles calculations based on density functional theory(DFT), the structural and electronic properties of hydrogenated antimonene have been systematically investigated. Phonon dispersion and molecular d...Using first-principles calculations based on density functional theory(DFT), the structural and electronic properties of hydrogenated antimonene have been systematically investigated. Phonon dispersion and molecular dynamics(MD)simulation reveal that fully hydrogenated(FH) antimonene has high dynamic stability and could be synthesized. A newσ-type Dirac cone related to Sb-px,y orbitals is found in FH antimonene, which is robust to tensile strain. Noticeably, the spin orbital coupling(SOC) opens a quantum spin Hall(QSH) gap of 425 meV at the Dirac cone, sufficiently large for practical applications at room temperature. Semi-hydrogenated antimonene is a non-magnetic metal. Our results show that FH antimonene may have great potential applications in next generation high-performance devices.展开更多
Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterpa...Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterparts SnTe and InI. We find that the band gap increases monotonically from Sb to SnTe to InI along with an increase in ionicity, independent of the structural phases. The band gaps of this material family cover the entire visible-light energy spectrum, ranging from 0.26 eV to 3.37 eV, rendering them promising candidates for optoelectronic applications. Meanwhile, band-edge positions of these materials are explored and all three types of band alignments can be achieved through properly combining antimonene with its isoelectronic counterparts to form heterostructures. The richness in electronic properties for this isoelectronic material family sheds light on possibilities to tailor the fundamental band gap of antimonene via lateral alloying or forming vertical heterostructures.展开更多
The study of energetics, structural, the electronic and optical properties of Ga and As atoms substituted for doped germanane monolayers were studied by first-principles calculations based on density functional theory...The study of energetics, structural, the electronic and optical properties of Ga and As atoms substituted for doped germanane monolayers were studied by first-principles calculations based on density functional theory. Both of the two doping are thermodynamically stable. According to the band structure and partial density of the states, gallium is p-type doping. Impurity bands below the conduction band lead the absorption spectrum moves in the infrared direction. Arsenic doping has impurity level passing through the Fermi level and is n-type doping. The analysis of optical properties confirms the value of bandgap and doping properties.展开更多
Recently, two-dimensional van der Waals(vd W) magnetic heterostructures have attracted intensive attention since they can show remarkable properties due to the magnetic proximity effect. In this work, the spin-polariz...Recently, two-dimensional van der Waals(vd W) magnetic heterostructures have attracted intensive attention since they can show remarkable properties due to the magnetic proximity effect. In this work, the spin-polarized electronic structures of antimonene/Fe_(3)GeTe_(2)vdW heterostructures were investigated through the first-principles calculations. Owing to the magnetic proximity effect, the spin splitting appears at the conduction-band minimum(CBM) and the valence-band maximum(VBM) of the antimonene. A low-energy effective Hamiltonian was proposed to depict the spin splitting. It was found that the spin splitting can be modulated by means of applying an external electric field, changing interlayer distance or changing stacking configuration. The spin splitting energy at the CBM monotonously increases as the external electric field changes from-5 V/nm to 5 V/nm, while the spin splitting energy at the VBM almost remains the same. Meanwhile,as the interlayer distance increases, the spin splitting energies at the CBM and VBM both decrease. The different stacking configurations can also induce different spin splitting energies at the CBM and VBM. Our work demonstrates that the spin splitting of antimonene in this heterostructure is not singly dependent on the nearest Sb–Fe distance, which indicates that magnetic proximity effect in heterostructures may be modulated by multiple factors, such as hybridization of electronic states and the local electronic environment. The results enrich the fundamental understanding of the magnetic proximity effect in two-dimensional vdW heterostructures.展开更多
锗烯是继石墨烯、硅烯发现以来最重要的二维纳米材料之一,以其优异的物理化学性质迅速得到人们的广泛关注.然而,锗烯具有的零带隙能带特点(狄拉克点)极大程度地限制了其在微电子纳米材料方面的应用.本文采用范德华力修正的密度泛函计算...锗烯是继石墨烯、硅烯发现以来最重要的二维纳米材料之一,以其优异的物理化学性质迅速得到人们的广泛关注.然而,锗烯具有的零带隙能带特点(狄拉克点)极大程度地限制了其在微电子纳米材料方面的应用.本文采用范德华力修正的密度泛函计算方法,研究了锗烯、锗烷、锗烯/锗烷的几何和电学性质.研究发现,锗烯和锗烷可以通过弱相互作用形成稳定的双层结构,并在锗烯中打开一个85 me V的带隙.电子结构分析表明,Ge—H/π的存在破坏了锗烯子晶格的对称性,从而在狄拉克点上打开一个带隙.差分电荷密度图分析表明有部分电荷从H原子的s轨道转移至Ge的pz轨道.该电荷转移机制增强了锗烯与锗烷之间的相互作用力,是形成锗烯/锗烷双层二维纳米结构的主要原因.进一步研究还发现,锗烷/锗烯/锗烷的三明治结构无法在锗烯中打开带隙.这是由于两侧的锗烷对夹层的锗烯作用力等价,无法破坏锗烯的子晶格对称性,所以无法打开锗烯带隙.最后,所有计算结果都在高精度杂化密度泛函HSE06计算精度下得到进一步验证.因此,本文从理论上提出了一种切实可行的打开锗烯狄拉克点的方法,为锗烯在场效应管和其他纳米材料中的应用提供了理论指导.展开更多
The synthesis of antimonene, which is a promising group-V 2D material for both fundamental studies and technological applications, remains highly challenging. Thus far, it has been synthesized only by exfoliation or g...The synthesis of antimonene, which is a promising group-V 2D material for both fundamental studies and technological applications, remains highly challenging. Thus far, it has been synthesized only by exfoliation or growth on a few substrates. In this study, we show that thin layers of antimonene can be grown on Ag（111） by molecular beam epitaxy. High-resolution scanning tunneling microscopy combined with theoretical calculations revealed that the submonolayer Sb deposited on a Ag（111） surface forms a layer of AgSb2 surface alloy upon annealing. Further deposition of Sb on the AgSb2 surface alloy causes an epitaxial layer of Sb to form, which is identified as antimonene with a buckled honeycomb structure. More interestingly, the lattice constant of the epitaxial antimonene （5 /-） is much larger than that of freestanding antimonene, indicating a high tensile strain of more than 20%. This kind of large strain is expected to make the antimonene a highly promising candidate for room- temperature quantum spin Hall material.展开更多
Photocatalytic reduction of CO_(2) into valuable fuels is one of the potential strategies to solve the carbon cycle and energy crisis.Graphitic carbon nitride(g-C_(3)N_(4)),as a typical two-dimensional(2D)semiconducto...Photocatalytic reduction of CO_(2) into valuable fuels is one of the potential strategies to solve the carbon cycle and energy crisis.Graphitic carbon nitride(g-C_(3)N_(4)),as a typical two-dimensional(2D)semiconductor with a bandgap of∼2.7 eV,has attracted wide attention in photocatalytic CO_(2) reduction.However,the performance of g-C_(3)N_(4) is greatly limited by the rapid recombination of photogenerated charge carriers and weak CO_(2) activation capacity.Construction of van der Waals heterostructure with the maximum interface contact area can improve the transfer/seperation efficiency of interface charge carriers.Ultrathin metal antimony(Sb)nanosheet(antimonene)with high carrier mobility and 2D layered structure,is a good candidate material to construct 2D/2D Sb/g-C_(3)N_(4) van der Waals heterostructure.In this work,the density functional theory(DFT)calculations indicated that antimonene has higher carrier mobility than g-C_(3)N_(4) nanosheets.Obvious charge transfer and in-plane structure distortion will occur at the interface of Sb/g-C_(3)N_(4),which endow stronger CO_(2) activation ability on di-coordinated N active site.The ultrathin g-C_(3)N_(4) and antimonene nanosheets were prepared by ultrasonic exfoliation method,and Sb/g-C_(3)N_(4) van der Waals heterostructures were constructed by self-assembly process.The photoluminescence(PL)and time-resolved photoluminescence(TRPL)indicated that the Sb/g-C_(3)N_(4) van der Waals heterostructures have a better photogenerated charge separation efficiency than pure g-C_(3)N_(4) nanosheets.In-situ FTIR spectroscopy demonstrated a stronger ability of CO_(2) activation to^ (∗)COOH on Sb/g-C_(3)N_(4) van der Waals heterostructure.As a result,the Sb/g-C_(3)N_(4) van der Waals heterostructures showed a higher CO yield with 2.03 umol g^(−1) h^(−1),which is 3.2 times that of pure g-C_(3)N_(4).This work provides a reference for activating CO_(2) and promoting CO_(2) reduction by van der Waals heterostructure.展开更多
利用含时密度泛函理论(time-dependent density functional theory(TDDFT)),研究了锑烯纳米结构表面等离激元的激发特性,并给出了微扰场沿着扶手椅边界和Z字边界激发时锑烯纳米结构的吸收光谱.结果表明沿不同的方向激发,吸收光谱不同....利用含时密度泛函理论(time-dependent density functional theory(TDDFT)),研究了锑烯纳米结构表面等离激元的激发特性,并给出了微扰场沿着扶手椅边界和Z字边界激发时锑烯纳米结构的吸收光谱.结果表明沿不同的方向激发,吸收光谱不同.距锑烯纳米结构表面0.9处的能量共振点的电荷密度分布表明,在低能共振区,等离激元共振属于键合二聚体的等离激元模式(BDP).展开更多
The overexpression of heat shock proteins(HSPs)in tumor cells can activate inherent defense mechanisms during hyperthermia-based treatments,inducing thermoresistance and thus diminishing the treatment efficacy.Here,we...The overexpression of heat shock proteins(HSPs)in tumor cells can activate inherent defense mechanisms during hyperthermia-based treatments,inducing thermoresistance and thus diminishing the treatment efficacy.Here,we report a distinct“non-inhibitor involvement”strategy to address this issue through engineering a calcium-based nanocatalyst(G/A@CaCO_(3)-PEG).The constructed nanocatalyst consists of calcium carbonate(CaCO_(3))-supported glucose oxidase(GOD)and 2D antimonene quantum dots(AQDs),with further surface modification by lipid bilayers and polyethylene glycol(PEG).The engineered G/A@CaCO_(3)-PEG nanocatalyst features prolonged blood circulation,which is stable at neutral pH but rapidly degrades under mildly acidic tumor microenvironment,resulting in rapid release of drug cargo in the tumor microenvironment.The integrated GOD effectively catalyzes the depletion of glucose for reducing the supplies of adenosine triphosphate(ATP)and subsequent down-regulation of HSP expression.This effect then augments the therapeutic efficacy of photothermal hyperthermia induced by 2D AQDs upon irradiation with near-infrared light as assisted by reversing the cancer cells’thermoresistance.Consequently,synergistic antineoplastic effects can be achieved via low-temperature photothermal therapy.Systematic in vitro and in vivo evaluations have demonstrated that G/A@CaCO_(3)-PEG nanocatalysts feature potent antitumor activity with a high tumor-inhibition rate(83.92%).This work thus paves an effective way for augmenting the hyperthermia-based tumor treatments via restriction of the ATP supply.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11864011).
文摘oscale devices.In the present work,we investigate the electronic structures of germanane/antimonene vdW heterostructure in response to normal strain and an external electric field by using the first-principles calculations based on density functional theory(DFT).The results demonstrate that the germanane/antimonene vdW heterostructure behaves as a metal in a[1,,0.6]V/A range,while it is a direct semiconductor in a[0.5,0.2]V/A range,and it is an indirect semiconduc-tor in a[0.3,1.0]V/A range.Interestingly,the band alignment of germanane/antimonene vdW heterostructure appears astype-II feature both in a[0.5,0.1]range and in a[0.3,1]V/A range,while it shows the type-I character at 0.2 V/A.In ad-dition,we find that the germanane/antimonene vdW heterostructure is an indirect semiconductor both in an in-plane biaxial strain range of[[5%,,3%]and in an in-plane biaxial strain range of[3%,5%],while it exhibits a direct semiconductor character in an in-plane biaxial strain range of[2%,2%].Furthermore,the band alignment of the germanane/antimonene vdW heterostructure changes from type-II to type-I at an in-plane biaxial strain of 3%.The adjustable electronic structure of this germanane/antimonene vdW heterostructure will pave the way for developing the nanoscale devices.
基金supported by Research Funds of Sichuan University of Arts and Science,China(Grant No.2012Z009Y)
文摘Using first-principles calculations based on density functional theory(DFT), the structural and electronic properties of hydrogenated antimonene have been systematically investigated. Phonon dispersion and molecular dynamics(MD)simulation reveal that fully hydrogenated(FH) antimonene has high dynamic stability and could be synthesized. A newσ-type Dirac cone related to Sb-px,y orbitals is found in FH antimonene, which is robust to tensile strain. Noticeably, the spin orbital coupling(SOC) opens a quantum spin Hall(QSH) gap of 425 meV at the Dirac cone, sufficiently large for practical applications at room temperature. Semi-hydrogenated antimonene is a non-magnetic metal. Our results show that FH antimonene may have great potential applications in next generation high-performance devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.51702146)the College Students’Innovation and Entrepreneurship Projects,China(Grant No.201710148000072)Liaoning Province Doctor Startup Fund,China(Grant No.201601325)。
文摘Using ab initio density functional theory calculations, we explore the three most stable structural phases, namely, α,β, and cubic(c) phases, of two-dimensional(2D) antimonene, as well as its isoelectronic counterparts SnTe and InI. We find that the band gap increases monotonically from Sb to SnTe to InI along with an increase in ionicity, independent of the structural phases. The band gaps of this material family cover the entire visible-light energy spectrum, ranging from 0.26 eV to 3.37 eV, rendering them promising candidates for optoelectronic applications. Meanwhile, band-edge positions of these materials are explored and all three types of band alignments can be achieved through properly combining antimonene with its isoelectronic counterparts to form heterostructures. The richness in electronic properties for this isoelectronic material family sheds light on possibilities to tailor the fundamental band gap of antimonene via lateral alloying or forming vertical heterostructures.
文摘The study of energetics, structural, the electronic and optical properties of Ga and As atoms substituted for doped germanane monolayers were studied by first-principles calculations based on density functional theory. Both of the two doping are thermodynamically stable. According to the band structure and partial density of the states, gallium is p-type doping. Impurity bands below the conduction band lead the absorption spectrum moves in the infrared direction. Arsenic doping has impurity level passing through the Fermi level and is n-type doping. The analysis of optical properties confirms the value of bandgap and doping properties.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11774434, 11974431, and 11832019)supported by National Supercomputer Center in Guangzhou。
文摘Recently, two-dimensional van der Waals(vd W) magnetic heterostructures have attracted intensive attention since they can show remarkable properties due to the magnetic proximity effect. In this work, the spin-polarized electronic structures of antimonene/Fe_(3)GeTe_(2)vdW heterostructures were investigated through the first-principles calculations. Owing to the magnetic proximity effect, the spin splitting appears at the conduction-band minimum(CBM) and the valence-band maximum(VBM) of the antimonene. A low-energy effective Hamiltonian was proposed to depict the spin splitting. It was found that the spin splitting can be modulated by means of applying an external electric field, changing interlayer distance or changing stacking configuration. The spin splitting energy at the CBM monotonously increases as the external electric field changes from-5 V/nm to 5 V/nm, while the spin splitting energy at the VBM almost remains the same. Meanwhile,as the interlayer distance increases, the spin splitting energies at the CBM and VBM both decrease. The different stacking configurations can also induce different spin splitting energies at the CBM and VBM. Our work demonstrates that the spin splitting of antimonene in this heterostructure is not singly dependent on the nearest Sb–Fe distance, which indicates that magnetic proximity effect in heterostructures may be modulated by multiple factors, such as hybridization of electronic states and the local electronic environment. The results enrich the fundamental understanding of the magnetic proximity effect in two-dimensional vdW heterostructures.
文摘锗烯是继石墨烯、硅烯发现以来最重要的二维纳米材料之一,以其优异的物理化学性质迅速得到人们的广泛关注.然而,锗烯具有的零带隙能带特点(狄拉克点)极大程度地限制了其在微电子纳米材料方面的应用.本文采用范德华力修正的密度泛函计算方法,研究了锗烯、锗烷、锗烯/锗烷的几何和电学性质.研究发现,锗烯和锗烷可以通过弱相互作用形成稳定的双层结构,并在锗烯中打开一个85 me V的带隙.电子结构分析表明,Ge—H/π的存在破坏了锗烯子晶格的对称性,从而在狄拉克点上打开一个带隙.差分电荷密度图分析表明有部分电荷从H原子的s轨道转移至Ge的pz轨道.该电荷转移机制增强了锗烯与锗烷之间的相互作用力,是形成锗烯/锗烷双层二维纳米结构的主要原因.进一步研究还发现,锗烷/锗烯/锗烷的三明治结构无法在锗烯中打开带隙.这是由于两侧的锗烷对夹层的锗烯作用力等价,无法破坏锗烯的子晶格对称性,所以无法打开锗烯带隙.最后,所有计算结果都在高精度杂化密度泛函HSE06计算精度下得到进一步验证.因此,本文从理论上提出了一种切实可行的打开锗烯狄拉克点的方法,为锗烯在场效应管和其他纳米材料中的应用提供了理论指导.
文摘The synthesis of antimonene, which is a promising group-V 2D material for both fundamental studies and technological applications, remains highly challenging. Thus far, it has been synthesized only by exfoliation or growth on a few substrates. In this study, we show that thin layers of antimonene can be grown on Ag（111） by molecular beam epitaxy. High-resolution scanning tunneling microscopy combined with theoretical calculations revealed that the submonolayer Sb deposited on a Ag（111） surface forms a layer of AgSb2 surface alloy upon annealing. Further deposition of Sb on the AgSb2 surface alloy causes an epitaxial layer of Sb to form, which is identified as antimonene with a buckled honeycomb structure. More interestingly, the lattice constant of the epitaxial antimonene （5 /-） is much larger than that of freestanding antimonene, indicating a high tensile strain of more than 20%. This kind of large strain is expected to make the antimonene a highly promising candidate for room- temperature quantum spin Hall material.
基金supported by National Natural Science Foundation of China(Nos.22002189 and 51973078)the Open Project from Key Laboratory of Green and Precise Synthetic Chemistry and Applications(No.2020KF07)+1 种基金the Distinguished Young Scholar of Anhui Province(No.1808085J14)the Key Foundation of Educational Commission of Anhui Province(Nos.KJ2019A0595 and KJ2020ZD005)。
文摘Photocatalytic reduction of CO_(2) into valuable fuels is one of the potential strategies to solve the carbon cycle and energy crisis.Graphitic carbon nitride(g-C_(3)N_(4)),as a typical two-dimensional(2D)semiconductor with a bandgap of∼2.7 eV,has attracted wide attention in photocatalytic CO_(2) reduction.However,the performance of g-C_(3)N_(4) is greatly limited by the rapid recombination of photogenerated charge carriers and weak CO_(2) activation capacity.Construction of van der Waals heterostructure with the maximum interface contact area can improve the transfer/seperation efficiency of interface charge carriers.Ultrathin metal antimony(Sb)nanosheet(antimonene)with high carrier mobility and 2D layered structure,is a good candidate material to construct 2D/2D Sb/g-C_(3)N_(4) van der Waals heterostructure.In this work,the density functional theory(DFT)calculations indicated that antimonene has higher carrier mobility than g-C_(3)N_(4) nanosheets.Obvious charge transfer and in-plane structure distortion will occur at the interface of Sb/g-C_(3)N_(4),which endow stronger CO_(2) activation ability on di-coordinated N active site.The ultrathin g-C_(3)N_(4) and antimonene nanosheets were prepared by ultrasonic exfoliation method,and Sb/g-C_(3)N_(4) van der Waals heterostructures were constructed by self-assembly process.The photoluminescence(PL)and time-resolved photoluminescence(TRPL)indicated that the Sb/g-C_(3)N_(4) van der Waals heterostructures have a better photogenerated charge separation efficiency than pure g-C_(3)N_(4) nanosheets.In-situ FTIR spectroscopy demonstrated a stronger ability of CO_(2) activation to^ (∗)COOH on Sb/g-C_(3)N_(4) van der Waals heterostructure.As a result,the Sb/g-C_(3)N_(4) van der Waals heterostructures showed a higher CO yield with 2.03 umol g^(−1) h^(−1),which is 3.2 times that of pure g-C_(3)N_(4).This work provides a reference for activating CO_(2) and promoting CO_(2) reduction by van der Waals heterostructure.
文摘利用含时密度泛函理论(time-dependent density functional theory(TDDFT)),研究了锑烯纳米结构表面等离激元的激发特性,并给出了微扰场沿着扶手椅边界和Z字边界激发时锑烯纳米结构的吸收光谱.结果表明沿不同的方向激发,吸收光谱不同.距锑烯纳米结构表面0.9处的能量共振点的电荷密度分布表明,在低能共振区,等离激元共振属于键合二聚体的等离激元模式(BDP).
基金the financial support from the NSFC Key Projects of International Cooperation and Exchanges(Grant No.81720108023)National Key R&D Program of China(Grant No.2018YFC0115200)+2 种基金National Natural Science Foundation of China(Grant No.82001943)Translational medicine national science and technology infrastructure(Shanghai)open project fund(TMSK-2020-004)China Postdoctoral Science Foundation(2020M681331,2021T140458).
文摘The overexpression of heat shock proteins(HSPs)in tumor cells can activate inherent defense mechanisms during hyperthermia-based treatments,inducing thermoresistance and thus diminishing the treatment efficacy.Here,we report a distinct“non-inhibitor involvement”strategy to address this issue through engineering a calcium-based nanocatalyst(G/A@CaCO_(3)-PEG).The constructed nanocatalyst consists of calcium carbonate(CaCO_(3))-supported glucose oxidase(GOD)and 2D antimonene quantum dots(AQDs),with further surface modification by lipid bilayers and polyethylene glycol(PEG).The engineered G/A@CaCO_(3)-PEG nanocatalyst features prolonged blood circulation,which is stable at neutral pH but rapidly degrades under mildly acidic tumor microenvironment,resulting in rapid release of drug cargo in the tumor microenvironment.The integrated GOD effectively catalyzes the depletion of glucose for reducing the supplies of adenosine triphosphate(ATP)and subsequent down-regulation of HSP expression.This effect then augments the therapeutic efficacy of photothermal hyperthermia induced by 2D AQDs upon irradiation with near-infrared light as assisted by reversing the cancer cells’thermoresistance.Consequently,synergistic antineoplastic effects can be achieved via low-temperature photothermal therapy.Systematic in vitro and in vivo evaluations have demonstrated that G/A@CaCO_(3)-PEG nanocatalysts feature potent antitumor activity with a high tumor-inhibition rate(83.92%).This work thus paves an effective way for augmenting the hyperthermia-based tumor treatments via restriction of the ATP supply.
