Double-resonance Raman(DRR)scattering in two-di-mensional(2D)materials describes the intravalley or intervalley scattering of an electron or a hole excited by incident photons.Although the presence of defects can prov...Double-resonance Raman(DRR)scattering in two-di-mensional(2D)materials describes the intravalley or intervalley scattering of an electron or a hole excited by incident photons.Although the presence of defects can provide additional momentum and influence the scat-tering process involving one or two phonons,only the idealized defects without any structural details are considered in tra-ditional DRR theory.Here,the second-order DRR spectra of WSe_(2) monolayer with different types of defects are calculated involving the combinations of acoustic and optical phonons in the vicinity of K(K')and M points of the Brillouin zone.The electronic band structures are modified due to the presence of defects,and the band unfolding method is adopted to show the bending of valence and conduction bands for the defective WSe_(2) monolayers.The associ-ated phononic band structures also exhibit different changes in phonon dispersion curves,re-sulting in different DRR spectra corresponding to the different types of defects in the WSe_(2) monolayers.For example,the existence of W vacancy in the WSe_(2) monolayer would result in downshifts in vibrational frequencies and asymmetrical broadenings in linewidths for most combination modes due to the dramatic changes in contour shape of electronic valleys at K and K'.Moreover,the scattering from K to Q is found to be forbidden for the two Se vacan-cies because of the elevation of conduction band at the Q point.Our work highlights the role of defect structures in the intervalley scattering and may provide better understanding in the underlying physics of DRR process in 2D materials.展开更多
To effectively address energy challenges,it is crucial to explore efficient and stable bifunctional nonprecious metal catalysts.In this study,a Mo-doped nickeliron layered double hydroxide with flower-cluster architec...To effectively address energy challenges,it is crucial to explore efficient and stable bifunctional nonprecious metal catalysts.In this study,a Mo-doped nickeliron layered double hydroxide with flower-cluster architecture was successfully prepared by a one-step hydrothermal method,which demonstrated a good water splitting performance.After an appropriate amount of Mo doping,some lattice distortions in the material provided reactive sites for the adsorption and conversion of intermediates,thus optimising the charge distribution of the material.Moreover,the multidimensional void structures formed after doping had a larger specific surface area and accelerated the penetration of the electrolyte,which significantly improved the activity of the catalyst in alkaline media.At 10 mA·cm^(-2),the hydrogen and oxygen evolution overpotentials of Mo-doped nickel-iron double hydroxides(Mo-NiFe LDH/NF-0.2)were 167 and 220 mV,respectively,with an excellent durability up to 24 h.When the Mo-NiFe LDH/NF-0,2 catalyst was used as the cathode and anode of an electrolytic cell,the catalyst achieved a current density of 10 mA·cm^(-2)at an applied voltage of 1.643 V.This study provides a novel approach for designing excellent bifunctional electrocatalysts containing nonprecious metals.展开更多
Quasi-two-dimensional(2D)perovskite embodies characteristics of both three-dimensional(3D)and 2D perovskites,achieving the superior external environment stability structure of 2D perovskites alongside the high efficie...Quasi-two-dimensional(2D)perovskite embodies characteristics of both three-dimensional(3D)and 2D perovskites,achieving the superior external environment stability structure of 2D perovskites alongside the high efficiency of 3D perovskites.This effect is realized through critical structural modifications in device fabrication.Typically,perovskites have an octahedral structure,generally ABX3,where an organic ammonium cation(A’)participates in forming the perovskite structure,with A’_(n)(n=1 or 2)sandwiched between A_(n-1)B_(n)X_(3n+1)perovskite layers.Depending on whether A’is a monovalent or divalent cation,2D perovskites are classified into Ruddlesden-Popper perovskite or Dion-Jacobson perovskite,each generating different structures.Although each structure achieves similar effects,they incorporate distinct mechanisms in their formation.And according to these different structures,various properties appear,and additive and optimizing methods to increase the efficiency of 3D perovskites also exist in 2D perovskites.In this review,scientific understanding and engineering perspectives of the quasi-2D perovskite is investigated,and the optimal structure quasi-2D and the device optimization is also discussed to provide the insight in the field.展开更多
With the development of unconventional hydrocarbon, how to improve the shale oil and gas recovery become urgent. Therefore hydraulic fracturing becomes the key due to the complicated properties of the reservoirs. The ...With the development of unconventional hydrocarbon, how to improve the shale oil and gas recovery become urgent. Therefore hydraulic fracturing becomes the key due to the complicated properties of the reservoirs. The pore structure not only plays an essential role in the formation of complex fracture networks after fracturing but also in resource accumulation mechanism analyses. The lacustrine organicrich shale samples were selected to carry out petrophysical experiments. Scanning Electron Microscopy(SEM) and X-ray Diffraction were performed to elucidate the geology characteristics. MICP, 2D NMR, CT,and N2adsorption were conducted to classify the pore structure types. The contribution of pore structure to oil accumulation and hydrocarbon enrichment was explained through the N2adsorption test on the original and extracted state and 2D NMR. The results show that micropores with diameter less than20 nm are well-developed. The pore structure was divided into three types. Type Ⅰ is characterized by high porosity, lower surface area, and good pore throat connectivity, with free oil existing in large pores,especially lamellation fractures. The dominant nano-pores are spongy organic pores and resources hosted in large pores have been expelled during high thermal evolution. The content of nano-pores(micropores) increases and the pore volume decreases in Type Ⅱ pore structure. In addition, more absorbed oil was enriched. The pore size distribution of type Ⅱ is similar to that of type Ⅰ. However, the maturity and hydrocarbon accumulation is quite different. The oil reserved in large pores was not expelled attributed to the relatively low thermal evolution compared with type Ⅰ. Structural vitrinite was observed through SEM indicating kerogen of type Ⅲ developed in this kind of reservoir while the type of kerogen in pore structure Ⅰ is type Ⅱ. Type Ⅲ pore structure is characterized by the largest surface area,lowest porosity, and almost isolated pores with rarely free oil. Type Ⅰ makes the most contribution to hydrocarbon accumulation and immigration, which shows the best prospect. Of all of these experiments,N2adsorption exhibits the best in characterizing pores in shales due to its high resolution for the assessment of nano-scale pores. MICP and NMR have a better advantage in characterizing pore space of sandstone reservoirs, even tight sandstone reservoirs. 2D NMR plays an essential role in fluid recognition and saturation calculation. CT scanning provides a 3D visualization of reservoir space and directly shows the relationship between pores and throats and the characteristics of fractures. This study hopes to guide experiment selection in pore structure characterization in different reservoirs. This research provides insight into hydrocarbon accumulation of shales and guidance in the exploration and development of unconventional resources, for example for geothermal and CCUS reservoirs.展开更多
Two-dimensional(2D) nanomaterials have always been regarded as having great development potential in the field of oil-based lubrication due to their designable structures,functional groups,and abundant active sites.Ho...Two-dimensional(2D) nanomaterials have always been regarded as having great development potential in the field of oil-based lubrication due to their designable structures,functional groups,and abundant active sites.However,understanding the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance from a comprehensive perspective is crucial for guiding their future development.This review provides a timely and comprehensive overview of the applications of 2D nanomaterials in oil-based lubrication.First,the bottlenecks and mechanisms of action of 2D nanomaterials are outlined,including adsorption protective films,charge adsorption effects,tribochemical reaction films,interlayer slip,and synergistic effects.On this basis,the review summarizes recent structural regulation strategies for 2D nanomaterials,including doping engineering,surface modification,structural optimization,and interfacial mixing engineering.Then,the focus was on analyzing the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance.The effects of thickness,number of layers,sheet diameter,interlayer spacing,Moiré patterns,wettability,functional groups,concentration,as well as interfacial compatibility and dispersion behavior of 2D nanomaterials were systematically investigated in oil-based lubrication,with the intrinsic correlations resolved through computational simulations.Finally,the review offers a preliminary summary of the significant challenges and future directions for 2D nanomaterials in oil-based lubrication.This review aims to provide valuable insights and development strategies for the rational design of high-performance oil-based lubrication materials.展开更多
The title complex [Zn(-O2CCH=CHCO2)(C3H4N2)(H2O)]n was prepared by the reaction of zinc carbonate with maleic acid and imidazole in an aqueous-alcohol solution at 333 K, and its crystal structure has been solved by si...The title complex [Zn(-O2CCH=CHCO2)(C3H4N2)(H2O)]n was prepared by the reaction of zinc carbonate with maleic acid and imidazole in an aqueous-alcohol solution at 333 K, and its crystal structure has been solved by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group Pc with a = 5.3858(7), b = 22.685(3), c = 7.6782(1) ? = 92.261(2)o, V = 937.4(2) 3, Z = 1, C14H16N4O10Zn2, Mr = 531.05, Dc = 1.882 g/cm3, = 2.623 mm1, F(000) = 532, the final R = 0.0372 and wR = 0.0930 for 1926 observed reflections with I>2s(I). The central zinc atom is five-coordinated in a distorted square pyramidal environment to three oxygen atoms of two different maleate ligands, a nitrogen atom of the imi- dazole ligand and an oxygen atom of water. In the complex two carboxylate groups of the maleate ligands have two coordination modes. One acts as a bidentate chelate ligand and the other a monoatomic monodentate ligand to bridge two zinc centers. As a result, 1-D infinite polymeric chains are formed, which are linked together by pairs of OH…O hydrogen bonds between the coordination water OH groups and carboxylate oxygen atoms to construct a 2-D layered polymer, and the layer structure is stabilized by p-p stacking of the imidozel ligands.展开更多
Two-dimensional materials are widely considered to be highly promising for the development of photodetectors.To improve the performance of these devices,researchers often employ techniques such as defect engineering.H...Two-dimensional materials are widely considered to be highly promising for the development of photodetectors.To improve the performance of these devices,researchers often employ techniques such as defect engineering.Herein,pressure is employed as a clean and novel means to manipulate the structural and physical properties of EuSbTe_(3),an emerging two-dimensional semiconductor.The experimental results demonstrate that the structural phase transformation of EuSbTe_(3)occurs under pressure,with an increase in infrared reflectivity,a band gap closure,and a metallization at pressures.Combined with X-ray diffraction(XRD)and Raman characterizations,it is evident that the pressure-driven transition from semiconductor Pmmn phase to metallic Cmcm phase causes the disappearance of the charge density wave.Furthermore,at a mild pressure,approximately 2 GPa,the maximum photocurrent of EuSbTe_(3)is three times higher than that at ambient condition,suggesting an untapped potential for various practical applications.展开更多
Synthetic two-dimensional（2 D） polymers have totally different topology structures compared with traditional linear or branched polymers. The peculiar 2 D structures bring superior properties. Although, from linear ...Synthetic two-dimensional（2 D） polymers have totally different topology structures compared with traditional linear or branched polymers. The peculiar 2 D structures bring superior properties. Although, from linear to 2 D polymers, the study of these new materials is still in its infancy, they already show potential applications especially in optoelectronics, membranes, energy storage and catalysis, etc. In this review, we summarize the recent progress of the 2 D materials from three respects：（1） Chemistry—different types of polymerization reactions or supramolecular assembly to construct the 2 D networks were described;（2） Preparation methods—surface science, crystal engineering approaches and solution synthesis were introduced;（3） Functionalization and some early applications.展开更多
Femtosecond laser pulses with GHz burst mode that consist of a series of trains of ultrashort laser pulses with a pulse interval of several hundred picoseconds offer distinct features in material processing that canno...Femtosecond laser pulses with GHz burst mode that consist of a series of trains of ultrashort laser pulses with a pulse interval of several hundred picoseconds offer distinct features in material processing that cannot be obtained by the conventional irradiation scheme of femtosecond laser pulses(single-pulse mode).However,most studies using the GHz burst mode femtosecond laser pulses focus on ablation of materials to achieve high-efficiency and high-quality material removal.In this study,we explore the ability of the GHz burst mode femtosecond laser processing to form laser-induced periodic surface structures(LIPSS)on silicon.It is well known that the direction of LIPSS formed by the single-pulse mode with linearly polarized laser pulses is typically perpendicular to the laser polarization direction.In contrast,we find that the GHz burst mode femtosecond laser(wavelength:1030 nm,intra-pulse duration:220 fs,intra-pulse interval time(intra-pulse repetition rate):205 ps(4.88 GHz),burst pulse repetition rate:200 kHz)creates unique two-dimensional(2D)LIPSS.We regard the formation mechanism of 2D LIPSS as the synergetic contribution of the electromagnetic mechanism and the hydrodynamic mechanism.Specifically,generation of hot spots with highly enhanced electric fields by the localized surface plasmon resonance of subsequent pulses in the bursts within the nanogrooves of one-dimensional LIPSS formed by the preceding pulses creates 2D LIPSS.Additionally,hydrodynamic instability including convection flow determines the final structure of 2D LIPSS.展开更多
We review experimental and theoretical results on thermal transport in semiconductor nanostructures（multilayer thin films, core/shell and segmented nanowires）, single-and few-layer graphene, hexagonal boron nitride,...We review experimental and theoretical results on thermal transport in semiconductor nanostructures（multilayer thin films, core/shell and segmented nanowires）, single-and few-layer graphene, hexagonal boron nitride, molybdenum disulfide, and black phosphorus. Different possibilities of phonon engineering for optimization of electrical and heat conductions are discussed. The role of the phonon energy spectra modification on the thermal conductivity in semiconductor nanostructures is revealed. The dependence of thermal conductivity in graphene and related two-dimensional（2 D） materials on temperature, flake size, defect concentration, edge roughness, and strain is analyzed.展开更多
The interface crack problems in the two-dimensional(2D)decagonal quasicrystal(QC)coating are theoretically and numerically investigated with a displacement discontinuity method.The 2D general solution is obtained base...The interface crack problems in the two-dimensional(2D)decagonal quasicrystal(QC)coating are theoretically and numerically investigated with a displacement discontinuity method.The 2D general solution is obtained based on the potential theory.An analogy method is proposed based on the relationship between the general solutions for 2D decagonal and one-dimensional(1D)hexagonal QCs.According to the analogy method,the fundamental solutions of concentrated point phonon displacement discontinuities are obtained on the interface.By using the superposition principle,the hypersingular boundary integral-differential equations in terms of displacement discontinuities are determined for a line interface crack.Further,Green’s functions are found for uniform displacement discontinuities on a line element.The oscillatory singularity near a crack tip is eliminated by adopting the Gaussian distribution to approximate the delta function.The stress intensity factors(SIFs)with ordinary singularity and the energy release rate(ERR)are derived.Finally,a boundary element method is put forward to investigate the effects of different factors on the fracture.展开更多
Hydrogen(H2)is considered to be a promising substitute for fossil fuels.Two-dimensional(2D)nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly,...Hydrogen(H2)is considered to be a promising substitute for fossil fuels.Two-dimensional(2D)nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly,phase engineering of 2D nanomaterials is opening a novel research direction to endow 2D nanostructures with fascinating properties for deep applications in catalyzing HER.In this review,we briefly summarize the research progress and present the current challenges on phase engineering of 2D nanomaterials for their applications in electrocatalytic HER.Our summary will be of significance to provide fundamental understanding for designing novel 2D nanomaterials with unconventional phases to electrochemically catalyze HER.展开更多
According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide（C_2O）.Using density functional theory（DFT）, C_2O is found to be a direct gap semiconductor. In additi...According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide（C_2O）.Using density functional theory（DFT）, C_2O is found to be a direct gap semiconductor. In addition, we obtain the absorption spectra of the periodic structure of C_2O, which show optical anisotropy. To study the optical properties of C_2O nanostructures, time-dependent density functional theory（TDDFT） is used. The C_2O nanostructure has a strong absorption near 7 eV when the incident light polarizes along the armchair-edge. Besides, we find that the optical properties can be controlled by the edge configuration and the size of the C_2O nanostructure. With the elongation strain increasing, the range of light absorption becomes wider and there is a red shift of absorption spectrum.展开更多
Due to their unique physical and chemical properties,two-dimensional(2D)boron nanosheets have received tremendous research attention and demonstrated substantial value in electronic devices,biomedicine,and energy conv...Due to their unique physical and chemical properties,two-dimensional(2D)boron nanosheets have received tremendous research attention and demonstrated substantial value in electronic devices,biomedicine,and energy conversion.In the preparation of boron nanosheets,compared with the bottom-up synthesis predominantly employed for electronics,the top-down synthesis route offers more facile and scalable production.In this mini-review,we mainly discuss the recent advances in the synthesis of boron nanosheets using the top-down strategy and the relevant applications in energy catalysis.Finally,inspired by our recent works on the novel applications of 2D silicon,we put forward prospects for designing boron nanosheets,providing insights into developing viable techniques for high-performance heterogeneous catalysis.展开更多
We investigate the magnetic and topological properties of Mn_(2)X_(2)Te_(5)(X=Bi,Sb)using first-principles calculations.We find that both Mn_(2)Bi_(2)Te_(5)and Mn_(2)Sb_(2)Te_(5)bilayers exhibit A-type antiferromagnet...We investigate the magnetic and topological properties of Mn_(2)X_(2)Te_(5)(X=Bi,Sb)using first-principles calculations.We find that both Mn_(2)Bi_(2)Te_(5)and Mn_(2)Sb_(2)Te_(5)bilayers exhibit A-type antiferromagnetic order,which can be understood based on the Goodenough-Kanamori-Anderson rules.We further find that an appropriate hole doping can induce a transition from the A-type antiferromagnetic phase to the ferromagnetic phase in these systems,which also experience a transition from a normal insulator to a quantum anomalous Hall phase.Our study thus demonstrates that tunable magnetism and band topology can be achieved in Mn_(2)X_(2)Te_(5),which may be utilized in the design of new functional electronic devices.展开更多
With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition...With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition.Two-dimensional(2D)materials have been widely welcomed by researchers as sensitive layers,which broadens the range and application of flexible sensors due to the advantages of their large specific surface area,tunable energy bands,controllable thickness at the atomic level,stable mechanical properties,and excellent optoelectronic properties.This review focuses on five different types of 2D materials for monitoring pressure,humidity,sound,gas,and so on,to realize the recognition and conversion of human body and environmental signals.Meanwhile,the main problems and possible solutions of flexible sensors based on 2D materials as sensitive layers are summarized.展开更多
Subsurface rocks,as complex porous media,exhibit multiscale pore structures and intricate physical properties.Digital rock physics technology has become increasingly influential in the study of subsurface rock propert...Subsurface rocks,as complex porous media,exhibit multiscale pore structures and intricate physical properties.Digital rock physics technology has become increasingly influential in the study of subsurface rock properties.Given the multiscale characteristics of rock pore structures,direct three-dimensional imaging at sub-micrometer and nanometer scales is typically infeasible.This study introduces a method for reconstructing porous media using multidimensional data,which combines one-dimensional pore structure parameters with two-dimensional images to reconstruct three-dimensional models.The pore network model(PNM)is stochastically reconstructed using one-dimensional parameters,and a generative adversarial network(GAN)is utilized to equip the PNM with pore morphologies derived from two-dimensional images.The digital rocks generated by this method possess excellent controllability.Using Berea sandstone and Grosmont carbonate samples,we performed digital rock reconstructions based on PNM extracted by the maximum ball algorithm and compared them with stochastically reconstructed PNM.Pore structure parameters,permeability,and formation factors were calculated.The results show that the generated samples exhibit good consistency with real samples in terms of pore morphology,pore structure,and physical properties.Furthermore,our method effectively supplements the micropores not captured in CT images,demonstrating its potential in multiscale carbonate samples.Thus,the proposed reconstruction method is promising for advancing porous media property research.展开更多
Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport.The construction of these unique structures always requires...Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport.The construction of these unique structures always requires new self-assembly behaviors with different building blocks,intriguing phenomena of colloidal chemistry.In this work,by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations,we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide(MoS_(2))hydrogel membranes with abundant fluidic channels.Given the interpenetrating ionic transport network,the MoS_(2)hydrogel membranes exhibit a highlevel capacitive performance 1.34 F/cm^(2)at an ultrahigh mass loading of 11.2 mg/cm^(2).Furthermore,the interlayer spacing of MoS_(2)in the hydrogel membranes can be controlled with angstrom-scale precision using different cations,which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.展开更多
基金supported by the National Natural Sci-ence Foundation of China(No.22174135,No.21790352)the National Key R&D Program of China(No.2021YFA1500500,No.2016YFA0200600)+4 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Anhui Initiative in Quantum Information Technologies(No.AHY090100)CAS Project for Young Scientists in Basic Research(No.YSBR-054)Innovation Program for Quantum Science and Technology(No.2021ZD0303301)the Fundamental Research Funds for the Central Universities.
文摘Double-resonance Raman(DRR)scattering in two-di-mensional(2D)materials describes the intravalley or intervalley scattering of an electron or a hole excited by incident photons.Although the presence of defects can provide additional momentum and influence the scat-tering process involving one or two phonons,only the idealized defects without any structural details are considered in tra-ditional DRR theory.Here,the second-order DRR spectra of WSe_(2) monolayer with different types of defects are calculated involving the combinations of acoustic and optical phonons in the vicinity of K(K')and M points of the Brillouin zone.The electronic band structures are modified due to the presence of defects,and the band unfolding method is adopted to show the bending of valence and conduction bands for the defective WSe_(2) monolayers.The associ-ated phononic band structures also exhibit different changes in phonon dispersion curves,re-sulting in different DRR spectra corresponding to the different types of defects in the WSe_(2) monolayers.For example,the existence of W vacancy in the WSe_(2) monolayer would result in downshifts in vibrational frequencies and asymmetrical broadenings in linewidths for most combination modes due to the dramatic changes in contour shape of electronic valleys at K and K'.Moreover,the scattering from K to Q is found to be forbidden for the two Se vacan-cies because of the elevation of conduction band at the Q point.Our work highlights the role of defect structures in the intervalley scattering and may provide better understanding in the underlying physics of DRR process in 2D materials.
基金financially supported by the National Natural Science Foundation of China(Nos.62001189 and 51802177)the Joint Funds of the National Natural Science Foundation of China(No.U22A20140)+2 种基金the Youth Innovation Group Plan of Shandong Province(No.2022KJ095)the Plan for the Introduction and Cultivation of Young Innovative Talent in the Colleges and Universities of Shandong ProvinceSupported by Guiding Fund of Zaozhuang Industrial Technology Research Institute of University of Jinan。
文摘To effectively address energy challenges,it is crucial to explore efficient and stable bifunctional nonprecious metal catalysts.In this study,a Mo-doped nickeliron layered double hydroxide with flower-cluster architecture was successfully prepared by a one-step hydrothermal method,which demonstrated a good water splitting performance.After an appropriate amount of Mo doping,some lattice distortions in the material provided reactive sites for the adsorption and conversion of intermediates,thus optimising the charge distribution of the material.Moreover,the multidimensional void structures formed after doping had a larger specific surface area and accelerated the penetration of the electrolyte,which significantly improved the activity of the catalyst in alkaline media.At 10 mA·cm^(-2),the hydrogen and oxygen evolution overpotentials of Mo-doped nickel-iron double hydroxides(Mo-NiFe LDH/NF-0.2)were 167 and 220 mV,respectively,with an excellent durability up to 24 h.When the Mo-NiFe LDH/NF-0,2 catalyst was used as the cathode and anode of an electrolytic cell,the catalyst achieved a current density of 10 mA·cm^(-2)at an applied voltage of 1.643 V.This study provides a novel approach for designing excellent bifunctional electrocatalysts containing nonprecious metals.
基金the Research Grant of Kwangwoon University in 2024 and the National Research Foundation of Korea(RS-2023-00236572 and RS-2023-00212110)funded by the Korea government(MSIT)the project for Collabo R&D between Industry,University,and Research Institute(RS-2024-00414524)funded by Korea Ministry of SMEs and Startups.
文摘Quasi-two-dimensional(2D)perovskite embodies characteristics of both three-dimensional(3D)and 2D perovskites,achieving the superior external environment stability structure of 2D perovskites alongside the high efficiency of 3D perovskites.This effect is realized through critical structural modifications in device fabrication.Typically,perovskites have an octahedral structure,generally ABX3,where an organic ammonium cation(A’)participates in forming the perovskite structure,with A’_(n)(n=1 or 2)sandwiched between A_(n-1)B_(n)X_(3n+1)perovskite layers.Depending on whether A’is a monovalent or divalent cation,2D perovskites are classified into Ruddlesden-Popper perovskite or Dion-Jacobson perovskite,each generating different structures.Although each structure achieves similar effects,they incorporate distinct mechanisms in their formation.And according to these different structures,various properties appear,and additive and optimizing methods to increase the efficiency of 3D perovskites also exist in 2D perovskites.In this review,scientific understanding and engineering perspectives of the quasi-2D perovskite is investigated,and the optimal structure quasi-2D and the device optimization is also discussed to provide the insight in the field.
基金financially supported by the National Natural Science Foundation of China (Grant No. 42002133)Science Foundation of China University of Petroleum,Beijing No.2462024XKBH009+1 种基金the 2022 AAPG Foundation Grants-in-Aid ProgramChina National Postdoctoral Science Foundation(BX20240425 and 2024M753611)
文摘With the development of unconventional hydrocarbon, how to improve the shale oil and gas recovery become urgent. Therefore hydraulic fracturing becomes the key due to the complicated properties of the reservoirs. The pore structure not only plays an essential role in the formation of complex fracture networks after fracturing but also in resource accumulation mechanism analyses. The lacustrine organicrich shale samples were selected to carry out petrophysical experiments. Scanning Electron Microscopy(SEM) and X-ray Diffraction were performed to elucidate the geology characteristics. MICP, 2D NMR, CT,and N2adsorption were conducted to classify the pore structure types. The contribution of pore structure to oil accumulation and hydrocarbon enrichment was explained through the N2adsorption test on the original and extracted state and 2D NMR. The results show that micropores with diameter less than20 nm are well-developed. The pore structure was divided into three types. Type Ⅰ is characterized by high porosity, lower surface area, and good pore throat connectivity, with free oil existing in large pores,especially lamellation fractures. The dominant nano-pores are spongy organic pores and resources hosted in large pores have been expelled during high thermal evolution. The content of nano-pores(micropores) increases and the pore volume decreases in Type Ⅱ pore structure. In addition, more absorbed oil was enriched. The pore size distribution of type Ⅱ is similar to that of type Ⅰ. However, the maturity and hydrocarbon accumulation is quite different. The oil reserved in large pores was not expelled attributed to the relatively low thermal evolution compared with type Ⅰ. Structural vitrinite was observed through SEM indicating kerogen of type Ⅲ developed in this kind of reservoir while the type of kerogen in pore structure Ⅰ is type Ⅱ. Type Ⅲ pore structure is characterized by the largest surface area,lowest porosity, and almost isolated pores with rarely free oil. Type Ⅰ makes the most contribution to hydrocarbon accumulation and immigration, which shows the best prospect. Of all of these experiments,N2adsorption exhibits the best in characterizing pores in shales due to its high resolution for the assessment of nano-scale pores. MICP and NMR have a better advantage in characterizing pore space of sandstone reservoirs, even tight sandstone reservoirs. 2D NMR plays an essential role in fluid recognition and saturation calculation. CT scanning provides a 3D visualization of reservoir space and directly shows the relationship between pores and throats and the characteristics of fractures. This study hopes to guide experiment selection in pore structure characterization in different reservoirs. This research provides insight into hydrocarbon accumulation of shales and guidance in the exploration and development of unconventional resources, for example for geothermal and CCUS reservoirs.
基金supported by the National Natural Science Foundation of China(No.51874036)the Natural Science Foundation of Ningxia(No.2024AAC02034)。
文摘Two-dimensional(2D) nanomaterials have always been regarded as having great development potential in the field of oil-based lubrication due to their designable structures,functional groups,and abundant active sites.However,understanding the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance from a comprehensive perspective is crucial for guiding their future development.This review provides a timely and comprehensive overview of the applications of 2D nanomaterials in oil-based lubrication.First,the bottlenecks and mechanisms of action of 2D nanomaterials are outlined,including adsorption protective films,charge adsorption effects,tribochemical reaction films,interlayer slip,and synergistic effects.On this basis,the review summarizes recent structural regulation strategies for 2D nanomaterials,including doping engineering,surface modification,structural optimization,and interfacial mixing engineering.Then,the focus was on analyzing the structure-performance relationship between the chemical structure of 2D nanomaterials and their lubrication performance.The effects of thickness,number of layers,sheet diameter,interlayer spacing,Moiré patterns,wettability,functional groups,concentration,as well as interfacial compatibility and dispersion behavior of 2D nanomaterials were systematically investigated in oil-based lubrication,with the intrinsic correlations resolved through computational simulations.Finally,the review offers a preliminary summary of the significant challenges and future directions for 2D nanomaterials in oil-based lubrication.This review aims to provide valuable insights and development strategies for the rational design of high-performance oil-based lubrication materials.
基金Supported by the National Natural Science Foundation of China (No. 29872037) and the Natural Science Foundation of Fujian province (No. C0120002)
文摘The title complex [Zn(-O2CCH=CHCO2)(C3H4N2)(H2O)]n was prepared by the reaction of zinc carbonate with maleic acid and imidazole in an aqueous-alcohol solution at 333 K, and its crystal structure has been solved by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group Pc with a = 5.3858(7), b = 22.685(3), c = 7.6782(1) ? = 92.261(2)o, V = 937.4(2) 3, Z = 1, C14H16N4O10Zn2, Mr = 531.05, Dc = 1.882 g/cm3, = 2.623 mm1, F(000) = 532, the final R = 0.0372 and wR = 0.0930 for 1926 observed reflections with I>2s(I). The central zinc atom is five-coordinated in a distorted square pyramidal environment to three oxygen atoms of two different maleate ligands, a nitrogen atom of the imi- dazole ligand and an oxygen atom of water. In the complex two carboxylate groups of the maleate ligands have two coordination modes. One acts as a bidentate chelate ligand and the other a monoatomic monodentate ligand to bridge two zinc centers. As a result, 1-D infinite polymeric chains are formed, which are linked together by pairs of OH…O hydrogen bonds between the coordination water OH groups and carboxylate oxygen atoms to construct a 2-D layered polymer, and the layer structure is stabilized by p-p stacking of the imidozel ligands.
基金financially supported by the National Natural Science Foundation of China(No.U2130116)Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments(MFree),China(No.22dz2260800)Shanghai Science and Technology Committee,China(No.22JC1410300)。
文摘Two-dimensional materials are widely considered to be highly promising for the development of photodetectors.To improve the performance of these devices,researchers often employ techniques such as defect engineering.Herein,pressure is employed as a clean and novel means to manipulate the structural and physical properties of EuSbTe_(3),an emerging two-dimensional semiconductor.The experimental results demonstrate that the structural phase transformation of EuSbTe_(3)occurs under pressure,with an increase in infrared reflectivity,a band gap closure,and a metallization at pressures.Combined with X-ray diffraction(XRD)and Raman characterizations,it is evident that the pressure-driven transition from semiconductor Pmmn phase to metallic Cmcm phase causes the disappearance of the charge density wave.Furthermore,at a mild pressure,approximately 2 GPa,the maximum photocurrent of EuSbTe_(3)is three times higher than that at ambient condition,suggesting an untapped potential for various practical applications.
基金financially supported by the National Natural Science Foundation of China(No.21604046)the National Young Thousand Talents Program,Shandong Provincial Natural Science Foundation,China(No.ZR2016XJ004)
文摘Synthetic two-dimensional（2 D） polymers have totally different topology structures compared with traditional linear or branched polymers. The peculiar 2 D structures bring superior properties. Although, from linear to 2 D polymers, the study of these new materials is still in its infancy, they already show potential applications especially in optoelectronics, membranes, energy storage and catalysis, etc. In this review, we summarize the recent progress of the 2 D materials from three respects：（1） Chemistry—different types of polymerization reactions or supramolecular assembly to construct the 2 D networks were described;（2） Preparation methods—surface science, crystal engineering approaches and solution synthesis were introduced;（3） Functionalization and some early applications.
基金supported by MEXT Quantum Leap Flagship Program(MEXT Q-LEAP)Grant Number JPMXS0118067246.
文摘Femtosecond laser pulses with GHz burst mode that consist of a series of trains of ultrashort laser pulses with a pulse interval of several hundred picoseconds offer distinct features in material processing that cannot be obtained by the conventional irradiation scheme of femtosecond laser pulses(single-pulse mode).However,most studies using the GHz burst mode femtosecond laser pulses focus on ablation of materials to achieve high-efficiency and high-quality material removal.In this study,we explore the ability of the GHz burst mode femtosecond laser processing to form laser-induced periodic surface structures(LIPSS)on silicon.It is well known that the direction of LIPSS formed by the single-pulse mode with linearly polarized laser pulses is typically perpendicular to the laser polarization direction.In contrast,we find that the GHz burst mode femtosecond laser(wavelength:1030 nm,intra-pulse duration:220 fs,intra-pulse interval time(intra-pulse repetition rate):205 ps(4.88 GHz),burst pulse repetition rate:200 kHz)creates unique two-dimensional(2D)LIPSS.We regard the formation mechanism of 2D LIPSS as the synergetic contribution of the electromagnetic mechanism and the hydrodynamic mechanism.Specifically,generation of hot spots with highly enhanced electric fields by the localized surface plasmon resonance of subsequent pulses in the bursts within the nanogrooves of one-dimensional LIPSS formed by the preceding pulses creates 2D LIPSS.Additionally,hydrodynamic instability including convection flow determines the final structure of 2D LIPSS.
基金Project supported by the Republic of Moldova through the projects 15.817.02.29F and 17.80013.16.02.04/Ua
文摘We review experimental and theoretical results on thermal transport in semiconductor nanostructures（multilayer thin films, core/shell and segmented nanowires）, single-and few-layer graphene, hexagonal boron nitride, molybdenum disulfide, and black phosphorus. Different possibilities of phonon engineering for optimization of electrical and heat conductions are discussed. The role of the phonon energy spectra modification on the thermal conductivity in semiconductor nanostructures is revealed. The dependence of thermal conductivity in graphene and related two-dimensional（2 D） materials on temperature, flake size, defect concentration, edge roughness, and strain is analyzed.
基金the National Natural Science Foundation of China (Nos. 11572289,1171407,11702252,and 11902293)the China Postdoctoral Science Foundation (No. 2019M652563)。
文摘The interface crack problems in the two-dimensional(2D)decagonal quasicrystal(QC)coating are theoretically and numerically investigated with a displacement discontinuity method.The 2D general solution is obtained based on the potential theory.An analogy method is proposed based on the relationship between the general solutions for 2D decagonal and one-dimensional(1D)hexagonal QCs.According to the analogy method,the fundamental solutions of concentrated point phonon displacement discontinuities are obtained on the interface.By using the superposition principle,the hypersingular boundary integral-differential equations in terms of displacement discontinuities are determined for a line interface crack.Further,Green’s functions are found for uniform displacement discontinuities on a line element.The oscillatory singularity near a crack tip is eliminated by adopting the Gaussian distribution to approximate the delta function.The stress intensity factors(SIFs)with ordinary singularity and the energy release rate(ERR)are derived.Finally,a boundary element method is put forward to investigate the effects of different factors on the fracture.
基金financially supported by the Key Grant for Special Professors in Jiangsu Province(No.RK030STP18001)the Scientific Research Foundation of Nanjing University of Posts and Telecommunications(No.NY218150)“1311 Talents Program”of Nanjing University of Posts and Telecommunications and the National Postdoctoral Program for Innovative Talents(No.BX20190156)。
文摘Hydrogen(H2)is considered to be a promising substitute for fossil fuels.Two-dimensional(2D)nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly,phase engineering of 2D nanomaterials is opening a novel research direction to endow 2D nanostructures with fascinating properties for deep applications in catalyzing HER.In this review,we briefly summarize the research progress and present the current challenges on phase engineering of 2D nanomaterials for their applications in electrocatalytic HER.Our summary will be of significance to provide fundamental understanding for designing novel 2D nanomaterials with unconventional phases to electrochemically catalyze HER.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant Nos.11474207 and 11374217)
文摘According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide（C_2O）.Using density functional theory（DFT）, C_2O is found to be a direct gap semiconductor. In addition, we obtain the absorption spectra of the periodic structure of C_2O, which show optical anisotropy. To study the optical properties of C_2O nanostructures, time-dependent density functional theory（TDDFT） is used. The C_2O nanostructure has a strong absorption near 7 eV when the incident light polarizes along the armchair-edge. Besides, we find that the optical properties can be controlled by the edge configuration and the size of the C_2O nanostructure. With the elongation strain increasing, the range of light absorption becomes wider and there is a red shift of absorption spectrum.
基金supported by the National Natural Science Foundation of China(No.52372233)the Fundamental Research Funds for the Central Universities(No.226-2022-00200),China.
文摘Due to their unique physical and chemical properties,two-dimensional(2D)boron nanosheets have received tremendous research attention and demonstrated substantial value in electronic devices,biomedicine,and energy conversion.In the preparation of boron nanosheets,compared with the bottom-up synthesis predominantly employed for electronics,the top-down synthesis route offers more facile and scalable production.In this mini-review,we mainly discuss the recent advances in the synthesis of boron nanosheets using the top-down strategy and the relevant applications in energy catalysis.Finally,inspired by our recent works on the novel applications of 2D silicon,we put forward prospects for designing boron nanosheets,providing insights into developing viable techniques for high-performance heterogeneous catalysis.
基金Project supported by the National Natural Science Foundation of China(Grants Nos.12174098 and 12574262)the Major Fundamental Research Program of Hunan Province(Grants No.2025ZYJ004)the State Key Laboratory of Powder Metallurgy,Central South University,China。
文摘We investigate the magnetic and topological properties of Mn_(2)X_(2)Te_(5)(X=Bi,Sb)using first-principles calculations.We find that both Mn_(2)Bi_(2)Te_(5)and Mn_(2)Sb_(2)Te_(5)bilayers exhibit A-type antiferromagnetic order,which can be understood based on the Goodenough-Kanamori-Anderson rules.We further find that an appropriate hole doping can induce a transition from the A-type antiferromagnetic phase to the ferromagnetic phase in these systems,which also experience a transition from a normal insulator to a quantum anomalous Hall phase.Our study thus demonstrates that tunable magnetism and band topology can be achieved in Mn_(2)X_(2)Te_(5),which may be utilized in the design of new functional electronic devices.
基金support of National Natural Science Foundation of China(Nos.52192610,62422120,52371202,52203307,52125205,52202181,and 52102184)Natural Science Foundation of Beijing(Nos.L223006 and 2222088).
文摘With the rapid development of the internet of things(IoT)and wearable electronics,the role of flexible sensors is becoming increasingly irreplaceable,due to their ability to process and convert information acquisition.Two-dimensional(2D)materials have been widely welcomed by researchers as sensitive layers,which broadens the range and application of flexible sensors due to the advantages of their large specific surface area,tunable energy bands,controllable thickness at the atomic level,stable mechanical properties,and excellent optoelectronic properties.This review focuses on five different types of 2D materials for monitoring pressure,humidity,sound,gas,and so on,to realize the recognition and conversion of human body and environmental signals.Meanwhile,the main problems and possible solutions of flexible sensors based on 2D materials as sensitive layers are summarized.
基金supported by the Shandong Provincial Natural Science Foundation(ZR2024MD116)National Natural Science Foundation of China(Grant Nos.42174143,42004098)Technology Innovation Leading Program of Shaanxi(No.2024 ZC-YYDP-27).
文摘Subsurface rocks,as complex porous media,exhibit multiscale pore structures and intricate physical properties.Digital rock physics technology has become increasingly influential in the study of subsurface rock properties.Given the multiscale characteristics of rock pore structures,direct three-dimensional imaging at sub-micrometer and nanometer scales is typically infeasible.This study introduces a method for reconstructing porous media using multidimensional data,which combines one-dimensional pore structure parameters with two-dimensional images to reconstruct three-dimensional models.The pore network model(PNM)is stochastically reconstructed using one-dimensional parameters,and a generative adversarial network(GAN)is utilized to equip the PNM with pore morphologies derived from two-dimensional images.The digital rocks generated by this method possess excellent controllability.Using Berea sandstone and Grosmont carbonate samples,we performed digital rock reconstructions based on PNM extracted by the maximum ball algorithm and compared them with stochastically reconstructed PNM.Pore structure parameters,permeability,and formation factors were calculated.The results show that the generated samples exhibit good consistency with real samples in terms of pore morphology,pore structure,and physical properties.Furthermore,our method effectively supplements the micropores not captured in CT images,demonstrating its potential in multiscale carbonate samples.Thus,the proposed reconstruction method is promising for advancing porous media property research.
基金supported by the National Natural Science Foundation of China(Nos.22078214,21905206,and 22065013)Special Fund for Science and Technology Innovation Team of Shanxi Province(No.202204051001009)。
文摘Conductive hydrogel membranes with nanofluids channels represent one of the most promising capacitive electrodes due to their rapid kinetics of ion transport.The construction of these unique structures always requires new self-assembly behaviors with different building blocks,intriguing phenomena of colloidal chemistry.In this work,by delicately balancing the electrostatic repulsions between 2D inorganic nanosheets and the electrostatic adsorption with cations,we develop a general strategy to fabricate stable free-standing 1T molybdenum disulphide(MoS_(2))hydrogel membranes with abundant fluidic channels.Given the interpenetrating ionic transport network,the MoS_(2)hydrogel membranes exhibit a highlevel capacitive performance 1.34 F/cm^(2)at an ultrahigh mass loading of 11.2 mg/cm^(2).Furthermore,the interlayer spacing of MoS_(2)in the hydrogel membranes can be controlled with angstrom-scale precision using different cations,which can promote further fundamental studies and potential applications of the transition-metal dichalcogenides hydrogel membranes.
