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We propose a novel semiconductor Sc2S3 monolayer with ultrahigh carrier mobility for UV blocking filter application.

With two suitable organic units (TAPA and HADQ), H-C3N2 and T-C3N2 are designed and proposed based on the high possibility for experimental realization. They show different structural features and exceptional optoelectronic properties.

Square chalcogen bonds are formed by dimers, fluoro-substituted dimers were also considered for comparison. A systematic first-principles investigation of square chalcogen interaction, and its adsorption behavior on Ag surface are presented.

In this study, based on ab initio calculations and the phonon Boltzmann transport equation, we found that magnetic phase transitions can lead to a significant change in the thermal conductivity of monolayer MnPS3.

Using swarm-intelligence structure-search method in conjunction with structure design via the assembly of organic units, we identified a novel holey α-C3N2 monolayer as superior anode material of LIBs with ultra-high specific capacity.

In this study, based on

Phosphorene allotrope monolayers such as blue and red phosphorus are being designed and synthesized to be used in the optoelectronics field due to their tunable bandgap and high mobility. Using the organic molecule self-assembly method similar to the synthesis of graphene allotropes, a novel phosphorene allotrope, P

Predicting the crystal structure of an energetic compound is an important aspect of energetic crystal engineering because an accurate crystal structure prediction (CSP) presents a base for accurate...

Anderson localization of phonons is a kind of phonon wave effect, which has been proved to occur in many structures with disorders. In this work, we introduced aperiodicity to boron nitride/carbon nanotube superlattices (BN/C NT SLs), and used molecular dynamics to calculate the thermal conductivity and the phonon transmission spectrum of the models. The existence of phonon Anderson localization was proved in this quasi one-dimensional structure by analyzing the phonon transmission spectra. Moreover, we introduced interfacial mixing to the aperiodic BN/C NT SLs and found that the coexistence of the two disorder entities (aperiodicity and interfacial mixing) can further decrease the thermal conductivity. In addition, we also showed that anharmonicity can destroy phonon localization at high temperatures. This work provides a reference for designing thermoelectric materials with low thermal conductivity by taking advantage of phonon localization.

The two-dimensional (2D) material-based thermal switch is attracting attention due to its novel applications, such as energy conversion and thermal management, in nanoscale devices. In this paper, we observed that the reversible 2H–1T′ phase transition in MoTe2 is associated with about a fourfold/tenfold change in thermal conductivity along the X/Y direction by using first-principles calculations. This phenomenon can be profoundly understood by comparing the Mo–Te bonding strength between the two phases. The 2H-MoTe2 has one stronger bonding type, while 1T′-MoTe2 has three weaker types of bonds, suggesting bonding inhomogeneity in 1T′-MoTe2. Meanwhile, the bonding inhomogeneity can induce more scattering of vibration modes. The weaker bonding indicates a softer structure, resulting in lower phonon group velocity, a shorter phonon relaxation lifetime and larger Grüneisen constants. The impact caused by the 2H to 1T′ phase transition in MoTe2 hinders the propagation of phonons, thereby reducing thermal conductivity. Our study describes the possibility for the provision of the MoTe2-based controllable and reversible thermal switch device.

The CaAs3 monolayer is a newly predicted two-dimensional material with attractive properties, such as a moderate direct bandgap, high carrier mobility, prominent visible-light absorption, etc. To evaluate its potential applications in thermoelectric (TE) fields, herein, the thermoelectric properties of CaAs3 monolayers were comprehensively investigated by a first-principles method in combination with Boltzmann transport theory. Our calculated results indicate that the CaAs3 monolayer has an exceptionally low lattice thermal conductivity of 0.44 W m−1 K−1 at 300 K, mainly because of the small group velocity and strong phonon–phonon scattering. The CaAs3 monolayer also exhibits a high power factor due to the large Seebeck coefficient and electrical conductivity. Therefore, large ZT values of 1.72/1.58 were achieved for the n-type/p-type CaAs3 monolayer at 800 K. Compared with conventional 2D TE materials, the CaAs3 monolayer does not contain expensive heavy elements, which is beneficial for its practical applications as a TE material. Our results qualify the CaAs3 monolayer as a promising candidate for building excellent 2D TE devices.

Thermoelectric (TE) materials as one of the effective solutions to the energy crisis are gaining more and more interest owing to their capability to generate electricity from waste heat without generating air pollution. In this work, the TE properties of α-XP monolayers such as the stability, electronic structure, electrical and phonon transport were thoroughly studied in combination with the first-principles calculations and Boltzmann transport equations. We found that α-SbP and α-BiP have indirect bandgaps of 0.85 eV and 0.73 eV, respectively, which are suitable for thermoelectric materials. Furthermore, due to the multiple valleys at the energy band edges and the high carrier mobility, α-XP possesses both large Seebeck coefficients and high electrical conductivities. It is also found that the lattice thermal conductivity of α-BiP is smaller than that of α-SbP due to lower phonon frequencies, smaller phonon group velocities, larger Gruneisen parameters and higher phonon relaxation times. High TE performance was achieved with the ZT values reaching 4.59 (for α-BiP at 500 K) and 1.34 (for α-SbP at 700 K). Our results quantify α-XP monolayers as promising candidates for building outstanding thermoelectric devices.

Black Arsenic-phosphorus (AsP) monolayer is a novel two-dimensional nanomaterial with the characteristics of modest direct bandgap and superhigh carrier mobility. However, little is known about how the surface adsorption affects the property of AsP monolayer. Motivated by this, we researched systematically the geometry, adsorption energy, magnetic moment and electronic structure of 11 different adatoms adsorbed on AsP monolayer using first-principles calculations. The adatoms used in this study include light nonmetallic (C, N, O) adatoms, period-3 metal (Na, Mg, Al) adatoms, and transition-metal (Ti, V, Cr, Mn, and Fe) adatoms. The adatoms cause an abundant variety of structural, magnetic and electronic properties. This study shows that AsP binds strongly with all adatoms under study and the adsorption energies in all systems are much stronger than that on graphene, SiC, BN, or MoS2. The semiconductor property of AsP is affected by the introduction of adsorbed atoms, which can induce mid-gap states or cause n-type doping. Moreover, the adatom adsorptions cause various spintronic characteristics: N-, Ti-, and Fe-adsorbed AsP become bipolar semiconductors, while the Mn-decorated AsP becomes a bipolar spin-gapless semiconductor. Our results suggest that atomic adsorption on AsP monolayers has potential application in the field of nanoelectronics and spintronics.

In this paper, we designed novel low-symmetry two-dimensional (2D) structures based on conventional XTe (X = Ge, Sn, Pb) thermoelectrics with large average atomic mass. The first-principles calculations combined with Boltzmann transport theory show that the beta-XTe exhibit good stability, high electron carrier mobility, and ultralow ΚL. The subsequent analyses show that the ultralow ΚL stems from the coexistence of resonant bonding, weak bonding, and lone-pair electrons in beta-XTe, which leads to large anharmonicities. On the other hand, the lowest energy conduction band of beta-GeTe and beta-SnTe show the convergence of the low-lying Ʃ band, which is the source of the high-power factor in the two systems. The calculated maximum ZT of beta-XTe (X = Ge, Sn, Pb) are 3.08, 1.60, and 0.57 at 300 K, respectively, which is significantly greater than that of the previously reported high-symmetry 2D alpha-XTe and the commercial thermoelectrics. We hope that this work can provide important guidance for the development of thermoelectric materials.

We studied the work function of cesium deposition and co-deposition with the electronegative element on the plasma grid (PG) using the first-principles calculations. The impurity particles may exist in the background plasma and vacuum chamber wall, and the work function of the PG will be affected. The results indicate that the minimum work functions of pure cesium deposition on Mo (110), W (110), and Mo (112) are reached at a partial monolayer. They are 1.66 eV (σ = 0.56 θ), 1.69 eV (σ = 0.75 θ), and 1.75 eV (σ = 0.88 θ), respectively. An appropriate co-deposition model consisting of cesium with electronegative elements can further decrease the work function. The coverage of cesium and electronegative elements are both 0.34 θ in all the co-deposition models. The F-Cs co-deposition model where the Cs atom and F atom are aligned along the surface normal obtains the lowest work function. They are 1.31 eV for F-Cs on Mo (110), and 1.23 eV for F-Cs on W (110), respectively. The change in work function is linearly related to the change in dipole moment density with a slope of −167.03 VÅ. For pure cesium deposition, two factors control the change in dipole-moment density, one is the electron transfer between adsorbates and the substrate, and another one is the restructuring of surface atoms. There are two additional factors for the co-deposition model. One is the intrinsic dipole moment of the double layer, the other is the angle between the intrinsic dipole moment and the surface. The latter two factors play important roles in increasing the total dipole moment.

During the operation of digital substations, they are vulnerable to the influence of different fault feature extraction, resulting in weak anti-interference in the detection process. To solve this problem, the singular value decomposition method is combined detection method to establish a prediction model. Firstly, the three-dimensional control mode model is established based on mathematical method to process the current signal with anti-interference; Secondly, the singular value method is used to optimize the current transmission process and denoise the fault signal feature extraction; Finally, the method of singular value decomposition is used to realize fault detection in substation operation.

The CaAs

Two-dimensional semiconductor material zirconium disulfide (ZrS2) monolayer is a new promising material with good prospects for nanoscale applications. Recently, a new zirconium disulfide (ZrS2) monolayer with a space group of 59_Pmmn has been successfully predicted. Using first-principles calculations, this new monolayer ZrS2 structure is obtained with stable indirect band gaps of 0.65 eV and 1.46 eV at the DFT-PBE (HSE06) functional levels, respectively. Strain engineering studies on ZrS2 monolayer show effective band gap modulation. The bandgap shows a linear regularity from narrow to wide under applied stresses (strain ranged from − 6% to + 8%). Young's modulus of elasticity of ZrS2 rectangular cells along the tensile directions (x-axis and y-axis) is 83.63 (N/m) and 63.61 (N/m) with Poisson's ratios of 0.09 and 0.07, respectively. The results of carrier mobility show that the electron mobility along the y-axis can reach 1.32×103 cm2V− 1s− 1. Besides, the order of magnitude of the light absorption coefficient in the ultraviolet spectral region is calculated to reach 2.0×105cm−1 for ZrS2 monolayers. Moreover, by regulating the bandgap under stress, some bandgaps of the stretched energy band exceed the free energy of 1.23 eV and possess a suitable energy band edge position. The results indicates that the new two-dimensional Pmmn-ZrS2 monolayer is a potential material for photovoltaic devices and photocatalytic water decomposition.

Thermoelectric (TE) materials are increasingly attracting the attention of researchers as new energy materials that are capable of converting thermal energy into electrical energy. In this work, combining first-principles calculations and the Boltzmann transport equation, the TE related properties of XTe (X = Ge, Sn and Pb) monolayers have been thoroughly studied. The calculated results show that XTe monolayers are indirect band gap semiconductors, and they possess small effective masses which lead to large carrier mobilities and high electrical conductivities. Except for p-type PbTe, the other XTe monolayers share extremely high PF, thanks to the high Seebeck coefficients and large electrical conductivity. Furthermore, owing to the low phonon group velocity and strong anharmonicity, the lattice thermal conductivities of SnTe and PbTe are quite low. At 500 K, the optimum figure of merit (ZT) values are calculated to be 1.26, 2.61 and 5.91 for GeTe, SnTe and PbTe respectively. The obtained ZT values of the XTe monolayers are larger than these of their bulk counterparts. These results qualify XTe monolayers as promising candidates for building outstanding TE devices.

Two-dimensional semiconductor material zirconium disulfide (ZrS

Given the highly possible existence of nickel and silicon in the Earth's core, the study of the reaction between Ni and Si and the resulting structures at the pressure corresponding to that of the Earth's core is highly required. Therefore, we have investigated the crystal structures of Ni–Si compounds at pressures of 0–350 GPa by adopting a crystal structure search algorithm in conjunction with first-principles calculations. We uncover two high Ni-content Ni5Si and Ni6Si compounds with 12-coordination Si bonded with Ni, with both showing strong chemical stability in the Earth’s core. Bonding analysis reveals that the Ni atoms in these Ni–Si compounds present oxidant features and act as electron acceptors. This distinctive anomaly is the natural result of the energy shifts of the Ni 3d and Si 3p bands, resulting in charge transfer from Si to Ni. By examining the key properties (e.g., density and sound velocities) of the Ni5Si and Ni6Si compounds, the obtained density lies within the range of the Earth’s inner core, and the estimated sound velocities are found to be consistent with seismic data. These results indicate that these two compounds could be considered as possible core constituents. Our findings provide valuable insights into the enigmatic Earth's core as well as geophysical and geochemical processes.

Triel bond, a recent emerging noncovalent interaction, has attracted extensive attention from physical and chemical scientists. Some triel atoms, such as Ga and In atoms, theirs valence, can be bivalent, trivalent, and even tetravalent. What is the influence of the valence of triel atom on the triel-bonding formation? This issue generates our initial research interest. Then, the influence of valence of triel atom on the triel bond has been theoretically investigated in thirty-two complexes composed by Lewis acids TrHX/TrH2X (Tr = Ga, In; X = F, Cl, Br, I) and Lewis base H2Y (Y = O, S) molecules at MP2/aug‐cc‐pVTZ(PP) theory level. MEP analyses show that both TrHX and TrH2X molecules possess π-holes on Tr atoms, which can be used as Lewis acids, and interact with Lewis bases to form triel bonds. AIM and Non-covalent interaction (NCI) analyses demonstrate that triel bond exists in all the studied thirty-two complexes. Hydrogen bond coexists with triel bond only in six of these complexes. In the process of triel bond formation, TrH2X molecule has stronger structural distortion than TrHX molecule. And TrH2X molecule can form a stronger triel bond than that of TrHX molecule by analyzing multiple factors that affect triel-bonding formation including substituents, electron donors, and nature of triel atoms. In addition, NBO analyses show that triel bond in TrH2X–H2Y complexes has stronger orbital interaction than that in TrHX–H2Y complexes.

We theoretically study chalcogen bonds involving SF2 and SFH, each paired with various unsaturated hydrocarbons ethyne, ethene, 1,3-butadiene, and benzene. The binding energies are calculated at theory level MP2, M06-2X-D3 and CCSD(T)/CBS, respectively. Geometry structure, binding energies, interaction type and strength are studied comparatively. SFH engages in a stronger chalcogen bond than does SF2 for all systems, which indicates that SFH is a stronger electron acceptor than SF2. Two kinds of energetic effects are observed, SF2···cis-butadiene complex contain the strongest chalcogen bond among all the SF2···π complexes, which is attributed to the energetic effect of two S···π interactions. For SFH···π complexes, the strongest interaction is formed between SFH and C6H6, which can be explained by the synergistic effects of the S···π and S H···π interaction. The largest charge transfer arises from the occupied C C bonding orbital to the σ*(S F) antibonding orbital. The quantity is considerably larger for SFH than for SF2.

Three-dimensional carbon honeycombs were experimentally discovered recently. In this work, we study the thermal conductivity of zigzag carbon foams with different sidewall widths. We found the anisotropic thermal conductivity along different directions. We noted that the local buckling introduced by the interconnections severely impedes the phonon transport. The phonon density of states was analyzed to compare the phonon modes in the planar and the interconnection regions. The structure-thermal transport property relationship obtained in this study provides important insights for future applications of three-dimensional carbon honeycombs, such as energy storage, catalysis, microelectronics, and the like.

Pressure is one of the thermodynamic factors that can change the bonding patterns of materials and lift the reactivity of elements, leading to the synthesis of unconventional compounds with fascinating properties. Iron-boride (Fe-B) compounds (e.g., FeB4) are attracting increasing attention due to their desirable electronic properties (e.g., superhard and superconductivity). Using the effective CALYPSO structure searching method combined with first-principles calculations, we theoretically explored various boride-rich Fe-B compounds at pressures ranging from 0 to 300 GPa. Our results revealed, unexpectedly, that pressure stabilizes one hitherto unknown stoichiometric boride-rich Fe2B3 compound. Fe2B3 crystallized in a monoclinic C2/c structure, whose remarkable feature is covalently polymerized B-network and B-sharing 8-fold FeB8 polyhedral, where Fe has the eight coordination number with B as the first time among all Fe-B structures. The existence of Fe2B3 compound aroused the thermodynamic instability of the FeB2 composition under high pressure. The underlying mechanisms for the stabilization of Fe2B3 with respect to that of FeB and FeB4, are analyzed by the coordination number and structure packing. Moreover, the electronic and mechanical properties of C2/c-Fe2B3 are evaluated and discussed in comparison with that of the stable phase of FeB and FeB4. Our current results unravel the unusual boride-rich stoichiometry of Fe-B compounds and provide further insight into the diverse electronic properties of Fe borides under high pressure.

Understanding the details of thermal transport in graphdiyne and its nanostructures would help to broaden their applications. On the basis of the molecular dynamics simulations and spectrally decomposed heat current analysis, we show that the high-frequency phonons in graphdiyne can be strongly hindered in nanoribbons because of the boundary scattering. The isotropic transport in graphdiyne can be switched to anisotropic along the armchair and zigzag directions. Adding side chains onto the nanoribbon edges further reduces the thermal conductivity (TC) along both armchair and zigzag directions thanks to the reduction of heat current carried by low-frequency modes, a mechanism that arises from the phonon resonances. The uniaxial tensile strain plays a different role in the TC of graphdiyne, armchair nanoribbons, and zigzag nanoribbons. Tensile strain causes the thermal conductivities of graphdiyne, and armchair nanoribbons increase first and then get reduced, whereas for zigzag nanoribbons, the TC decreases with strain first and reaches to a plateau. The different low-frequency phonon response on strain is the main reason for the different TC behavior. For graphdiyne and armchair nanoribbons, the low-frequency heat current is enhanced gradually first and then get reduced with the increase of strain, while that of zigzag nanoribbons decreases with strain and then increases slightly. The current studies could help us understand the phonon transport in graphdiyne and its nanoribbons, which is useful for their TC engineering.

Bone morphogenetic protein (BMP) adsorption plays an important role in the osteoinduction properties of graphene (G)-based biomaterials. Meanwhile, the physical and chemical properties of G vary in a large range according to the different oxidation degrees. In this study, molecular dynamic simulations were utilized to understand the interfacial interactions of G's oxidation degree on the BMP-7 adsorption behaviors. According to the adsorption energy, the distance distribution of BMP-7 adsorption sites/G, and artificial intelligence based principal component analysis, the effects of G's oxidation degree on BMP-7 adsorption were systematically studied. Then, the variations of the BMP-7 configuration were explored by the analysis of the secondary structures, root mean square deviation and Ramachandran plots. It is indicated that the adsorption of BMP-7 on G is strongly related to its oxidation rate. The surface polarities and the wrinkle degrees of G can be regulated by the oxidation rate and consequently impact the interactions between BMP-7 and G. A 50% oxidation degree of G exhibits the equilibrated regulation effects on both the adsorption strength and the configurations of BMP-7. Our study provides critical information on the relationship between BMP-7 adsorption and the oxidation degree of G at the atomistic scale, which can guide the design of novel BMP-7 loaded G-based tissue engineering scaffolds.

A new type of memristive memory device with an edible garlic-constructed Ag/garlic/fluorine-doped SnO2 (FTO) structure for analog neuromorphic sensor applications was designed. The memristive device shows stable memory behavior with good retention and endurance (over ∼3.0 × 104 s). These memristive properties, which can be induced through acid and alkali ion manipulation by pH modulation, are reported here for the first time. To clarify the pH-controlled memristive mechanism, conduction current fitting was applied and, meanwhile, an internal ion distribution model in the active allicin layer was proposed to explain the origin of the current variation. The pH-controlled manipulation is an efficient method to modify the memristive behavior, and this investigation also provides a potential application in terms of performing neuron functions.