Variety Of Electronic Properties Research Articles

Concentration-Diversified Magnetic and Electronic Properties of Halogen-Adsorbed Silicene

Diverse magnetic and electronic properties of halogen-adsorbed silicene are investigated by the first-principle theoretical framework, including the adatom-diversified geometric structures, atom-dominated energy bands, spatial spin density distributions, spatial charge density distributions and its variations, and orbital-projected density of states. Also, such physical quantities are sufficient to identify similar and different features in the double-side and single-side adsorptions. The former belongs to the concentration-depended finite gap semiconductors or p-type metals, while the latter display the valence energy bands with/without spin-splitting intersecting with the Fermi level. Both adsorption types show the halogen-related weakly dispersed bands at deep energies, the adatom-modified middle-energy σ bands, and the recovery of low-energy π bands during the decrease of the halogen concentrations. Such feature-rich band structures can be verified by the angle-resolved photoemission spectroscopy experiment.

Synthetically Tuned Pd-Based Intermetallic Compounds and their Structural Influence on the O2 Dissociation in Benzylamine Oxidation.

Intermetallic compounds (IMCs) have diverse electronic and geometrical properties to offer. However, the synthesis of intermetallic nanoparticles is not always easy; developing new methodologies that are conventional for many systems can be challenging, especially when incorporating highly electropositive metals to reduce to IMCs using solution synthesis methodologies. In this study, we report a comprehensive approach to access nanocrystalline PdxMy (M = Cu, Zn, Ga, Ge, Sn, Pb, Cd, In) intermetallic (IM) via the coreduction method employing sodium borohydride as the reductant. A combination of diffraction, spectroscopic, and microscopic techniques were performed to characterize the formed nanoparticles in terms of their phase composition, purity, particle size distribution, and surface oxidation properties of metals, respectively. IMCs of Pd with the elements such as Cu, Zn, Ga, and Ge exhibited higher catalytic activity that with elements such as In, Sn, Pb, and Cd. The DFT studies on these compounds revealed that the adsorption of benzylamine at the Pd site and the dissociative adsorption of O2 on the IM surface play a significant effect on catalytic activity. Among them, PdCu IM exhibited an excellent conversion of benzylamine (94.0%), with 92.2% of dibenzylimine selectivity compared to other IMCs. Moreover, PdCu exhibited decent recyclability and activity for the oxidation of different substituted primary amines.

Nickel Hydrides under High Pressure

The Fe–H system demonstrates a complex phase diagram and diverse electronic properties under high pressure. Ni has a similar electronic configuration to Fe, showing similar and different chemical p...

Electronic and magnetic properties of 3d transition-metal atom adsorbed vacancy-defected arsenene: A first-principles study

Abstract Using first-principle calculations, we investigated the effects of vacancy-defect and adsorption of 3d transition metal (TM) atoms on arsenene. The results indicated that the adsorption of TM-adatoms on vacancy-defected arsenene exhibited higher stability than that in perfect arsenene. The analysis of the electronic structures suggested that the strong hybridization existed between the 3d-oribital of TM-adatoms and the 4p-oribital of As atoms around the defect. Furthermore, the nonmagnetic arsenene present magnetism by the introducing of vacancy and TM-atoms, where the magnetism mainly originated from TM-adatom and the As atoms around the vacancy. Moreover, the adsorption of Co, Ni, and Zn on the defected arsenene induced a half-metallic behavior. The diverse electronic and magnetic properties indicate a promising potential application of arsenene in electronic and spintronic devices.

Novel electronic and planar magnetic properties of two-dimensional surface decorated antimonene

The structural, magnetic and electronic properties of antimonenes decorated by hydrogen and halogen have been systematically investigated by density functional theory. The results indicate that semi-decorated antimonene (SX-Sb) (X = H, F, Cl, Br and I) exhibit quasi-planar magnetism, while fully-decorated antimonene (FX-Sb) is a planar Dirac material. Due to the existence of Dirac-cone-like feature, the electronic properties of FX-Sb monolayer can be effectively tuned by applying an external biaxial strain or an electric field and meanwhile maintain a high carrier mobility. In addition, the ferromagnetic state of SX-Sb monolayer is found to be energetically stable. SF-Sb and SCl-Sb nanosheets are predicted to be room-temperature ferromagnetic. The diverse electronic and magnetic properties of antimonene highlight the potential applications in electronics and spintronics.

The diverse electronic properties of C/BN heteronanotubes with polar discontinuity

Linear interfaces from within the heteronanotubes between carbon nanotubes (CNTs) and h-BN nanotubes (BNNTs) introduce unexpected electronic and spintronic properties that are different from individual components. In particular, for heteronanotubes with zigzag boundaries (ZCBNNTs) polar discontinuities occur at the interfaces, generating an intrinsic electric field acting on the segment CNTs. In turn, the electric field will cause a charge transfer between the two interfaces to compensate for the potential difference, thus the interface states (or boundary states) show new phenomena. For example, the half-metallic can be found in ZCBNNTs. Furthermore, the length and diameter of the ZCBNNTs can effectively adjust the electronic properties, due to the compensatory effects of the free charge to the polarization charge. Our results shed light on the future design of miniature superconducting spintronic devices and the realization of high performance nanoelectronic devices with negligible interface contact resistance barriers.

A New Family of Two-Dimensional Crystals: Open-Framework T3 X ( T = C, Si, Ge, Sn; X = O, S, Se, Te) Compounds with Tetrahedral Bonding.

To accelerate development of innovative materials, their modelings and predictions with useful functionalities are of vital importance. Here, based on a recently developed crystal structure prediction method, we find a new family of stable two-dimensional crystals with an open-channel tetrahedral bonding network, rendering a potential prototype for electronic and energy applications. The proposed structural prototype with a space group of Cmme hosts at least 13 different freestanding T3 X compounds with group IV ( T = C, Si, Ge, Sn) and VI ( X = O, S, Se, Te) elements. Moreover, the proposed materials display diverse electronic properties ranging from direct band gap semiconductor to topological insulator at their pristine forms, which are further tunable by mechanical strain.

Exploring high-pressure iron boride compounds: Structural electronics and mechanical properties

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.

Effect of atom adsorption on the electronic, magnetic, and optical properties of the GeP monolayer: A first-principle study

First-principles calculations have been carried out to explore the effect of atom surface adsorption on the electronic, magnetic, and optical properties of the germanium phosphide (GeP) monolayer. It is shown that the GeP monolayer exhibits good adsorption capability to all the selected adatoms and can preserve the structural integrity upon the adsorption of most adatoms. The adatoms can bring out diverse electronic properties to the GeP monolayer. The H, Li, Na, K, and Al adatoms donate electrons to the GeP monolayer and result in its metallization. The other adatoms do not change the semiconducting nature of the GeP monolayer and will induce midgap states (Mg, Ca, Si, Ge, Ag, and Au) or reduce the bandgaps (Ni, Pd, and Pt). The B, N, P, As, V, Cr, Mn, Fe, and Co adatoms induce spin magnetic moments into the GeP monolayer. Especially, the spin magnetic moments are mainly located on the adatoms for the GeP decorated with the V, Cr, Mn, Fe, and Co atoms. As a result, the dilute magnetic semiconductor can be obtained. In addition, all the adatoms decrease the work function, except O. Thus, some effects on the optical properties are highly expected. The GeP monolayer exhibits a wide range of light absorption and the Mg, Si, Ge, Cu, Ag, Au, and Pt adatoms can further redshift the absorption edge of the GeP monolayer along the x and y directions. Our calculations provide an effective method to modulate the electronic, magnetic, and optical properties of the GeP monolayer for device applications.

Recent advances in graphene-based platinum and palladium electrocatalysts for the methanol oxidation reaction

Graphene-based electrocatalysts have recently attracted considerable research interest because of the abundant choices they present, with tunable and diverse optical, electronic and chemical properties.

Electronic structures of ultra-thin tellurium nanoribbons.

The structural stability and electronic properties of monolayer and bilayer tellurium nanoribbons (TNRs) with different edge structures have been systematically investigated by means of first-principles calculations, revealing that the stability of both monolayer and bilayer TNRs largely rely on their width. Regardless of width, tip TNRs are metallic, while notch TNRs are p-type-like conductors. Interestingly, both mono- and bi-layer chain TNRs exhibit a semiconductor-to-metal transition as the width increases. The electronic structures of tip and notch TNRs are mainly determined by atomic reconstruction and the unsaturated electronic states on the edges. For chain TNRs, the origin of the semiconductor-to-metal transition can be attributed to the spontaneous in-plane electronic polarization across the ribbon. Our work reveals diverse electronic properties of one-dimensional elemental tellurium nanostructures, which considerably extend the potential applications of tellurene-based materials in nanodevices.

Silver-Catalyzed Three-Component Difunctionalization of Alkenes via Radical Pathways: Access to CF3-Functionalized Alkyl-Substituted 1,4-Naphthoquinone Derivatives.

A silver-catalyzed three-component difunctionalization of alkenes by using 2-amino- and 2-hydroxy-1,4-naphthoquinone derivatives as the radical-trapping reagents is reported. Various alkenes and 2-amino- or 2-hydroxy-1,4-naphthoquinones with diverse structures and electronic properties are applied to the reaction. The methodology provides an alternative method to access CF3-functionalized alkyl-substituted quinone derivatives which are prevalent structures in bioactive molecules. Furthermore, a plausible radical pathway for the reaction is proposed based on results from primary control experiments.

All-Silicon Topological Semimetals with Closed Nodal Line.

Because of the natural compatibility with current semiconductor industry, silicon allotropes with diverse structural and electronic properties provide promising platforms for next-generation Si-based devices. After screening 230 all-silicon crystals in the zeolite frameworks by first-principles calculations, we disclose two structurally stable Si allotropes (AHT-Si24 and VFI-Si36) containing open channels as topological node-line semimetals with Dirac nodal points forming a nodal loop in the k z = 0 plane of the Brillouin zone. Interestingly, their nodal loops protected by inversion and time-reversal symmetries are robust against SU(2) symmetry breaking because of the very weak spin-orbit coupling of Si. When the nodal lines are projected onto the (001) surface, flat surface bands can be observed because of the nontrivial topology of the bulk band structures. Our discoveries extend the topological physics to the three-dimensional Si materials, highlighting the possibility of realizing low-cost, nontoxic, and semiconductor-compatible Si-based electronics with topological quantum states.

Diverse Electronic and Magnetic Properties of Chlorination-Related Graphene Nanoribbons

The dramatic changes in electronic and magnetic properties are investigated using the first-principles calculations for halogen(X: Cl, Br, I, At)-adsorbed graphene nanoribbons. The rich and unique features are clearly revealed in the atoms-dominated electronic band structures, spin arrangement/magnetic moment, spatial charge distribution, and orbital- and spin-projected density of states. Halogen adsorptions can create the non-magnetic, ferromagnetic or anti-ferromagnetic metals, being mainly determined by concentrations and edge structures. The number of holes per unit cell increases with the adatom concentrations. Furthermore, magnetism becomes nonmagnetic when the adatom concentration is beyond 60% adsorption. There are many low-lying spin-dependent van Hove singularities. The diversified properties are attributed to the significant X-C bonds, the strong X-X bonds, and the adatom- and edge-carbon-induced spin states.

Interplay of structural, electronic, and transport features in copper alloys

Copper alloys show a structural variability leading to a range of diverse electronic, transport, and mechanical properties. Here, we investigate the influence of the type and amount of alloying on the electronic transport properties across copper alloys. Specifically, we investigate the electronic transmission along copper in its fcc crystal structure. The characteristic change when adding impurities, such as nickel, aluminum, and silicon in the structure and transport properties is assessed through density functional theory calculations together with the non-equilibrium Greens functions approach. The results are analyzed with respect to the structural characteristics, the electronic and transport properties in these alloys for different concentrations of the impurities. A clear trend in the electronic transmission, thus the conductance, along these materials was found with the addition of certain impurities and their clusters. Coherent with experimental observations, we conclude that the higher the concentration of the impurities, the lower the electronic transmission along the alloys as compared to a pure copper crystal. Furthermore, we show that the bonding environment in the impurity clusters can be associated to additional valence states and significantly influences the conductance. In the end, we discuss the relevance of our results for practical applications.

Spin gapless semiconductor and half-metal properties in magnetic penta-hexa-graphene nanotubes

Abstract Penta-hexa-graphene (PHG) is the name given to a novel puckered monolayer of carbon atoms tightly packed into an inerratic mixing pentagonal and hexagonal network. Theoretically, it exhibits excellent electronic properties and can be rolled into penta-hexa-graphene nanotubes (PHGNTs). By using first-principles combined with density functional theory, the PHGNTs with two types of chirality and different diameters were studied. Studies show that not only the nanotubes have intrinsic magnetic properties, but also the magnetic ground state changes with the tube diameter. Interestingly, the nanotubes exhibit semiconducting properties that do not vary with chirality in the antiferromagnetic (AFM) state. And in the ferromagnetic (FM) state, the materials realize the transitions from metal to spin gapless semiconductors (SGS), and to semiconductor with the change of tube diameter. Furthermore, first-principles calculation shows that PHGNTs exhibit diverse electronic properties when the external electrical field is applied, ranging not only from semiconductor to SGS and to metal, but also from semiconductor to half-metal and to metal. Our simulations have an impact on their possible applications in spintronic devices.

Computational Studies of Nanographene Systems: Extended Discotics, Covalently Linked “Supermolecules,” and Functionalized Supramolecular Assemblies

Finite nanographene molecules in the form of discotic mesogens constitute a promising family of materials for a plethora of applications, primarily focused on organic electronics. Flexible side chains around the periphery of such molecules impart solubility and prompt self-organization mechanisms inherent to soft matter systems. In this work, both quantum chemical and classical simulation methodologies are employed to examine electronic, charge transport, structural, and dynamical properties of discotic materials at multiple scales, ranging from single-molecule representations to bulk supramolecular assemblies. In addition to planar molecules of variable core extent, a series of covalently linked “supermolecules” are considered, exhibiting diverse electronic properties and low charge reorganization energies, and unique self-organization capabilities in the form of triple helix molecular wires. A hybrid Monte Carlo methodology is proposed and utilized for the creation of plausible initial configurations fo...

Achieving half-metallicity in zigzag MoS2 nanoribbon with a sulfur vacancy by edge passivation

We performed density functional theory calculations to investigate the electronic and magnetic properties of zigzag MoS2 nanoribbons with a S vacancy (ZMoS2NRs-VS). The systems are all magnetic with magnetism concentrated on the edge Mo and S atoms. Interestingly, ZMoS2NR-VS can be tuned from metallicity to half-metallicity. Moreover, passivation of functional groups such as H, F, OH or NH2 with a passivated concentration of 25% can not only provide half-metallicity in ZMoS2NR-VS but also enhance the stability of the system. These diverse electronic and magnetic properties might open great opportunities for MoS2 materials in spintronics in the future.

Photofunctions of Phthalocyanine Complexes

Phthalocyanines (Pcs, Figure 1) have attracted attention as a result of their diverse electronic and optical properties, offer applications in the fields of luminophores, sensors, non-linear optics, photosensitizers for singlet oxygen generation, photovoltaic cells, red or near-infrared light absorbers in optical data storage systems, and photoconductor devices. Because of a recent surge of interest in both the functionalization of various molecules, focusing on photofunctions of Pcs has become essential. I'll present recent topics especially from the viewpoint of photofunctions of Pc complexes, i.e., photoelectrochemical catalysts, singlet oxygen generators, redox-based fluorescent probes, and magneto-optical effects. Figure 1

First-principles study of the role of strain and hydrogenation on C3N

C3N has been synthesized recently and demonstrated to possess specific physical and chemical properties. In this work, we investigated the strain effect on it's electronic and phonon properties and on the adsorption property of Li atom through first-principles calculations. Phonon dispersions demonstrate that the crystal structure of C3N is dynamical stable under tensile strain up to 14%. Calculation results show that C3N is always an indirect gap semiconductor as the applied tensile strain is 0%–12% and the band gap reaches its maximum at strain = 9%. While when strain is 13% and 14%, C3N become metallic. Li atom prefers to occupy the C-C hexagonal sites on C3N surface with a diffusion barrier of 0.43eV and the adsorption energies of different adsorption configurations increase with strain. What's more, phonon dispersion calculations and ab initio molecular dynamics simulations reveal that the fully hydrogenated extension of C3N, C3NH3 has two stable conformations, in which one is an indirect semiconductor with band gap of 4.09eV while the other possesses a direct band gap of 2.88eV suitable for photocatalytic application. The strained and hydrogenated C3N with diverse structures and electronic properties provide new prospects in the applications of lithium ion batteries and photoelectrochemistry.