First-principles calculations are performed to study the electronic and magnetic properties of VX(2) monolayers (X = S, Se). Our results unveil that VX(2) monolayers exhibit exciting ferromagnetic behavior, offering evidence of the existence of magnetic behavior in pristine 2D monolayers. Furthermore, interestingly, both the magnetic moments and strength of magnetic coupling increase rapidly with increasing isotropic strain from -5% to 5% for VX(2) monolayers. It is proposed that the strain-dependent magnetic moment is related to the strong ionic-covalent bonds, while both the ferromagnetism and the variation in strength of magnetic coupling with strain arise from the combined effects of both through-bond and through-space interactions. These findings suggest a new route to facilitate the design of nanoelectronic devices for complementing graphene.

One of the main challenges for advanced metallic nanoparticles (NPs) supported functional perovskite catalysts is the simultaneous achievement of a high population of NPs with uniform distribution as well as long-lasting high performance. These are also the essential requirements for optimal electrode catalysts used in solid oxide fuel cells and electrolysis cells (SOFCs and SOECs). Herein, we report a facile operando manufacture way that the crystal reconstruction of double perovskite under reducing atmosphere can spontaneously lead to the formation of ordered layered oxygen deficiency and yield segregation of massively and finely dispersed NPs. The real-time observation of this emergent process was performed via an environmental transmission electron microscope. Density functional theory calculations prove that the crystal reconstruction induces the loss of coordinated oxygen surrounding B-site cations, serving as the driving force for steering fast NP growth. The prepared material shows promising capability as an active and stable electrode for SOFCs in various fuels and SOECs for CO2 reduction. The conception exemplified here could conceivably be extended to fabricate a series of supported NPs perovskite catalysts with diverse functionalities.

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Recently, Cu2(OH)PO4 was found as the first photocatalyst active in the near-infrared(NIR) region of the solar spectrum (Angew. Chem., Int. Ed., 2013, 52, 4810; Chem. Eng. News, 2013, 91, 36), motivating us to explore systemically its photocatalytic mechanism under near-infrared light and how to improve and tune its photocatalytic performance. Herein, electronic structures, and effective masses of electron and hole at energy band edges are theoretically investigated by employing spin-polarized density functional theory calculations. The calculated energy band structure supports the absorption spectra of Cu2(OH)PO4 in the NIR region corresponding to the electron excitation from the valence band to the unoccupied bands in the gap. Our charge density analysis indicates that the O atoms in the hydroxyl serves as the effective bridge for the favoring separation of the photogenerated electron-hole pairs. Furthermore, the effective masses of electron and hole analysis demonstrate that the separation and transfer of photogenerated carriers along the [011] direction may be more effective than other possible directions. A qualitative comparison of carrier transfer ability along all the directions in the specific planes is displayed by the three-dimensional band structure. Interestingly, the calculated net dipole moment for the two basic units of Cu2(OH)PO4, octahedron and trigonal bipyramid, indicate that the macroscopic dipole moment for Cu2(OH)PO4 is zero, however, the distorted octahedron unit has a net dipole moment, which enables us to tune the macroscopic dipole moment by doping. The present work provides theoretical insight leading to a better understanding of the photocatalytic performance of Cu2(OH)PO4 and it may be beneficial to prepare more efficient Cu2(OH)PO4 for NIR light photocatalysis, which will also be helpful to design and prepare novel photocatalysts.

Although there is plenty of research work being done in the field of carbon nanotube reinforced composite materials, no special attention has been paid to the factors of the polymer's repeat unit arrangement and conformation. In this paper we use molecular dynamics simulation based on a Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies (COMPASS) force field to study the interactions between five types of polymers and (10, 10) single-walled carbon nanotubes (SWNTs). When we study the interactions, we pay special attention to the polymer's different repeat unit arrangements and different conformations. We find that the interaction strength between the poly(phenylacetylene) molecules and SWNTs is obviously influenced by these factors, and the degree of the poly(p-phenylenevinylene) wrapping around the SWNT is associated with its repeat unit arrangement. Based on the present simulations, we think that the nanocomposite should have high mechanical properties if the polymer with an appropriate repeat unit arrangement and conformation is used to form the first layer around the SWNT.