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The in-plane hybrid structure of hexagonal boron nitride (BN) and graphene (Gr) with carbon–boron and carbon–nitrogen interfaces under different boron-nitride and graphene concentrations for hydrogen storage properties is summarized in detail. The stability of these structures is verified from the cohesive energy and molecular dynamics calculations. The electronic band gap of the pristine hybrid structures is reduced with an increase in the graphene concentration. The structural properties such as bond length and bond angle are preserved for both graphene and boron nitride in the hybrid system. The pristine C–B-terminated system has an average adsorption energy of −0.046 to −0.076 eV/H2in the field-free condition upon dual site hydrogen molecules insertion with a theoretical hydrogen storage capacity of 10.18–10.38 wt %. In the presence of an external electric field, the adsorption energy of the hydrogen molecules linearly increases due to the polarization of the adsorbed hydrogen molecules. From our study, we report a threshold external electric field strength of ≥1.6 V/Å to achieve the lower bound criteria of average adsorption energy set by the United States Department of Energy (US-DOE) for a C–B-terminated structure and higher threshold EF for the C–N-terminated structure. While in the presence of the electric field, the average adsorption energy goes beyond −0.20 eV/H2with the hydrogen storage capacity of 10.18–10.38 wt % upon dual site hydrogen molecules adsorption on in-plane nBN-mGr (n= 5, 4, 3, 2, 1 and m= 1, 2, 3, 4, 5).

We explore the structural, electronic, mechanical, thermodynamic, and thermoelectric properties of lead perovskite PbXO3(X = Ti, Zr, and Hf) by using density functional theory (DFT). Our calculated results are in good agreement with the available experimental data, especially the lattice parameter and the electronic profile. PbXO3meets the necessary and sufficient Born criteria to prove mechanical stability. The thermal stabilities were tested by performing the molecular dynamics simulation with canonical (nVT) ensemble. In this work, we report the nature of the energy band structure (direct/indirect) which is a key in deriving the electron part of thermoelectric properties. The calculated thermoelectric efficiency is ZT > 0.5 at T> 800 K, suggesting that these materials are potential thermoelectric materials able to operate at high temperature.

Electronic band structures of B- and C-doped ZnO monolayers (ML) at high doping concentration are studied based on spin-polarized plane-wave DFT with Projector Augmented Wave Potentials and Generalized Gradient Approximation. Our results show that both the B- and C-doped structures at 3.13% impurity atom per supercell exhibit half-metallic ferromagnetic behaviour due to the spin-polarized 2p orbitals of the dopant atom, which are localized within the energy gap of the host lattice. A net magnetic moment of 1μB and 2μB are, respectively, found in the B- and C-doped structures mainly due to the partially filled dopant atom 2 p orbitals. Due to ferromagnetic coupling, magnetic moments from the neighbouring Zn atoms and the subsequent O atoms also contribute to the net magnetic moment. At a higher doping concentration of 6.25% impurity atom per supercell, both the materials completely transformed into metal. It is also found that while C doping maintains its ferromagnetic property at this doping concentration, the B-doped ZnO ML becomes antiferromagnetic metal. Our findings would provide valuable theoretical data for material scientists in fabrication of the doped ZnO ML in laboratory

We report the hydrogen storage properties of the bilayer h-BN/Gr heterostructure using the density functional theory calculations incorporating DFT-D2 and D3 dispersion corrections. The hydrogen molecules are adsorbed in between the two monolayers and on top of the graphene layer with a maximum gravimetric density of 5.83 wt %. The average adsorption energy per hydrogen molecules (−0.23 eV/H2) is in line with the USDOE benchmark. DFT-D3 shows an enhancement in the adsorption energy by 0.01–0.02 eV. The potentiality of the h-BN/Gr heterostructure for hydrogen storage material can be ascertained from the fact that the material can adsorb hydrogen molecules at all available sites within the binding energy limit (−0.15 to −0.60 eV/H2) without external factors such as metal decorations, electric field, or strain. The hydrogen adsorption on h-BN/Gr is highly modulated by weak van der Waals and electrostatic interactions.