Graphene is known for its exceptional mechanical and electrical properties when in the form of a hexagonal monolayer of carbon atoms. In this study, the mechanical properties of hexagonal boron-doped graphene (h-BdGr) sheets with a 2% concentration of boron atoms distributed randomly throughout the layer were investigated. The effects of mono/multi-atomic vacancy defects, with different concentrations and various orientations, as well as temperature, on the tensile behavior of the sheets were examined utilizing molecular dynamic simulations. Meanwhile, the deformation behavior and corresponding stress distribution of the graphene sheets were demonstrated. The results obtained provide valuable insights into the mechanical behavior of graphene based nano-structures.

Silicon nanotubes (SiNTs) have been successfully synthesized recently. Despite the wide potential applications of SiNTs, their mechanical properties are rarely reported. In this study, as the first step, the mechanical behavior of clamped-free single-walled silicon nanotubes (SWSiNTs) for both armchair and zigzag structures is investigated by using molecular dynamics (MD) simulations while the inter-atomic forces are described by the Tersoff-Brenner many-body potential energy function. Meanwhile, the results of the total strain energy are used to establish an expression for predicting Young's modulus of the nanotubes. Afterward, the free vibrational analysis including torsional, longitudinal and transverse vibrations behavior of SWSiNTs with different diameters and lengths are investigated to report the corresponding fundamental frequencies as a significant design parameter. In this study, also, an important stress-strain parameter ratio is defined for vibration analyses named dynamic Young's modulus. Thereafter, the natural frequencies that are obtained using the current atomistic model are successfully compared with those evaluated by the continuum mechanics model. It is concluded that the utilized approach can predict the frequencies with reasonable accuracy. Furthermore, the effects of geometry on the natural frequencies for both armchair and zigzag structures are examined. The obtained results provide valuable insights into the vibrational behavior of silicon-based nanotubes.

In this paper, we report the synthesis and characterization of Nitrogen-doped Graphene oxide with Metal-Organic Framework (MOF) material as a catalyst for Polymer Electrolyte Membrane Fuel Cell (PEMFC). Transition metal, Cobalt is doped into Zeolitic Imidazolate Frameworks (ZIF-8) in varying amounts (different molar ratios of metal precursor to ZIF-8, 0.6, 0.9 and 1.2) to understand its effect on the catalytic performance. Various characterization techniques, viz., FTIR, Raman spectroscopy, XRD, SEM and EDS were performed to analyze various physical and chemical properties. XRD results showed the formation of the (100) Cobalt-doped ZIF-8 phase with grain size around 20 nm. Cyclic Voltammetry studies showed that the addition of the transition metal plays a major role in the enhancement of electrochemical performance compared to that of non-transition metal carbon-based catalysts. The electrochemical performance is correlated with the physical properties for different metal precursor loadings (0.6, 0.9 and1.2 molar ratios).

Non-Platinum Group Metal (non-PGM) catalysts have recently attracted huge attention for use in the Polymer Electrolyte Membrane Fuel Cell (PEMFC) vehicles, as the demand for alternative and sustainable transportation is increasing exponentially. Carbon-based catalysts have advantages such as relative ease of manufacturing, low cost of synthesis, high electrochemical durability, and high electrical conductivity which makes them a potential alternative. While there are several ways to improve the catalytic activity of carbon catalysts, one promising technique is doping heteroatoms into the lattices of the sp2 carbon structure. The most commonly used doping is by nitrogen (N-doping) where a nitrogen precursor is used to incorporate N atoms to help improve electrochemical performances. Transition Cobalt-Nitrogen-Carbon (Co-N-C) catalysts show promising catalytic performance and durability due to their fast electron transfer rates leading to increased kinetic reaction rates. In this paper, we report the synthesis and characterization of Nitrogen-doped Graphene/Graphene oxide with Metal-Organic Framework (MOF) material using wet chemical and pyrolysis techniques for the development of an efficient catalytic material to tackle the sluggish cathodic Oxygen Reduction Reaction (ORR) in fuel cells (FCs). Transition metal, Cobalt is doped into Zeolite Imidazole Frameworks (ZIF-8) using Cobalt Nitrate as precursor to enhance the mass and kinetic rates of the ORR reaction at the cathode. The synthesized metal-doped MOF catalysts (Co-ZIFx) are further pyrolyzed by one-step pyrolysis in an argon atmosphere at 600oC for 2 hours. These catalysts are produced with varying amounts of precursor metals (different molar ratios of metal precursor to ZIF-8 such as 0.6, 0.9 and 1.2 respectively; x denotes molar ratio values) to analyze the effects of each element proportion on the electrochemical performance. The pyrolyzed electrocatalysts (named Co-ZIFx-600 respectively) were further synthesized chemically using nitrogen-doped graphene (N-Gr) catalysts through wet chemical synthesis procedure and are named as N-Gr-Co-ZIFx and N-Gr-Co-ZIFx-600 (x changes with the molar ratios of metal precursor). Doping of graphene carbon lattice with nitrogen heteroatoms has proven to influence charge densities and adsorption mechanism which further enhances the catalytic activity. Nitrogen loading effects were also analyzed to study the electronic and electrochemical behavior of individually varied graphene materials. Various characterization techniques, viz., FTIR, Raman spectroscopy, XRD, SEM and EDS were performed to analyze various physical and chemical properties affecting the electrochemical performances. FTIR of N-Gr-Co-ZIF-600 catalysts showed the presence of cobalt-doped ZIF-8 peaks around 420 cm-1 and the presence of nitrogen bonds at a stretching frequency of around 3000 cm-1. XRD results showed the formation of crystalline phases of the Cobalt-doped ZIF-8 with a (100) orientation. Further, it was observed that the crystallinity was affecte...