stable CdS monolayer sheets are proposed using the state-of-the-art theoretical calculations. Three different conformers (planar, distorted, and buckled) are predicted which are separated by low energy barriers. These monolayer sheets are not only thermodynamically, mechanically, and dynamically stable but also can withstand temperature as high as 1000 K. Band edge alignment of these monolayer sheets and bulk CdS is done with respect to the water oxidation and reduction potential to evaluate their photocatalytic activities. Here we show a planar CdS monolayer sheet is the most promising material for visible light photocatalysis and can be used for electronic and optoelectronic devices.
Density functional theory (DFT) calculations are performed to understand and address the previous experimental results that showed the reduction of nitrobenzene to aniline prefers direct over indirect reaction pathways irrespective of the catalyst surface. Nitrobenzene to aniline conversion occurs via the hydroxyl amine intermediate (direct pathway) or via the azoxybenzene intermediate (indirect pathway). Through our computational study we calculated the spin polarized and dispersion corrected reaction energies and activation barriers corresponding to various reaction pathways for the reduction of nitrobenzene to aniline over a Ni catalyst surface. The adsorption behaviour of the substrate, nitrobenzene, on the catalyst surface was also considered and the energetically most preferable structural orientation was elucidated. Our study indicates that the parallel adsorption behaviour of the molecules over a catalyst surface is preferable over vertical adsorption behaviour. Based on the reaction energies and activation barrier of the various elementary steps involved in direct or indirect reaction pathways, we find that the direct reduction pathway of nitrobenzene over the Ni(111) catalyst surface is more favourable than the indirect reaction pathway.
We have performed density functional theory (DFT) calculations to study the gas (CO, CO 2 , NO, and NO 2 ) sensing mechanism of pure and doped (B@, N@, and B−N@) graphene surfaces. The calculated adsorption energies of the various toxic gases (CO, CO 2 , NO, and NO 2 ) on the pure and doped graphene surfaces show, doping improves adsorption energy and selectivity. The electronic properties of the B−N@graphene surfaces change significantly compared to pure and B@ and N@graphene surfaces, while selective gas molecules are adsorbed. So, we report B−N codoping on graphene can be highly sensitive and selective for semiconductor-based gas sensor.
For the progressive
development of spintronics as the next generation
information technology source, it is essential to look for materials
with high abundance, long spin lifetime, easy manipulation of spin
current, and temperature/strain resistivity of spin properties. In
this respect, the main group based two-dimensional (2D) semiconductors
are systems of immense research interest in the field of spintronic
devices for their novel characteristics and notable application in
spintronics nanotechnology. The discovery of graphene set off the
journey of 2D materials, and many of them have been identified as
potential candidates for spintronics applications owing to their extraordinary
properties and atomically thin structures. Since the last few decades,
several theoretical and experimental reports agreed with the novel
chemistry between 2D materials and nanoscale spintronic devices. This
review highlights the most progressive and important theoretical and
experimental studies of main group based 2D spintronics reported until
present which have contributed to inspiring new spintronic devices
and have given direction for further development. We have systematically
discussed the main group based 2D spintronic materials in the two
categories of metal incorporated and metal-free systems. Besides,
vital focus is given to the useful theoretical techniques for spintronics
studies and suitable designing of spintronic materials and devices.
We have also briefly discussed the past, present, and future perspective
of spintronic devices.
Metal–organic frameworks (MOFs) as photocatalysts and photocatalyst supports combine several advantages of homogeneous and heterogeneous catalyses, including stability, post‐reaction separation, catalyst reusability, and tunability, and they have been intensively studied for photocatalytic applications. There are several reviews that focus mainly or even entirely on experimental work. The present review is intended to complement those reviews by focusing on computational work that can provide a further understanding of the photocatalytic properties of MOF photocatalysts. We first present a summary of computational methods, including density functional theory, combined quantum mechanical and molecular mechanical methods, and force fields for MOFs. Then, computational investigations on MOF‐based photocatalysis are briefly discussed. The discussions focus on the electronic structure, photoexcitation, charge mobility, and photoredox catalysis of MOFs, especially the widely studied UiO‐66‐based MOFs.
High-temperature ferromagnetic materials with planar surfaces are promising candidates for spintronics applications. Using state-of-the-art density functional theory (DFT) calculations, transition metal (TM = Cr, Mn, and Fe) incorporated graphitic carbon nitride (TM@gt-C3N4) systems are investigated as possible spintronics devices. Interestingly, ferromagnetism and half-metallicity were observed in all of the TM@gt-C3N4 systems. We find that Cr@gt-C3N4 is a nearly half-metallic ferromagnetic material with a Curie temperature of ∼450 K. The calculated Curie temperature is noticeably higher than other planar 2D materials studied to date. Furthermore, it has a steel-like mechanical stability and also possesses remarkable dynamic and thermal (500 K) stability. The calculated magnetic anisotropy energy (MAE) in Cr@gt-C3N4 is as high as 137.26 μeV per Cr. Thereby, such material with a high Curie temperature can be operated at high temperatures for spintronics devices.
Abstract:Stanene is a quantum spin hall insulator and a promising material for electronic and optoelectronic devices. Density functional theory (DFT) calculations are performed to study the band gap opening in stanene by elemental mono-(B, N) and co-doping (B-N). Different patterned B-N co-doping is studied to change the electronic properties in stanene. A patterned B-N co-doping opens the band gap in stanene and the semiconducting nature persists with strain. Molecular dynamics (MD) simulations are performed to confirm the thermal stability of such doped system. The stress-strain study indicates that such doped system is as stable as pure stanene. Our work function calculations show that stanene and doped stanene has lower work function than graphene and thus promising material for photocatalysis and electronic devices.
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