Since
the breakthrough of graphene, 2D materials have engrossed
tremendous research attention due to their extraordinary properties
and potential applications in electronic and optoelectronic devices.
The high carrier mobility in the semiconducting material is critical
to guarantee a high switching speed and low
power dissipation in the corresponding device. Here, we review significant
recent advances and important new developments in the carrier mobility
of 2D materials based on theoretical investigations. We focus on some
of the most widely studied 2D materials, their development, and future
applications. Based on the current progress in this field, we conclude
the review by providing challenges and an outlook in this field.
The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) have been envisaged on a two-dimensional (2D) boron sheet through electronic structure calculations based on a density functional theory framework. To date, boron sheets are the lightest 2D material and, therefore, exploring the catalytic activity of such a monolayer system would be quite intuitive both from fundamental and application perspectives. We have functionalized the boron sheet (BS) with different elemental dopants like carbon, nitrogen, phosphorous, sulphur, and lithium and determined the adsorption energy for each case while hydrogen and oxygen are on top of the doping site of the boron sheet. The free energy calculated from the individual adsorption energy for each functionalized BS subsequently guides us to predict which case of functionalization serves better for the HER or the OER.
In this study, we investigated the catalytic activity of ultrathin PtS2 and WS2 nanostructures for the hydrogen evolution reaction by electronic structure calculations based on the spin-polarised density functional theory.
The capture, activation, and dissociation
of carbon dioxide (CO2) is of fundamental interest to overcome
the ramifications
of the greenhouse effect. In this regard, high-throughput screening
of two-dimensional MXenes has been examined using well-resolved first-principles
simulations through DFT-D3 dispersion correction. We systematically
investigated different types of structural defects to understand their
influence on the performance of M2X-type MXenes. Defect
calculations demonstrate that the formation of M2C(VMC) and M2N(VMN) vacancies require higher
energy, while M2C(VC) and M2N(VN) vacancies are favorable to form during the synthesis of
M2X-type MXenes. The M2X-type MXenes from group
III to VII series show remarkable behavior for active capturing of
CO2, especially group IV (Ti2X and Zr2X) MXenes exhibit unprecedentedly high adsorption energies and charge
transfer (>2e) from M2X to CO2. The potential CO2 capture, activation, and dissociation
abilities of MXenes are emanated from Dewar interactions involving
hybridization between π orbitals of CO2 and metal
d-orbitals. Our high-throughput screening demonstrates chemisorption
of CO2 on pure and defective MXenes, followed by dissociation
into CO and O species.
The large-scale production of CO2 in the atmosphere
has triggered global warming, the greenhouse effect, and ocean acidification.
The CO2 conversion to valuable chemical products or its
capture and storage are of fundamental importance to mitigate the
greenhouse effect on the environment. Therefore, exploring new two-dimensional
(2D) materials is indispensable due to their potential intriguing
properties. Here, we report a new family of 2D transition metal borides
(M2B2, M = Sc, Ti, V, Cr, Mn, and Fe; known
as MBenes) and demonstrate their static and dynamic stability. These
MBenes show a metallic nature and exhibit excellent electrical conductivity.
The CO2 adsorption energy on MBenes ranges from −1.04
to −3.95 eV and exhibits the decreasing order as Sc2B2 > Ti2B2 > V2B2 > Cr2B2 > Mn2B2 > Fe2B2. The spin-polarization
calculation
shows a reduction in the adsorption energy for magnetic systems. Bader
charge transfer indicates the formation of CO2
δ− moiety on the MBene
surface, so-called activated CO2, which is essential for
its reaction with other surface chemicals. Differential charge density
plots reveal a significant charge accumulation around the CO2 molecule. Our theoretical results predict the usage of new MBenes
as a cost-effective catalyst for CO2 capture and activation.
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