Janus ScYCBr2 MXene as a Promising Thermoelectric Material.

Finding green energy resources that contribute to the battle against global warming and the pollution of our planet is an urgent challenge. Thermoelectric electricity production is a clean and efficient method of producing energy; consequently, scientists are currently researching and creating thermoelectric materials to increase the efficiency of thermoelectric electricity production and expand the potential of the thermoelectric effect for clean energy production. This work focuses on a comprehensive study of the thermoelectric properties of two-dimensional ScYCBr2. We report here a computational analysis of this Janus-like MXene, which is predicted to exhibit outstanding thermoelectric properties. The study uses density-functional theory to provide evidence of the important role played by symmetry breaking to promote low-thermal transport by favoring certain phonon scattering channels. Compared to its symmetric parent compounds, the asymmetric Janus-type ScYCBr2 displays additional phonon scattering channels reducing the thermal conductivity. An exhaustive investigation of the dynamical stability for both zero-temperature and high-temperature conditions was also performed to support the stability of ScYCBr2. Our analysis shows that thanks to its asymmetric structure, the ScYCBr2 MXene has thermoelectric properties that largely surpass those of its parent symmetric counterpart Sc2CBr2, being a material with a remarkable thermoelectric high figure of merit. Another advantage of ScYCBr2 is its high carrier mobility. This work not only demonstrates that this material is a promising thermoelectric material but also shows that ScYCBr2 can operate efficiently at high temperatures up to 1200 K.

Tuning the electronic properties of asymmetric YZrCOF MXene for water splitting applications: an ab initio study.

Identifying and evaluating novel and extremely stable materials for catalysis is one of the major challenges that mankind faces today to rapidly reduce the dependence on fossil fuels. To contribute to achieving this goal, we have evaluated within the density-functional framework the properties of a new two-dimensional MXene structure, the asymmetric MXene YZrCOF monolayer. Phonon dispersion calculations at 0 K and 300 K indicate that the studied material is dynamically stable. The calculations also indicate that the material has a rigid crystal structure with a wide band gap, a strong potential difference, and a band-gap alignment that favors the production of both H2 and O2 molecules from water splitting. We also report the outcome of the strain effect on the electrical and photocatalytic characteristics of the studied material. We will demonstrate that even under a large strain, the YZrCOF monolayer is stable and useful for photocatalytic applications.

Unveiling the structural, dynamical, elastic, and electronic properties of cuboid silver tetrathiotungstate by means ofab initiocalculations.

We present for the first time a theoretical study of the structural stability and physical properties of the newly synthesized Ag2WS4. The study contributes to a better understanding of its electronic and vibrational properties, which is fundamental for the optimization of the technological applications of Ag2WS4. Calculations have been carried out by means of density-functional theory. The obtained results support that Ag2WS4is thermodynamically, mechanically, and dynamically stable in a tetragonal layered structure, in good agreement with experiments. Calculations have also been used to obtain phonon frequencies, their assignments, and the Raman scattering spectrum. Furthermore, we show that Ag2WS4has a brittle structure, that is governed by van der Waals interactions, which favors its exfoliation as a low-dimensional structure. Additionally, the results show that Ag2WS4has a band gap of 2.02 eV with a favorable band-edge diagram for water splitting as well as for optoelectronic applications.