Strain-induced band modulation and excellent stability, transport and optical properties of penta-MP2 (M = Ni, Pd, and Pt) monolayers

2D Sb2C3 monolayer: A promising material for the recyclable gas sensor for environmentally toxic nitrogen-containing gases (NCGs)

Based on density functional theory investigation, we exposed the potential application of hexagonal Sb₂C₃ nanosheet as highly sensitive material for nitrogen-containing gases (NCGs) NH₃, NO₂ and NO molecules. Our rigorous simulations show that NH₃, NO₂ and NO molecules shows physisorption on the Sb₂C₃ nanosheet via vdW DFT-D3 interactions. The calculations were carried out by considering that the monolayer Sb₂C₃ as the sensor material modulated with its electrical conductivity when its surface adsorbs the gas molecules for their various orientations and positions. It is also found that the magnetic properties are induced in non-magnetic Sb₂C₃ nanosheet by adsorption of NO molecule. The interaction of the Sb₂C₃ nanosheet with the gas molecules is further analysed by the charge density difference (CDD), electrostatic potential (ESP) and Bader charge analysis. Our analysis indicates a strong possibility for the detection of NO₂ and NO gas molecules by the Sb₂C₃ based sensor, due to the associated significant changes in the conductivity and reasonable adsorption energy. Also, in the visible region at T = 300 K, very low recovery times have been found as 431 μs, 785.01 s and 53.8 μs for NH₃, NO₂ and NO, respectively, which strongly suggest the Sb₂C₃ nanosheets as a better reversible multi-time gas sensor material towards the NCGs adsorption. We also explored the humidity effect on the NCGs based 2D Sb₂C₃ sensor material. The current-voltage (I-V) characteristics also confirmed the suitability of 2D Sb₂C₃ in real-time applications. Overall, present work reveals that the 2D Sb₂C₃ nanosheets as a promising material for semiconductor-based nano sensors for environmentally hazard pollutants like NCG molecules.

Hydrogen-induced tunable electronic and optical properties of a two-dimensional penta-Pt2N4 monolayer

Most known two-dimensional materials lack a suitable wide-bandgap, and hydrogenation can be effectively utilized to tune the bandgap of some 2D materials. By employing density functional theory calculations, we investigate the effect of hydrogenation on the electronic and optical properties of a recently reported anisotropic penta-Pt2N4 monolayer. The results show that penta-Pt2N4 is thermally and mechanically stable after hydrogenation and also possesses anisotropic Young's modulus and Poisson's ratio. The electronic property analysis using the hybrid functional reveals that penta-Pt2N4 exhibits a bandgap of 1.10 eV, and the hydrogenation significantly enhances the bandgap to 2.70 eV. Furthermore, the hydrogenated Pt2N4 displays a strong optical absorption of up to 6.45 × 105 cm-1 in the ultraviolet region, and low absorption and low reflectivity in the visible region. Our results strongly suggest that the hydrogenated Pt2N4 has tunable electronic and optical properties for applications as a hole-transport material layer in solar cells in the visible region, and as an ultraviolet detector in the ultraviolet region of the electromagnetic spectrum.