We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te), i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT) method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently.

Using DFT calculations we revealed the origins of the variation of the H solution energy induced in high-entropy alloys (HEAs), and then proposed a predictive model that is universal and available for assessing the distributions of H solution energies in HEAs.

The melting temperature and behaviour of gold nanowire in a single-walled carbon nanotube (SWNT) were investigated in detail using molecular dynamics simulations. The results showed that the melting temperature of the enclosed Au nanowire is lower than its bulk counterpart and higher than that observed for free-standing ones. Different from the melting behaviour of freestanding Au nanowires, the melting of Au nanowires enclosed in SWNTs with tube diameters (D) in the range 1.08 nm < D < 2.09 nm investigated here was found to initiate from the centre layers. The predicted melting temperature and behaviour of gold nanowires in SWNTs were clearly shown to be dependent on the interaction between C and Au atoms. The interaction is helpful to further stabilize the structure of enclosed Au nanowires, in particular, the outermost layer.