Tunable band gaps and conduction band edges of CdS/ZnS heterostructures - a first-principles-based prediction.

CdS/ZnS heterostructures with tunable band gaps are promising photocatalysts for solar- or visible-light-driven H production through water splitting. To predict how the bandgap changes with the heterostructure composition, density functional theory calculations with meta-GGA correction are performed. It is found that the band gaps of CdS and ZnS are reduced by up to 14.

Self-formed asymmetric Schottky contacts between graphene and WSiGeN.

In this paper, the electronic properties and transport characteristics of WSiGeN/graphene heterostructures were explored by combining the quantum transport method with first-principle calculations. The band structures indicate that the heterostructures can form either p-type or n-type Schottky contacts, depending on the stacking mode. Due to the self-formed asymmetric Schottky contacts, we design an asymmetric van der Waals (vdW) metal-semiconductor-metal (MSM) structure, which exhibits a pronounced asymmetric current-voltage (-) curve.

Effect of Copper Doping on Electronic Structure and Optical Absorption of CdSe Quantum Dots.

The photophysical properties of Cu-doped CdSe quantum dots (QDs) can be affected by the oxidation state of Cu impurity, but disagreement still exists on the Cu oxidation state (+1 or +2) in these QDs, which is debated and poorly understood for many years. In this work, by using density functional theory (DFT)-based calculations with the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional, we clearly demonstrate that the incorporation of Cu dopants into the surface of the magic sized CdSe QD leads to non-magnetic Cu 3d orbitals distribution and Cu oxidation state, while doping Cu atoms in the core region of QDs can lead to both Cu and Cu oxidation states, depending on the local environment of Cu atoms in the QDs. In addition, it is found that the optical absorption of the Cu-doped CdSe QD in the visible region is mainly affected by Cu concentration, while the absorption in the infrared regime is closely related to the oxidation state of Cu.

First-Principles Study of Thermo-Physical Properties of Pu-Containing Gd₂Zr₂O₇.

A density functional theory plus Hubbard U method is used to investigate how the incorporation of Pu waste into Gd₂Zr₂O₇ pyrochlore influences its thermo-physical properties. It is found that immobilization of Pu at Gd-site of Gd₂Zr₂O₇ has minor effects on the mechanical and thermal properties, whereas substitution of Pu for Zr-site results in remarkable influences on the structural parameters, elastic moduli, elastic isotropy, Debye temperature and electronic structure. The discrepancy in thermo-physical properties between GdPuZr₂O₇ and Gd₂ZrPuO₇ may be a result of their different structural and electronic structures.