Layer-dependent stability of 2D mica nanosheets.

We report on the layer-dependent stability of muscovite-type two-dimensional (2D) mica nanosheets (KAlSiO(OH)). First-principles calculations on mica nanosheets with different layer thicknesses (n = 1, 2, and 3) reveal their layer-dependent stability; odd-numbered 2D mica nanosheets are more stable than even-numbered ones, and the preferable stability of odd-numbered layers originates from electronic effects. A core-shielding model is proposed with a reasonable assumption, successfully proving the instability of the even-numbered mica nanosheets.

Ab initio study of Li, Mg and Al insertion into rutile VO: fast diffusion and enhanced voltages for multivalent batteries.

Vanadium oxides are among the most promising materials that can be used as electrodes in rechargeable metal-ion batteries. In this work, we systematically investigate thermodynamic, electronic, and kinetic properties associated with the insertion of Li, Mg and Al atoms into rutile VO. Using first-principles calculations, we systematically study the structural evolution and voltage curves of LiVO, MgVO and AlVO (0 < x < 1) compounds.

Surface reactivity and vacancy defects in single-layer borophene polymorphs.

Single-layer borophene is a novel 2D material which combines high strength, light weight and metallicity. Using first-principles calculations, we systematically investigate the defect formation and surface reactivity in three major borophene polymorphs (α, β and triangular). We find that β-B is generally the most reactive borophene form, while α-B is the least reactive.

Aluminium and magnesium insertion in sulfur-based spinels: a first-principles study.

We computationally screen several sulfur-based materials with a spinel crystal structure as potential Al and Mg insertion hosts for Al- and Mg-ion batteries. We evaluate the effect of transition-metal substitution (TM = Ti, Cr, Mn, Fe, Co, Ni) on the key properties determining electrode performance. We systematically calculate the thermodynamic stability, average voltage, binding energy, volume expansion, and Al/Mg diffusion for all compounds.

Volume dependence of the dielectric properties of amorphous SiO2.

Using first principles calculations, the analysis of the dielectric properties of amorphous SiO2 (am-SiO2) was performed. We found that the am-SiO2 properties are volume dependent, and the dependence is mainly induced by the variation of nanoporosity at the atomic scale. In particular, both ionic and electronic contributions to the static dielectric constants are functions of volume with clear trends.

Phosphorene as an anode material for Na-ion batteries: a first-principles study.

We systematically investigate a novel two-dimensional nanomaterial, phosphorene, as an anode for Na-ion batteries. Using first-principles calculations, we determine the Na adsorption energy, specific capacity and Na diffusion barriers on monolayer phosphorene. We examine the main trends in the electronic structure and mechanical properties as a function of Na concentration.

Adsorption of metal adatoms on single-layer phosphorene.

Single- or few-layer phosphorene is a novel two-dimensional direct-bandgap nanomaterial. Based on first-principles calculations, we present a systematic study on the binding energy, geometry, magnetic moment and electronic structure of 20 different adatoms adsorbed on phosphorene. The adatoms cover a wide range of valences, including s and p valence metals, 3d transition metals, noble metals, semiconductors, hydrogen and oxygen.

Acceptor-compensated charge transport and surface chemical reactions in Au-implanted SnO₂ nanowires.

A new deep acceptor state is identified by density functional theory calculations, and physically activated by an Au ion implantation technique to overcome the high energy barriers. And an acceptor-compensated charge transport mechanism that controls the chemical sensing performance of Au-implanted SnO2 nanowires is established. Subsequently, an equation of electrical resistance is set up as a function of the thermal vibrations, structural defects (Au implantation), surface chemistry (1 ppm NO2), and solute concentration.

Controlling Na diffusion by rational design of Si-based layered architectures.

By means of density functional theory, we systematically investigate the insertion and diffusion of Na and Li in layered Si materials (polysilane and H-passivated silicene), in comparison with bulk Si. It is found that Na binding and mobility can be significantly facilitated in layered Si structures. In contrast to the Si bulk, where Na insertion is energetically unfavorable, Na storage can be achieved in polysilane and silicene.

Enhanced Li adsorption and diffusion in single-walled silicon nanotubes: an ab initio study.

We report a first-principles investigation of Li adsorption and diffusion in single-walled Si nanotubes (SWSiNTs) of interest to Li-ion battery anodes. We calculate Li insertion characteristics in SWSiNTs and compare them with the respective ones in carbon nanotubes (CNTs) and other silicon nanostructures. From our calculations, SWSiNTs show higher reactivity toward the adsorption of Li adatoms than CNTs and Si nanoclusters.