Oleksandr Malyi

Inverse Materials Design group

We systematically evaluate the prospects of a novel 2D nanomaterial, phosphorene, as 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 electronic structure and mechanical properties as a function...

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 valenc...

Using Born-Oppenheimer molecular dynamics (BOMD) simulations and “static” density functional theory (DFT) calculations, the stability of cleaved and reconstructed α-SiO2(001) surfaces was studied. We found reconstructions (“dense”, 2×2 reoptimized “dense”, and 3×3 reoptimized “dense”) which minimize the surface energy. The analysis of the surface e...

To assess the potential of amorphous Si (a-Si) as an anode for Li, Na, and Mg-ion batteries, the energetics of Li, Na, and Mg atoms in a-Si are computed from first-principles and compared to those in crystalline Si (c-Si). It is shown that Si preamorphization increases the average anode voltage and reduces the volume expansion of the anode during t...

Based on the density functional theory, we study the insertion of Li and Na atoms into both bulk Sn and Sn(111) nanosheets. Analysis of the bonding between the metal atoms and the Sn systems shows that the interactions have significant ionicity—the electron charge reductions on the metal atoms are up to ~ 0.87e. We predict that the diffusion of the...

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 i...

We present a comparative density functional theory study of Li, Na, and Mg storage energetics and diffusion in α-Sn, including the effects of temperature (vibrations). We study several concentrations corresponding to initial stages of insertion (number densities x= 1/64, 1/32, 1/16, and 1/8) as well as the final state of charge (Li17Sn4, Na15Sn4, a...

For the purpose of efficiently utilizing the renewable solar energy, it is of vital importance to understand the key factors that contribute to the performance merits for photocatalysis applications. In this work, we find that anatase titania nanostructures with high efficiency in photoelectrochemical cell (PEC) do not necessarily retain the same g...

Si is one of the most efficient anode materials for Li-ion batteries, but its potential for both Na and Mg-ion batteries is not well studied. We present a comparative computational study of diffusion barriers of Li, Na, and Mg in crystalline Si including the influence of vibrations on the storage energetics and on the diffusion barriers. Zero-point...

We show in a theoretical density functional theory study that amorphous Si (a-Si) has more favorable energetics for Mg storage compared to crystalline Si (c-Si). Specifically, Mg and Li insertion is compared in a model a-Si simulation cell. Multiple sites for Mg insertion with a wide range of binding energies are identified. For many sites, Mg defe...

We explore, via density functional theory (DFT) calculations, the effect on the barrier height for Li and Na diffusion in bulk Si of the presence of an extra Li/Na atom at the neighboring tetrahedral (T) or hexagonal (H) interstitial site. For both neighboring sites, the lowest diffusion barrier height is reduced, although the magnitude of the redu...

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...

We use first-principles calculations to investigate the geometric structure, energetics and electronic properties of silicon cluster/carbon nanotube (Si/CNT) hybrid nanostructures with potential application as Li-ion battery anodes. The effects of the main components (i.e. Si cluster, CNT support and linker) on the properties of hybrid system, such...

We present a comparative computational study of sodiated vs lithiated bulk Si, including the effects of Li–Li and Na–Na interactions on dopant mobility. Both Na and Li prefer to act as interstitial defects located at the tetragonal sites of the Si matrix. The migration barrier between tetragonal sites is 0.54 eV larger for Na than for Li, which is...

First-principles density functional theory calculations are employed to investigate novel ultrathin silicon nanosheets (SiNSs) for its potential application as the anode materials for Li-ion batteries. We find that Li has a higher tendency to bind on the surface of SiNS rather than penetrating through inside. The binding energies of Li show a stron...

Formation of metastable alloys, the solubility limits of which are much higher than the corresponding equilibrium values and depend on the deformation rate, are observed very often in experiments dealing with diffusion in metals and alloys under pulse loading. Three microscopic models based on the concept of "ballistic jumps", which was put forward...

Based on the density functional theory (DFT), we evaluate the effect of sulfur impurity on the stability of cubic zirconia (c-ZrO(2)) and its interfaces with metals (Ni, Cu). It is observed that, at low concentration, sulfur atoms have the tendency to locate at the zirconia surface, while at high concentration (similar to 23.0 wt%), homogeneous ZrO...

Oxygen ionic conductivity through zirconia (ZrO2) is essential to the performance of solid oxide fuel cells, thermal barrier coatings, and zirconium alloys for nuclear fuel cladding. Since sulfur (S) atoms can replace oxygen atoms at ZrO2 surface or even induce formation of homogeneous zirconium oxysulfide (ZrOS) structure at high S partial pressur...

We study two possible mechanisms of sulfur (S) poisoning of copper (Cu) surfaces: S adsorption and formation of Cu-S compounds. Based on the performed calculations, we predict new Cu-S phase diagram that not only describes the formation of Cu-S compounds but also predicts a dependence of the transition temperature between clean and contaminated Cu...

Reactions of hydrogen sulfide (H2S) with Nickel/Ytrria-doped zirconia (Ni/YDZ) anode materials might cause degradation of the performance of solid oxide fuel cells when S containing fuels are used. In this paper, we employ density functional theory to investigate S adsorption on metal (M)-doped and undoped Ni(0 0 1) and Ni(1 1 1) surfaces. Based on...

In the experiments on investigation of diffusion in metals and alloys at fast plastic deformations under the pulse loads, formation of metastable alloys is observed every so often. Their solubility limits are far greater than their equilibrium values and depend on the deformation rate. In the case of presence of intermetallic compounds in the equil...