Origin of the Improved Photoelectrochemical and Photocatalytic Activity in a ZnO-TiO<sub>2</sub> Nanohybrid Revealed by Experimental and Density Functional Theory Studies

Nanoscale and condensed matter systems evolve on multiple length-and time-scales, and rare events such as local phase transformation, ion segregation, defect migration, interface reconstruction, and grain boundary sliding can have a profound influence on material properties. We demonstrate how outlier detection indices can be used to identify rare events in machinelearning based, high-dimensional molecular dynamics (MD) simulations. Designed to order data-points from typical to untypical, the indices enable one to capture atomic events that are hard to detect otherwise. We demonstrate the approach with a nanosecond MD simulation of a grain boundary in a metal halide perovskite that is extensively studied for solar energy and optoelectronic applications. The method captures the initial grain boundary sliding and a spontaneous fluctuation half a nanosecond later, both events giving rise to persistent deep electronic trap states that impact charge carrier lifetime and transport and material performance. The approach offers a generalizable and simple method for identifying outlier events in complex condensed matter, molecular, and nanoscale systems.

Identifying Rare Events in Quantum Molecular Dynamics of Nanomaterials with Outlier Detection Indices

Wang,

Liu,

et al. 2024

Ab Initio Study of the Influence of Spin and Orbital Magnetic Moments on the Stability of Magnetic and Charge Distribution in Co:ZnO Monolayer

Prokhorenko,

Chibisov,

Gnidenko

et al. 2024

The development of ultrathin magnets with tunable magnetic properties is essential for advancing quantum computing technologies. In this study, density functional theory (DFT) calculations were employed to investigate the atomic and electronic structures of a ZnO monolayer embedded with cobalt atoms. The impact of spin dynamics on charge transfer within the Co:ZnO system was thoroughly examined. Results revealed that the orbital magnetic moment of the cobalt atoms plays a crucial role in stabilizing the magnetic and charge distributions across the system. These findings offer valuable insights for the design and fabrication of quantum devices, thereby highlighting the potential of Co-doped ZnO monolayers in quantum computing applications.

Gas Adsorption on the Co₂Te₃ Monolayer: Density Functional Theory Study

Kobernik,

Kartsev

2024

We report a numerical investigation of the chemical adsorption of acetone and carbon dioxide gases by a cobalt telluride (III) 2D layer. Calculations were performed using first principles calculations within the density functional theory to evaluate the adsorbed gas impact on the material's conductivity. The adsorption of carbon dioxide was found to significantly affect the Co 2 Te 3 monolayer electronic structure and its electrical conductivity, which is not observed in the case of acetone. This letter demonstrates that the calculated bond formation energy for carbon dioxide is approximately 2 times higher than that for the acetone. It proved that the quasi-2D cobalt telluride (III) could be introduced as a selective electrochemical sensor for carbon dioxide in quick medical diagnoses and other technological applications.