Structural, electronic, and electrochemical studies of WS2 phases using density functional theory and machine learning

Transition metal dichalcogenides have attracted significant attention in green energy production and storage due to their two-dimensional structure and tunable electronic properties. In this study, four phases of WS2, including 2H, 1H, 1 T’, and 1 T, were studied using Density Functional Theory (DFT) and Machine Learning (ML). Accordingly, diffraction pattern, stability, binding energy, phonon dispersion, band structure, work function, surface energy, and electrochemical activity were simulated. It was shown that 2H monolayers are the easiest to produce and 1 T monolayers are most vulnerable to restacking. It was also observed that intercalation is more likely to produce 1H phase rather than 1 T; while diffraction and Raman methods cannot distinguish these two phases. Additionally, it was found that increasing interlayer distance increases the band gap and vice versa. Finally, it was shown that trigonal phases are suitable for faradaic energy storage, while 1H phase shows promising capabilities for photoelectrochemical and double layer applications.