Predicting Novel 2D AsBiX3 (X = S, Se, and Te) Auxetic Monolayers with Favorable Optical and Photocatalytic Water-Splitting Properties

The design of two-dimensional multifunctional materials is highly desirable for nanoscale device applications. In this study, we report the structural, electronic, mechanical, and photocatalytic properties of chalcogenide-based monolayers AsBiX3 (X = S, Se, and Te) using first-principles calculations. The stability of these monolayers is confirmed through energetic and mechanical analyses, as well as ab initio molecular dynamics simulations. The analysis of mechanical properties reveals significant mechanical anisotropy and a bidirectional in-plane negative Poisson ratio in the monolayers. Additionally, the computed electronic band structures, obtained with and without spin–orbit coupling, indicate that these monolayers are indirect-gap semiconductors. At the Heyd–Scuseria–Ernzerhof level, the values of the band gap are determined to be 1.91 eV for AsBiS3, 1.66 eV for AsBiSe3, and 1.32 eV for AsBiTe3. These monolayers have a very high absorbance on the order of ∼5 × 105 cm–1 in the visible and ultraviolet regions with considerable anisotropy. We also found that monolayers hold a high mobility anisotropy. The predicted solar-to-hydrogen efficiency of all monolayers surpasses the critical value (>10%) for the economical production of hydrogen from photocatalytic water splitting. Notably, AsBiS3 and AsBiSe3 monolayers have appropriate band-edge positions that perfectly match the conditions for photocatalytic water splitting at pH = 0, and the band gap and band-edge positions can be adjusted through strain engineering. With these outstanding properties, AsBiX3 (X = S, Se, and Te) monolayers present themselves as promising candidates for applications in optoelectronics, mechanics, and photocatalytic water splitting.