A new class of 2D Materials: Hexagonal janus ScIX (X=S, Se, Te) monolayers with outstanding optoelectronic and photocatalytic properties for water splitting

Hydrogen generation is the most efficient and effective answer to the energy and environmental crises achieved by the photocatalytic splitting of water. The quest for photocatalysts with optimal band alignments and energy gaps conducive to exceptional electrical and optical characteristics continues. We propose a novel twodimensional material, the Janus monolayers of ScIX (X = S, Se, Te), which exhibit appropriate energy gaps of 2.28/2.56 eV and 3.61 eV for ScIS, 2.19/2.53 eV and 3.60 eV for ScISe, and 1.39/1.82 eV and 2.73 eV for ScITe, as determined by the PBE/PBE + Ueff and HSE06 functionals, respectively. Our results revealed that ScIX (X = S, Se, Te) monolayers are dynamic and thermal stable as confirmed by phonon dispersion curve and ab initio molecular dynamics (AIMD) simulations. Furthermore, the ScIX (X = S, Se, Te) monolayers exhibit broad optical absorption, particularly in the visible light spectrum, are approximately 1.14 x 104 cm-1, 1.42 x 104 cm-1 and 2.05 x 104 cm- 1 for ScIS, ScISe, and ScITe, respectively. Moreover, ScITe monolayer possesses a solar-tohydrogen conversion (STH) efficiency of 13.28 %, which is higher that the 10 % threshold of the STH efficiency. Finally, these properties make ScIX (X = S, Se, Te) single-layer semiconductors a promising photocatalyst for water splitting. These discoveries demonstrate novel monolayers as feasible platforms for adjustable photovoltaics and wideband optoelectronics, offering vital insights into the creation of high-efficiency 2D materialbased energy devices.