Structural, Thermal, Electronic, and Optical Properties of Defective and Oxidized WSSe for Efficient Photocatalytic Water Splitting

The structural symmetry of transition metal dichalcogenides (TMDs) in the out-of-plane direction diminishes photoconversion efficiency, leading to ineffective photocatalytic water splitting. However, an improved method to enhance water splitting catalysis is the polarization of the asymmetric Janus-TMD monolayer, which creates an intrinsic electric field and an electrostatic potential difference. We have introduced a new technique for achieving efficient photoconversion through oxidative modification of asymmetric Janus WSSe by theoretical methodologies such as density functional theory (DFT) and ab initio molecular dynamics (AIMD). Through investigating structural, thermal, electronic, and optical properties, we found that any alteration in the material is primarily electronic in nature rather than structural, which creates the perfect conditions for WSSe to function as a photocatalyst without compromising its crystal lattice. Binding energy and AIMD results indicate that WSSe has an asymmetric doping tolerance toward O and OH, which is directly related to its long-term and short-term catalytic stability depending on the specific chalcogen site. Defect and functional group engineering modulate the electronic structure and enhance optical absorption and charge separation. Thus, all configurations WSVSe, WSSeV, WSOSe, WSSeO, WSOHSe, and WSSeOH are strategic assets that can be utilized for efficient photocatalytic water splitting. The external electronic field further optimizes these configurations for an improved photocatalytic efficiency.