Research Projects

Due to large surface area and tunable electronic structure, two-dimensional (2D) semiconductor materials are attractive candidates for photocatalytic water splitting. Numerous 2D semiconductor photocatalysts have been developed, however, with the limitations of high carriers’ recombination and low solar power conversion efficiency. The suitable bands location of 2D semiconductor does not reveals their suitability for the overall water splitting photocatalysis. Because of the large overpotential, many of these photocatalysts becomes either suitable for hydrogen reduction or for water oxidation reaction which limits the overall efficiency for photocatalytic water splitting. Also, the wide-range absorption of light and strong redox ability to undergo photocatalytic reaction are contrasting targets as the former require relatively smaller bandgap whereas the latter is associated with a wider bandgap of photocatalyst materials. Therefore, only a few photocatalyst materials possess capability of overall water splitting. Currently, it is widely known that photocatalyst bandgap must be more than 1.23 eV for reaction mechanism of water splitting, so infrared light is rarely used. However, designing of type-II van der Waals (vdW) heterostructure can breach the 1.23 eV limit, can overcome the limitation of charge recombination and can greatly boost solar power conversion efficiency. In addition, an intrinsic intralayer polarization from Janus monolayer in the Janus vdW heterostructures can couple with the interlayer polarization field of heterostructure, thereby, providing an extra degree of freedom to play with for the overall water splitting photocatalysis. The exploration of 2D Janus vdW heterostructures for photocatalytic water splitting is still in its infancy stage with numerous opportunities. Particularly, the Janus vdW heterostructures consists of recently synthesized Janus PtSSe monolayer and well established various allotropic forms of phosphorene may be potential candidate for photocatalytic water splitting. Also, it is interesting explore the influence of the rotation of phosphorene layer over a certain angle for the photocatalytic performance of these heterostructures. The investigations for deeper understanding of various aspects of these heterostructures are need of the hour. Particularly, the fundamental parameters for an efficient water splitting photocatalysts (PtSSe/phosphorene heterostructures) such as the thermodynamical stability, band gap, band location, exciton binding energy, absorption coefficients, dielectric constants, oxidation and reduction overpotential, carrier mobility and solar-to-hydrogen (STH) efficiency required detailed investigation at the highest level of theory such as ab-initio molecular dynamics (AIMD) simulations, HSE and GW+BSE level of theories, and including vdW functional and solvation effects.