Multifunctional PbS2 Monolayer with an In-Plane Negative Poisson Ratio and Photocatalytic Water Splitting Properties.

ABSTRACT

Designing novel multifunctional materials at the nanoscale is vitally important for flexible electronics. Here, we have uncovered a two-dimensional metal dichalcogenide PbS2 with intriguing negative Poisson ratio behavior and favorable optical and photocatalytic water splitting properties. The calculations indicate that the Poisson ratio of the PbS2 monolayer is -0.061 along both x and y lattice directions, which is attributed to its unique tetrahedral motif and the ligand field of the local PbS4 units in the PbS2 monolayer. The electronic band structures show that the narrow band gap (1.59 eV) of the PbS2 monolayer could be effectively modulated by strain engineering. Most importantly, the strain-induced tunability of optical absorbance and suitable band edge alignment make the PbS2 monolayer a promising catalyst for photocatalytic water splitting, which is further confirmed by the reaction free energies. These findings offer an effective avenue for the design and synthesis of a novel optoelectronic functional material.