WS₂ Monolayer for Piezo–Phototronic Dye Degradation and Bacterial Disinfection

Two-dimensional nanomaterials prosperous with a direct band gap, high mobility, and superior mechanical properties are an excellent choice for probing the effect of piezoelectric polarization on photogenerated electrons for a variety of applications. In this report, a chemical-vapor-deposition-grown, uniform large-area WS₂ monolayer on a sapphire (Al₂O₃) substrate has been demonstrated for piezocatalytic bacterial disinfection and the degradation of organic pollutants. WS₂ as a photocatalyst degrades 80% dye in 120 min, whereas the addition of a piezocatalytic effect helps to degrade it up to ∼87%. The addition of piezoelectric polarization has been shown to enrich the separation of electrons and holes to generate more reactive oxygen species. These reactive oxygen species help to degrade organic dyes as well as bacteria. This three-atom subnanometer-thick piezo–photocatalyst shows reusability toward a different set of organic pollutants (methylene blue, rhodamine B, and methyl orange). Piezo- and photocatalysis results presented in this work prove that WS₂ monolayer is a multifunctional catalyst and highlight the importance of coupling between mechanical strain-induced polarization and visible-light absorbance for the efficient manipulation of charge carriers by external stimuli for various applications.