Recoverable and reusable visible-light photocatalytic performance of CVD grown atomically thin MoS₂ films

The decomposition of water pollutants including industrial dyes and chemicals via photocatalytic decontamination is one of the major investigated problems in recent years. Two-dimensional molybdenum disulfide (MoS₂) layers have shown great promise as an efficient visible-light photocatalyst owing to its numerous active sites and large surface area. In this study, atomically thin MoS₂ films of different thicknesses from monolayer to five-layer and ten layers were fabricated on sapphire substrates using chemical vapor deposition (CVD). We demonstrate that these MoS₂ thin films can be used as a photocatalyst to degrade Methylene Blue (MB) dye and can be recovered completely with utmost structural and chemical stability. Under visible-light irradiation, the MB absorption peak completely disappears with ∼95.6% of degradation after 120 min. We also demonstrate the reusability of the MoS₂ thin films without significantly losing the photocatalytic activity even after 5-cycles of degradation studies. The chemical and structural stability of the MoS₂ films after 5-cycles of degradation studies were affirmed using various spectroscopic studies. Our findings suggest that the MB degradation efficiency increases from 19.01% to 98.46% with an increase in pH from 4 to 14. Our approach may facilitate a further design of other transition metal dichalcogenides-based recoverable photocatalysts for industrial applications.