Synergetic Exfoliation and Lateral Size Engineering of MoS₂ for Enhanced Photocatalytic Hydrogen Generation

Generally, exfoliation is an efficient strategy to create more edge site so as to expose more active sites on molybdenum disulphide (MoS₂ ). However, the lateral sizes of the resultant MoS₂ monolayers are relatively large (≈50-500 nm), which retain great potential to release more active sites. To further enhance the catalytic performance of MoS₂ , a facile cascade centrifugation-assisted liquid phase exfoliation method is introduced here to fabricate monolayer enriched MoS₂ nanosheets with nanoscale lateral sizes. The as-prepared MoS₂ revealed a high monolayer yield of 36% and small average lateral sizes ranging from 42 to 9 nm under gradient centrifugations, all exhibiting superior catalytic performances toward photocatalytic H₂ generation. Particularly, the optimized monolayer MoS₂ with an average lateral size of 9 nm achieves an apparent quantum efficiency as high as 77.2% on cadmium sulphide at 420 nm. This work demonstrates that the catalytic performances of MoS₂ could be dramatically enhanced by synergistic exfoliation and lateral size engineering as a result of increased density of active sites and shortened charge diffusion distance, paving a new way for design and fabrication of transition-metal dichalcogenides-based materials in the application of hydrogen generation.