Transition metal dichalcogenides (TMDs) have recently emerged within the group of 2D materials due to their electrical, catalytic and optical properties significantly enhanced and useful when down-sized to single layer. In particular, MoS2 has attracted much attention due to its semiconducting nature with a useful band gap when present as single layer, the enhanced photoluminescence, but also importantly the excellent catalytic properties towards the electrochemical hydrogen evolution. We present here the preparation of thin layers MoS2 nanosheets with enhanced catalytic properties towards the hydrogen evolution reaction by means of an easy and fast electrochemical top-down exfoliation procedure in aqueous solution from a naturally occurring MoS2 crystal. After structural and chemical characterization with STEM, AFM, XPS and Raman spectroscopy electrochemical investigations were performed to test catalytic properties in acidic solution for the electrogeneration of hydrogen and compare it to MoS2 nanosheets obtained through the widely employed chemical Li intercalation/exfoliation. Electrochemically exfoliated MoS2 shows lower Tafel slope than its counterpart obtained with chemical exfoliation.

Central European Institute of Technology Brno University of Technology Purkynova 123 61200 Brno Czech Republic

Division of Chemistry and Biological Chemistry School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore

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Electrochemical molecular intercalation and exfoliation of solution-processable two-dimensional crystals