Ultrathin WS 2 Nanoflakes as a High‐Performance Electrocatalyst for the Hydrogen Evolution Reaction

Much has been done to search for highly efficient and inexpensive electrocatalysts for the hydrogen evolution reaction (HER), which is critical to a range of electrochemical and photoelectrochemical processes. A new, high‐temperature solution‐phase method for the synthesis of ultrathin WS 2 nanoflakes is now reported. The resulting product possesses monolayer thickness with dimensions in the nanometer range and abundant edges. These favorable structural features render the WS 2 nanoflakes highly active and durable catalysts for the HER in acids. The catalyst exhibits a small HER overpotential of approximately 100 mV and a Tafel slope of 48 mV/decade. These ultrathin WS 2 nanoflakes represent an attractive alternative to the precious platinum benchmark catalyst and rival MoS 2 materials that have recently been heavily scrutinized for the electrocatalytic HER.