Electrochemically chopped WS ₂ quantum dots as an efficient and stable electrocatalyst for water reduction

Advancements in the search for efficient H ₂ evolving electrocatalysts by engineering the structure and electronic properties of bulk materials at the nano regime have had a constructive impact on realizing better performance with ultralow catalyst loading. In this work, we investigate the electrochemical hydrogen evolution catalysis of WS ₂ quantum dots (QDs) synthesized electrochemically. WS ₂ QDs were evaluated for a hydrogen evolution reaction (HER) in 0.5 M H ₂ SO ₄ as a binder-less electrocatalyst, which necessitated a low HER onset of 190 mV and reached -200 mA cm ^-2 at 473 mV. In contrast, the bulk WS ₂ exhibited a poor performance, which required 780 mV to drive -50 mA cm ^-2 . The electrochemical disintegration of bulk WS ₂ into QDs is the key behind such activation.