Edge-Site Nanoengineering of WS(2) by Low-Temperature Plasma-Enhanced Atomic Layer Deposition for Electrocatalytic Hydrogen Evolution

[Image: see text] Edge-enriched transition metal dichalcogenides, such as WS(2), are promising electrocatalysts for sustainable production of H(2) through the electrochemical hydrogen evolution reaction (HER). The reliable and controlled growth of such edge-enriched electrocatalysts at low temperatures has, however, remained elusive. In this work, we demonstrate how plasma-enhanced atomic layer deposition (PEALD) can be used as a new approach to nanoengineer and enhance the HER performance of WS(2) by maximizing the density of reactive edge sites at a low temperature of 300 °C. By altering the plasma gas composition from H(2)S to H(2) + H(2)S during PEALD, we could precisely control the morphology and composition and, consequently, the edge-site density as well as chemistry in our WS(2) films. The precise control over edge-site density was verified by evaluating the number of exposed edge sites using electrochemical copper underpotential depositions. Subsequently, we demonstrate the HER performance of the edge-enriched WS(2) electrocatalyst, and a clear correlation among plasma conditions, edge-site density, and the HER performance is obtained. Additionally, using density functional theory calculations we provide insights and explain how the addition of H(2) to the H(2)S plasma impacts the PEALD growth behavior and, consequently, the material properties, when compared to only H(2)S plasma.