Nanoscale Defect Engineering to Tune Electronic Structure and Surface Property of Two-Dimensional MoS₂ Film for Hydrogen Evolution Reaction

Abstract

Molybdenum disulfide (MoS 2 ), a typical transition metal dichalcogenide, has drawn massive attention in the field of electrocatalytic hydrogen (H 2 ) production. Defect engineering is one of the most feasible ways to enhance the hydrogen evolution reaction (HER) activity of MoS 2 , while there still remains a great challenge to achieve precise adaptation of defect structures to desirable electronic structures and surface properties. Herein, MoS 2 electrocatalysts with stepped edge defect structures are manufactured by focused ion beam etching for superior HER performance. Comparing with defects with ordinary vertical edges, the stepped samples demonstrate much lower overpotential (−115 mV at the current density of −10 mA•cm −2 ), tremendously accelerated kinetics (Tafel slope of 36.0 mV•dec −1 ), and relatively high stability. The great leap of HER activity mainly benefits from the direct control of both the electronic structure and surface property of the material via accurate manipulation. According to the results of density functional theory calculation, contact angle test, and COMSOL Multiphysics simulation, the stepped edges not only speed up the generation rate of H 2 by more optimized free energy of hydrogen adsorption and more suitable band structure for higher conductivity but also shorten the desorption time of H 2 on the electrode surface attributing to its unique hydrophilic structure. It is believed that this study would play a constructive role in extending the design ideas of ultrahigh-performance MoS 2 -based electrocatalysts.

Flexible tungsten disulfide superstructure engineering for efficient alkaline hydrogen evolution in anion exchange membrane water electrolysers

“…This result is in good consistent with the above XRD analysis. Such edge-stepped defect structure has been reported in MoS 2 and demonstrated to possess abundant catalytic active sites as well as suitable Gibbs free energy (ΔG H* ) for acidic HER 48 , 49 . Given the compatibility between alkaline HER and industrial AEMWE 50 , we employed first principles to explore the potential of WS 2 superstructure featuring abundant unsaturated edge-stepped defects as highly effective non-precious metal electrocatalysts for alkaline HER.…”