Enhanced Hydrogen Evolution Activity of MoS2 Through Solid Solution Modification of Its Edge Sites With Ruthenium.

Abstract

In hydrogen production, electrocatalysts featuring edge sites as active centers, modulation of its edge site coordination environment could greatly improve the reaction kinetics by effectively reducing the energy barrier. Here, we report a novel catalyst formulation obtained by the electrochemical deposition of ruthenium onto the edge sites and near-edge basal plane of MoS2 to yield Ru-coordinated solid solution species. The Ru atom acts as a site for water dissociation, increasing the proton supply rate and, in turn, the catalytic activity of MoS2. Based on the Tafel slope, in situ Raman, and electrochemical impedance spectroscopy (EIS) analysis, the edge solid solution creates a locally acidic chemical environment, enhancing the kinetics of the hydrogen evolution reaction by altering the reaction pathway from Volmer-Heyrovsky observed for pristine MoS2 to Volmer-Tafel. Edge-coordinated Ru solid solution catalyst features a very high current density in anion exchange membrane water electrolysis (AEMWE) and demonstrates excellent long-term stability when compared with other reported MoS2- and Ru-based catalysts. Overall, our studies demonstrate that modification of MoS2 by the incorporation of an edge solid solution can markedly improve its catalytic activity and, therefore, represents a promising strategy for materials design in the field of renewable fuel generation.