Synergy between active sites and electric conductivity of molybdenum sulfide for efficient electrochemical hydrogen production

Abstract

Molybdenum sulfide is a promising non-precious material for electrochemical hydrogen production from water. The number of active sites, the intrinsic activity and the electric conductivity of molybdenum sulfide have a significant influence on hydrogen evolution activity. Poor performance of any of these three factors may hamper the hydrogen evolution activity, so synergy between active sites and electric conductivity is of great importance. Here, we report a scalable wet chemistry method coupled with controllable calcination and the incorporation of carbon nanotubes. In this way, molybdenum sulfides showing optimum synergy between tailored and abundant active sites and high electric conductivity become accessible. Major factors governing the intrinsic catalytic activity could be identified. The optimized molybdenum sulfide based catalyst obtained by this method shows higher activity than sole molybdenum sulfide or molybdenum sulfide modified by either calcination or CNT addition. A low overpotential of 154 mV at a current density of 10 mA cm⁻², a low Tafel slope of 31 mV per decade and very good stability were achieved. This versatile approach paves the way for the systematic optimization of various 2D materials utilizing the synergy between active site design and enhanced electric conductivity.