Highly active MoS₂/carbon electrocatalysts for the hydrogen evolution reaction – insight into the effect of the internal resistance and roughness factor on the Tafel slope

/Vulcan carbon and the cause for this has been investigated based on roughness factor measurements. A linear dependence of the Tafel slope on the roughness factor points to a concomitant increase in the limitations on mass transport. The results show that the benefit of increasing the roughness factor of the electrocatalyst is counterbalanced by increasing the Tafel slope, and hence the need for designing an optimal HER electrocatalyst balancing the roughness factor and Tafel slope is deduced.