Unveiling the Interfacial Effects for Enhanced Hydrogen Evolution Reaction on MoS /WTe Hybrid Structures.

Using the MoS -WTe heterostructure as a model system combined with electrochemical microreactors and density function theory calculations, it is shown that heterostructured contacts enhance the hydrogen evolution reaction (HER) activity of monolayer MoS . Two possible mechanisms are suggested to explain this enhancement: efficient charge injection through large-area heterojunctions between MoS and WTe and effective screening of mirror charges due to the semimetallic nature of WTe . The dielectric screening effect is proven minor, probed by measuring the HER activity of monolayer MoS on various support substrates with dielectric constants ranging from 4 to 300. Thus, the enhanced HER is attributed to the increased charge injection into MoS through large-area heterojunctions. Based on this understanding, a MoS /WTe hybrid catalyst is fabricated with an HER overpotential of -140 mV at 10 mA cm , a Tafel slope of 40 mV dec , and long stability. These results demonstrate the importance of interfacial design in transition metal dichalcogenide HER catalysts. The microreactor platform presents an unambiguous approach to probe interfacial effects in various electrocatalytic reactions.