Efficient Electrocatalytic Hydrogen Evolution from MoS2-Functionalized Mo2N Nanostructures.

Molybdenum-based compounds and their composites were investigated as an alternative to Pt for hydrogen evolution reactions. The presence of interfaces and junctions between Mo2N and MoS2 grains in the composites were investigated to understand their role in electrochemical processes. Here we found that the electrocatalytic activity of Mo2N nanostructures was enhanced remarkably by conjugation with few-layer MoS2 sheets. The electrocatalytic performance of Mo2N-MoS2 composites in the hydrogen evolution reaction (HER) was revealed from the high catalytic current density of ∼175 mA cm-2 (at 400 mV) and good electrochemical stability (more than 18 h) in acidic media. Increasing the amount of MoS2 in the composite, decreases the HER activity. The mechanism and kinetics of the HER process on the Mo2N-MoS2 surface were analyzed using Tafel slopes and charge transfer resistance.