Elucidating the Origin of Hydrogen Evolution Reaction Activity in Mono- and Bimetallic Metal- and Nitrogen-Doped Carbon Catalysts (Me-N-C)

In this work, we present a comprehensive study on the role of metal species in MOF-based Me–N–C (mono- and bimetallic) catalysts for the hydrogen evolution reaction (HER). The catalysts are investigated with respect to HER activity and stability in alkaline electrolyte. On the basis of the structural analysis by X-ray diffraction, X-ray-induced photoelectron spectroscopy, and transmission electron microscopy, it is concluded that MeN4 sites seem to dominate the HER activity of these catalysts. There is a strong relation between the amount of MeN4 sites that are formed and the energy of formation related to these sites integrated at the edge of a graphene layer, as obtained from density functional theory (DFT) calculations. Our results show, for the first time, that the combination of two metals (Co and Mo) in a bimetallic (Co,Mo)–N–C catalyst allows hydrogen production with a significantly improved overpotential in comparison to its monometallic counterparts and other Me–N–C catalysts. By the combination ...