Synergy between molybdenum nitride and gold leading to platinum-like activity for hydrogen evolution

Reduced size and direct electrochemical H-2 compression are two distinct advantages of electrolyzers based on the acid-polymer electrolyte membrane technology over those relying on alkaline electrolytes. However, recourse to catalysts based on the scarce platinum-group-metals has hitherto been the price to pay. While the transition metal sulfides and nitrides of group VI have recently shown interesting activities for H-2 evolution, the remaining activity gap with Pt needs to be reduced. Platinum owes its high activity to its optimum metal-hydrogen bond strength for H-2 evolution, which is a proven descriptor of the activity on single-component catalysts. Here, we unravel a major synergetic effect between gold and molybdenum nitride which multiplies the hydrogen evolution activity ca. 100 times over that of either gold or molybdenum nitride. This two-phase catalytic material, featuring both strong and weak metal-hydrogen bonds, overcomes the limitations described by Sabatier's principle for single-component catalysts.