Is platinum necessary for efficient hydrogen evolution? – DFT study of metal monolayers on tungsten carbide

• Metal monolayers on WC(0001) were studied systematically using DFT.
• Adhesion of monolayers and electronic structure were analyzed.
• Hydrogen adsorption on metal monolayers was correlated to catalytic activity.
• Volcano type relationship was used to search for new low-cost HER electrocatalysts.
• CuML/WC(0001) and RhML/WC(0001) were identified as possible HER electrocatalysts.

In this work WC-supported metal monolayers (Cu, Ru, Rh, Pd, Ag, Ir, Pt and Au) are investigated using Density Functional Theory in order to establish general trends regarding monolayer stability, electronic structure and reactivity. Using calculated hydrogen–metal bond energies and available data on the exchange current densities (j0) for hydrogen evolution reaction (HER) volcano-type curve is obtained enabling prediction of HER j0 for the entire series of MML/WC systems not considered so far as HER electrocatalysts. Among investigated surfaces, CuML/WC(0001) and RhML/WC(0001) are identified as promising HER electrocatalysts with (i) HER exchange current density matching the one of Pt and (ii) stability in electrochemical environment under HER conditions. Provided results point to a general conclusion that Pt might not be necessary for efficient catalysis of hydrogen electrode reactions – superior catalysts can be obtained by rational design approach with suitable choice of overlayer/support system not involving Pt at all.