Proton Relay in Hydrogen-Bond Networks Promotes Alkaline Hydrogen Evolution Electrocatalysis.

Abstract

Common O-/H-down orientation of H₂O molecules on electrocatalysts brings favorable OH/H delivery; however, adverse H/OH delivery in their dissociation process hampers the H₂O dissociation kinetics of the alkaline hydrogen evolution reaction (HER). To overcome this challenge, we raised a synergetic H₂O dissociation concept of metal-supported electrocatalysts involving efficient OH delivery from O-down H₂O to the metal, timely proton relay from O-down H₂O on the metal to H-down H₂O on the support through the hydrogen-bond network, and prompt H delivery from H-down H₂O to the support. After theoretically profiling that a high work function difference between the metal and the support (ΔΦ) induces a strong electric field at the metal-support interface that increases hydrogen-bond connectivity to promote proton relay, we practiced this concept over cobalt phosphide-supported ruthenium (Ru/CoP) catalysts with a high ΔΦ = 0.4 eV, achieving a record-high Ru utilization HER activity of 66.1 A mg_Ru^-1 at -0.1 V vs RHE. The insights into this synergetic H₂O dissociation mechanism provide opportunity for the design of bicomponent alkaline HER electrocatalysts.