Construction of heterogeneous interfaces for water activation and dissociation to synergistically boost overall water...

Construction of heterogeneous interfaces with dual active components to synergistically promote both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an effective strategy for facilitating electrochemical water splitting, but the appropriate active component regulation via simple synthesis procedures is still challenging. Herein, the Co and Co₂Mo₃O₈ active components are screened to construct effective heterogeneous interfaces and successfully integrated on Ni foam by thermal reduction of cobalt molybdate precursor. And this bifunctional electrode (Co/Co₂Mo₃O₈/NF) required overpotentials of only 164 and 360 mV to drive the 100 mA cm^-2 for HER and OER in alkaline media, respectively. Theoretical calculations showed that the electron transfer occurred from Co to Co₂Mo₃O₈ at the interface, then the formed interfacial cobalt atoms with deficient electron were beneficial for water activation, and reduced energy barrier of water dissociation under the synergistic effect of Co₂Mo₃O₈. Notably, the alkaline electrolyzer based on symmetric Co/Co₂Mo₃O₈/NF electrodes generated 100 mA cm^-2 at a voltage of only 1.75 V, surpassing commercially available precious-metal Pt/RuO₂-based catalysts.