Enhanced electrocatalytic activity through facet engineering of single-crystal bimetallic hydroxide

Facet engineering is frequently employed to give catalysts the desired surface atom configurations and morphologies for enhanced catalytic performances. However, constructing single-crystal bimetallic hydroxides and understanding their facet effects are still challenging. Here, by adjusting the dissociated OH− concentration, 2D nanosheets (NSs) exposing (020) facet (CoCu(020) NS) and 1D nanorods mainly exposing (031) facet of single-crystal bimetallic kolwezite are precisely synthesized. CoCu(020) NS shows superior performances in alkaline hydrogen evolution and anion exchange membrane water electrolyzer. Combining characterizations and theoretical calculations shows that CoCu(020) NS exhibits a local geometric structure with low coordination number and an electron structure with appropriate d-band center level and charge density of active sites, both of which are strongly correlated with the adsorption properties of H2O and intermediates. This work might pave the way for development of single-crystal bimetallic hydroxides and further applications of facet engineering in electrocatalysis.