Vanadium-incorporated CoP2 with lattice expansion for highly efficient acidic overall water splitting

Proton exchange membrane water electrolyzer (PEMWE) in acidic media is a hopeful scenario for hydrogen production by using renewable energy sources, but the grand challenge lies in substituting active and stable noble-metal catalysts. Herein, a robust electrocatalyst of V-CoP2 porous nanowires arranged on carbon cloth is successfully fabricated via incorporating vanadium into CoP2 lattice. Structural characterizations and theoretical analysis indicate that lattice expansion of CoP2 caused by V incorporation results in the upshift of d-band center, which is conducive to hydrogen adsorption for boosting HER activity. Besides, V promotes surface reconstruction to generate a thicker Co3O4 layer that enhances acid-corrosion resistance and optimizes the adsorption of water and oxygen-containing species, thus improving OER activity and stability. Accordingly, it presents a superior acidic overall water splitting activity (1.47 V@10 mA cm-2) over Pt-C/CC||RuO2/CC, and remarkable stability. This work proposes a new route to design efficient electrocatalysts via lattice engineering for PEMWE.