Heterotriphase crystalline-amorphous cobalt boride catalysts: accelerating surface reconstruction for efficient alkaline seawater OER

Abstract

We report crystalline Co₂B and CoB (c-Co₂B and c-CoB)-involved amorphous CoB_x (a-CoB_x) hollow-microspheres (CoB_0.8) for enhanced OER performance in alkaline seawater electrolytes. MOF-derived transition metal borides (CoB_0.8) possess excellent crystalline-amorphous interfaces, synergistically enhancing charge transfer kinetics and active-site accessibility. Electrochemical analysis reveals a low overpotential of 232 mV at 10 mA cm⁻² in 1.0 M KOH seawater and stability tests over 75 h at 10 mA cm⁻², outperforming most reported Co-based catalysts. In situ Raman spectroscopy confirms that Co-B electronic coupling accelerates the electrochemical reconstruction to highly oxidized cobalt species (CoOOH) at ultralow potential.