Phase transition in V-doped cobalt hydroxide for a superior alkaline hydrogen evolution reaction.

Herein, V-doped cobalt hydroxides grown on carbon cloth (V-Co(OH) 2 /CC) were prepared via hydrothermal method. The incorporation of V can trigger phase transition and tune the local electronic structure of Co(OH) 2 , thereby improving the intrinsic alkaline HER activity. We find that the V-Co(OH) 2 dominated by β-Co(OH) 2 exhibits excellent HER activity with only 83 mV overpotential at a current density of 10 mA cm -2 , which outperforms most reported hydroxide-based catalysts and even surpasses the commercial Pt/C at large current density (>160 mA cm -2 ).