Sodium Cobalt Metaphosphate as an Efficient Oxygen Evolution Reaction Catalyst in Alkaline Solution

Sodium cobalt metaphosphate [NaCo(PO3)(3)] has CoO octahedra (CoO6) and shows superior oxygen evolution reaction (OER) activity in alkaline solution, comparable with the state-of-the-art precious-metal RuO2 catalyst. OER catalysts of this metaphosphate are prepared by combustion (Cb) and solid-state (SS) methods. The combustion-assisted method offers a facile synthesis and one-step carbon composite formation. Unusually high catalytic activity was observed in NCoM-Cb-Ar and could be due to chemical coupling effects between NaCo(PO3)(3) and partially graphitized carbon. This novel electrocatalyst exhibits very small overpotential of 340mV with high mass activity of 532Ag(-1). Good charge transfer abilities and chemical coupling between NaCo(PO3)(3) and amorphous carbon gives the OER activity in NCoM-Cb-Ar.