Hierarchically Porous Co/CoxMy (M = P, N) as an Efficient Mott-Schottky Electrocatalyst for Oxygen Evolution in Rechargeable Zn-Air Batteries

Tailoring composition and morphology of electrocatalysts is of great importance in improving their catalytic performance. Herein, a salt-templated strategy is proposed to construct novel multicomponent Co/CoxMy (M = P, N) hybrids with outstanding electrocatalytic performance for the oxygen evolution reaction (OER). The obtained Co/CoxMy hybrids present porous sheet-like architecture consisting of many hierarchical secondary building-units. The synthetic strategy depends on a facile and effective dissolution-recrystallization-pyrolysis process under NH3 atmosphere of the precursors, which does not involve any surfactant or long-time hydrothermal pretreatment. That is different from the conventional methods for the synthesis of hierarchical nitrides/phosphides. Benefitting from unique composition/structure-dependent merits, the Co/CoxMy hybrids as a typical Mott-Schottky electrocatalyst exhibit good OER performance in an alkaline medium compared with their counterparts, as evidenced by a low overpotential of 334 mV at 10 mA cm(-2) and a small Tafel slope of 79.2 mV dec(-1), as well as superior long-term stability. More importantly, the Co/CoxMy+Pt/C achieves higher voltaic efficiency and several times longer cycle life than conventional RuO2+Pt/C catalysts in rechargeable Zn-air batteries. It is envisioned that the present work can provide a new avenue for the development of Mott-Schottky electrocatalysts for sustainable energy storage.