Simultaneous modulation of composition and oxygen vacancies on hierarchical ZnCo2O4/Co3O4/NC-CNT mesoporous dodecahedron for enhanced oxygen evolution reaction.

Electrochemical water splitting is a promising way for the sustainable production of hydrogen, but the efficiency of the overall water splitting reactions largely depends on the oxygen evolution reaction (OER) because of its sluggish kinetics. Herein, a series of hierarchical ZnCo2O4/Co3O4/NC-CNT mesoporous dodecahedrons with carbon-nanotubes grafting have been synthesized via sequential pyrolysis in nitrogen and mild oxidation in air from ZnCo-bimetallic zeolitic imidazolite frameworks (ZnCo-ZIF). The simultaneous modulation of oxygen vacancies, composition together with hierarchical mesoporous architecture remarkably enhanced their electronic conduction, the amount and reactivity of accessible actives, thus boosted their intrinsic activity in OER. The optimal ZnCo2O4/Co3O4/NC-CNT-700 exhibited a large current density of 50 mA cm-2 at potential of 1.65 V, small Tafel slope of 88.5 mV dec-1, and superior stability in alkaline media. This work should provide a facile strategy for the rational design of advanced OER catalysts by simultaneous engineering oxygen vacancies and composition.