Prussian blue analogues-derived Ni-doped CoFe2O4 hollow nanocubes as electrocatalysts for oxygen evolution reaction

Oxygen evolution reaction (OER) severely restricts the generation of O2 due to complex reaction mechanism; improving the efficiency and stability of catalysts remains a longstanding gauntlet. To replace noble metals, bimetallic oxides are promising OER catalysts owing to their natural abundant reserves and favorable catalytic activity. Herein, nickel-doped CoFe2O4 (Ni@CoFe2O4) hollow nanocubes are synthesized by controlled pyrolysis of prussian blue analogues at low temperature and employed as OER catalyst for water splitting and lithium oxygen battery. Specifically, the prepared sample has a porous hollow cubic architecture, which is conducive to accelerating the substance and electron transport, providing abundant active sites and large electrolyte contact area. The Ni doping and resultant oxygen vacancies can tune the electronic structure and improve the conductivity and intrinsic activity of metal oxides. Benefiting from the special structural design and multi-metal synergy, the OER overpotential of Ni@CoFe2O4 nanocubes for water splitting is 415 mV@100 mA cm-2 with a good stability. The Li-O2 cells assembled with Ni@CoFe2O4 nanocubes also exhibit superior electrochemical properties with a charge/discharge capacity of 12453/11976 mAh g-1 and OER/ORR overpotentials of 1.04/ 0.37 V. This work proposes new insights for the structural design and composition modulation of metal oxide to promote the OER kinetics.