Highly efficient CoFe2O4 electrocatalysts prepared facilely by metal-organic decomposition process for the oxygen evolution reaction

Highlights: • The novel solution route based on metal-organic decomposition (MOD) process is successfully developed for a facile preparation of CoFe₂O₄. • The effect of cation distribution on the OER activity in CoFe₂O₄ is elucidated with emphasis placed on the structure–property relationship. • A cation redistribution in octahedral and tetrahedral sites within the spinel structure leads to the enhancement in hole density and concomitant OER activity. • The CoFe₂O₄ integrated on carbon fiber paper (CFP) exhibits high electrocatalytic performance. • An overpotential (η₁₀) of 359 mV at 10 mA cm⁻² and a Tafel slope of 53.8 mV dec⁻¹ are obtained for the electrocatalyst in 1 M KOH aqueous solution. -- Abstract: The novel solution route based on metal-organic decomposition (MOD) process is successfully developed for a facile preparation of CoFe₂O₄. The electrocatalytic activity of CoFe₂O₄ for the oxygen evolution reaction (OER) of electrochemical water splitting is investigated as a function of calcination temperature in the range between 300 and 450 °C. It is significantly found that a drastic cation redistribution in octahedral and tetrahedral sites within the spinel structure of 450 °C-calcinated CoFe₂O₄ p-type semiconductor leads to the dramatic enhancement in hole density and concomitant OER activity. The CoFe₂O₄ integrated on carbon fiber paper (CFP) exhibits high electrocatalytic performance, including an overpotential (η₁₀) of 359 mV at10 mA cm⁻² and a Tafel slope of 53.8 mV dec⁻¹ in 1 M KOH aqueous solution. Based on this work, a design principle of the MOD solution process developed can be applied to preparation of a greater variety of compounds. Also, elucidation of structure-OER activity relationships in spinel-type CoFe₂O₄ electrocatalysts will be able to advance further.