Nickel ferrite nanoparticles with abundant oxygen vacancies as an electrocatalyst for oxygen evolution reaction

초록

Electrochemical water splitting, based on oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), has attracted great attention as a future sustainable and renewing energy source. However, OER is kinetically sluggish process and requires a high overpotential because of the stepwise four-electron oxidation reaction. To solve these problems, nickel-based nanomaterials are widely investigated as an effective electrocatalyst for OER. Herein, oxygen-deficient NiFe2O4 nanoparticles were simply synthesized using a hydrothermal method and reduction by heat treatment in hydrogen, and was used as an electrocatalyst for OER. After heat treatment of spinel-type oxide under hydrogen flowing, oxygen defects of the spinel type oxide was generated, leading to oxygen-vacancy-induced structural variations of NiFe2O4. The oxygen-deficient NiFe2O4 spinel-type oxide nanoparticles exhibited higher electrocatalytic activity for OER compared with pristine sample, which was attributed to enhanced electroconductivity derived from oxygen vacancies in nickel ferrite nanoparticles. The successful preparation of these spinel type oxides nanomaterials with abundant oxygen vacancies may be widely applied to efficient electrocatalysis.