Spinel-type oxide electrocatalysts with oxygen vacancies for water

초록

Electrochemical water splitting, consisted of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), has attracted increasing attention as a sustainable and renewing energy source. However, OER is kinetically sluggish reaction and requires a high overpotential due to the stepwise four-electron oxidation process. To address the issue, nickelbased materials are widely explored 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 atmosphere, oxygen defects of the spinel type oxide were generated, leading to oxygen-vacancy-induced structural variations of NiFe2O4. The oxygen-deficient NiFe2O4 spinel-type oxide nanoparticles exhibited higher electrocatalytic performance 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.