Redox-active Sn(II) to lead to SnFe₂O₄ spinel as a bi-functional water splitting catalyst

Despite several reports on metal ferrites for water splitting studies, SnFe₂O₄ is a rarely explored spinel oxide. Herein, solvothermally prepared ca. 5 nm SnFe₂O₄ nanoparticles deposited on nickel foam (NF) behaves as a bi-functional electrocatalyst. In alkaline pH, the SnFe₂O₄/NF electrode exhibits oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at moderate overpotentials and shows a fair chronoamperometric stability. Detailed study indicates that iron sites of the spinel are preferably active for the OER while the Sn^II sites not only enhance the electrical conductivity of the material but also favor the HER.