Introducing phosphorus into spinel nickel ferrite to enhance lattice oxygen participation towards water oxidation electrocatalysis

Oxygen evolution reaction (OER) restricts the efficiency of overall water splitting due to its complex transfer process and sluggish intrinsic kinetics. The novel lattice oxygen oxidation mechanism (LOM) could lift the theoretical scaling limits of the traditional adsorbate evolution mechanism (AEM), but increasing the participation of lattice oxygen still remains a great challenge. Herein, we introduce phosphorus into spinel nickel ferrite as electrocatalyst with an overpotential of 264 mV at 10 mA cm-2 towards water oxidation. Experimental results confirm the enhanced participation of lattice oxygen for OER in P-NiFe2O4. Further theoretical modelling reveals that the incorporated phosphorus results in an upshift of O 2p band center relative to Fermi level and enhances hybridization of the metal-oxygen bond, thus facilitating LOM and accelerating the OER process on spinel NiFe2O4. This work provides some deep insights into the OER mechanism and a sound strategy for improving the electrocatalytic activity of spinel oxides.