Unveiling the critical role of the Mn dopant in a NiFe(OH)2 catalyst for water oxidation

Abstract

Elemental doping has been proved to be an efficient approach to adjust the performance of NiFe layered double hydroxides (NiFe LDHs) for water oxidation. However, the mechanism by which elemental doping affects catalytic activity remains unclear. Herein, we doped NiFe LDH with the Mn element and investigated the effect of elemental doping on the electronic structure of NiFe LDH and oxygen evolution reaction (OER) performance. Operando X-ray absorption spectroscopy analysis indicates that Mn doping promotes the formation of Ni(IV) ions. Density functional theory calculations reveal that Mn doping causes hybridization between Ni 3d and O 2p orbitals which facilitates the oxidation of Ni(II) ions. Resultantly, more active Ni(IV) sites could be generated at a lower applied voltage, which is beneficial for the OER performance.