Elucidation of Structure Activity Correlations in a Nickel Manganese Oxide Oxygen Evolution Reaction Catalyst by Operando Ni L Edge X ray Absorption Spectroscopy and 2p3d Resonant Inelastic X ray Scattering
Herein, we report the synthesis and electrochemical oxygen evolution experiments for a graphene supported Ni3MnO4 catalyst. The changes that occur at the Ni active sites during the electrocatalyic oxygen evolution reaction (OER) were elucidated by a combination of operando Ni L edge X ray absorption spectroscopy (XAS) and Ni 2p3d resonant inelastic X ray scattering (RIXS) These data are compared to reference measurements on NiO, b Ni(OH)2, b NiOOH, and g NiOOH. Through this comparative analysis, we are able to show that under alkaline conditions (0.1 M KOH) the oxides of the Ni3MnO4 catalyst are converted to hydroxides. At the onset of catalysis (1.47 V) the b Ni(OH)2 like phase is oxidized and converted to a dominantly g NiOOH phase. The present study thus challenges the notion that the b NiOOH phase is the active phase in OER and provides further evidence that the g NiOOH phase is catalytically active. The ability to use Ni L edge XAS and 2p3d RIXS to provide a rational basis for structure activity c.
ACS Applied Materials Interfaces