Promoting surface reconstruction of NiFe layered double hydroxides via intercalating [Cr(C2O4)3]3− for enhanced oxygen evolution

Abstract

Rationally manipulating surface reconstruction of catalysts for water oxidation, inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges. Herein, the introduction of [Cr(C2O4)3]3− into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction (OER) activity. In view of the weak electronegativity of Cr3+ in [Cr(C2O4)3]3−, the intercalation of [Cr(C2O4)3]3− is expected to result in an electron-rich structure of Fe sites in NiFe LDHs, and higher valence state of Ni can be formed with the charge transfer between Fe and Ni. The optimized electronic structure of NiFe-[Cr(C2O4)3]3−-LDHs with more active Ni3+ species and the expedited dynamic generation of Ni3+(Fe)OOH phase during the OER process contributed to its excellent catalytic property, revealed by in situ X-ray absorption spectroscopy, Raman spectroscopy, and quasi-in situ X-ray photoelectron spectroscopy. With the modulated electronic structure of metal sites, NiFe-[Cr(C2O4)3]3−-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm−2. This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni3+ sites with the optimal electronic environment for improved OER electrocatalysis.