Dynamic equilibrium of external Fe3+ to effectively construct catalytic surface of perovskite LaNi1−xFexO3 for water oxidation

Abstract

The introduction of Fe into rare earth nickelate perovskite oxides such as LaNiO3 can effectively improve its intrinsic activity for oxygen evolution reaction (OER). Whereas, it is still difficult to achieve exact incorporation of Fe ion and maintain the efficient and stable catalytic surface. Bimetallic NiFe-based active sites have been constructed on the surface of LaNiO3 using a straightforward electrochemical technique that involves introducing external and trace Fe3+ ions into the electrolyte. The optimized LaNiO3 with more Ni-O bonds facilitates the adsorption of Fe3+ ions, which promotes the formation of LaNi1−xFexO3 through electrochemical activation. The synthesized LaNi1−xFexO3 exhibited a synergistic impact and electron rearrangement, resulting in a boost in intrinsic activity. The OER measurements show that the overpotential of LaNi1−xFexO3 reduces to 340 mV (η10) and the Cdl value increases by 21 times (0.10 mF cm−2 to 2.18 mF cm−2) in the existence of external Fe3+. Notably, the dynamic equilibrium between the external Fe3+ and Fe3+ in LaNi1−xFexO3 may stabilize the bimetallic NiFe-based active sites and keep the activity during the long-term OER process. The strategy of utilizing dynamic equilibrium of external ion to obtain the robust catalytic surface offers a novel approach to achieving excellent performance for OER.