Exsolution of Iron Nanoparticles from LCTFeO3 for Oxygen Evolution Reaction

Abstract

Perovskite oxides (ABO3) with stable structures and flexible compositions are considered to be alternative catalysts for the oxygen evolution reaction (OER). With A-site deficiency in a perovskite, the doping metals in the B-site may be exsolved by calcination in a reduction atmosphere, which is a promising approach to increasing the activity of the catalyst. Here, an iron doped La(0.2+x)Ca(0.7-x)Ti(1-x)FexO3 (x = 0.05, 0.3, LCTFex) perovskite is successfully synthesized by a mild sol-gel method, and the iron nanoparticles anchored perovskite (R-LCTFex) can be fabricated after reduction under 5% H2/N2 atmosphere in a tubular furnace, which can be seen clearly in SEM and STEM images. Notably, the onset overpotential of R-LCTFe0.3 is reduced by 130 mV compared with LCTFe0.3 and the current density of R-LCTFe0.3 is 12-fold higher than LCTFe0.3 at the overpotential of 530 mV. The enhanced OER performance is triggered by the exsolution of Fe nanoparticles. This study establishes that exsolution of metal nanoparticles from a perovskite is a useful tactic for enhancing OER performance.