In situ exsolution of ternary alloy nanoparticles from perovskite oxides to realize enhanced oxygen evolution reactivity

Perovskite oxides are promising electrocatalysts for oxygen evolution reaction (OER), while the rational modification on their surface may further improve the performance. Herein, through facile in situ exsolution, CoFeNi ternary alloy nanoparticles exsolved on Sr0.9Co0.5Fe0.35Ni0.15O3-δ (SCFN) parent with embedded and well-anchored structure is proposed as an excellent electrocatalyst for OER. The strong metal-perovskite interaction caused by the exsolution generates the unique synergistic coupling effect, activating the surface oxygen to achieve oxygen species (O22-/O-) and inducing abundant oxygen vacancies and multiple active sites. The electrocatalyst SCFN350, which was reduced in 10 % H2/Ar at 350 ℃ for 1 h, exhibits remarkable OER performance with an overpotential of 282 mV at a current density of 10 mA cm-2 in 1.0 M KOH electrolyte and good durability for 10 h in practical operation. The low Tafel slope (36.53 mV dec−1) and small charge transfer resistance (8.50 Ω) indicate its good charge transfer kinetics and electrical conductivity during OER. Our work not only reveals that a nanostructured ternary alloy phase can be exsolved from the perovskite matrix but also confirms that in situ exsolution is an effective strategy for designing OER catalysts.