Nanoscale Architecture of RuO2/La0.9Fe0.92Ru0.08–xO3−δ Composite via Manipulating the Exsolution of Low Ru-Substituted A-Site Deficient Perovskite

The exsolution of noble metal nanoparticles (NPs) from perovskite usually requires high doping ratio of noble metal. Herein, we constructed a RuO2/LFRO composite by the exsolution of a low Ru-substituted A-site deficient perovskite, La0.9Fe0.92Ru0.08O3 (LFRO). In this process, pure Ru NPs are in situ exsolved from LFRO via a relatively low temperature heat treatment in 5% H2/Ar. Then the exsolved Ru NPs were oxidized to RuO2 for oxygen evolution reaction (OER) applications. The RuO2/LFRO composite achieved a high OER performance compared with the pristine LFRO, which is mainly originated from the generation of electrochemically active RuO2 NPs and the improvement of conductivity. In addition, the exsolution is a reversible process that the exsolved Ru NPs can disappear into the perovskite lattice at 550 °C in air. Our work thereof demonstrates an effective strategy to minimize the dosage of precious metals for catalytic applications in different fields.