Top–Down Synthesis of Noble Metal Particles on High-Entropy Oxide Supports for Electrocatalysis

Designing and fabricating bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial to high-performance rechargeable metal–air batteries. Herein, we introduce a generic dealloying procedure to fabricate nanoporous spinel high-entropy oxides (HEO) (AlCoFeMoCr)3O4 as the OER catalysts, incorporated with highly dispersed Pt or PtPdCuAgAu clusters/nanoparticles of ∼1.5 nm in diameters as the ORR catalysts on the porous HEO. Our combined experimental results and first-principles density functional theory (DFT) calculations clearly indicate that the ORR activity of Pt clusters can be enhanced and stabilized through strong interactions with the HEO substrates, and at the same time, the presence of Pt can boost the OER performance of the HEO. In particular, the nanoporous AlCoFeMoCr/Pt composite exhibits a comparable OER activity as the best reported data, while its ORR activity exceeds the performance of commercial Pt/C in alkaline solutions. We expect such multicomponent HEO/metal composite systems would provide a new combinatorial materials design path to ensure multiple catalytic functionalities.