In situ coupling of Ag nanoparticles with high-entropy oxides as highly stable bifunctional catalysts for wearable Zn-Ag/Zn-air hybrid batteries

With the combination of the advantages of both Zn-Ag and Zn-air batteries, hybrid Zn-Ag/Zn-air batteries nevertheless suffer greatly from structural instability and activity degradation of the catalysts at the air electrodes. Herein, we introduce a scalable chemical dealloying procedure to synthesize mutually interacting and stable bifunctional catalysts, consisting of imbedded Ag nanoparticles for the oxygen reduction reaction (ORR) and quantitatively designed multicomponent high-entropy oxides (HEOs) for the oxygen evolution reaction (OER). The ORR performance and the Zn-Ag battery capacity can be precisely controlled by the content of Ag nanoparticles. Impressively, with a significantly low Ag content (∼9.13 wt%) in the bifunctional (AlNiCoFeCr)3O4/Ag, our hybrid Zn-Ag/Zn-air batteries using such catalysts are able to be continuously charged/discharged for more than 450 h and deliver a high energy density of 810 W h kg-1. We expect that these stabilized noble metals in HEO nanocomposites may work as multifunctional electrocatalysts in many other energy conversion devices.