High-entropy single-atomic sites anchored on macroporous carbon nanofibers for oxygen electrocatalysis and sustainable Zn-air batteries

High-entropy single-atomic sites (HESAs) outperform single atomic sites (SAs) by high mixed-entropy, modulated atomic configuration and promoted oxygen adsorption. Herein, we report the design of high-entropy single-atomic sites (FeCoNiMnCu HESA) that are anchored on the macroporous carbon nanofiber (NMCF) to fabricate highly efficient (HESA@NMCF) catalysts for oxygen reactions. Theoretical calculations results reveal that the high-entropy heteroatoms play an important role in decreasing the symmetry of electronic structure of carbon substrate and modulating the adsorption capability of oxygen intermediate, which contribute to the boosted electrocatalytic performance. Electrochemical test results reveal the HESA@NMCF catalyst with HESA sites and macroporous substrate shows the superior catalytic properties, fast kinetics, and good stability. In particularly, it exhibits the pH-universal oxygen reduction properties with the higher half-wave potentials (E 1/2 ) of 0.920 V, 0.800 V and 0.631 V vs. RHE in alkaline, acidic, and neutral electrolytes over the Fe-SA@NMCF counterpart that only has Fe single-atom site. Moreover, Zn-air battery with HESA@NMCF cathode shows a high power density of 236.1 W kg −1 and a long lifespan over 900 h cycling. Combined with the anti-freezing hydrogel electrolyte, the quasi-solid-state Zn-air batteries show a superior high-rate long-term cycle life over 400 h at 20 mA cm −2 , a smooth operation over a wide-temperature range, and an outstanding low-temperature adaptation with 240 h stable cycling at −40 °C. Therefore, this work presents a novel strategy on engineering the electronic structure and modulating the local environment for HESAs. It gives a new clue to design pH-universal electrocatalysts for a wide range of applications, such as metal-air batteries, fuel cells, water splitting, etc.