Electronically coupled layered double hydroxide/MXene quantum dot metallic hybrids for high-performance flexible zinc–air batteries

Precise control of the local electronic structure and properties of electrocatalysts is important for enhancing the multifunctionality and durability of electrocatalysts and for correlating the structure/chemistry with the catalytic properties.Herein,we report electronically coupled metallic hybrids of NiFe layered double hydroxide nanosheet/Ti3C2 MXene quantum dots deposited on a nitrogen-doped graphene surface(LDH/MQD/NG)for high-performance flexible Zn-air batteries(ZABs).As verified from the Mott-Schottky and Nyquist plots,as well as spectroscopic,electrochemical,and computational analyses,the electronic and chemical coupling of LDH/MQD/NG modulates the local electronic and surface structure of the active LDH to provide metallic conductivity and abundant active sites,leading to significantly improved bifunctional activity and electrocatalytic kinetics.The rechargeable ZABs with LDH/MQD/NG hybrids are superior to the previous LDH-based ZABs,demonstrating a high power density(113.8 mW cm^(-2))and excellent cycle stability(150 h at 5 mA cm^(-2)).Moreover,the corresponding quasi solid-state ZABs are completely flexible and practical,affording a high power density of 57.6 mW cm^(-2)even in the bent state,and in real-life operation of tandem cells for powering various electronic devices.