Manipulating microenvironment of Fe/Mn dual-atomic sites by defect-driven strategy for enhanced oxygen electrocatalysis

Dual single-atom catalysts (DACs) provide an efficient clue to conquer the sluggish kinetics of oxygen reactions in Zn-air batteries (ZABs). However, the precise modulation on local microenvironment of DACs sites are still challenging. Herein, we report a defect-driven strategy to manipulate the microenvironment of Fe/Mn dual atomic sites that anchor on a carbon nanofiber (def-FeMn/CNF). Theoretical calculation results reveal that the defects modulate the local microenvironment of dual atom sites, which decreases the energy barrier and enhances the catalytic behaviors. Finite element analysis (FEA) modeling results demonstrate the porous carbon nanofiber is beneficial to mass transports and ensures fast kinetics. Benefitting from both aspects of advantages, the def-FeMn/CNF catalyst displays the superior pH-universal electrocatalytic properties, fast kinetics, and high stability. It exhibits the half-wave potentials of 0.92 V and 0.87 V in alkaline and acidic conditions, which outperform the FeMn-DAC/CNF, N–FeMn/CNF, Fe-SAC/CNF, and Mn-SAC/CNF reference samples. Moreover, the full Zn-air battery (ZABs) with def-FeMn/CNF cathode shows the high power densities of 295 W kg −1 and high stability over long-term (1000 h) cycling. Furthermore, the quasi-solid-state Zn-air batteries achieve a smooth operation over a wide-temperature range and a long-term (800 h) operational stability at curved state. Therefore, the defect-driven approach provides an efficient strategy to manipulate the local microenvironment of DACs for boosted catalytic properties. Moreover, it also gives a new clue to design and fabrication of pH-universal electrocatalysts towards diverse working conditions. Download: Download high-res image (485KB) Download: Download full-size image