Engineering Dual Single-Atom Sites on 2D Ultrathin N-doped Carbon Nanosheets Attaining Ultra-Low Temperature Zn-Air Battery.

Herein, a novel dual single-atom catalyst comprising adjacent Fe-N4 and Mn-N4 sites on 2D ultrathin N-doped carbon nanosheets with porous structure (FeMn-DSAC) was constructed as the cathode for a flexible low-temperature Zn-air battery (ZAB). FeMn-DSAC exhibits remarkable bifunctional activities for oxygen reduction reaction and oxygen evolution reaction. Control experiments and density functional theory calculations reveal that the augmenting catalytic activity arises from Fe-Mn dual-sites synergistic effect facilitating *OOH dissociation as well as the porous 2D nanosheet structure promoting active sits exposure and mass transfer during the reaction process. The excellent bifunctional activity of FeMn-DSAC renders the fabricated ZAB operating efficiently at ultra-low temperature of -40 ℃, delivering 30 mW cm-2 peak power density and retaining up to 86% specific capacity from the room temperature counterpart, representing the top-level performance among previously reported results.