Dual-Sites Coordination Engineering of Single Atom Catalysts for Flexible Metal-Air Batteries

Dual-sites single atom catalysts hold promise for efficiently regulating multiple reaction processes and explicitly explaining the underlying mechanisms. However, delicate atomic engineering for dual-site single atom catalysts remains a huge challenge. Herein, atomically dispersed Fe-Ni single atoms embedded in a nitrogen-doped carbon matrix (FeNi SAs/NC) are successfully developed with extraordinary activity for electrocatalytic oxygen reduction and evolution reactions (ORR/OER). The atomic FeNi SAs/NC catalyst displays high onset potential (0.98 V) and half-wave potential (0.84 V) for the ORR, as well as, low overpotential of (270 mV) at 10 mA cm(-2) for the OER. The density functional theory calculations indicate that the Fe site as the active center can facilitate the four-electron reaction process, while Ni sites regulate the electronic structure of Fe sites and further reduce the energy barrier of the rate-determining step. In addition, the nitrogen-doped carbon matrix prevents the metal atoms from aggregation and corrosion, leading to the improvement of catalyst durability. As a proof of concept, flexible quasi-solid-state zinc- and aluminum-air batteries assembled with the FeNi SAs/NC catalyst exhibit superior peak power densities and discharging specific capacities outperforming the commercial Pt/C. This work provides rational guidance for the synthesis of bifunctional electrocatalysts in next-generation energy devices for flexible consumer electronics.