Vapor deposition strategy for implanting isolated Fe sites into papermaking nanofibers-derived N-doped carbon aerogels for liquid Electrolyte-/All-Solid-State Zn-Air batteries

Single-atom catalysts (SACs), with precisely controlled metal atom distribution and adjustable coordination architecture, have gained intensive concerns as efficient oxygen reduction reaction (ORR) electrocatalysts in Zn-air batteries (ZAB). The attainment of a monodispersed state for metallic atoms anchored on the carbonaceous substrate remains the foremost research priority; however, the persistent challenges lie in the relatively weak metal-support interactions and the instability of captured single atom active sites. Furthermore, in order to achieve rapid transport of O2 and other reactive substances within the carbon matrix, manufacturing SACs based on multi-stage porous carbon substrates is highly anticipated. Here, we propose a methodology for the fabrication of carbon aerogels (CA)-supported SACs utilizing papermaking nanofibers, which incorporates advanced strategies for N-atom self-doping, defect/vacancy introduction, and single-atom interface engineering. Specifically, taking advantages of using green and energy-efficient feedstocks, combining with a direct pore-forming template volatilization and chemical vapor deposition approach, we successfully developed N-doped carbon aerogels immobilized with separated iron sites (Fe-SAC@N/CA-Cd). The obtained Fe-SAC@N/CA-Cd exhibited substantially large specific surface area (SBET = 1173 m2/g) and a multi-level pore structure, which can effectively mitigate the random aggregation of Fe atoms during pyrolysis. As a result, it demonstrated appreciable activity and stability in catalyzing the ORR progress (E1/2 = 0.88 V, Eonset = 0.96 V). Furthermore, the assembled liquid electrolyte-state Zn-air batteries (LES-ZAB) and all-solid-state Zn-air battery (ASS-ZAB) also provides encouraging performance, with a peak power density of 169 mW cm−2 for LES-ZAB and a maximum power density of 124 mW cm−2 for ASS-ZAB.