Wrinkled Graphene Nanoscroll-Fibers as a Support Platform to Encapsulate the CrFe-Codoped Cobalt Nanoparticles for Robust Zn–Air Batteries

Abstract

Major challenge of developing bifunctional electrocatalyst for rechargeable Zn–air batteries (ZABs) is their structural instability and inferior electrochemical performance. To solve these issues, we propose the strategy of anchoring ZIF-derived CrFe-codoped Co nanoparticles (NPs) into the wrinkled graphene nanoscroll-fibers (WGNF) to synthesize the CoCrFe@WGNF as bifunctional catalysts for ZABs. The CoCrFe@WGNF catalyst exhibits decent oxygen evolution and reduction performance in an alkaline medium, and the resulting ZABs deliver exceptional cycling stability up to 1140 h at 5 mA·cm⁻², superior to the ones based on CoCrFe (340 h) and Pt/C + RuO₂ (220 h). Meanwhile, the assembled solid-state ZABs with PAM hydrogel as electrolytes exhibit excellent cycling durability and high-power density at both room-temperature and -40 ºC. The excellent stability originates from the unique wrinkled structure of graphene nanoscroll-fibers and CrFe co-doping. The graphene nanoscroll-fibers with abundant wrinkles and tubular channel can serve as a platform for anchoring to NPs by avoiding aggregation and dissolution of NPs, while the co-dopping of Cr and Fe may optimize the electronic structure of Co to boost the performance of ZABs with wide-temperature range. In short, we believe that the WGNF can be considered as an excellent support platform to encapsulate NPs for other target reactions.

Graphical abstract

CrFe-doping Co NPs were anchored into ultralong graphene nanoscroll-fibers with 1D wrinkles and ultrathin layer (CoCrFe@WGNF). The assembled liquid and solid-state ZABs showed long-life durability and high-power density even under deformation and at − 40 °C, mainly attributed to the carrier and protection effect of wrinkled graphene nanoscroll-fibers and the CrFe co-doping induced electronic coupling