Rationally designed nitrogen-doped carbon macroporous fibers with loading of single cobalt sites for efficient aqueous Zn-CO₂ batteries

Atomically dispersed metal catalysts supported on the rigidly hollow matrix are promising materials for developing carbon-neutral technologies. Herein, we develop an elaborate multistep templating approach to fabricate cobalt single-atom-decorated nitrogen-doped carbon macroporous fibers (Co SAs@NCMFs). During the thermal reduction, the cobalt nanoparticles derived from the sintered Co²⁺ ions are formed at 600°C, which can be further transformed into unevenly loaded atomically dispersed cobalt sites at 1,000°C. The Co SAs@NCMF catalyst delivers excellent CO Faradaic efficiency (98.4%) and turnover frequency (38,390 h⁻¹) at −1.0V versus reversible hydrogen electrode for CO₂ electroreduction. Furthermore, benefiting from the multiple advantageous features, including rigidly hollow structure, high specific surface area, and accessible active sites, the Co SAs@NCMF electrode shows outstanding rechargeability and stable cycle life in aqueous Zn-CO₂ batteries. © 2022 Elsevier Inc.