Electrocatalysts of Co₉S₈ Nanoparticles on Functionalized Carbon Nanotubes for Applications as Rechargeable Zinc-Air Batteries

It is challenging yet highly desirable to explore high-performance inexpensive electrocatalysts toward advanced zinc-air batteries (ZABs). Herein, a bifunctional oxygen electrocatalyst composed of Co 9 S 8 incorporated into N-doped porous cross-linked carbon nanotubes (denoted as Co 9 S 8 –NC/NTs) is reported through a folic acid-assisted hydrothermal, pyrolysis, and sulfurization process. Owing to the synergistic effect of Co 9 S 8 nanoparticles (NPs), Co–N x active sites, and the three-dimensional (3D) cross-linked network, Co 9 S 8 –NC/NTs show enhanced bifunctional activity of a small potential gap of 0.72 V. Moreover, a ZAB assembled with Co 9 S 8 –NC/NTs serving as the cathode exhibits satisfactory long-term durability up to 140 h (840 cycles) and large power density of 116.6 mW cm –2 . The present study offers an effective strategy for constructing bifunctional catalysts based on multielements-functionalized carbon nanotubes toward rechargeable ZABs.