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 Co₉S₈ incorporated into N-doped porous cross-linked carbon nanotubes (denoted as Co₉S₈–NC/NTs) is reported through a folic acid-assisted hydrothermal, pyrolysis, and sulfurization process. Owing to the synergistic effect of Co₉S₈ nanoparticles (NPs), Co–N_x active sites, and the three-dimensional (3D) cross-linked network, Co₉S₈–NC/NTs show enhanced bifunctional activity of a small potential gap of 0.72 V. Moreover, a ZAB assembled with Co₉S₈–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.