Biomass-Derived Activated Carbon Sheets with Tunable Oxygen Functional Groups and Pore Volume for High-Performance Oxygen Reduction and Zn–Air Batteries

Biomass-derived activated carbon has attracted much attention in electrochemical energy systems, and its great potential can be further unlocked for achieving high-performance by tuning its composition and structure. Herein, we prepared activated carbon using wheat straw as the biomass feedstock. The oxygen functional groups and pore volume of the target activated carbon were successfully tuned using the mixed activator of potassium carbonate and potassium hydroxide. As a result, the activated carbon (named as AC-HC) displayed an excellent oxygen reduction reaction (ORR) behavior in terms of a small half-wave potential of 0.77 V and a large limiting current density, resulting in Zn–air batteries with a high trip efficiency of 60.7% and a long cycle life (280 h/1680 cycles).