Pineapple Waste-Derived Carbon as a Metal Free Catalyst in Zinc-Air Battery

Catalysts made from biomass are promising oxygen catalysts for zinc-air batteries (ZABs) because of their inexpensive cost and long-term availability. In this study, we utilize pineapple waste (crown and core) to produce a metal-free oxygen reduction catalyst through a facile potassium hydroxide activation and pyrolysis treatment at 800 °C. Both produced catalysts have a porous structure. The C-Pineapple Core catalyst, on the other hand, has a greater double-layer capacitance (Cdl) of 1.75 mF, suggesting that there are more active sites present than on the C-Pineapple Crown catalyst (1.3 mF). The electrochemical performance test in 0.1 M KOH electrolyte demonstrates that the C-Pineapple Core and C-Pineapple Crown catalysts have a good oxygen reduction reaction (ORR) activity, with onset potentials vs. RHE of 0.95 V and 0.91 V, respectively. An air cathode ZAB constructed with the C-Pineapple Core catalyst could deliver a power density of 85.75 mW cm-2 with an outstanding cycling behavior over 504 cycles (168 h). This research turns agricultural waste into a metal-free oxygen catalyst with good stability.