Watermelon Peel-Derived Nitrogen-Doped Porous Carbon as a Superior Oxygen Reduction Electrocatalyst for Zinc-Air Batteries

Metal-free carbon materials derived from biomass wastes are considered as prospective electrocatalysts applied in the oxygen reduction reaction (ORR) field on account of their extremely low costs and good stabilities. Herein, we develop a watermelon peel-derived nitrogen-doped hierarchically porous carbon (N-WPAC) catalyst by using a simple chemical method without additional templates. The N-WPAC catalyst exhibits an excellent ORR activity and more outstanding durability than the commercial Pt/C catalyst. The superior ORR performances of N-WPAC are mainly ascribed to its hierarchically porous carbon structure with abundant defects, which is beneficial to expose sufficient active sites and accelerate the mass-transfer process. Moreover, the Zn-air battery based on N-WPAC displays eminent discharge performances, which are close to those of the Zn-air battery based on Pt/C. This work broadens our horizon to design efficient ORR catalysts derived from biomass wastes by a facile and scalable approach.

Automated summary

Metal-free carbon materials derived from biomass wastes have shown great potential as low-cost and stable electrocatalysts for the oxygen reduction reaction (ORR). In this study, a watermelon peel-derived nitrogen-doped hierarchically porous carbon (N-WPAC) catalyst was developed using a simple chemical method, showing excellent ORR activity and durability outperforming commercial Pt/C catalyst. The superior ORR performances of N-WPAC are attributed to its hierarchically porous carbon structure with abundant defects, facilitating the exposure of active sites and acceleration of mass transfer processes. Moreover, the Zn-air battery based on N-WPAC exhibits outstanding discharge performances comparable to those based on Pt/C, showcasing the potential of biomass waste-derived catalysts in energy applications.