Upcycling Durian Shell Waste into Highly Active Catalysts for Oxygen Reduction

Abstract

The global durian industry's rapid expansion, exceeding 3.5 million tons annually, results in substantial waste, primarily durian shells, which pose environmental challenges due to landfill disposal. This study explores the potential of up-cycling durian-shell biomass into effective oxygen reduction reaction (ORR) catalysts. Utilizing melamine and FeCl₃ in a scalable pyrolysis process, we developed a catalyst, notably Dur-2Fe-Mel, which exhibits exceptional ORR activity in alkaline media, achieving a half-wave potential of 0.90 V, rivaling commercial Pt/C catalysts and surpassing most recently reported ORR catalysts. Extensive characterization reveals enhanced mesoporosity, homogeneous Fe/N distribution, and critical Fe-Nₓ active sites. The optimized catalyst demonstrates remarkable stability (98.4% activity retention after 40,000 s), methanol immunity, and nearly complete four-electron pathway selectivity. This work not only provides a sustainable route for biomass waste upcycling but also advances the development of economical, high-efficiency ORR catalysts for energy applications.