Astridia velutina-like S, N-codoped hierarchical porous carbon from silk cocoon for superior oxygen reduction reaction

Abstract

The development of heteroatom-doped nanostructured metal-free carbon materials for the oxygen reduction reaction (ORR) is a critical challenge. In this work, through a one-step heat treatment, Astridia velutina-like S, N-codoped micro–mesoporous carbon (SNC-x) was synthesized from silk cocoon. The product was fully characterized by physicochemical and electrochemical techniques. The sample obtained at 800 °C possessed a unique hierarchical porous structure with 9.75 at% N and 1.79 at% S content, providing abundant active sites and thus facilitating efficient mass transport. The ORR activity was observed with an onset potential of 0.853 V (vs. RHE), comparable current density (4.5 mA cm⁻² at 0 V) to commercial Pt/C as well as good methanol tolerance and electrochemical stability in alkaline electrolyte. Benefiting from the cheap biomass precursor and unique structural features, the product may serve as a potential candidate for energy storage, conservation and environmental applications, etc.