Orange Peel Derived-Nitrogen and Sulfur Co-doped Carbon Dots: a Nano-booster for Enhancing ORR Electrocatalytic Performance of 3D Graphene Networks

Herein, nitrogen, sulfur co-doped carbon dots (N,S−CDs) have been synthesized by a cost-natural fabrication method using waste orange-peel as a natural-carbon-precursor. N,S−CDs have been hydrothermally anchored to the three-dimensional-graphene-networks (3D−GNs) to boost the electrocatalytic activity by a defective surface effect. Due to the synergistic utilization of heteroatoms, and effective mass-transfer and improved transport kinetics resulting from interconnected 3D-architecture, N,S−CDs anchored 3D−GNs (N,S−CDs@3D−GNs) grant superior oxygen-reduction-reaction (ORR) activity. N,S−CDs@3D−GNs exhibit a dominant four-electron pathway (n=3.89) for ORR in alkaline media besides superior methanol tolerance and robust stability. This work opens a door for converting low-value agricultural wastes into value-added materials for utilizing in energy application.