Microwave-assisted synthesis of N/S-doped CNC/SnO2 nanocomposite as a promising catalyst for oxygen reduction in alkaline media

In this study, we report an all-green approach for the synthesis of novel catalysts for oxygen reduction reaction (ORR) via a simple two-step procedure. In particular, conductive cellulose nanocrystals (CNCs) were obtained via pyrolysis, and a successive microwave-assisted hydrothermal process was employed to activate the carbon lattice by introducing sulfur (S) and nitrogen (N) dopants, and to decorate the surface with tin oxide (SnO2) nanocrystals. The successful synthesis of N/S-doped CNC/SnO2 nanocomposite was confirmed by X-ray Photoelectron Spectroscopy analysis, Energy Dispersive X-ray microanalysis, X-ray Diffraction and Field Emission Scanning Electron Microscopy. The synergistic effects of the dopants and SnO2 nanocrystals in modifying the catalytic performance were proved by various electrochemical characterizations. Particularly, the nanocomposite material reaches remarkable catalytic performance towards the ORR, close to the Pt/C benchmark, in alkaline environviment, showing promising potential to be implemented in alkaline fuel cell and metal-air battery applications.