One-step synthesis of three-dimensional nitrogen and sulfur co-doped graphene networks as low cost metal-free counter electrodes for dye-sensitized solar cells

Three-dimensional nitrogen and sulfur co-doped graphene networks are synthesized via a simple one-step hydrothermal route. The nitrogen and sulfur co-doping strategy significantly enhances the electrocatalytic activity for triiodide reduction. The dye-sensitized solar cell based on the nitrogen and sulfur co-doped graphene exhibits an efficiency of 9.40%, which is higher than the efficiency of the Pt-based device. The superior electrochemical performance can be attributed to the synergistic effect of sulfur and nitrogen atoms in graphene, the conductive three-dimensional graphene networks with a large surface area and an interconnected porous structure.