Nitrogen/sulfur dual-doped porous carbon microtubes prepared from poplar catkins as high-performance counter electrode of dye-sensitized solar cells

Abstract

The fabrication of low-cost counter electrode using heteroatom-doped porous carbon derived from renewable biomass is a promising strategy to assemble cost-effective dye-sensitized solar cells (DSCs). Here, nitrogen/sulfur dual-doped porous carbon microtubes (NSPCMTs) are prepared by a direct pyrolysis process using poplar catkins as the carbon source and thiourea as the nitrogen (N) and sulfur (S) source. It is found that the as-prepared NSPCMTs inherit the microtube morphology of poplar catkins and the thiourea addition results in the dual-doping of N and S and promotes the pore formation on the wall of carbon microtubes. The obtained NSPCMTs display a specific surface area of 379.55 m² g⁻¹. The N/S dual-doping and the high surface area enhance the surface accessibility and increase the electrocatalytic active sites of NSPCMTs, which endows NSPCMTs with a superior electrocatalytic performance. Cyclic voltammetry and electrochemical impedance spectroscopy measurements indicates that NSPCMT electrode has the same electrocatalytic activity as conventional Pt electrode. Consequently, the DSC with NSPCMT electrode demonstrates an efficiency of 8.27 %, approaching to the performance of Pt electrode-based cell.