Highly efficient tungsten-doped hierarchical structural N-Enriched porous carbon counter electrode material for dye-sensitized solar cells

Abstract

In this study, a novel hierarchical hybrid of tungsten species nanoparticles anchored on nitrogen-doped hollow mesoporous carbon (WC/N-HHMC) with high surface area and hierarchical porosity is synthesized and investigated as a noble metal-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). The unique characteristics such as co-doping of graphitic nitrogen and tungsten species nanoparticles, high specific surface area, and interconnected hierarchical porosity render WC(0.7)/N-HHMC an alternative of Pt-based CE for DSSCs. The tungsten species serve as high electrocatalytic activity centers providing available active sites for regeneration of I−/I3− electrolyte, while N-HHMC endows a high-speed transport pathway to facilitate the electron transfer from carbon skeleton to active sites. Electrochemical investigations indicate that WC(0.7)/N-HHMC electrode displays excellent electrocatalytic activity for I3− reduction due to lower charge-transfer resistance (RCT) at CE/electrolyte interface. Benefiting from the above advantages, a DSSC based on WC(0.7)/N-HHMC CE shows an energy conversion efficiency of 8.0%, which is superior to that of cell assembled with platinized CE (7.8%). More remarkably, WC(0.7)/N-HHMC exhibits a good electrochemical stability toward I−/I3− redox reaction. The present study demonstrates the rationality for preparation of inexpensive WC(0.7)/N-HHMC electrocatalyst with special structures and its application as a great alternative to Pt-based CE for DSSCs.