Self-assembled one-dimensional Co coated with N-doped carbon nanotubes for dye-sensitized solar cells with high activity and remarkable durability

Abstract

An important challenge for commercializing dye-sensitized solar cells (DSSCs) is the development of efficient non-precious metal counter electrode (CE) materials, which must be solved using non-precious metal catalysts because of their poor stability and low efficiency. In this work, N-doping was applied to synthesize Co/NC based on the preparation of one-dimensional carbon nanotube-encapsulating metal Co monomers, which showed excellent application prospects as DSSC counter electrodes. The coating of carbon nanotubes makes the metal Co monomers less susceptible to corrosion in the electrolyte, ensures structural stability, and functions as a high-speed transport pathway, facilitating accelerated electron transfer to the active site. The synergistic effect of N-doped carbon and metal Co monomers can further improve the electrocatalytic activity, electrical conductivity and accelerate the reduction of triiodide and enhance the catalytic activity of triiodide, thus improving its photoelectric conversion efficiency (PCE). An excellent PCE of 8.56% was obtained during detailed electrochemical tests and good long-term electrochemical stability was also demonstrated in iodine-based electrolytes. This study illustrates that the encapsulation of metallic Co nanocrystals in nitrogen-doped carbon nanotubes is an effective strategy to increase the overall catalytic activity.