Bimetallic sulfide Co8FeS8/N–C dodecahedral nanocages via cation exchange as counter electrode for dye-sensitized solar cells

Abstract

The bimetallic sulfides with unique catalytic ability are highly attractive in energy conversion field. Herein, Co8FeS8/N–C dodecahedral nanocages (DNCs) are synthesized by ZIF-67 as a template through subsequent sulfidation and cation exchange strategy. Co8FeS8/N–C DNCs are fabricated by Co8FeS8 nanoparticles with superior crystallinity, which are coated with the N-doped carbon shell derived from organic ligands in ZIF-67. When Co8FeS8/N–C DNCs are applied as an efficient and low-cost Pt-free counter electrode (CE) for the dye-sensitized solar cells, they achieve a high power conversion efficiency (PCE) of 8.06%. The electrochemical results show that Co8FeS8 DNCs exhibit the best electrocatalytic activity for the reduction of triiodide (the smallest peak-to-peak separation and electron transfer impedance) than those of Pt counter electrode and monometallic sulfide Co9S8/N–C counter electrode.