Facile synthesis of Co0.85Se nanotubes/reduced graphene oxide nanocomposite as Pt-free counter electrode with enhanced electrocatalytic performance in dye-sensitized solar cells

A novel nanocomposite of Co 0.85 Se nanotubes with reduced graphene oxide (Co 0.85 Se/RGO) is prepared by a facile hydrothermal approach coupled with in situ selenization, which is applied as counter electrode in dye-sensitized solar cells. Electrochemical analysis shows that the Co 0.85 Se/RGO composite displays a higher electrocatalytic activity for the reduction of triiodide respect to its single components due to the unique hollow structure of Co 0.85 Se as well as the synergistic effects of high catalytically active Co 0.85 Se and conductive RGO. As a consequence, the dye-sensitized solar cell (DSSC) fabricated with the Co 0.85 Se/RGO electrode presents a high photovoltaic conversion efficiency of 7.81%, exceeding the cell based on a Pt electrode (7.55%). Moreover, a considerable electrochemical stability is also achieved when the material was used as a counter electrode in a I − /I 3 − electrolyte. Therefore, the Co 0.85 Se/RGO exhibits a huge potential as efficient and low-cost Pt-free counter electrode material to replace Pt allowing for large-scale fabrication of DSSCs.