Electrospun NiCo2S4 with extraordinary electrocatalytic activity as counter electrodes for dye-sensitized solar cells

The performance of dye-sensitized solar cells (DSSCs) is critically dependent on the catalytic activity of their counter electrode (CE) materials. There are great research interests to develop alternative CE materials to replace the conventional Pt electrode. Herein, nickel cobalt sulfide (NiCo2S4, NCS) particles were prepared through sulfurization of NiCo2O4 (NCO) electrospun nanofibers. The bimetallic sulfide was used as CE for DSSC and exhibited an excellent photoenergy conversion efficiency (PCE) of 7.12%, which is higher than the dye-sensitized solar cells using NCO (5.24%) and Pt CEs (7.05%). Systematic electrochemical characterization suggests that this extraordinary performance of NCS might be related to the improved electrocatalytic ability and electrical conductivity. In view of the low-cost synthesis and outstanding electrochemical performance, the NCS counter electrode would hold great promise for applications in dye-sensitized solar cells.