Graphene with cobalt oxide and tungsten carbide as a low-cost counter electrode catalyst applied in Pt-free dye-sensitized solar cells

In this work, the nanomaterial Co3O4-WC-CN/rGO (CN is nitrogen-doped carbon; rGO is reduced graphene oxide), as an efficient alternative to platinum for the counter electrode (CE), has been prepared by the high temperature calcination of the Na6H2W12O40 center dot H2O (H2W12) embedded metal-organic framework in argon gas and air atmosphere. It shows high catalytic activity as the CE in the dye-sensitized solar cells (DSSCs), which is due to the excellent catalytic activity of Co3O4-WC and high conductivity of rGO. The photoelectric conversion efficiency (PCE) of DSSC with Co3O4-WC-CN/rGO as the CE is 7.38%, which is superior to that of Pt as the CE (eta = 6.85%).