Construction of magnetic Fe2P2O7/Ni2P@Mxene composite counter electrode for efficient dye-sensitized solar cells

Exploring an effective synthesis method for preparing platinum (Pt)-free counter electrode (CE) catalysts with low-cost, superior catalytic ability and electrochemical stability is essential for dye-sensitized solar cells (DSSCs). In this work, the synthesis of Fe2P2O7/Ni2P was realized through hydrothermal treatment of Fe2P2O7/Ni2P precursor and followed phosphorization process. Next, the Fe2P2O7/Ni2P@Mxene composite was prepared by physical grinding with different contents of Ti3C2 Mxene. The Fe2P2O7/Ni2P@Mxene CE exhibits the most excellent catalytic reduction ability and the fine charge-transfer resistance of 1.0 omega cm2 for the reduction of triiodide electrolyte with 80 wt% Ti3C2 Mxene, which has surpassed the Pt CE. As consequence, the photoelectric conversion efficiency of 9.29 % is achieved for the DSSC with the Fe2P2O7/Ni2P@Mxene CE under the optimized conditions, which is much higher than that of the DSSC Pt-based (7 %). Its high conductivity, prefect catalytic activity, and their synergistic effects of Fe2P2O7/Ni2P and Ti3C2 Mxene towards iodide/triiodide electrolyte of the Fe2P2O7/Ni2P@Mxene CE play an important role in the generation of high efficiency for the cells.