A dye-sensitized solar cells with enhanced efficiency based on a “pillared effect” of CoMoP2 @Mxene@CNTs composite counter electrode

Abstract

Cobalt phosphide has exhibited good electrochemical performance as the counter electrode (CE) for the dye-sensitized solar cells (DSSCs), but its conductivity and catalytic capacity can still be further improved. Mxene, a two-dimensional layered material with high specific surface area and electrical conductivity, plays an important role in accelerating the catalytic reduction of iodide ion for DSSCs. Herein, we constructed a strategic hybrid containing optimal proportion of CoMoP2 and Mxene while adopting CNTs to inhibit the agglomeration and repeated stacking between Mxene layers, therefore enabling a formation of “pillared effect” in Mxene. The DSSC with the CoMoP2 @Mxene@CNTs CE achieves a high power conversion efficiency of 10.64%, much higher than that of the Pt (7.04%) and CoMoP2 @Mxene (7.08%) CEs. Through a suite of morphological and electrochemical analysis, we attribute the performance improvement to the synergistic effect of the excellent conductivity and unique two-dimensional chemical structure of Mxene, the effective blending of the CoMoP2, Mxene and CNTs materials, and especially, the formation of “pillared effect” due to Mxene adoption. The efficient CoMoP2 @Mxene@CNTs CE with facile synthesis process is a promising alternative to the expensive Pt CE for DSSCs in the future.