Improving the catalytic performance of Ni 3 S 4 -PtCo heteronanorods via Mott-Schottky effect toward the reduction of iodine couples in dye-sensitized solar cells

Metal-semiconductor based Mott-Schottky (M-S) heterojunctions combining two or more functionalities in one unit can effectively improve their catalytic activity and durability due to the electronic coupling effects between distinct components. Although tremendous progress has been made in structure fabrication, controllable synthesis of one-dimensional (1D) M-S heterojunction and its application as electrocatalysts is still lacking. Herein, uniform and well-defined 1D Ni3S4-PtCo heteronanorods are synthesized via a facile solution method and employed as counter electrode (CE) catalyst in the dye-sensitized solar cells (DSSCs). By exploiting the benefits of both structural and compositional characteristics, namely, the direct electrical pathways of 1D nanostructure, optimized work function of metal alloy as well as the synergistic effect between Ni3S4 and PtCo, the as-designed Ni3S4-PtCo heteronanorods exhibit excellent catalytic activity and stability toward the reduction of triiodide in DSSCs. A DSSC with Ni3S4-PtCo achieves a high power conversion efficiency of 8.66% under AM1.5G illumination (100 mW cm−2), higher than that of pristine Pt-based device (8.12%). Moreover, the fast activity onset and relatively long stability further demonstrate that the Ni3S4-PtCo heteronanorod is a promising alternative to Pt in DSSCs. Considering the diversity of structures and components in heterostructures, the strategy presented here can be extended for synthesizing other well-defined 1D M-S heterojunctions, which may be used in the fields of catalysis, energy conversion and storage.