Nickel nanocrystals grown on sparse hierarchical CuS microflowers as high-performance counter electrodes for dye-sensitized solar cells

Three kinds of hierarchical CuS microflowers composed of thin nanosheets have been synthesized by a simple wet chemical method. It is shown that the CuS microflowers provide suitable substrates to grow nickel nanocrystals. The prepared Ni@CuS hybrids combined with conductive glass (FTO) have been used as counter electrodes for dye-sensitized solar cells (DSSCs). The electrode made of the active material of Ni@CuS microflowers with sparsest petals show an optimal photoelectric conversion efficiency of 4.89%, better than those made of single component of Ni (3.39%) or CuS (1.65%), and other two Ni@CuS composites. The improved performances could be ascribed to the synergetic effect of the catalytic effect towards I-3(-)/I- from sparse CuS hierarchical structure and uniformly grown Ni nanocrystals. Besides, the introduced Ni nanocrystals could increase the conductivity of the hybrid and facilitate the transport of electrons. The hybrid Ni@CuS composites serving as counter electrodes have much enhanced electrochemical properties, which provide a feasible route to develop high-active non-noble hybrid counter electrode materials.