Synthesis of ternary nickel cobalt phosphide nanowires through phosphorization for use in platinum-free dye-sensitized solar cells

Abstract

Nickel cobalt phosphide nanowires are fabricated on titanium foil through phosphating reaction from their nickel and cobalt hydroxide precursors, which are employed as the counter electrode materials for the dye-sensitized solar cell. Electrochemical investigations demonstrate that the ternary nickel cobalt phosphide counter electrode exhibits higher catalytic activity than that of the binary nickel phosphide and cobalt phosphide counter electrodes, which is due to that the introduction of two transition metals can adjust the valence electron and provide two electron donating active sites. The dye-sensitized solar cell with the ternary nickel cobalt phosphide counter electrode achieves a competitive photoelectric conversion efficiency of 8.01%, which is higher than that of the binary nickel phosphide (3.73%) and cobalt phosphide (2.80%) counter electrodes under the same conditions and comparable photovoltaic performance to that using the conventional platinum counter electrode (8.69%) for the dye-sensitized solar cell.