Cyclic voltammetric deposition of discrete nickel phosphide clusters with mesoporous nanoparticles on fluorine-doped tin oxide glass as a counter electrode for dye-sensitized solar cells

Abstract

A monolayer of widely spaced nickel phosphide clusters with mesoporous nanoparticles was directly formed on fluorine-doped tin oxide glass by cyclic voltammetric deposition as a counter electrode for a dye-sensitized solar cell (DSC). Cyclic voltammetry included the anodic dissolution of Ni-rich regions following the cathodic deposition, leading to the formation of discrete clusters with mesoporous nanoparticles. After annealing at 500 °C, the nickel phosphide could be characterized as Ni₅P₄ and its electrocatalytic behavior was evaluated by cyclic voltammetry and electrochemical impedance in an iodide/triiodide system. The mesoporous Ni₅P₄ catalyst prepared by the cyclic voltammetric method exhibits good electrocatalytic ability towards the iodide/triiodide redox couple as a result of its low charge-transfer resistance and diffusion impedance. The photoelectron conversion efficiency of a DSC employing the Ni₅P₄ counter electrode could reach 7.6%, which is higher than that of a DSC employing a Pt nanocluster counter electrode (7.2%). The successful utilization of ultra-low loading of the Ni₅P₄ catalyst for DSCs makes the application of such material more economically viable.