Surface-Nitrided Nickel with Bifunctional Structure As Low-Cost Counter Electrode for Dye-Sensitized Solar Cells

Surface-nitrided nickel foil and particle films were prepared through the nitridation of metallic nickel foil and particle films in ammonia atmosphere. The microstructure of the obtained surface nitrided nickel foil and particle films was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It is shown that only a thin nitrided layer can be formed on the surface of the metallic nickel after the nitridation, while the bulk phase still remains the stable metallic nickel structure. Surface-nitrided nickel film is directly investigated as a low cost counter electrode material for dye-sensitized solar cells. Clearly, the surface-nitrided nickel layer shows high electrocatalytic activity for reduction of triiodide, and the bulk metallic phase provides good electrical conductivity. Correspondingly, the assembly of these two important functions makes surface-nitrided nickel present an excellent photovoltaic performance of dye-sensitized solar cells (DSSCs), competing with the conventional Pt counter electrode. Therefore, the surface-nitrided Ni with a bifunctional structure as presented in this work is a potential low-cost alternative to the expensive noble metal Pt in future applications of dye-sensitized solar cells.