Transition-metal nitride nanoparticles embedded in N-doped reduced graphene oxide: superior synergistic electrocatalytic materials for the counter electrodes of dye-sensitized solar cells

Abstract

Transition-metal nitride TMN (MoN, TiN, VN) nanoparticle–N-doped reduced graphene oxide (NG) hybrid materials are presented as alternative low-cost platinum-free counter electrodes for dye-sensitized solar cells (DSCs). A high concentration of active catalytic sites and an efficient electronic/ionic mixed conducting network generated by the nanostructure afford promising synergistic effects on the electrocatalytic characteristics for triiodide reduction. On the basis of these advantages, these nanostructured hybrid based cells deliver significantly enhanced photovoltaic performances. The efficiencies of devices employing VN–NG, TiN–NG and MoN–NG are 6.279%, 7.498% and 7.913% respectively, which are comparable with that of Pt devices (7.858%). Such a design strategy is facile, cost effective and versatile, thus it may be extended to other inexpensive platinum-free counter electrode materials.