One-step growth of CoNi2S4 nanoribbons on carbon fibers as platinum-free counter electrodes for fiber-shaped dye-sensitized solar cells with high performance: Polymorph-dependent conversion efficiency

Both the CoNi2S4 nanoribbon on carbon fibers (CoNi2S4 nanoribbon-CF) and CoNi2S4 nanorod on carbon fibers (CoNi2S4 nanorod-CF) were fabricated as counter electrodes (CEs) for fiber-shaped dye-sensitized solar cells (FDSSCs). The CoNi2S4 nanorod-CF-based FDSSC with high conversion efficiency of 7.03%, comparable or even superior to Pt wire CE (6.45%). However, the CoNi2S4 nanorod-CF-based counterpart with conversion efficiency of 4.10%, demonstrates that the high conversion efficiency of the CoNi2S4 nanoribbon-CF-based FDSSC is not only strongly dependent on the intrinsic properties of the selected CE species, but also closely related to their polymorph structure. The different exposed crystal facet is suggested responsible for the significant distinction of conversion efficiency between two one-dimensional CoNi2S4 nanostructures. This work also gives some clues to the future development and rational design of ternary nickel-cobalt chalcogens potentially used in fiber-shaped fuel cells or supercapacitors. (C) 2014 Elsevier Ltd. All rights reserved.