HyeLan An

Fabrication of Octahedral Co 3 O 4 /Carbon Nanofiber Composites for Pt-Free Counter Electrode in Dye-Sensitized Solar Cells

Octahedral Co3O4/carbon nanofiber (CNF) composites are fabricated using electrospinning and hydrothermal methods. Their morphological characteristics, chemical bonding states, and electrochemical properties are used to demonstrate the improved photovoltaic properties of the samples. Octahedral Co3O4 grown on CNFs is based on metallic Co nanoparticles acting as seeds in the CNFs, which seeds are directly related to the high performance of DSSCs. The octahedral Co3O4/CNFs composites exhibit high photocurrent density (12.73 mA/m2), superb fill factor (62.1 %), and excellent power conversion efficiency (5.61 %) compared to those characteristics of commercial Co3O4, conventional CNFs, and metallic Co-seed/CNFs. These results can be described as stemmnig from the synergistic effect of the porous and graphitized matrix formed by catalytic graphitization using the metal cobalt catalyst on CNFs, which leads to an increase in the catalytic activity for the reduction of triiodide ions. Therefore, octahedral Co3O4/CNFs composites can be used as a counter electrode for Pt-free dye-sensitized solar cells.

Spindle-shaped Fe 2 O 3 Nanoparticle Coated Carbon Nanofiber Composites for Low-cost Dye-sensitized Solar Cells

Carbon nanofiber (CNF) composites coated with spindle-shaped nanoparticles (NPs) are fabricated by a combination of an electrospinning method and a hydrothermal method, and their morphological, structural, and chemical properties are measured by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. For comparison, CNFs and spindle-shaped NPs are prepared by either an electrospinning method or a hydrothermal method, respectively. Dye-sensitized solar cells (DSSCs) fabricated with the composites exhibit enhanced open circuit voltage (0.70 V), short-circuit current density (), fill factor (61.30%), and power conversion efficiency (5.52%) compared to those of the CNFs (0.66 V, , 51.96%, and 3.97%) and spindle-shaped NPs (0.67 V, , 50.17%, and 3.86%). This performance improvement can be attributed to a synergistic effect of a superb catalytic reaction of spindle-shaped NPs and efficient charge transfer relative to the one-dimensional nanostructure of the CNFs. Therefore, spindle-shaped -NP-coated CNF composites may be proposed as a potential alternative material for low-cost counter electrodes in DSSCs.