Growth of carbon nanotubes over transition metal loaded on Co-SBA-15 and its application for high performance dye-sensitized solar cells

Abstract

High quality MWCNT material based counter electrodes for dye-sensitized solar cells (DSSCs) were fabricated using a novel route and their power-conversion efficiency was studied. Transition metals such as Fe, Ni, V, Mn, Cr, Mo, Ru and Pd loaded on Co-SBA-15 molecular sieves were synthesized and tested for the formation of MWCNTs at different temperatures (700–1000 °C) using a chemical vapour deposition (CVD) method. This result showed that Fe/Co-SBA-15 and Ru/Co-SBA-15 systems are highly suitable sources as catalysts for the growth of MWCNTs compared to other bimetallic systems. TEM and Raman spectroscopy revealed that the synthesized MWCNTs were of high quality and well-graphitized. The MWCNTs were applied to the counter electrode of dye-sensitized solar cells (DSSCs). Cyclic voltammetry measurements proved that the catalytic activity of the MWCNT coated electrode towards I₃⁻ reduction was significantly higher than that of the Pt coated electrode. Electrochemical impedance measurement of the symmetric cell revealed that the charge transfer resistance of the MWCNT coated electrode was less than that of the Pt coated electrode. Due to the low charge transfer resistance of the synthesized MWCNTs, the DSSCs with MWCNTs as counter electrode gave better photoelectric performance compared to DSSCs equipped with a conventional Pt counter electrode.