Electrochemical Formation of Pt Nanoparticles on Multiwalled Carbon Nanotubes: Useful for Fabricating Electrodes for Use in Dye-Sensitized Solar Cells

In the present work, hydrophobic multiwalled carbon nanotubes (MWCNTs) were modified, by the substitution of poly(acrylic acid) (PAA) and inorganic acids (H2SO4 and HNO3), as hydrophilic MWCNTsPAA and MWCNTsAcid. The modified nanotubes were dispersed in an ethanol solution containing 3,4-ethylenedioxythiophene (EDOT). PtCl6 2− ions were reduced electrochemically to platinum (Pt) by electrons supplied by the polymerization of EDOT. The reduced platinum was deposited as Pt nanoparticles (nps) on the MWCNTs, to form MWCNTsPAA-PEDOT-Pt(nps) and MWCNTsAcid-PEDOT-Pt(nps). Electrostatic interactions between carboxyl groups on the MWCNTs and EDOT monomers allowed the Pt(nps) to be adsorbed onto the MWCNTs. The quantity of Pt(nps) associated with the MWCNTsPAA-PEDOT-Pt(nps) composite was greater than that with the MWCNTsAcid-PEDOT-Pt(nps) composite, due to the substitution of the carboxyl group in MWCNTsPAA. UV−visible spectroscopy was used to measure the reducing ability of EDOT. FTIR-ATR, TGA, ZETA potential analysis, SEM, and TEM were used to analyze the morphologies and properties of the MWCNTsPAA-PEDOT-Pt(nps) and MWCNTsAcid-PEDOT-Pt(nps) electrodes: the cell efficiencies of these new materials, when used to fabricate composite counter electrodes in dye-sensitized solar cells (DSSCs), were found to be 4.78% and 2.71%, respectively.