Pt-NP–MWNT nanohybrid as a robust and low-cost counter electrode material for dye-sensitized solar cells

Pt-NPs hybridized inside and outside multi-walled carbon nanotubes (MWNTs) were successfully synthesized using a liquid plasma system with 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide under atmospheric pressure. The Pt-NPs with a size of 3-4 nm were stably and uniformly hybridized on both inner and outer surfaces of the MWNTs. The nanohybrid materials were applied to the counter electrode of dye-sensitized solar cells (DSCs). Electrochemical impedance measurement of DSCs revealed that the charge-transfer resistance of a MWNT-Pt nanohybrid-coated electrode was less than that of Pt-sputtered and MWNT-coated electrodes. Due to the low charge-transfer resistance, the DSC exhibited fairly improved energy conversion efficiency compared to the DSCs equipped with Pt-sputtered and MWNT-coated counter electrodes.