Enhancement of photovoltage generation, storage capacity and energy conversion efficiency of photoelectrochemial cell of mixed dye system: Role of oxidized multi-walled carbon nanotubes

In the crisis of fast diminishing fossil fuels, looking for alternative energy sources by utilizing solar energy has the highest research priority and engineered nanoparticles play a very important role here.

Using a specially designed photoelectrochemical cell and  a mixture of  two dyes, Phenosaffranine (PSF) and Azure C (AZC) conjugated with oxidized multi-walled carbon nanotubes (OMWCNTs) we have been able to generate photovoltage  of  reasonably high magnitude (763 mV). The storage time is also quite high ~ 66 hrs. The photovoltage cycle was reproducible upon further illumination. Energy conversion efficiency (η%) of the cell has been calculated for the system (η% = 4.33).

Spectral studies show that with addition of OMWCNTs to a fixed concentration of PSF and  AZC solution, the absorbance increases throughout the spectral range. FTIR spectrum reveals that there is no chemical change in the mixed system indicating that only the dyes got adsorbed on the side walls on the OMWCNTs. From fluorescence spectral study, it has been seen that while fluorescence intensity of PSF quenches with addition of  AZC, which does not have any fluorescence of its own, the  intensity regains with addition of  OMWCNTs. This emphasizes the role of oxidized multi-walled carbon nanotubes in the performance of photoelectrochemical cell of mixed dye system.