Reduction of 4-Nitrophenol using electrocatalytic ZnS nanoparticles for counter electrode application in dye-sensitized solar cells

Polycrystalline ZnS nanoparticles of c.a 5 nm were synthesized by simple hydrothermal method. X-ray diffraction analysis confirms the formation of cubic zinc blende phase of ZnS. HRSEM image reveals the sample is composed of agglomerated trigonal flake shaped ZnS nanoparticulates. UV-Visible absorption spectrum of ZnS ensures the absorption maximum at 340 nm and its band gap energy is found to be reduced (3.2 eV) owing to its surface light scattering effect. Nyquist plot of ZnS nanoparticles show decrease in electrical resistance with increasing the applied potential resulting in increased conductivity. The fast reduction process of n-nitrophenol (4-NP) into n-aminophenol (4-AP) reveals a high catalytic behavior of ZnS. Hence, the prepared ZnS nanoparticles with high electrical conductivity and catalytic activity can be useful for counter electrode application in DSSC.