Photocurrent generation and conductivity relaxation in reduced graphene oxide Cd_0.75Zn_0.25S nanocomposite and its photocatalytic activity

We report the photocurrent generation in reduced graphene oxide-cadmium zinc sulfide (RGO-Cd_0.75Zn_0.25S) nano composite material under simulated solar light irradiation, where the photocurrent increases linearly with increasing incident light intensity. We also report the temperature dependent electrical conductivity and conductivity relaxation in RGO-Cd_0.75Zn_0.25S composite. At low frequency, the real part of conductivity is independent of frequency, and above a characteristic crossover frequency, the conductivity decreases with the increase in frequency, which indicates the onset of a relaxation phenomenon. The dc conductivity of the RGO-Cd_0.75Zn_0.25S composite shows Arrhenius behavior. From the scaling of real part of conductivity spectra, we have observed that the dynamic process occurring at different temperatures have the same thermal activation energy. The RGO-Cd_0.75Zn_0.25S composite shows an enhancement of photo catalytic activity in comparison to control sample under simulated solar light irradiation to degrade Rhodamine B. The RGO sheets prolong the separation of photo induced electrons and holes in Cd_0.75Zn_0.25S, which hinder the electron-hole recombination and subsequently enhances the photocurrent generation and photocatalytic activity under simulated solar light irradiation.