Photocatalytic degradation and adsorption of Rhodamin B dye on CdSe and CdS nanoparticles

Herein, we study the adsorption and photodegradation of Rhodamin B (RhB) dye on surfaces of CdSe and CdS nanoparticles. First, the nanoparticles were synthesized and characterized. Then the photocatalytic degradation was carried out in a glass photoreactor equipped with a Tungsten lamp. The results showed that the degradation kinetics obeys the Langmuir–Hinshelwood model. Therefore, the values of adsorption equilibrium-constants and the kinetics rate-constants were calculated. The results show that the photocatalytic degradation of RhB under visible light irradiation using CdSe nanoparticles has more efficiency than using CdS nanoparticles. To obtain the adsorption properties, the (0001) facet of CdSe and CdS nanoparticles were modeled as Cd19Se27H16 and Cd19S27H16 clusters, respectively. Then, the adsorption properties were studied using density functional theory methods and the values of adsorption energy were calculated. The calculations show that the adsorption energy of RhB on CdSe surface is larger than the adsorption energy of RhB on CdS surface. The results show that RhB prefers to be adsorbed molecularly (non-dissociative) on the CdSe and CdS surfaces.