Novel Co and Ni metal nanostructures as efficient photocatalysts for photodegradation of organic dyes

Novel Co and Ni metal nanostructured photocatalysts were synthesized using simple hydrothermal method and studied their photocatalytic activity towards degradation of Alizarin red S (ARS). From the UV-visible absorbance spectra, the observed peak at ∼300 nm confirms zero-valent transition metals (ZVTM). Polyvinylpyrrolidone (PVP) directs the growth of particle shape and the size of samples resulted in different morphology. PL spectra of Co sample showed lower the PL emission over Ni sample. Co sample exhibited a higher photocurrent and absorbance coefficient due to concentrating the incident photon energy on the Co particles. The electrical energy and rate constant influence the photocatalytic activity. Co 3+ ions and produce reactive hydroxyl free radicals and takes place both +2 and +3 oxidation state for continues cyclic system. In addition, an in situ creation of hydroxyl free radicals is the reason for the fast removal of ARS.