Nano-designed λ-CaCO₃@rGO photo-catalyst for effective adsorption and simultaneous removal of organic pollutant

Well-dispersed λ-CaCO₃ thin layers @ rGO as photo-catalyst for the removal of organic pollutant was synthesized by hydrothermal treatment. The coordination between the functional groups on graphene and Ca²⁺ ion provides the path for the nucleation of CaCO₃ and form a vander waal force with graphene sheet. The presented λ-CaCO₃@rGO nanocomposite was characterized by using X-ray diffraction, FTIR, field-emission scanning electron microscopy and high resolution transmission electron microscopy analysis. The photo-catalytic activities of as-prepared CaCO₃ nanoparticles, rGO and λ-CaCO₃@rGO nanocomposite were evaluated by the photo-catalytic degradation of methyl orange in aqueous solutions under visible light irradiation. Alone, it is expected, that CaCO₃ and graphene do have insignificant photo-catalytic activity due to optical properties of both materials. However, synthesis of λ-CaCO₃ thin layers @ rGO shows good performance due to alteration of band gap. Therefore, compared to pristine CaCO₃ nanoparticles and rGO, the λ-CaCO₃@rGO photo-catalysts showed significant enhancement in photocatalytic activity.