Enhanced electron transfer due to rGO makes Ag–CaTiO3@rGO a promising plasmonic photocatalyst

Herein, the synthesis of a new ternary nanocomposite, Ag–CaTiO3@rGO, exhibiting high photocatalytic dye degradation efficiency is reported. The photocatalytic activity of Ag–CaTiO3@rGO was studied under natural sunlight with a model dye pollutant sulforhodamine B. This photocatalyst's high degradation efficiency is attributed to the synergistic effect of plasmon-induced visible light-harvesting due to Ag and enhanced adsorption and electron–transport properties due to rGO. It is found that the Ag-induced surface plasmon characteristics of the nanocomposites are sensitive to rGO concentration. Absorption spectra of the nanocomposites indicated that Ag and rGO enhance and extend the absorbance in the visible region, which is beneficial for creating photo-carriers during the photocatalytic reaction under sunlight. In the X-ray photoelectron spectra, ∼0.7–0.8 eV positive binding energy shift is observed in Ca 2p, Ti 2p, and O 1s peaks of typical Ag–CaTiO3@rGO compared to Ag–CaTiO3 and CaTiO3, indicating that electrons are transferred to the electron acceptor, rGO. The reusability of this photocatalyst Ag–CaTiO3@rGO was analyzed by conducting repeated dye degradation tests. The adsorption characteristics of the designed catalyst followed the Langmuir isotherm model. A model for the plausible mechanism of enhanced sunlight-driven photocatalysis by Ag–CaTiO3@rGO with 7.5 wt% GO is also proposed.