Synthesis and Characterization of a Perovskite Nanocomposite of CdTiO3@S with Orthorhombic Structure: Investigation of Photoluminescence Properties and Its Photocatalytic Performance for the Degradation of Congo Red and Crystal Violet Under Sunlight

Abstract

Perovskite phase of CdTiO3 nanoparticles (CTO NP) was synthesized by a simple hydrothermal method at 180 °C for 12 h and 24 h. It was then annealed at 1050 °C for 3 h. Perovskite CdTiO3@S nanocomposites (CTO@S NCs) with a needle-like morphology were synthesized by mixing CTO and S powders at 600 °C for 2 h. The obtained samples were characterized by Fourier transform-infrared (FT-IR), X-ray diffraction (XRD), Thermogravimetric/differential scanning calorimetry analysis (TGA–DSC), Transmission electron microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), Zeta potential, N2 adsorption–desorption isotherms, and UV–visible diffuse reflectance spectroscopy (DRS). The optical, photoluminescence, and photocatalytic properties were investigated further. The diffuse reflection adsorption spectrum indicated that absorption peaks of the CTO@S NCs with the various S contents (5–30%) shifted towards the visible region. Tauc’s plots presented the band gap energy values for direct transitions, whereby 2.98 eV and 2.51 eV were obtained for CTO and CTO@S NCs (30), respectively. Photoluminescence spectra excited at both 370 nm and 400 nm wavelengths revealed a decline in the intensity of the emission spectra and had a minor red-shift at λex = 370 nm. The photocatalyst performance was investigated for degradation of Crystal violet (CV) and Congo red (CR) dyes under natural sunlight. The results showed that the degradation efficiency of CTO@S NCs was better than that of CTO NP in both dyes. Kinetics studies indicated CTO@S NCs fallowed Pseudo-first- order kinetics for CV degradation and pseudo-second-order kinetics for CR degradation.