Improving photocatalyst performance of CdTiO3 via binary Co@CdTiO3 and ternary Co@CdTiO3@S nanocomposites utilizing synergistic effect of adsorption-photocatalytic under sunlight

Abstract

Binary and ternary nanocomposites of Co@CdTiO 3 (Co@CTO) and Co@CdTiO 3 @S (Co@CTO@S) were synthesized via the hydrothermal method and used as photocatalysts under visible-light. The structural properties, morphology, and size of the nanocomposites were evaluated by XRD, Fe-SEM, and TEM techniques, respectively. The impurities and chemical composition of the samples were characterized by FT-IR, Map, and EDX. BET analysis was also utilized to determine the specific surface area, total pore volume, and average pore diameter of the nanocomposites. The pore size distribution of the Co@CTO and Co@CTO@S was obtained through the BJH method. Optical properties were investigated via DRS spectra and the results showed a reduction in the band-gap energy due to the penetration of cobalt and sulfur in the structure of CdTiO 3 (CTO). Zeta potential measurements were utilized for determining the surface charge showed the change from + 24 mv to − 25 mv within the pHs range of 2–10. The photocatalytic performance of the CTO, Co@CTO, and Co@CTO@S was investigated by UV-Vis spectroscopy. The Co@CTO@S nanocomposite offered the highest photocatalytic performance in degrading Crystal-Violet (CV) dye as a pollutant (> 96% during 60 min adsorption and 30 min solar irradiation). The main responsible factors for this gain could be considered as: higher surface area, the synergistic effect of the adsorption-photodegradation process, as well as reducing the band-gap energy. Kinetics studies showed that the degradation of CV by Co@CTO@S followed the pseudo-second-order kinetics with R 2 = 0.9532. Its degradation rate was 22x and 225x faster than that of Co@CTO and CTO, respectively. The investigation of reusability and stability revealed that Co@CTO@S photocatalyst remained stable after five consecutive cycles as tested by the leaching process. • Binary Co@CdTiO3 and ternary Co@CdTiO3@S nanocomposites synthesized by hydrothermal and hydrothermal/solid-state respectively. • The band-gap energy of CdTiO3 reduced due to the influence of cobalt and sulfur in the crystal lattice. • Co@CdTiO3@S nanocomposites degraded azo dye of Crytal-Violet better than Co@CdTiO3 and CdTiO3 under sunlight. • Synergistic effect of cationic and anionic phases of Co and S enhanced the photodegradation of Crystal-Violet. • Co@CdTiO3@S nanocomposites decomposed Crystal-Violet 22x and 255x times faster than Co@CdTiO3 and CdTiO3, respectively.