Ultrasound-assisted synthesis of strontium-bismuth titanate and its application in environmental remediation.

The pollution of water and air in our world has become a global challenge that requires innovative and sustainable strategies. In this work, the ultrasound-assisted synthesis of bare strontium titanate (STO) and bismuth-doped STO (Bi-STO) is proposed to enhance the photocatalytic and piezocatalytic performance of STO in environmental remediation. The materials were fully characterized using various physicochemical techniques, such as XRD, XPS, BET, UV-DRS, PL, SEM, TEM, and piezoelectric measurements, to assess their structural, optical, morphological and piezoelectric properties. The results revealed that Bi-STO induced lattice distortion, reduced band gap energy, enhanced charge separation efficiency, and improved piezoelectricity respect STO. The activity of the as-prepared materials was investigated in the field of wastewater remediation through three different approaches: photocatalysis, piezocatalysis, and piezo-photocatalysis, applied in the ibuprofen (IBU) degradation, as well as in the photocatalytic removal of volatile organic compounds (VOCs) and nitrogen oxides (NOx) under different irradiation conditions. The results demonstrated that Bi-STO exhibited superior catalytic performance respect STO, achieving up to 60% IBU degradation under piezo-photocatalysis, thanks to the synergy between light and ultrasound. Furthermore, Bi-STO enabled the complete removal of ethanol and NOx and more than 90% propionic acid reduction under UV irradiation. This study demonstrates the potential of Bi-STO as an efficient catalyst for environmental remediation, offering an alternative to conventional materials. The present work opens new possibilities for optimizing and improving wastewater treatment and air purification.