Enhanced piezo-induced photocatalytic activity of BaTiO₃/Cd_0.5Zn_0.5S S-scheme heterojunction for water pollution remediation: Performance, degradation pathway, and toxicity evaluation

Pharmaceutical pollutants in water pose a threat to ecosystems and human health by disrupting aquatic life, contributing to antibiotic resistance, and causing hormonal imbalances and increased disease susceptibility in humans. Thus, we report the fabrication of a novel BaTiO₃/Cd_0.5Zn_0.5S heterojunction for the piezo-photocatalytic degradation of ciprofloxacin (CIP) in wastewater. The BaTiO₃/Cd_0.5Zn_0.5S was synthesized via solvothermal deposition of Cd_0.5Zn_0.5S (CZS) onto BaTiO₃ (BTO) nanorods. This heterojunction exhibited superior photocatalytic activity, degrading ciprofloxacin ∼85 % and ∼3 times more effectively than pristine CZS and BTO, respectively. Its enhanced piezo-photocatalytic performance is attributed to the induced piezoelectric effect, sulfur defects, internal electric field, and S-Scheme charge transfer. Scavenger studies identified h⁺, O₂^-, and ^•OH as the major reactive species responsible for CIP degradation. After 90 min, the extent of mineralization reached 46.7 %, and intermediate products were evaluated using Ultra-performance liquid chromatography-mass spectrometry(UPLC-MS), with their toxicity assessed using the Toxicity Estimation Software Tool (T.E.S.T). The catalyst demonstrated excellent stability over four reuse cycles. The successful development of the BTO/CZS heterojunction holds significant promise for advancing environmentally sustainable water treatment and pollution remediation technologies.