0D/2D/0D heterostructure of SrTiO3/BiOBr/Cu2O double Z-scheme for elimination sulfadiazine: Insight into performance, mechanism, and toxicity assessment

Z-scheme heterojunction photocatalysts, notable for their efficient generated charge separation performance, have attracted significant attention for solving environmental pollution. Herein, novel 0D/2D/0D SrTiO3/BiOBr/Cu2O double Z-scheme ternary heterojunction are fabricated via a simple synthetic strategy. The double Z-scheme heterojunction facilitates the separation and migration of photogenerated charges, as confirmed by the photoluminescence (PL), transient photocurrent response (I–T), and electrochemical impedance spectrum (EIS). The catalyst presented in this work exhibits excellent photocatalytic performance under visible light, degrading 94.3% of sulfadiazine (SDZ) in 30 min. Moreover, it has a rate constant that is 1.95 and 2.0 times greater than that of SrTiO3/BiOBr and BiOBr, respectively. The X-ray photoelectron spectroscopy valence band (VB–XPS) and Mott–Schottky (M–S) measurement results provide further insights into the double Z-scheme heterojunction charge-transfer mechanism of Cu2O/BiOBr/SrTiO3. According to density functional theory (DFT) calculations, free radical capture tests, and identification based on liquid chromatography-mass spectrometry (LC–MS), the reaction species (h+, •OH, and •O2–) are crucial in the photocatalytic degradation of SDZ and its intermediates. Furthermore, the toxicity of the intermediates was analyzed using mung bean sprouting experiment and Toxicity Estimation Software Tool (T.E.S.T) software.