Visible-light-driven photocatalytic degradation of tetracycline by S/CeO2 Co-doped Bi2WO6 heterojunction composites: from bandgap engineering to practical water treatment

Abstract

Photocatalytic technology represents a promising approach for environmental remediation with broad application prospects. This study employs high-temperature calcination and hydrothermal methods to fabricate bismuth tungstate-based ternary composite photocatalysts, followed by comprehensive characterization of their morphological, structural, optical and photoelectrochemical properties. Results reveal that the ternary composite photocatalyst displays a distinctive flower-like architecture, which originates from the synergistic co-doping of sulfur (S) and cerium dioxide (CeO₂). The S/CeO₂ co-doping strategy effectively narrows the bandgap to 3.18 eV, representing a reduction from pristine Bi₂WO₆ (3.58 eV). This modification substantially enhances charge carrier mobility and electron–hole separation efficiency, leading to markedly improved photocatalytic performance. The system parameters including initial tetracycline concentration, solution pH, and catalyst loading undergo systematic optimization. Under optimized conditions, the composite achieves 99.7% tetracycline degradation efficiency within 120 minutes of visible-light exposure. Flow-through experiments using authentic water samples further demonstrate the material maintained high photocatalytic activity in complex aqueous matrices, highlighting its practical potential for water remediation applications.