Preparation and characterisation of a Bi₂WO₆/ZnFe₂O₄ heterojunction photoanode for photoelectrocatalytic degradation of ciprofloxacin in water

Towards understanding the effect of light and voltage on a Bi₂WO₆/ZnFe₂O₄ heterojunction photoanode for use in wastewater treatment, we report the synthesis and application of a Bi₂WO₆/ZnFe₂O₄ heterojunction for the degradation of ciprofloxacin in synthetic and real wastewater. The pristine and heterojunction semiconductors were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence, and transmission electron microscopy. Electrochemical impedance spectroscopy, chronoamperometry, photoluminescence, and Mott-Schottky were used to study the electrochemical and photoelectrocatalytic properties of the pristine and heterojunction photoanodes. The Bi₂WO₆/ZnFe₂O₄ showed enhanced electro and photocatalytic properties deduced from the lowest charge transfer resistance and highest photocurrent response. The high degradation of the pollutant at the heterojunction was attributed to the type-(II) mechanism that allowed direct oxidation of the pollutant by the holes. The Bi₂WO₆/ZnFe₂O₄ heterojunction demonstrated excellent stability and reusability up to seven cycles. This work is a demonstration of the effect of heterojunction photoanode formation on the performance of PEC in the removal of organic pollutants in water.