Three-dimensional nanostructured BiOI/WO3 photoelectrode enhances photoelectrocatalytic degradation activity of ciprofloxacin

Three-dimensional BiOI/WO 3 composite photoelectrodes were synthesized using a solvothermal method. Material characterization showed good crystallinity and purity, with BiOI nanosheets interlaced and firmly attached to WO 3 nanorods to form a three-dimensional structure. Using 2-methoxyethanol as the solvent, ultra-thin BiOI nanosheets were successfully synthesized. These nanosheets were closely combined with WO 3 nanorods and formed a large number of interlaced pore structures on their surfaces. As a result, the specific surface area was larger and the active sites were more numerous. The photoelectrodes utilized light with wavelengths below approximately 540 nm for catalytic degradation. The photoelectrode with an appropriate BiOI loading ratio (BIW-1.2) exhibited the strongest photoelectric performance and photoelectrocatalytic (PEC) degradation activity. When a 1.2 V bias was applied, a 20 mg/L ciprofloxacin solution was degraded with an efficiency of 97.1% after 3 h. The catalyst also maintained good stability over five cycles. Analysis of the band structure and reactive species indicated that the Z-scheme charge-migration mechanism, together with the applied bias, promoted efficient separation of photogenerated charges. The interlaced three-dimensional structure provides strong adsorption capacity, abundant catalytic sites, and high light-utilization efficiency, which together increase radical generation and enhance PEC performance.