Visible light driven photoelectrocatalysis on a FTO/BiVO4/BiOI anode for water treatment involving emerging pharmaceutical pollutants

Highlights: • A solar active BiVO₄/BIOI heterojunction photoanode is prepared for water treatment. • BiVO₄/BIOI heterojunction was prepared in a two-step electrodeposition on FTO glass. • Mott-Schottky plot and photocurrent response study confirmed a p-n heterojunction. • Photoelectrocatalytic degradation of acetaminophen and ciprofloxacin was achieved. -- Abstract: Contamination of water bodies by harmful and recalcitrant organic substances is a global challenge. A promising technique for removing these organics from water/wastewater is photoelectrocatalytic oxidation which combines electrolytic and photocatalytic processes. Herein, we report the degradation of emerging pharmaceutical pollutants – acetaminophen and ciprofloxacin – at a BiVO₄/BiOI photoanode under visible irradiation via photoelectrocatalytic process. The BiVO₄/BiOI was electrodeposited on a FTO glass and characterised with XRD, SEM, EDS and diffusive reflectance UV–Vis. The results confirmed the successful electrodeposition of BiVO₄/BiOI on the glass substrate. Mott-Schotty plots confirmed the formation of p-n heterojunction between the two electrodeposited semiconductors. The calculated charge carrier density of BiVO₄/BiOI was higher than those of pristine BiVO₄ and BiOI. The binary electrode also gave improved photocurrent response compared with unitary electrodes. Degradation efficiencies of 68% and 62% were achieved upon the application of the prepared photoanode (FTO/BiVO₄/BiOI) in PEC degradation of acetaminophen and ciprofloxacin respectively using a bias potential of 1.5 V within 2 h. A synthetic pharmaceutical wastewater containing a mixture acetaminophen and ciprofloxacin was also treated with the photoanode. The photoanode was also effective in the degradation of dye. The findings of this study suggest the suitability of the prepared photoanode for the photoelectrocatalytic degradation of organic pharmaceutical pollutants in wastewater.