Towards visible light driven photoelectrocatalysis for water treatment: Application of a FTO/BiVO4/Ag2S heterojunction anode for the removal of emerging pharmaceutical pollutants

Abstract

Pharmaceuticals have been classified as emerging water pollutants which are recalcitrant in nature. In the quest to find a suitable technique in removing them from contaminated water, photoelectrocatalytic oxidation method has attracted much attention in recent years. this report examined the feasibility of degrading ciprofloxacin and sulfamethoxazole through photoelectrocatalytic oxidation using fto-BiVo 4 /Ag 2 S with p-n heterojunction as anode. BiVo 4 /Ag 2 S was prepared through electrodeposition and successive ionic layer adsorption/reaction on fto glass. Structural and morphological studies using XRD, SEM, EDS and diffusive reflectance UV-Vis confirmed the successful construction of p-n heterojunction of BiVo 4 /Ag 2 S. electrochemical techniques were used to investigate enhanced charge separation in the binary electrode. the fto-BiVo 4 /Ag 2 S electrode exhibited the highest photocurrent response (1.194 mA/cm −2 ) and longest electron lifetime (0.40 ms) than both pristine BiVo 4 and Ag 2 S electrodes which confirmed the reduction in recombination of charge carriers in the electrode. Upon application of the prepared FTO-BiVO 4 /Ag 2 S in photoelectrocatalytic removal of ciprofloxacin and sulfamethoxazole, percentage removal of 80% and 86% were achieved respectively with a low bias potential of 1.2 V (vs Ag/AgCl) within 120 min. The electrode possesses good stability and reusability. the results obtained revealed BiVo 4 /Ag 2 S as a suitable photoanode for removing recalcitrant pharmaceutical molecules in water. open Scientific RepoRtS | (2020) 10:5348 | https://doi.org/10.1038/s41598-020-62425-w www.nature.com/scientificreports www.nature.com/scientificreports/ Scientific RepoRtS | (2020) 10:5348 | https://doi.org/10.1038/s41598-020-62425-wwww.nature.com/scientificreports www.nature.com/scientificreports/ the BiOI electrode. The electrode was subsequently placed in a furnace at 420 °C for 1 h. Finally, excess V 2 O 5 was washed off from the electrode by soaking it in 1.0 M NaOH solution for 40 min. The resulting BiVO 4 /FTO electrode was thoroughly washed with deionized water and dried at room temperature. In order to obtain BiVO 4 / Ag 2 S electrode, the prepared FTO/BiVO 4 was dipped in a 0.3 M AgNO 3 solution for 10 s and followed by immersion in 0.3 M Na 2 S for 10 s. The cycle was repeated ten times and the obtained electrode was rinsed with deionized water and air dried at room temperature for 24 h. Scientific RepoRtS |(2020) 10:5348 | https://doi.org/10.1038/s41598-020-62425-w www.nature.com/scientificreports www.nature.com/scientificreports/ conclusion A photoanode of BiVO 4 /Ag 2 S with p-n heterojunction was successful prepared through electrodeposition and successive ionic layer adsorption/reaction method on FTO glass. The construction of p-n heterojunction reduced the common problem of rapid recombination of photogenerated electron-hole pairs. This was confirmed through the photocurrent response of BiVO 4 /Ag 2 S (1.194 mA/cm −2 ) which was higher than both pristine BiVO 4 (0.802 mA/cm −2 ) and...

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