2D nanosheet CoOx/BiVO4 heterojunction for promoting peroxysulphate activation: Performance and mechanistic

Bisphenol A (BPA) is an emerging organic pollutant that can disturb endocrine systems at trace levels in water. This study constructed a photocatalyst of cobalt oxide modified bismuth vanadate (CoO x ${}_{\mathrm{x}}$ /BiVO 4 ) coupled with peroxymonosulfate (PMS) oxidation system to investigate its photocatalytic mechanism for degrading BPA in wastewater. The CoO x ${}_{\mathrm{x}}$ /BiVO 4 photocatalyst was fabricated through a precipitation-hydrothermal method and systematically characterized. The results showed that modifying BiVO 4 with CoO x ${}_{\mathrm{x}}$ significantly improved the separation and migration efficiency of photogenerated electron–hole pairs, thereby enhancing the photocatalytic activity of the system. Through active species trapping experiments using different scavengers, singlet oxygen ( 1 O 2 ) and sulfate radicals (SO 4 − ⋅ ${}^{-}\mathit{\cdot }$ ) were identified as the predominant reactive oxygen species responsible for BPA degradation. BPA photocatalytic reaction intermediates were analyzed using HPLC-MS, which proposed three possible degradation pathways: (1) Initial hydroxylation of BPA by SO 4 − ⋅ ${}^{-}\mathit{\cdot }$ and ⋅ $\mathit{\cdot }$ OH radicals; (2) Ring-opening oxidation of hydroxylated intermediates into carboxylic acids; (3) Further mineralization of all intermediates into CO 2 and H 2 O by 1 O 2 and ⋅ $\mathit{\cdot }$ OH. In summary, the CoO x ${}_{\mathrm{x}}$ /BiVO 4 -PMS system provides an efficient and promising technology for eliminating trace BPA in wastewater via synergistic effects of SO 4 − ⋅ ${}^{-}\mathit{\cdot }$ and 1 O 2 . Further optimization of CoO x ${}_{\mathrm{x}}$ loading and PMS dosage is still needed to maximize the overall photocatalytic performance.