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${}_x$/BiVO₄) coupled with peroxymonosulfate (PMS) oxidation system to investigate its photocatalytic mechanism for degrading BPA in wastewater. The CoO${}_x$/BiVO₄ photocatalyst was fabricated through a precipitation-hydrothermal method and systematically characterized. The results showed that modifying BiVO₄ with CoO${}_x$ 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 (¹O₂) and sulfate radicals (SO₄ ${}^{-}\cdot$) 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 SO₄ ${}^{-}\cdot$ and $\cdot$OH radicals; (2) Ring-opening oxidation of hydroxylated intermediates into carboxylic acids; (3) Further mineralization of all intermediates into CO₂ and H₂O by ¹O₂ and $\cdot$OH. In summary, the CoO${}_x$/BiVO ₄-PMS system provides an efficient and promising technology for eliminating trace BPA in wastewater via synergistic effects of SO₄ ${}^{-}\cdot$ and ¹O₂. Further optimization of CoO${}_x$ loading and PMS dosage is still needed to maximize the overall photocatalytic performance.