Construction of a CuO/TiO₂@C S-scheme heterojunction for phenol removal by activated peroxymonosulfate

Phenol is a volatile organic compound whose effective degradation using conventional methods is challenging. Rapid charge-carrier recombination and slow Cu(II)/Cu(I) conversion rate in copper-based photocatalysts hinder their activation efficiency of potassium persulfate (PMS). Herein, an S-scheme heterojunction structure comprising TiO₂@C and CuO was successfully constructed using an in situ calcination method, enabling the spatial separation of photogenerated charge carriers and thus enhancing the synergistic effect of PMS in the photocatalytic degradation of phenol. The resulting CuO/TiO₂@C nanocomposite exhibited notably higher phenol removal efficiency than CuO or TiO₂@C alone, removing an 88 % phenol (40 mg/L) and a 48 % total organic carbon within 25 min. The material maintained high degradation efficiency after four cycles. Liquid chromatography-mass spectrometry was employed to identify intermediates generated during phenol degradation, and a potential charge-transfer mechanism was proposed based on the analysis of catalytic active species and energy band structure. Thus, this study provides new insights for enhancing PMS activation for phenol remediation.