Efficient LED visible-light photocatalytic activation of peroxymonosulfate by N-doped TiO2/Ti3C2 MXene for degrading refractory pollutants

Visible-light photocatalytic activation of peroxymonosulfate (PMS) is a promising strategy for treating refractory organic pollutants. In this study, a novel nitrogen-doped TiO 2 /Ti 3 C 2 MXene composite (N-TiO 2 /Ti 3 C 2 ) was synthesized via an impregnation-calcination method using cetyltrimethylammonium bromide (CTAB) as the nitrogen source. N-doping effectively narrowed the bandgap of TiO 2 , while the highly conductive Ti 3 C 2 MXene served as an electron-transfer platform, thereby synergistically enhancing light absorption and charge carrier separation. The N-TiO 2 /Ti 3 C 2 exhibited a Brunauer-Emmett-Teller surface area of 35.86 m 2 /g, approximately 1.94 times higher than that of the undoped TiO 2 /Ti 3 C 2 , due to CTAB intercalation-induced structural regulation. Under LED visible light, the N-TiO 2 /Ti 3 C 2 /PMS system achieved 98.5% of rhodamine B degradation within 100   min and 81.3% of tetracycline degradation within 40   min, with good stability over a wide pH range (3.1-10.0). Mechanistic studies identified that sulfate radicals (SO 4 • − ), singlet oxygen ( 1 O 2 ), and holes (h⁺) were the dominant reactive species. LC-MS analysis elucidated the degradation pathways of rhodamine B and tetracycline. This study presents an efficient MXene-based photocatalyst for PMS activation, offering a promising strategy for wastewater treatment.