Mn-Cu co-doped graphitic carbon nitride accelerates permonosulfate to generate more singlet oxygen in pollutant degradation

Graphitic carbon nitride (g-C 3 N 4 ), a nitrogen-rich polymeric semiconductor, has gained significant attention as a photocatalyst . However, its potential to activate permonosulfate (PMS) has been somewhat limited. Prior research has demonstrated that manganese-doped g-C 3 N 4 can effectively activate PMS to degrade pollutants, with Mn 3+ playing a pivotal role. Consequently, enhancing the Mn 3+ content within the system is of paramount importance. In this study, we developed a novel class of manganese‑copper doped g-C 3 N 4 materials using a hydrothermal-calcination process. The optimized material, denoted as Mn 5 Cu 5 -CN, was synthesized at a Mn/Cu molar ratio of 1:1. When applied to degrade a model contaminant, acetaminophen (ACP), the Mn 5 Cu 5 -CN/PMS system demonstrated remarkable efficiency, degrading nearly 20 mg/L of ACP within 30 min (material dosage = 0.4 g/L, PMS concentration = 2.0 mM). The Mn 5 Cu 5 -CN exhibited favourable performance across a broad pH range. Singlet oxygen ( 1 O 2 ) was identified as a major player in the degradation of ACP. X-ray photoelectron spectroscopy (XPS) analyses revealed that the cyclic redox reactions of Mn 3+ /Mn 4+ and Cu + /Cu 2+ led to the abundant generation of 1 O 2 . Superoxide (O 2 •- ) was identified as an important intermediate product in these processes. Additionally, the g-C 3 N 4 present in the material also facilitated the generation of reactive oxygen species (ROS). This study provides a fresh perspective on the utilization of g-C 3 N 4 for pollutant degradation, highlighting the potential of Mn Cu doped g-C 3 N 4 materials in environmental remediation.