Unveiling the origin of high-efficiency charge transport effect of C₃N₅/C₃N₄ homojunction for activating peroxymonosulfate to degrade atrazine under visible light

Photocatalytic activation of PMS is a potential advanced oxidation process in refractory wastewater purification. Herein, a C₃N₅/C₃N₄ homojunction (AT-CN) catalyst as an efficient photocatalyst for PMS activation is reported, which owns interlaced band structure, high-efficiency charge transfer, and PMS activation capability. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation. As experimental result, the reaction rate constants of atrazine in AT-CN/PMS/Vis system increased to 2.9-fold and 7.4-fold, compared with C₃N₄/PMS/Vis and C₃N₅/PMS/Vis system. The photocatalytic activation of PMS for atrazine removal efficiency reached 97 % within 60 min (under pH = 3). The band structure, the charge density difference, the PMS adsorption behavior of AT-CN, and the activation pathways of PMS have been studied through the DFT calculation. According to experimental and DFT simulation, the AT-CN homojunction not only suppress the charge recombination via built-in electric field, but also exhibited a better PMS activation capability. In brief, this study through the combination of experiment and simulation is providing more inspiration for designing appropriate nonmetal homojunction in the photo-activated PMS process.