Interface engineered S-scheme CoMoO₄/CN heterojunctions with N-vacancy modulation: Photogenerated hole-dominated...

The light utilization efficiency of the photocatalytic process is always limited by the high recombination rate of photogenerated carriers, and the construction of S-scheme heterojunction catalyst and the assistance of permonosulfate (PMS) activation have been proven to be beneficial to overcome this shortcoming. However, it is challenging to construct an ideal and efficient S-scheme heterojunction catalyst, and the mechanism in the Vis/PMS system remains unclear. In this work, a CMO/CN-Nv S-scheme heterojunction catalyst of porous ultrathin graphitic carbon nitride with nitrogen vacancies (CN-Nv) composite with CoMoO₄ has been synthesized by hydrothermal-calcination for the oxidation of organic pollutants by PMS activation-assisted photocatalytic system and the reaction mechanism has been explored. The 45CMO/CN-Nv/PMS/Vis system achieved near-complete (100 %) removal of p-nitrophenol (PNP, 5 ppm) within 15 min, significantly outperforming most reported catalysts. Electron paramagnetic resonance (EPR) analysis and quenching experiments identified holes (h⁺) and singlet oxygen (¹O₂) as the primary active species, with the S-scheme structure critically enhancing h⁺ utilization. Photoelectrochemical and XPS analyses elucidated the efficient carrier separation/transfer mechanism. This study provides new insights into the synergistic PMS activation mechanism by nitrogen-vacancy-regulated S-scheme heterojunctions under visible light. We innovatively establish a "defect engineering regulation and interfacial charge transport" synergy, offering a promising strategy for deep treatment of complex organic pollutants.