CDs/CeVO₄ nanohybrids synergistic visible light for activation of peroxymonosulfate toward tetracycline degradation

The limited absorption of visible light and high recombination rate of photogenerated electron-hole pairs impede the practical application of CeVO₄ in photocatalysis. The unique π-conjugated structure of carbon dots (CDs) endows them with exceptional capabilities for the storing and transferring photogenerated electrons. Herein, CDs/CeVO₄ was successfully synthesized by two-step method of hydrothermal and co-precipitation, resulting in a significant enhancement of photogenerated carrier transfer and separation efficiency with the incorporation of CDs. Under visible light irradiation, CDs/CeVO₄ exhibit enhanced activity towards peroxymonosulfate (PMS) for the degradation of tetracycline hydrochloride (TC), resulting in a 90% degradation rate of TC after 60 min of reaction. The reaction rate constant is 4.1 times higher than that of CeVO₄. XPS, UV-Vis DRS, and time-resolved fluorescence spectra demonstrate that CDs/CeVO₄ exhibits a narrower band gap, an enhanced capacity for absorbing visible light, and a 15.1-fold increase in the fluorescence lifetime compared to CeVO₄. The results of electron paramagnetic resonance (EPR) and XPS tests confirm the presence of abundant oxygen vacancies in CDs/CeVO₄, thereby further enhancing their capacity for activating PMS. Capture experiments of active substances show that h⁺, \textSO_4^-\text• and •OH are the active species in the reaction system, and a plausible degradation mechanism was proposed. After five cycles of experiments, the degradation rate decreased slightly, showing good photocatalytic performance. This work provides a new strategy for the degradation of organic pollutants in wastewater.