SnO_2–x Nanoparticles Decorated on Graphitic Carbon Nitride as S-Scheme Photocatalysts for Activation of Peroxymonosulfate

Designing a heterojunction that can effectively degrade pollutants under different reaction conditions remains a challenge and question. Herein, an S-scheme model of oxygen-vacancies-defected tin dioxide nanoparticles and graphitic carbon nitride (SnO2–x/g-C3N4) is fabricated. This is also the first study activating photocatalysts by potassium peroxymonosulfate (PMS) for degrading rhodamine B (RhB) dye. Empirical evidence, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR), show the presence and a combination of SnO2–x nanoparticles and g-C3N4 nanosheets. Optical, electrochemical analysis, and trapping experiments reveal the contribution of different charge states of oxygen vacancies, a visible light responsibility of 3.2 eV, and an S-scheme charge transfer to the strengthened photocatalytic performance of SnO2–x/g-C3N4. Besides, an S-scheme is accelerated to higher performance from 20% to 99.8% RhB 20 mg L–1 degradation via activating PMS in solution. This design and activation may promise applications in efficient water treatment.