Nongraphitic Carbon Nitride Melem Oligomer Nanosheets for Photocatalytic Degradation of Organic Pollutants

The 2 nm ultrathin nongraphitic carbon nitride melem oligomer nanosheets (MO-NS) were prepared by the combination of melamine pyrolysis process at low temperature and dimethyl sulfoxide solvation centrifugation. The properties of the prepared MO-NS were determined by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, atomic force microscopy, Brunauer–Emmett–Teller (BET), UV–vis, photoluminescence, electrochemical impedance spectroscopy, transient photocurrent response, and Mott–Schottky technologies. The results reveal that the composition and structure of the MO-NS photocatalyst are significantly different from those of the conventional bulk g-C3N4. The presence of "defects" might enhance the photocatalytic activity of a melem oligomer compared with the traditional bulk g-C3N4. The large BET specific surface area, better light absorption ability, and photogenerated carrier separation efficiency further impoved the photodegradation performance of MO-NS. These all lead to the excellent photodegradation efficiency of MO-NS for alizarin red S (ARS), rhodamine B, methyl orange, hydrochloride tetracycline, aureomycin, and acid fuchsin. MO-NS also has good stability even after 10 repeated degradation uses, and a superoxide radical •O2– is the main active species during photodegradation. This paper provides an idea for the design and construction of nongraphitic carbon nitride materials.