Extraordinary photodegradation performance of graphitic carbon nitride derived from tin foil–wrapped urea

Graphitic carbon nitride (g-C3N4), as a novel carbon material, has gained widespread attention during the last years. Although the g-C3N4 can be synthesized by utilizing various N-rich precursors, the photocatalytic performance of the derived g-C3N4 significantly alters depending on the type of used precursor. In our study, we choose economical urea, dicyandiamide, and melamine as precursors to prepare g-C3N4 under the wrap with tin foil, which are labeled as g-C3N4-U, g-C3N4-D, and g-C3N4-M, respectively. The sizes of g-C3N4-U, g-C3N4-D, and g-C3N4-M are about 2 μm, 4 μm, and 3 μm, and the thickness of them is around 8 nm, 15 nm, and 15 nm, respectively. We find that the g-C3N4-U exhibits the best photocatalytic degradation effect towards Rhodamine B (RhB) among the synthesized g-C3N4 samples. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), atomic force microscopy (AFM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflectance spectra (UV-visible DRS), photoluminescence (PL) spectra, electrochemical measurements, N2 adsorption-desorption isotherms, and electron spin resonance (ESR) are used to study the characteristics of the prepared g-C3N4 samples. It is found that the thinner mesoporous nanostructure of g-C3N4-U results in enhanced separation efficiency of the photo-induced carriers as well as effective utilization of the superoxide radical ( $$ \cdotp {\mathrm{O}}_2^- $$ ), which improved the catalytic performance of g-C3N4-U.