Structure and photocatalytic activity of porous g-C3N4 and Cu2O@g-C3N4 system toward Rhodamine B degradation under solar light irradiation

Bulk g-C3N4 (CNI) was prepared via direct pyrolysis of urea at 550 degrees C. Two porous g-C3N4 materials (CNII and CNIII) were synthesized using silica nanoparticles template obtained via two different routes with keeping the mass ratio of urea to silica constant at (1:1). CNIII sample was load with different amounts of CuO to prepare Cu2O@CNIII photocatalysts. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, N-2 adsorption-desorption measurements, ultraviolet-visible spectroscopy (UV-Vis), and X-ray photoelectron spectroscopy. N-2 adsorption-desorption measurements showed that the porous structure of CNII and CNIII has a huge surface area (50.4-85.2 m(2)/g) than that of bulk g-C3N4 (CNI). The surface area of CNIII samples decreased with the increase of Cu2O content in Cu2O@CNIII materials. The data obtained from the photocatalytic degradation of Rhodamine B (RhB) dye reveal that the addition of Cu2O to CNIII increased the photocatalytic activity when compared to CNI, CNII and metal free-CNIII photocatalysts. The high activity of CNII and CNIII samples was attributed to the texture properties while that for Cu2O@CNIII samples was related to the synergetic effect of both surface area and the presence of Cu2O nanoparticles. The experimental data was explained in terms of pseudo-first-order kinetics model. The recyclability study reveals that the investigated photocatalysts were highly stable and can be reused for up to four successful runs without a major loss in their activity. From free radical trapping studies, the major reactive species photoinduced holes and super oxide radicals play an important role in the degradation of RhB.

Automated summary

In this study, various g-C3N4 materials with different characteristics were successfully prepared and Cu2O was doped into the materials for photocatalytic degradation of RhB. The results showed that the addition of Cu2O positively affected the photocatalytic activity. Furthermore, through the characterization of different materials and the study of the photocatalytic degradation process, the relationship between material structure and reaction mechanism was revealed.