Synthesis of mesoporous carbon nitride by molten salt-assisted silica aerociel for Rhodamine B adsorption and photocatalytic degradation

As a new nonmetallic photocatalysis material, it is of great attention to develop the carbon nitride (g-C3N4) with good structure and optical properties. Herein, a mesoporous g-C3N4 was prepared by molten salt-assisted silica (SiO2) aerogel template method, the properties of physicochemical and optical were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), specific surface area and pore analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray energy spectrum (XPS), diffuse reflectance spectrum, fluorescence spectrum (PL) and zeta potential, respectively. Rhodamine B (RhB) was used for a series of adsorption and photocatalytic degradation experiments, and the reactive species and the degree of RhB degradation in the reaction process were tested by electron spin resonance (ESR) and UV-Vis absorption spectrum, respectively. The synergistic effect of adsorption and photocatalytic degradation was investigated. The results show that the mesoporous g-C3N4 was synthesized successfully, and presented a hollow tubular porous structure and good optical properties. With the highest specific surface area (164.65 m(2).g(-1)) and narrower band gap (2.47 eV), the sample of M-CN-500 shown the highest degradation rate of RhB (90.9%) after 150 min illumination, and the adsorption capacity and zeta potential were both affected by pH variation. The kinetic model verified that the photocatalytic degradation rate of RhB by mesoporous g-C3N4 was enhanced with the synergistic effect of adsorption. It was also demonstrated that the O2- and h(+) were the primary reactive species, and the RhB structure fracture was the main reason in the photocatalytic degradation. [GRAPHICS] .

Automated summary

The mesoporous g-C3N4 was successfully synthesized with good structure and optical properties using molten salt-assisted silica aerogel template method. The sample M-CN-500 showed the highest degradation rate for RhB, influenced by both adsorption capacity and zeta potential varying with pH. Adsorption and photocatalytic degradation had a synergistic effect on the photocatalytic process, with O2- and h(+) identified as primary reactive species.