Facile fabrication of ordered mesoporous graphitic carbon nitride for RhB photocatalytic degradation

Abstract

Ordered mesoporous graphitic carbon nitrides were prepared by directly condensing the uniform mixtures of melamine and KIT-6. After removal of the KIT-6 sacrificial template, the carbon nitrides were characterized with TEM, N2 physical adsorption, XRD, FT-IR, XPS, UV–vis and PL spectrometries, and tested for their RhB photocatalytic degradation activity. Together, these characterizations confirmed the as-prepared tunable mesoporous materials with enhanced charge separation efficiency and superior photocatalytic performance. Compared with a conventional bulk g-C3N4, ordered mesoporous g-C3N4 exhibits a larger specific surface area of 279.3m2/g and a pore size distribution about 4.0nm and 13.0nm. Meanwhile, the reduced bandgap energy of 2.77eV and lower photogenerated electron-hole pair recombination frequency were evidenced by UV–Vis and PL spectra. The RhB photocatalytic degradation activity maximizes with a mass ratio of KIT-6/melamine of 80% (KCN80), and the kinetic constant reaches 0.0760min−1 which is 16 times higher than that of the bulk sample. Reusability of KCN80 was demonstrated by a lack of evident deactivation after three consecutive reaction periods. The direct condensation of the KIT-6 and melamine mixture does not require pre-casting of the precursor into the pore system of the templates. Owing to its high product yield, improved SBET, reduced bandgap energy and limited charge recombination, the facile-prepared ordered mesoporous g-C3N4 is a practical candidate for further modification.