Constructing benzene ring modified graphitic carbon nitride with narrowed bandgap and enhanced molecular oxygen activation for efficient photocatalytic degradation of oxytetracycline

Popular graphitic carbon nitride (g-C3N4) photocatalyst always faces the problems of weak visible light absorption and fast recombination of photogenerated electron-hole pairs. Herein, a novel benzene ring modified gC3N4 nanosheet (BCNNS) was synthesized by a simple calcination method. The degradation rate of oxytetracycline by BCNNS under visible light can reach 72% (within 60 min), significantly higher than that of the unmodified g-C3N4 nanosheet (50%). And the degradation rate constant of BCNNS is 0.025 min- 1, which is 2.1 times higher than that of g-C3N4 (0.012 min- 1). The improvement in the photocatalytic degradation performance can be attributed to the introduction of benzene ring, which can significantly broaden the light absorption range and intensify. In addition, the introduction of benzene ring can adjust the original electronic structure, thereby effectively suppressing the recombination of electron-hole pairs. Furthermore, density functional theory (DFT) calculations demonstrate that the introduction of benzene ring can significantly promote the surface adsorption of molecular oxygen and promote the transfer of electrons to molecular oxygen. This demonstrates that the embedded benzene ring can effectually advance the activation of molecular oxygen, which also well confirms that & BULL;O2- and 1O2 are the main active species in the system of BCNNS photocatalytic degradation of oxytetracycline. This study reveals that benzene ring modified g-C3N4 has great potential in environmental purification, and provides a promising strategy for the removal of stubborn water contaminants.

Automated summary

A novel benzene ring modified gC3N4 nanosheet (BCNNS) was synthesized by a simple calcination method. BCNNS showed significantly higher degradation rate of oxytetracycline under visible light compared to unmodified g-C3N4 nanosheet. The introduction of benzene ring broadened the light absorption range, intensified the degradation performance, and effectively suppressed the recombination of electron-hole pairs.