One-pot synthesis of defect engineered carbon nitride for highly efficient visible light photocatalysis

Abstract

Continued industrial growth along with population growth is putting pressure on clean water supplies. Photocatalysis is an eco-friendly and cost-effective technology that can treat polluted water. As a visible-light-responsive photocatalyst, polymeric carbon nitride (CN) has shown significant potential for photocatalytic pollutant degradation. However, the fast charge recombination, slow charge transport and relatively large band gap restrict its photocatalytic performance. To overcome these challenges and develop a highly efficient photocatalyst, CN with robust visible-light photoactivity was solvothermally synthesised through defect engineering by carbon doping and surface vacancy modification. The additional carbon induces charge delocalization for enhancing charge tranfer and broadens the wavelength range of absorbance. The introduction of surface cyano functionality (–CN) not only enhances charge separation but also serves as electron-rich sites, thereby facilitating the generation of superoxide radicals. The controlled introduction of the C dopant and surface cyano group by simply introducing citric acid and varying the LiOH volume during synthesis demonstrated their synergy in optimising the electronic structure and the charge transport. As a consequence, there was a substantial generation of superoxide radicals when exposed to visible light (wavelengths > 420 nm), facilitating the efficient photodegradation of pollutants, such as tetracycline and Rhodamine B. Furthermore, the defect-engineered CN exhibited exceptional performance in the degradation of real-world wastewater. These findings underscore the promising potential of engineered CN for the advancement of visible-light-driven water purification technologies.