Engineering the nanoarchitecture and texture of polymeric carbon nitride semiconductor for enhanced visible light photocatalytic activity

• Published in: Journal of colloid and interface science 2013-07, Vol.401, p.70-79
• Main Authors: Dong, Fan, Wang, Zhenyu, Sun, Yanjuan, Ho, Wing-Kei, Zhang, Haidong
• Format: Article
• Language: English
• Subjects: Carbon nitride; Catalysis; Chemistry; crystal structure; engineering; Exact sciences and technology; General and physical chemistry; irradiation; Light; Nanoarchitecture engineering; Nanocomposites; Nanomaterials; nanosheets; Nanostructure; Nanostructures - chemistry; nitric oxide; Nitric oxide and RhB; Nitriles - chemistry; Particle Size; Photocatalysis; photocatalysts; Photochemical Processes; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Polymers - chemistry; Pyrolysis; Pyrolysis of urea; Semiconductors; surface area; Surface Properties; Texture; urea; Ureas; Visible light photocatalysis
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2013.03.034

•The g-C3N4 was synthesized by direct pyrolysis of cheap urea at 550°C in air.•The g-C3N4 treated for longer time possessed high surface area of 288m2/g.•A layer exfoliation and splitting mechanism was proposed.•The nanoarchitectures of g-C3N4 can be simply engineered by pyrolysis time.•The activity enhancement was ascribed to the synergistic effects of multiple factors. In order to develop g-C3N4 for better visible light photocatalysis, g-C3N4 nanoarchitectures was synthesized by direct pyrolysis of cheap urea at 550°C and engineered through the variation of pyrolysis time. By prolonging the pyrolysis time, the crystallinity of the resulted sample was enhanced, the thickness and size of the layers were reduced, the surface area and pore volume were significantly enlarged, and the band structure was modified. Especially for urea treated for 4h, the obtained g-C3N4 nanosheets possessed high surface area (288m2/g) due to the reduced layer thickness and the improved porous structure. A layer exfoliation and splitting mechanism was proposed to explain the gradual reduction of layer thickness and size of g-C3N4 nanoarchitectures with increased pyrolysis time. The as-synthesized g-C3N4 samples were applied for photocatalytic removal of gaseous NO and aqueous RhB under visible light irradiation. It was found that the activity of g-C3N4 was gradually improved as the pyrolysis time was prolonged from 0min to 240min. The enhanced crystallinity, reduced layer thickness, high surface area, large pore volume, enlarged band gap, and reduced number of defects were responsible for the activity enhancement of g-C3N4 sample treated for a longer time. As the precursor urea is very cheap and the synthesis method is facile template-free, the as-synthesized g-C3N4 nanoscale sheets could provide an efficient visible light driven photocatalyst for large-scale applications.