Synergic Effect between Adsorption and Photocatalysis of Metal-Free g-C3N4 Derived from Different Precursors

• Published in: PloS one 2015-11, Vol.10 (11), p.e0142616-e0142616
• Main Authors: Xu, Huan-Yan, Wu, Li-Cheng, Zhao, Hang, Jin, Li-Guo, Qi, Shu-Yan
• Format: Article
• Language: English
• Subjects: Activated carbon; Adsorption; Carbon nitride; Catalysis; Catalytic activity; Cationic dyes; Diffuse reflection; Discoloration; Dyes; Electron microscopy; Engineering; Environmental Pollutants - isolation & purification; Fourier transforms; Fuel cells; Functional groups; Graphite - chemistry; Guanidines - chemistry; Infrared spectroscopy; Irradiation; Light; Light irradiation; Materials science; Melamine; Methylene blue; Methylene Blue - isolation & purification; Microscopy; Morphology; Nitriles - chemistry; Nitrogen; Phase composition; Photocatalysis; Photoelectron spectroscopy; Photoelectrons; Photolysis; Pollutants; Precursors; Reaction time; Scanning electron microscopy; Solar energy; Spectroscopy; Spectrum analysis; Surface area; Surface chemistry; Surface properties; Transmission electron microscopy; Triazines - chemistry; X-ray diffraction; Zeolites
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0142616

Graphitic carbon nitride (g-C3N4) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.