Fabrication and Photocatalytic Application of Aromatic Ring Functionalized Melem Oligomers

• Published in: Journal of physical chemistry. C Vol. 122; no. 6; pp. 3506 - 3512
• Main Authors: Hsu, Chu-Yen, Chang, Kao-Shuo
• Format: Journal Article
• Language: English
• Published: American Chemical Society 15.02.2018
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.7b12539

This paper reports the fabrication of aromatic ring functionalized melem oligomers (AFMOs) and the study of their synergistic photodegradation properties. Highlights include the following: (1) the fabrication of various carbon nitrides (CNs) through thermal polycondensation; (2) the intrinsic modulation of the molecular nature of polymeric CNs using different amounts of melamine precursors; and (3) the extrinsic functionalization of melem oligomers (MOs) with aromatic rings, which enhanced visible light absorption, reduced dark absorption, and enhanced π electron delocalization, thus inhibiting electron–hole (e––h+) pair recombination. X-ray diffraction and UV–vis spectroscopy qualitatively indicated the fabrication of MOs after washing with 135 °C dimethyl sulfoxide. 15N solid state nuclear magnetic resonance spectroscopy revealed that the MO sample consisted mainly of trimers before and after aromatic ring functionalization. Fourier-transform infrared spectroscopy indicated the structures of polymerized heptazine rings and the effective functionalization of aromatic rings. A scavenger study demonstrated that •O2 – predominated in the AFMO photodegradation mechanism of methylene blue solutions. The AFMO sample exhibited a photodegradation rate constant of approximately 9.8 × 10–3 min–1, which was nearly 8 times higher than that of melon. The superior photocatalytic properties were attributed to the substantial improvement in visible light absorption and poor e––h+ pair recombination because of π electron delocalization, which were verified using UV–vis and photoluminescence spectra, respectively.