Photocatalytic degradation of organic pollutants coupled with simultaneous photocatalytic H2 evolution over graphene quantum dots/Mn-N-TiO2/g-C3N4 composite catalysts: Performance and mechanism

• Published in: Applied catalysis. B, Environmental Vol. 227; no. C; pp. 312 - 321
• Main Authors: Nie, Yu-Chun, Yu, Fan, Wang, Lai-Chun, Xing, Qiu-Ju, Liu, Xia, Pei, Yong, Zou, Jian-Ping, Dai, Wei-Li, Li, Yan, Suib, Steven L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 05.07.2018; Elsevier
• Subjects: Degradation; ENVIRONMENTAL SCIENCES; Graphitic carbon nitride; Hydrogen evolution; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Organic pollutants; Photocatalysis; Degradation; Organic pollutants; Hydrogen evolution; Photocatalysis; Graphitic carbon nitride
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.01.033

[Display omitted] •Novel GQDs/Mn-N-TiO2/g-C3N4 catalysts were successfully designed and prepared.•Simultaneous degradation of organic pollutants with photocatalytic production of H2 was achieved.•A mechanism was proposed to explain different effect of organic pollutants on photocatalytic H2 evolution. Graphene quantum dots/Mn-N-TiO2/g-C3N4 (GQDs/TCN) composite photocatalysts have been designed, synthesized and characterized by XRD, SEM, TEM, Raman, BET, and XPS. The photodegradation of organic pollutants (p-nitrophenol, diethyl phthalate and ciprofloxacin, called as 4-NP, CIP and DEP, respectively) coupled with simultaneous photocatalytic production of hydrogen was successfully achieved using the GQDs/TCN catalysts. The 5%GQDs/TCN-0.4 sample shows the best photocatalytic hydrogen production and organic pollutant degradation rate under simulated solar irradiation in the simultaneous photocatalytic oxidation and reduction system. Furthermore, the photocatalytic H2 evolution rates in the solution of 4-NP, CIP and DEP are all larger than that in pure water system over the 5%GQDs/TCN-0.4 catalyst. And the H2 evolution rate in the solution of 4-NP is smaller than that in the solutions of CIP and DEP. Accordingly, the photodegradation rate of 4-NP is larger than that of CIP and DEP. The analyses of density functional theory and liquid chromatography mass spectrometry indicate that some photogenerated electrons were used in the photodegradation process of 4-NP but not in that of CIP and DEP. And it leads to the photocatalytic rate of H2 evolution in the 4-NP solution smaller than that in the solution of CIP and DEP. For the first time, the present work illuminates the photocatalytic enhancement of the GQDs/TCN-0.4 catalyst and the mechanism of the effect of different organic pollutants on photocatalytic H2 evolution.