Upconversion nanocomposite CeO2:Tm3+/attapulgite intermediated by carbon quantum dots for photocatalytic desulfurization

Upconversion CeO2:Tm3+/attapulgite (ATP) nanocomposites intermediated by carbon quantum dots (CQDs) were synthesized by a facile deposition method using hexamethylenetetramine as precipitator. The products were characterized by various techniques. The photocatalytic degradation of dibenzothiophene (DBT) in simulated gasoline was conducted under visible light irradiation by taking advantage of CeO2:Tm3+/CQDs/ATP nanocomposites as catalyst. The influence of Tm3+ doping amount and the mass fraction of CeO2 to ATP on the desulfurization performance were investigated. Results indicated that the CeO2:Tm3+ nanoparticles were coupled uniformly on the CQDs/ATP surface. The desulfurization rate of DBT reached the highest 96% when the molar fraction of Tm3+ in CeO2 was 2% and the mass fraction of CeO2 to ATP was 20 wt%. The enhanced photocatalytic oxidative desulfurization was attributed to the upconversion property of CeO2:Tm3+ which transformed visible light into ultraviolet light increasing the utilization of solar energy, while CeO2:Tm3+ built indirect Z-scheme heterojunction with modified ATP mediated by CQDs, both favored the separation of the charges carriers and benefits the redox potentials. (C) 2019 Elsevier B.V. All rights reserved.