Photocatalytic degradation of Rhodamine B and Ibuprofen with upconversion luminescence in Ag-BaMoO4: Er3+/Yb3+/K+ microcrystals

Silver dispersed BaMoO4 octahedron microcrystals doped with Er3+, Yb3+, and K- were synthesized by microwave hydrothermal process. The photocatalytic activity of different samples toward the degradation of Rhodamine B (Rh B) dye and Ibuprofen (IBP) drug were carried in solar light and visible light irradiation, respectively. The sample, Ag-BaMoO4: Er3+/Yb3+, degraded the Rh B within 90 min about 99.60%, which is nearly 30 times as compared to the host material BaMoO4. Similarly, Ag-BaMoO4: Er3./Yb3+, degraded the IBP within 90 min about 41.49%, which is nearly 31 times as compared to the host in visible light. IBP photodegradation intermediates were identified by high-resolution quadrupole -time of flight-electrospray ionization-mass spectrometry (HR-QTOF ESI/MS) in negative ion mode and detailed degradation pathway mechanism was proposed. Under 980nm,, excitation, two strong green emission peaks (526 nm and 555 nm) and a less intense red emission peak (661 nm) were observed, which are assigned to the H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2) transitions of the Er3+ ions, respectively. Two photons upconversion process for green emission was observed. The upconversion luminescence intensity was increased by two -fold in magnitude by the addition of K+ ion in Er3+/Yb3+ doped BaMoO4. Moreover, silver particles were found to favor the photocatalytic activity while K+ ions significantly enhanced upconversion. The photocatalytic as well as upconversion mechanism was explained. The combination of efficient photocatalytic activity and upconversion emission of the Ag-BaMoO4: Er3+Yb3+/K+ make the material suitable for the multifunctional application. (C) 2017 Elsevier B.V. All rights reserved.