Construction of full solar-light driven NaYF4:Yb,Tm,Er@NaYF4:Eu/NH2-MIL-101(Fe) composite photocatalyst toward degradation of antibiotics: introducing the energy trapping centers

Abstract

Photocatalysis is a promising pathway to degrade the pollution in the water with the distinct advantages. However, to remove the antibiotics in the aqueous solution is still a perplexing issue due to the stability. Development of full solar-driven heterogeneous photocatalyst is a feasible strategy to decompose the antibiotics into the nontoxic small molecules. A novel heterogeneous photocatalyst, NaYF4:Yb,Tm,Er@NaYF4:20% Eu/NH2-MIL-101(Fe) (TmEr@YEu(20%)/NMF) is synthesized, in which the energy trapping center is introduced in the shell to reduce the energy loss and improve the upconversion efficiency. Under the simulated solar light, the degradation extent of TmEr@YEu(20%)/NMF toward amoxicillin (AMX) is 90%, which is 40% larger than that of NMF. It is attributed to the wide light absorption range and heterogeneous structure of TmEr@YEu(20%)/NMF. As compared with the TmEr/NMF, the photocatalytic activity of TmEr@Y/NMF is increased by 14 %. And it is further enhanced by 16% for TmEr@YEu(20%)/NMF indicating that the core-shell structure and involvement of energy trapping center play the same important role. The mechanism is proposed according to upconversion emission spectra, active species trapping experiments and pump power dependence of upconversion emission intensities. Involvement of shell and energy trapping center is a robust approach to achieve the enhanced upconversion efficiency and achieve the expected photocatalytic activity. This work suggests a new strategy to synthesize the upconversion nanoparticles with the improved upconversion efficiency.