Enhanced photocatalytic degradation of organic pollutants and pathogens in wastewater using a full-spectrum response NaYF4:Yb,Tm@TiO2/Ag3PO4 nanoheterojunction

Organic and microbial pollution in water bodies is becoming increasingly problematic. However, only a few technologies can be used to simultaneously treat these pollutants in wastewater. In this study, nanosized NaYF4:Yb,Tm@TiO2/Ag3PO4 heterojunctions with core–shell structures were fabricated via hydrothermal synthesis and an in situ deposition method. The synthesized ternary nanocomposites exhibited crystalline structures and the diameter of the nanoheterojunctions were ∼35 nm. Under light irradiation, fluorescence resonance energy transfer can be optimally performed among several constituting nanomaterials. The nanoheterojunctions exhibited wide spectral response capability. Under simulated sunlight irradiation, the nanoheterojunction degraded 91% Rhodamine B within 60 min. The minimum bactericidal concentrations of Staphylococcus aureus were 50 and 100μg mL−1 under irradiation by a 980 nm laser and a xenon lamp, respectively, while that of Escherichia coli was 50μg mL−1 under all irradiation conditions. These results are closely related to the manufactured core–shell heterojunction structure. In addition, the nanoheterojunction exhibited relatively low toxicity in the dark. Under near-infrared or simulated sunlight irradiation, the nanoheterojunction exhibited low cytotoxicity. Therefore, the nanoheterojunction broadens the spectral response range, increases the separation of photogenerated carriers, and enhances photocatalytic activity. To the best of our knowledge, this is the first time that a core–shell structured NaYF4:Yb,Tm@TiO2/Ag3PO4 nanoheterojunction was fabricated and applied to treat organic pollutants and pathogenic bacteria. This research offers a powerful platform for the further development and application of NaYF4:Yb,Tm@TiO2/Ag3PO4 nanoheterojunctions in the mitigation of organic and biological pollutants in wastewater.