Highly sensitivity, selectivity chemosensor for methyl orange using upconversion NaBiF4: Yb/Tm nanosheets

Pursuing high sensitivity and selectivity towards toxic dye molecules becomes an urgent task for sustainable development of environment. Methyl orange is a representative toxic dye containing azo structures, which is hazardous to human health even at low concentrations. At present, there are many methods for testing methyl orange, but there is no method specifically for the detection of trace methyl orange. In this work, NaBiF4: Yb3+/Tm3+ upconversion nanosheets (NSs) were proposed to detect toxic methyl orange (MO) dye molecule for the first time. Quantitative analysis of trace MO was achieved by recording the change of upconversion luminescence intensity of NaBiF4:Yb3+/Tm3+ NSs. A good regression coefficient of R = ​0.9966 was demonstrated between the quantitative trace MO and the relative intensity of NaBiF4: Yb3+/Tm3+ NSs. A detection limit of LOD ​= ​1.5 ​μg/mL (4.5 ​μM) was realized, revealing an excellent sensitivity for probe concentration of MO. Moreover, other dye molecules and typical metal ions such as methylene blue, 1,10 phenanthroline, rhodamine, Zr+, Cu2+, Mg2+, Ba2+, Pb2+, and Ca2+ in different solutions were also studied, showing high selectivity to the sensing of MO. This work offers an alternative strategies for detecting trace MO based on the upconversion nanomaterials and has great potential applications in environmental protection.