Fast and Selective Detection of Cr(III) in Environmental Water Samples Using Phosphovanadate Y(V_0.2P_0.8O₄):Eu³⁺...

Phosphovanadate Y(V_0.2P_0.8O₄):Eu³⁺ nanorods have been created via a simple hydrothermal method and used for the highly sensitive and selective fluorescence detection of Cr³⁺ over other common heavy metal ions within a 10 min period. It was found that the fluorescence intensity of Y(V_0.2P_0.8O₄):Eu³⁺ linearly decreases with Cr³⁺ concentrations ranging from 1 × 10^-9 to 1.2 × 10^-6 M. The sensing mechanism for Cr³⁺ is ascribed to the aggregation of Y(V_0.2P_0.8O₄):Eu³⁺ nanorods triggered by Cr³⁺ ions owing to the high affinity of phosphate groups to metal ions. The excellent chemical stability, photostability over a wide pH range of 3-12, and high salt-tolerance performance with ionic strength from 1× 10^-3 to 12 M of Y(V_0.2P_0.8O₄):Eu³⁺ allow these nanorods to successfully overcome the photobleaching and pH-dependent fluorescence property of traditional organic fluorescence probes. These characteristics ensure their applicability to environmental monitoring of Cr³⁺. The sensitive determination of Cr³⁺ in different environmental water samples demonstrated the potential application of Y(V_0.2P_0.8O₄):Eu³⁺ as a practical environmental probe. With the help of a UV lamp (254 nm), the visual Cr³⁺ values for dynamic monitoring in industrial wastewater further verified that this method can even exhibit on-site visible features in daytime and night easily. This allows for the direct monitoring of environmental Cr³⁺.