Development of a ZnQ@Zn-HKUST-1-Based Fluorescence Sensor for Trace-Level Arsenate Ion Detection

Arsenic contamination in water sources poses serious environmental and health risks, necessitating sensitive and selective detection systems. Among arsenic species, arsenate ions (AsO₄3⁻) are particularly widespread and hazardous, demanding efficient trace-level monitoring methods. This study presents a fluorescence-based sensor developed using two-dimensional (2D) Zn-HKUST-1 nanosheets for the selective detection of arsenate ions in groundwater. The sensor's fluorescence performance was enhanced by incorporating 8-hydroxyquinoline (8-Q) during solvothermal synthesis, which coordinated with Zn2⁺ ions to form fluorescent ZnQ compounds. These ZnQ units were uniformly encapsulated within the Zn-HKUST-1 framework, yielding ZnQ@Zn-HKUST-1 nanosheets with improved physicochemical and optical properties. The material's structure and morphology were characterized using FTIR, XRD, and SEM, while fluorescence spectroscopy evaluated its sensing capabilities. The sensor exhibited a highly sensitive detection limit of 0.0521 nM for AsO₄3⁻ and outstanding selectivity over other metal ions such as Ni2⁺, Cu2⁺, Cr₂O₇2⁻, and Pb2⁺. This selectivity stems from the strong affinity of the ZnQ-modified framework for arsenate ions. The study highlights the potential of ZnQ@Zn-HKUST-1 as a powerful material for fluorescence-based arsenate sensing, offering a promising tool for water quality monitoring and public health protection.