One-dimensional CeO2 nanostructures from Ce-BTC MOFs as fluorescent probes for hexavalent chromium

Abstract

Hexavalent chromium (Cr⁶⁺), a Group 1 carcinogen, poses a concern for contaminating aquatic systems due to its high solubility, mobility, and extreme toxicity, even at trace levels. While fluorescence-based detection techniques offer high sensitivity and potential for real-time monitoring, the development of efficient sensing materials remains a key challenge. Existing research has primarily focused on bulk or irregular CeO₂ nanostructures and complex hybrid systems, which often suffer from limited selectivity, synthetic complexity, or toxicity concerns. Addressing this gap, the objective of this study is to synthesize and evaluate a simple yet effective one-dimensional (1D) nanostructured CeO₂ derived from Ce-BTC MOFs via thermal decomposition for Cr⁶⁺ detection. The methodology involves MOF-assisted synthesis, followed by detailed structural, morphological, and optical characterization of the resulting nanobar-shaped CeO₂. The CeO₂ has a good fluorescence response in aqueous media, having excitation at 280 nm with 409 nm emission. Fluorescence sensing experiments demonstrate the material’s strong quenching response to Cr⁶⁺, with excellent selectivity and sensitivity, exhibiting a linear response between 0.1 and 10 μg/mL. The developed system has a good limit of detection (LOD) of 0.58 μg/mL. The interaction between CeO₂ and Cr⁶⁺ is attributed to its high surface area, porous architecture, and abundant Ce³⁺/Ce⁴⁺ redox sites. These findings highlight the promise of MOF-derived 1D CeO₂ as a viable candidate for efficient and selective detection of Cr⁶⁺ in environmental water samples, offering significant implications for practical water quality monitoring and public health protection.