Dual-signal electrochemical sensor based on Cu-MOF and MnCO₃ for ultra-sensitive detection of mercury ions in water

Owing to the internal correction function and good resistance to complex factors, dual-signal electrochemical sensors have abilities to avoid false positives. In this work, Cu-MOF and MnCO₃ were combined and further prepared the Cu²⁺ and Hg²⁺ dual-signal electrochemical sensor for ultra-sensitive detection of Hg²⁺. Notably, beyond the commonness of the general MOFs, Cu-MOF could undergo oxidation-reduction to provide an internal reference signal. MnCO₃, a porous structure with good electrocatalysis, exhibits an obvious signal amplification effect on the detection of Hg²⁺. Differential pulse voltammetry was applied for the detection of Hg²⁺. The current signal of Cu²⁺ and Hg²⁺ reduced regularly with Hg²⁺ concentration decreased. Under optimized conditions, the LOD of Hg²⁺ was calculated around 6.82 nM with a linear range of 0.10 ∼ 2.50 μM. The proposed sensor was proven to show satisfactory anti-interference, stability, and reliability, which is promising for the ultra-sensitive detection of Hg²⁺ in real life.