Metal–Organic Framework-Based Dual-Mode Electrochemical Sensor for Simultaneous Electrochemical Determination of Hydroquinone and Catechol

Abstract

Hydroquinone (HQ) and catechol (CC) pose significant risks to human health and the environment due to their toxicity and widespread contamination. However, their structural similarity (ortho- vs para-hydroxylation) often causes interferences during detection, necessitating the development of electrochemical sensors capable of simultaneous discrimination. In this work, a tetraphenylethylene (TPE)-based 3D cadmium metal-organic framework (Cd-MOF, [Cd₂^II(tmpe-F)•DMF•3H₂O]•2DMF•2.5H₂O (tmpe-F = 4',4″',4″″',4″″″'-(ethene-1,1,2,2-tetrayl)tetrakis(4-fluoro-[1,1'-biphenyl]-3-carboxylic acid, DMF = N,N-dimethylformamide)) was synthesized via an in situ hydrothermal method and employed as a dual-mode electrochemical sensor for the simultaneous detection of HQ and CC. The Cd-MOF exhibits exceptional electrochemical performance with wide linear detection ranges of 0.5 to 4000 μM and 0.5 to 2000 μM, high sensitivities of 1031.3 and 2082.0 μA mM^-1 cm^-2, as well as low limits of detection 0.067 and 0.053 μΜ for HQ and CC, respectively. Notably, the electrode with Cd-MOF in situ grown on carbon paper (Cd-MOF/CP) demonstrates robust anti-interference ability, high reproducibility (RSD < 3.0%), and long-term stability (retaining 95.0% of its initial current signal after 35 days of operation), validated through real water sample analysis with recovery rates of 96.9-103.2%. This work not only establishes a novel platform for structurally similar pollutants discrimination but also provides mechanistic insights into MOF-based electrochemical sensing.