Metal–Organic Framework Nanosheets as an Initiator of Polymerizing Pyrrole for Application in Electrochemical Dopamine Detection

Nanocomposites composed of metal–organic frameworks (MOFs) and conducting polymers have emerged as highly attractive materials for a range of electrochemical, electronic, and sensing applications, and their synthetic processes usually require the addition of an external initiator for polymerization. Herein, iron(III) sites are postsynthetically modified in a water-stable two-dimensional MOF, ZrBTB (BTB = 1,3,5-tri(4-carboxyphenyl)benzene), and the resulting dispersible MOF sheets are directly utilized as an initiator to polymerize pyrrole in aqueous solutions. A series of 2D MOF–polypyrrole nanocomposites are thus synthesized, and their crystallinity, morphologies, porosity, and compositions are characterized. All composites are employed as active materials for the electrochemical detection of dopamine in neutral aqueous electrolytes. With the optimal nanocomposite, a sensitivity of 2554.9 μA/mM-cm², a linear range of 0–250 μM, and a limit of detection of 0.17 μM can be achieved for sensing DA, which are much better than those achieved by both the pristine polypyrrole synthesized using the soluble initiator and the pristine MOF. The composite can also selectively detect dopamine in the presence of common interferents including ascorbic acid and uric acid. Findings here shed light on the use of such dispersible porous supports as initiators for polymerization to synthesize a range of conducting polymer-based nanocomposites, which are appealing for diverse applications.