A Strandberg-type polyoxometalate-based supramolecular complex for electrochemical detection of H2O2

Abstract Accurate detection of hydrogen peroxide (H2O2) is crucial in biomedical and clinical fields, driving the need for high-performance, low-cost non-enzymatic electrochemical sensors. Polyoxometalates (POMs), with their distinctive structures and rich redox activity, offer great promise as sensing materials. Herein, a Strandberg-type POM-based supramolecular complex, [Co3(H2O)6L(HL)2(H2L)] [HP2Mo5O23]2·2H2O (1) (L = 1,4-di(1H-imidazol-1-yl)benzene), was synthesized under hydrothermal conditions. To further confirm its composition and structure, additional characterizations including IR, PXRD, SEM, and EDS were conducted. In compound 1, the metal-organic unit [Co2(H2O)2L(HL)2]6+ is connected via Co-O bonds to the polyoxometalate dimeric anion [Co(H2O)4(HP2Mo5O23)2]8−, forming a 2D layer structure. Meanwhile, free doubly protonated ligand H2L is incorporated within the 2D layers through intermolecular π-π interactions. These layers further stack via π-π stacking interactions, resulting in a 3D supramolecular architecture. Electrochemical studies reveal that compound 1 exhibits multi-electron redox processes originating from the MoVI centers and shows good electrocatalytic activity toward the reduction of H2O2. A modified electrode fabricated using compound 1 as the electrode material demonstrates excellent electrochemical performance for H2O2 detection, achieving a low detection limit of 2.16 μM over a wide linear range of 50–350 μM. GRAPHICAL ABSTRACT