A base-stable metal-organic framework for sensitive and non-enzymatic electrochemical detection of hydrogen peroxide

Highlights: • A Cr-MOF (MIL-53-Cr^III) was utilized for H₂O₂ sensing for the first time. • The Cr-MOF exhibits high chemical and electrochemical stability in NaOH solution. • The redox processes of Cr^III/II in MIL-53-Cr^III have induced the direct reduction of H₂O₂. • The sensor shows a wide linear range, good sensitivity, and low method detection limit. Stability of metal-organic frameworks (MOFs) in aqueous medium and extreme solution conditions (acidic or basic) are important for the development of stable, reproducible, and sensitive electrochemical biosensors. Herein, a base-stable chromium(III) dicarboxylate MOF was synthesized by microwave assisted solvothermal method for non-enzymatic detection of hydrogen peroxide (H₂O₂). The as-synthesized MOF exhibited excellent base stability without any obvious changes in crystallinity, morphology, and spectroscopic behaviors after base treatment. This MOF-modified glassy carbon electrode showed negligible change in charge transfer resistance at the electrode|electrolyte interface after redox cycling and good catalytic activity for the reduction of H₂O₂ in 0.1 M NaOH_(aq.). The enhanced catalytic activity of H₂O₂ reduction is enabled by the redox process of Cr^III/II in the chromium (III) dicarboxylate. The sensor showed the sensitivity of ca. 11.9 μA mM⁻¹, wide linear range from 25 to 500 μM, and a method detection limit of ca. 3.52 μM. The validation of this sensing platform was evaluated by standard addition method. Thus, the present biosensor could be used for the point of care detection of H₂O₂.