A Novel Copper-Functionalized MOF Modified Composite Electrode for High-Efficiency Detection of Nitrite and Histamine

A nonenzymatic electrochemical sensor with high efficiency and selectivity to determine sodium nitrite (NaNO2) and histamine (HA) was prepared and thoroughly investigated. Cu-functionalized MOF material, denoted as Cu@UiO-67-BPY, was synthesized through the post-synthetic modification method of incorporating copper ions with UiO-67-BPY (BPY stands for 2,2′-bipyridine-5,5′-dicarboxylic acid), which enhances proton conductivity and electrochemical signals. The electrode was fabricated by mixing Cu@UiO-67-BPY and graphene oxide (GO), followed by electrochemical reduction of GO to ERG (electrochemically reduced graphene). The composite electrode Cu@UiO-67-BPY/ERG/GCE exhibits a synergistically enhanced electron transfer. XRD, SEM, and FT-IR illustrate that Cu@UiO-67-BPY and GO were mixed successfully. EIS proves that the synergistic enhancement promotes charge transfer on the composite electrode's surface. CV studies show that the electrochemical sensor readily oxidizes NaNO2 and effectively reduces the oxidation potential. DPV studies exhibit a broad linear response range for NaNO2 and HA, with the detection limits being as low as 1.2 μM and 0.595 μM, respectively. The sensor displays good reproducibility, stability, and satisfying recovery in testing NaNO2 and HA in actual samples. The study exhibits that copper-functionalized MOFs composite electrodes have great potential as an innovative platform for developing future high-performance electrochemical sensors.