Cu-Based Conductive MOF Grown in situ on Cu Foam as a Highly Selective and Stable Non-Enzymatic Glucose Sensor

A non-enzymatic electrochemical sensor for glucose detection is executed by using a conductive metal–organic framework (MOF) Cu-MOF, which is built from the 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) ligand and copper acetate by hydrothermal reaction. The Cu-MOF demonstrates superior electrocatalytic activity for glucose oxidation under alkaline pH conditions. As an excellent non-enzymatic sensor, the Cu-MOF grown on Cu foam (Cu-MOF/CF) displays an ultra-low detection limit of 0.076 μM through a wide concentration range (0.001–0.95 mM) and a strong sensitivity of 30,030 mA μM−1 cm−2. Overall, the Cu-MOF/CF exhibits a low detection limit, high selectivity, excellent stability, fast response time, and good practical application feasibility for glucose detection and can promote the development of MOF materials in the field of electrochemical sensors.

Electrochemical Fabrication of Porous Interconnected Copper Foam

An interconnected copper network or copper foam was successfully fabricated by electrochemical deposition using polyethylene glycol (PEG) and sodium bromide (NaBr) as additives. Both the amount of PEG and the current density were varied to obtain a Cu foam with the smallest pore diameter and wall thickness. The increasing amount of PEG resulted in a decrease in pore diameter. However, the wall thickness of the Cu network was increased. At 800 mg/L PEG and 20 mM NaBr, the average pore size of the foam was about 11.03 µm. Dendritic formation was also observed on the walls of the Cu foam. Further, higher current density resulted in increased dendritic growth. X-ray diffraction confirms that the Cu foam was spontaneously oxidized in air, leading to the formation of cuprous oxide (Cu2O).