Synthesis of hierarchical mesoporous graphite oxide/Al₂O₃ from MIL-100(Al) for the electrochemical determination of caffeic acid in red wine samples

We have synthesized the hierarchical mesoporous graphite oxide (HMGO) through simple single step carbonization method by using MIL-100(Al) metal-organic framework as a template. To study the influence of temperature in the synthesis of HMGO, various carbonization temperatures (700, 800, and 900 °C) were fixed without any additional carbon sources. The newly prepared HMGO showed uniform morphology, pore-size distribution centered on 10 nm with high surface area (370–470 m²/g) and excellent electrochemical ability. Hence, we have constructed an amperometric sensor for the trace level detection of caffeic acid (CA) by using HMGO as a modifier in glassy carbon electrode (GCE). The good electro catalytic activity of HMGO film modified GCE can be explained from the low over potential and high redox peak current obtained toward the detection of CA. Our demonstrated sensor works in a wide linear range (0.01–608 µM) with low limits of detection (0.004 µM) and high sensitivity (429 µA/mM/cm²). In addition, the selective determination of CA even in presence of other interfering molecules, reveals the good selectivity of HMGO/GCE. The commercially available wine samples were further utilized to demonstrate the practical feasibility of HMGO modified GCE. The acceptable values of stability, repeatability and reproducibility also support the practical applications of our fabricated electrode.