Fabrication of post-synthetic modified Fe (III)-based metal organic framework for the electrochemical detection of 4-amino phenol

4-Aminophenol (4-AP) is an aromatic compound with reactive hydroxyl and amino groups. It is widely used in the production of dyes, pharmaceuticals, and polymer stabilizers but poses significant environmental and health hazards. Therefore, developing a reliable method for the detection of trace amounts of 4-AP is crucial. This study focuses on the fabrication of a cost-effective electrochemical sensor for 4-AP based on the post-synthetic modification of Fe-MIL-101-NH₂. The sensor demonstrated a linear detection range of 0.5–400 µM with a low limit of detection (LOD) of 0.12 µM and a sensitivity value of 0.29 µA/µM/cm² under optimized conditions. The synergistic effect of Fe-MIL-101-NH₂, the Schiff base, and nickel enhances its electronic properties, including reduced band gap energy, lower charge transfer resistance, and improved conductivity, leading to superior redox behavior of 4-AP. Key features of the sensor include high sensitivity, favorable selectivity, outstanding stability, and excellent reusability. It exhibits minimal interference from common organic and inorganic species, making it suitable for real-world applications. The use of earth-abundant materials further underscores its cost-effectiveness and environmental sustainability. The sensor has been applied in detecting 4-AP in tap water and paracetamol samples and achieved positive results further demonstrating its practicality for real-world applications.