Construction of Electrochemical Sensors Based on Zirconium-Based Metal–Organic Framework Composites and Their Detection of Cadmium

Abstract

This study presents a high-performance electrochemical sensor for the sensitive and selective detection of Cd²⁺ in water. The sensor was fabricated by modifying a glassy carbon electrode with a composite of amino-functionalized zirconium-based metal-organic framework (NH₂-UiO-66) and carbon black (CB). The amino groups of NH₂-UiO-66 serve as specific capture sites for Cd²⁺, enriching the analyte on the electrode surface. Simultaneously, the CB forms a three-dimensional conductive network that facilitates efficient electron transfer. This synergistic “enrichment-conduction” mechanism effectively compensates for the poor conductivity of the metal-organic framework (MOF) and significantly amplifies the electrochemical response signal. Quantitative analysis was performed using differential pulse voltammetry, with key parameters including deposition potential, deposition time, and supporting electrolyte pH systematically optimized. Under optimal conditions, the sensor exhibited a linear detection range of 0.1–10 μM (R² = 0.9998), a high sensitivity of 9.475 μA/μM, and a low detection limit of 0.02 μM. Furthermore, the sensor demonstrated excellent reproducibility, stability, and anti-interference ability. It was successfully applied to determine Cd²⁺ in real water samples, with spiked recovery rates ranging from 93.34% to 103.8%. This NH₂-UiO-66@CB-based electrochemical sensing platform offers significant potential for the rapid and sensitive monitoring of heavy metal ions in environmental applications.