Core–shell mesoporous silica-based ion-imprinted electrochemical sensor for the determination of trace Cd 2+ in water

A selective and sensitive ion-imprinted electrochemical sensor was proposed to detect cadmium ion (Cd 2+ ) through differential pulse voltammetry (DPV) method based on core–shell mesoporous cadmium ion-imprinted polymers (IIP) and gold nanoparticles (AuNPs). The ion-imprinted polymers were prepared by the surface ion-imprinting technique using core–shell mesoporous silica as the carrier, Cd 2+ as the template ion, and 3-mercaptopropyl trimethoxysilane (MPTMS) as the functional monomer. Due to the implementation of surface ion imprinting strategy on core–shell mesoporous structure, the polymer was endowed with excellent specific surface area and imprinted cavities, thus showing effective transmission and recognition ability for Cd 2+ . Furthermore, the introduction of gold nanoparticles synthesized through electrodeposition can accelerate the electron transfer rate and also increase the modified area of electrode for ion-imprinted polymers, resulting in higher sensitivity of the modified electrodes when ion-imprinted polymers was self-assembled on the surface of gold nanoparticle-modified electrode through Au–S. The linear range of the sensor varied from 1 to 100 µg L −1 , with the minimum detection limit of 0.22 µg L −1 . In addition, excellent anti-interference ability in Cd 2+ detection was obtained in the presence of various interfering ions, and the sensor has also been proved to have good practicability in actual water sample detection, with the recovery rate in the range of 82.2% and 116.0% and the RSD is in the range of 0.33−7.30%. Therefore, this work is expected to provide an electrochemical sensor with excellent selectivity, good stability, and sensitivity for detecting trace Cd 2+ in real-water samples. Graphical Abstract