Investigation of a new electrochemical cyanide sensor based on Ag nanoparticles embedded in a three-dimensional sol–gel

In this study, a novel sensor for cyanide detection was developed by self-assembling of a sol–gel network and silver nanoparticles. Silver doped silica nanocomposite was synthesized via a sol–gel technique combined with a nanoparticle preparing method. Then a cleaned gold electrode (GE) was immersed in a hydrolyzed mercaptopropyltrimethoxysilane (MPS) sol–gel solution containing Ag nanoparticles (AgNPs) to assemble three-dimensional silica gel. Thus, modified electrode (GE/sol–gel/AgNPs) was prepared to detect cyanide based on the specific reaction of Ag nanoparticle and CN−. The size of Ag nanoparticles and silica pores was examined by atomic force microscopy (AFM) around 34.5 nm and 91.3 nm, respectively. The performance and factors influencing the performance of the resulting sensor were studied in detail. The detection limit of the sensor was 1.4 × 10−8 mol L−1, and the linear range was from 1.5 × 10−6 mol L−1 to 2.1 × 10−4 mol L−1. And also, common contaminants at levels presenting in industrial waste water did not interfere with the assay. Moreover, the studied sensor exhibited high sensitivity, good reproducibility, and long-term stability.