Electrochemical Sensors Modification with Metal Oxide Nanoparticles

Due to their simplicity of manufacture , use, electrochemical sensors have been continuously developed for more than a century , have achieved numerous improvements, particularly re-lated to increasing sensitivity and selectivity, extending the linear dynamic range, and lowering the limit of detection. The mentioned improvements are the result of innovations in electrochemical sensor design, as well as the more frequent use of different nanomaterials as modifiers. Among the modifiers most frequently used are metal oxide nanoparticles, which are founding sensors alone or in combination with other materials. The combination of metal oxide nanoparticles and graphene or (reduced) graphene oxide is particularly noteworthy. These two materials positively influence each other, as the graphene layers are responsible for better electrical conductivity and the metal oxide nanoparticles for preventing their aggregation. Combinations with multi-walled or single-walled carbon nanotubes and metal nanoparticles are commonly described too. There are publications giving the description of combined different types of metal oxide nanoparticles, which is particularly evident in the combination of Al2O3 and ZnO. In addition to aluminium and zinc oxide, this article reviews the literature on iron and copper oxide nanoparticles used in the modification of electrochemical sensors, the analyte, the method of determination, the linear dynamic range of the sensor, and the limit of detection. The types of analytes that can be deter-mined with these sensors are as varied as the methods used. However, among the methods, the voltammetric method is the most represented, while the potentiometric method has been used in only a few references.