Electrochemical Conversion of Copper‐Based Hierarchical Micro/Nanostructures to Copper Metal Nanoparticles and Their Testing in Nitrate Sensing

Metallic copper nanoparticles (CuNP) are formed from the reduction of hierarchical copper‐based micro/nanostructures previously electrodeposited on polypyrrole‐polystyrene sulfonate (PPy‐PSS) thin films. The application of a high reduction potential causes the erosion of the micro/nanostructures nanosheets and the formation of CuNP. The CuNP are used in a series of preliminary tests in order to assess their performance in the sensing of nitrate. The sensing performance is improved with the introduction of polyethyleneimine‐functionalized multiwall carbon nanotubes (MWNT‐PEI) to the PPy‐PSS films. Electrochemical impedance spectroscopy studies show that the nanotubes increased the electronic conductivity of the reduced films. The limit of detection of the PPy‐PSS‐MWNT‐PEI‐CuNP nanocomposite is 30 µM nitrate. The materials need further development and optimization work in order to be applied as sensors.