Facile and highly sensitive nitrate ion detection via an electrochemical sensor based on a poly 1,8-diaminonaphthalene and copper oxide particle film†

Excessive nitrate accumulation in soil and water has become a critical environmental concern, threatening ecosystems and public health. This drives the need for designing new electrochemical nitrate sensors based on novel electroactive materials. In this work, we synthesized a hybrid film material composed of poly 1,8-diaminonaphthalene and copper oxide particles electrodeposited on the surface of a carbon paste electrode (Cu₂O–CuO/poly 1,8-DAN/CPE). The electrodeposition of the polymer was conducted in galvanostatic mode at a positive current, followed by the electrodeposition of copper in potentiostatic mode at a negative potential. The polymeric film obtained through this facile electropolymerization method showed a uniform dispersion of copper particles and could improve the mechanical stability of the fabricated sensors, thereby leading to a low detection limit of nitrate ions. The Cu₂O–CuO/poly 1,8-DAN/CPE was prepared in just 3 min in both the galvanostatic and potentiostatic mode. The developed sensor exhibited a good electrochemical performance for nitrate ions, with a linear range from 2 to 200 μM, strong stability, high reproducibility, and a low detection limit of 0.5 μM. This work revealed that the deposition of polymer can be applied as a promising material in new applications, such as water denitrification.