A non-enzymatic highly stable electrochemical sensing platform based on allylamine capped copper nanoparticles for the detection of the soil nitrate content.

Nitrate (NO) ion contamination of water is a major issue that affects many parts of the world due to excessive usage of nitrogen containing fertilizers in the soil. Hence, quantification of NO ions in the soil is of utmost importance. In the present research work, we have developed an efficient and highly stable non-enzymatic electrochemical sensor for NO ion detection based on allylamine capped copper nanoparticles (Alym@CuNPs) decorated on exfoliated multi-walled carbon nanotubes (Exf-CNTs). Herein, we have addressed the sensor surface storage stability issue of copper nanoparticle based electrochemical sensors for the first time and confirmed the superior storage stability of the Alym@CuNPs modified glassy carbon electrode (GCE) over uncapped copper nanoparticles (uCuNPs) and electrodeposited copper nanoparticles (eCuNPs) modified GCEs. In comparison to the bare GCE, Exf-CNT/GCE and Alym@CuNPs/Exf-CNT/GCE, the proposed Alym@CuNPs-Nafion (NF)/Exf-CNT/GCE demonstrated enhanced catalytic activity towards the electro-reduction of NO ions (pH = 2) under optimal experimental conditions, with a considerable increase in cathodic peak currents. Along with that, no inert gas was purged into the electrolyte medium prior to the detection of NO ions which makes the sensor more reliable under real environmental conditions. The sensor displayed broad linear ranges from 10 to 1000 μM ( = 0.997), with a limit of detection (LOD) of 5.28 μM ( = 3) for NO ion detection. The sensor surface shows excellent storage stability even up to 45 days with 97.8% retention in current value which is much higher compared to the previously reported works. Additionally, the sensor surface shows promising reproducibility and repeatability results with RSD values of 1.78% and 0.91%, respectively. Moreover, the proposed sensor is successfully utilized to detect NO ions in real soil samples.