Search

Elevated nitrate (NO 3 - ) levels in potable water due to anthropogenic and geogenic activities pose a significant environmental threat. Herein, we report a highly efficient electrochemical sensor device for NO 3 - detection using a copper-anchored magnetite (Cu@Fe 3 O 4 ) nanocomposite. The electrochemical performance of the NO 3 - sensor was highly durable and reliable on a glassy carbon electrode (GCE) and as a proof of concept, it has been translated to thermal vapor deposited gold electrodes (Au electrodes) chip integrated with a hand-held portable potentiostat connected to a smartphone with read out capabilities for onsite real field application. The Cu@Fe 3 O 4 nanocomposite was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) mapping, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) to confirm phase purity and successful synthesis. The sensor exhibited high selectivity for NO 3 - ( P ≤ 0.05), stability up to 21 days with a minimal 1.2% signal decrease, and a linear detection range of 10-1000 μM, with a detection limit of 1.35 μM and sensitivity of 0.0342 μA/μM. It also showed reproducibility of a relative standard deviation (RSD 1.33%) and successfully detected NO 3 - in real water samples. This robust sensor provides an effective tool for real-time environmental assessment of NO 3 - , aiding public health protection. more...

Nitrate (NO 3 - ) 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 3 - 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 3 - 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 3 - 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 3 - ions which makes the sensor more reliable under real environmental conditions. The sensor displayed broad linear ranges from 10 to 1000 μM ( R 2 = 0.997), with a limit of detection (LOD) of 5.28 μM ( n = 3) for NO 3 - 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 3 - ions in real soil samples. more...