Cobalt oxide nanoparticles based carbon electrode for the detection of residual nitrite in the soil of agricultural fields

ABSTRACT

In the past few decades, accumulation of excess fertiliser in soil leads to deterioration of soil quality with carcinogenic effects on animals and humans. Hence, a quick, effective and reliable method of nitrite detection is necessary. In this regard, cobalt oxide nanoparticle-based carbon electrodes have excellent sensitivity towards electro-catalytic detection of nitrite ions. In this research, cobalt oxide nanoparticles were synthesised by precipitation reaction followed by calcination. Various spectroscopic methods have been used for the characterisation of nanomaterial, such as TEM, SEM-EDAX, FT-IR and XRD. A carbon-based electrode was developed using cobalt oxide, graphite and silicon oil. The electrode showed a good sensitivity towards detection of nitrite with limit of detection 0.3 µm and wider linear range. Due to low-cost preparation, sensitivity towards NO₂⁻ ions and high conductivity, the sensor can be employed for the detection of nitrite in agricultural field soil samples.

Graphical Abstract

KEYWORDS:

• Fertilisers
• innovative
• nitrite
• electrochemical sensors
• nanoparticles
• green synthesis

Highlights

• Cobalt oxide nanoparticles were synthesised by precipitation method and were calcined.

• SEM-EDAX, XRD and TEM analyses were done to characterise the nanomaterial.

• A carbon paste electrode was constructed using Cobalt oxide, graphite and silicon oil in proper proportions.

• Cyclic voltammetry studies for the detection of nitrite were carried out in the presence of nitrite concentration ranges.

• The electrode exhibited a good sensitivity towards detection of nitrite with less limit of detection.

• Due to low-cost preparation, sensitivity towards NO₂^– ions and high conductivity, the sensor can be employed for the detection of nitrite in agricultural field soil samples.

Acknowledgements

The authors are grateful to Siddaganga Institute of Technology for providing the facilities for the analysis and for guiding us. The authors are also grateful to Sophisticated Analytical Instrument Facility, STIC, Kochi, for providing characterisation results. Dr Prashanth SA greatly thanks Karnataka Science and Technology Academy (KSTA), Government of Karnataka, for the financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Karnataka Science and Technology Academy, Govt. of Karnataka, INDIA [31/2021-2022].