Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-019-01847-3 Electrochemical detection of Chromium(VI) using NiO nanoparticles B. Kowsalya 1  · V. V. Anusha Thampi 1  · V. Sivakumar 2  · B. Subramanian 1 Received: 26 January 2019 / Accepted: 8 July 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract We report the detection of toxic heavy metal ion Chromium(VI) through a simpler cyclic voltammetry study. The sol–gel synthesized Nickel Oxide (NiO) nanoparticles were coated onto the fluorine doped tin oxide plate used as a working electrode for the heavy metal detection. The synthesized nanoparticles were characterized using X-ray diffraction, Fourier Transform Infrared Spectroscopy and UV–Vis Spectroscopy. The effect of varying concentration of chromium at different scan rate was studied in a three-electrode system with hydrochloric acid as electrolyte within a potential window from − 0.4 to − 0.8 V. Oxidation and reduction potentials were studied and it reflected a diffusion controlled process. The obtained experimental data were compared with the theoretical calculations using the Randles–Servick equation. Atomic Absorption spectroscopy was applied for the quantitative determination of the metal. The results suggested the efficacy of synthesized NiO nanopar- ticles for the detection of heavy metal ion via electrochemical techniques. 1 Introduction Chromium (Cr) with an atomic number of 24 is a steel-grey, hard and brittle metal. It is known for its high melting point and tarnish resistance, which is widely used in the steel industry in its metallic Cr (0) form. Chromium is identified to exist in its two oxidation states via Chromium(III) and Chromium(VI) and is present in wastewaters from various sectors like textile, leather tanning, electroplating, cataly- sis, electronic industries etc., causing adverse biological and ecological effects [1, 2]. Cr(III) and Cr(VI) possess different physicochemical properties and toxicity, while chromium in its 3 + state is less toxic than 6 + . Cr(III) is nearly insoluble at neutral pH and it constitutes a minor role as trace nutrient for the proper functioning of controlled glucose and lipid metabolism in mammals. Cr(VI) exerts hazardous effects and reduces Cr(III) by penetrating the cell wall and forming reactive oxygen species leading to inhibition of the metal- loenzyme system. The United States Environmental Pro- tection Agency (US EPA) has identified Cr(VI) as one of the 17 chemicals posing the greatest threat to humans. To protect human health and the environment, World Health Organization (WHO) has set a maximum limit of 50 mg L −1 (1.0 mM) Cr(VI) in groundwater system and concentration in industrial waste generally varies from 40 to 1000 mg L −1 (0.8–19.2 mM). Furthermore, Cr(VI) compounds are sig- nificantly soluble and mobile in both biological and natural systems. Therefore, selective detection and monitoring of Cr is important in order to provide control of this highly toxic substance for human and environmental concerns [3]. Various methods like inductively coupled plasma mass spectrometry (ICP-MS), high-performance liquid chroma- tography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS), and atomic absorption spectroscopy (AAS) have been used for the detection of chromium; however the voltammetric technique provides an easy means of heavy metal detection having advantage of low cost and easy to operate system [4]. Cyclic voltam- metry (CV) helps to study how the electrons transfer and related chemical reactions by the induction of oxidation and reduction of chemical species. They provide infor- mation related to the physical and chemical processes at the time of reaction. CV curves are based on a fun- damental equilibrium relationship between an electrode and electrolyte. When an electrode potential is changed Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10854-019-01847-3) contains supplementary material, which is available to authorized users. * B. Subramanian bsmanian@cecri.res.in; bsmaniancecri@gmail.com 1 Electrochemical Materials Science Division, CSIR-Central Electrochemical Research Institute, Karaikudi, Tamil Nadu, India 2 Department of Physics, University College of Engineering, BIT Campus, Tiruchirappalli, Tamil Nadu, India