An efficient chemical sensor based on CeO₂ nanoparticles for the detection of acetylacetone chemical

Highlights

• CeO₂ nanoparticles are synthesized by hydrothermal process.

• CeO₂ nanoparticles are utilized as electro-active materials for chemical sensor.

• Modified electrode shows quick sensing response to acetylacetone chemical.

• The sensing performance is evaluated by measuring cyclicvoltametry analysis.

Abstract

Facile, economic, template free and low-temperature hydrothermal synthesis of CeO₂ nanoparticles was carried out in this research article. As-synthesized CeO₂ nanoparticles were characterized through different techniques including FESEM, TEM, XRD, FTIR, UV–visible spectroscopy, Raman spectroscopy, and XPS analysis. XRD diffraction peaks confirmed the cubic fluorite structure for CeO₂ nanoparticle. Highly agglomerated nanostructures with an average particle diameter of 15 ± 2 nm were observed from FESEM and TEM analyses. A single defined absorbance at 302 nm corresponding to the bandgap energy of 4.11 eV was recorded from the UV–visible spectrum. Vibrational and scattering properties as analyzed from FTIR and Raman spectra confirmed the formation of CeO₂ nanoparticle. The CeO₂ nanoparticles were immobilized on a glassy carbon electrode which showed excellent electrocatalytic activity in 0.1 M PBS with pH 7.4 for acetylacetone. The sensitivity, LOD and regression coefficient (R²) were respectively, 262 mA·mM⁻¹ cm⁻¹, 11.6 mM and 0.87339 for the fabricated chemical sensor. The study conducted herein confirms that CeO₂ nanoparticles are promising candidates for electro-analytical sensing applications.

Introduction

Due to excellent electrochemical, electronic, photocatalytic, sensing and electromagnetic applications, lanthanum oxides, especially cerium oxide (CeO₂), is considered as an important multifunctional material [[1], [2], [3]]. CeO₂ has excellent physical and physicochemical properties such as semiconductor properties, a wide bandgap of ~3.2 eV, remarkable thermal and chemical stability, low toxicity, easy synthesis, etc. CeO₂ nanostructures including nanocubes [4], nanorods [5], hollow spheres [6], nanosheets [7], nanoflakes [8], nanoflowers [9], nano-octahedrons [10], nanotubes [11] and nanoparticles [12] have already been synthesized by various techniques such as hydrothermal, sol-gel, chemical precipitation, solution combustion etc. [13,14].

As compared to conventional sensing techniques like gas chromatography–mass spectrometry (GC–MS), mass spectroscopy, atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectroscopy (ICP-MS), fluorescence, electrophoresis, nitrotometry, liquid chromatography-mass spectrometry (LC-MS), potentiometry, atomic emission spectroscopy (AES), an electrochemical sensing provides an alternate faster, economical and easier way to detect the toxic and hazardous materials [15,16]. The chemical modification of the electrode is the key to increase the overall sensitivity and selectivity to a particular target compound, along with a low detection limit and minimized over-potential during electrochemical sensing applications [17,18]. Owing to their unique electrochemical redox properties, n-type semiconductor properties, high surface to volume ratio and propensity as an electron mediator, CeO₂ nanoparticles are used to fabricate modified electrodes for analytical sensing applications [19,20]. Co-CeO₂ nanocomposites synergistically performed the role of electro-catalyst as well as an electro-active for the sensing of hydrazine and showed reasonable sensitivity of 7.7 mA·mM⁻¹ cm⁻², limit of detection of 0.006 μM and good linearity of 0.005 mM to 0.37 mM [8]. Jha et al. [21] observed a very low detection limit of 30.40 nM for H₂O₂ using the CeO₂/rGO xerogel composite modified glassy carbon electrode. Biosensor sensitivity of 0.165 μA mM⁻¹ cm⁻² was recorded for glucose by Patil et al. [22] through ITO coated CeO₂ nanorod films. Sacara et al. modified GCE with CeO₂ nanoparticles/Nafion for the electrochemical detection of hazardous malachite green dye [23]. CeO₂ nanoparticles based electrode was used for the amperometric sensing for eugenol by Ziyatdinova et al. [24]. Many other toxic and hazardous chemicals like 4-nitrophenol [25], dopamine [26], xanthine, hypoxanthine and uric acid [27], picric acid [28], etc. are detected using CeO₂ nanostructures of various morphologies. No literature is reported for the electrochemical sensing behavior of CeO₂ nanoparticles towards acetylacetone (2,4-pentanedione) which causes mild skin and respiratory tract irritation and severe eye damage on short term exposure.

Herein, a facile template-less hydrothermal process was used to prepare CeO₂ nanoparticles. The prepared nanoparticles were characterized for their compositional, morphological, structural, vibrational and optical properties. As-synthesized CeO₂ nanoparticles were used to fabricate electrochemical sensors to detect acetylacetone. The fabricated acetylacetone sensor exhibited excellent sensing performance, i.e. low limit of detection, wide-linear range, high sensitivity, and long-term stability. To the extent of our awareness, this is the first-ever report which illustrates the development and characterization of acetylacetone chemical sensor based on CeO₂/GCE electrode system.