Fabrication of Highly Sensitive Ethanol Chemical Sensor Based on Sm-Doped Co3O4 Nanokernels by a Hydrothermal Method

Abstract

Here, we report a large-scale synthesis of Sm-doped grain-shaped nanokernels of Co3O4 by a simple hydrothermal method at a low and active temperature of 150.0 °C. The synthesized Sm-doped Co3O4 nanokernels were characterized in detail in terms of their morphological, structural, and optical properties and efficiently applied as an ethanol chemical sensor. The morphological and structural examinations were executed by using field emission scanning electron microscopy (FESEM) attached with energy-dispersive spectroscopy, X-ray diffraction pattern, and Fourier transform infrared spectroscopy (FT-IR) measurements. It is noticed that the small nanostructures are assembled in such a simple approach that they acquired nanokernel-like morphologies. Detailed structural examinations also exposed that the calcined (at 400.0 °C) Sm-doped Co3O4 products are well-crystalline and comprising the face-centered cubic phase. The optical property, executed by UV–visible spectroscopy, demonstrated good optical properties for calcined Sm-doped Co3O4 nanokernels. Sm-doped Co3O4 is an attractive nanokernel to be employed in chemical sensing by a simple and reliable I–V method, where a toxic chemical (ethanol) is used as a target analyte. The ethanol sensor performances are explored, and the results displayed that the excellent sensitivity, constancy, stability, and reproducibility of the sensor improved comprehensively by Sm-doped Co3O4 nanokernels with a fabricated surface coated with conducting binders onto silver electrodes (AgE). In the analytical investigation, the calibration plot is linear above the large concentration range (1.0 nM to 10.0 mM), where the sensitivity is around 2.1991 ± 0.10 μA cm–2 mM–1 with a very low detection limit (LOD) of 0.63 ± 0.02 nM based on the signal-to-noise ratio in a short response time. Consequently, on the basis of the sensitive features between structures, morphologies, and properties, it is confirmed that the morphologies and the optical behaviors can be improved to a large range in doped semiconductor nano-kernel and proficient chemical sensor applications in wide scale.