Temperature dependent electrical and gas sensing properties of ce/cuo nanostructures

Abstract

Research on semiconducting metal oxide (MO) nanostructures is a fascinating field that has received massive interest due to their significant physical and chemical properties which can be useful in the development of highly efficient nanodevices. Incorporating impurities such as metal elements into the MO matrix offers tailored properties for various applications. Doped MO nanostructures exhibit modified structural, optical, electrical and morphological properties rendering them useful for fabricating high-performance devices. This study focuses on the synthesis of Cerium-Copper Oxide (Ce/CuO) nanopowders and thin films using simple hydrothermal and spray pyrolysis methods that are both inexpensive and eco friendly. Characterization techniques including X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), Ultraviolet-Visible spectroscopy (Uv-Vis), Scanning Electron microscopy (SEM), Energy dispersive spectroscopy (EDX), Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and two-point probe method were employed to gauge the characteristics of the synthesized samples. XRD analysis revealed formation of monoclinic phase of CuO with decreasing crystallinity of the samples as the Ce content increased. Analysis with EDX detected Cu, Ce, and O in the samples. A Raman peak corresponding to the CeO2 phase was identified at higher Ce doping levels. SEM imaging revealed that Ce incorporation induces changes in nanostructure morphology. The optical bandgap (Eg) depicted a blue shift as the Ce content increased in the samples. The Ce/CuO samples exhibited enhanced temperature-controlled DC conductivity with the 4% Ce sample showing the lowest activation energy, lowest Tmax and consequently the maximum conductivity peaking at a temperature of 503K. Ethanol sensing capabilities of Ce/CuO thin films were measured at different ethanol concentrations and working temperatures. Good stability and maximum response were observed for the 4 % Ce thin film. The sensor exhibited greater response to ethanol compared to methanol, acetone, acentronile, and ammonia. These results suggest that the Ce/CuO is a promising ethanol gas detector, with the Ce dopant playing a significant role in improving the electrical and sensing properties of CuO.