Facile synthesis of nano-structured magnesium oxide via sol-gel Method: Insights into structural, electrical, and humidity sensing characteristics

The growing electronic industry has led to widespread use of electronic devices, where environmental humidity can impact their performance. Consequently, there has been increasing interest in the development of humidity sensors to ensure optimum functionality. This work focuses on the preparation and performance of magnesium oxide nanoparticles-based humidity sensor, with nanoparticle being synthesized using sol gel method. Physical analysis of the synthesized MgO nanoparticles was done by different analytical techniques including Fourier Transform Infra-red Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Ultraviolet–Visible spectroscopy (UV–Vis), Thermogravimetric Analysis (TGA) and Brunauer-Emmett-Teller (BET) analysis. Average crystallite size obtained from XRD was 31 nm while particle size calculated from FESEM images was noted to be 190 nm. The band gap energy of the as prepared nanoparticles was found to be 2.78 eV with maximum absorbance at 200 nm. XPS proved the existence of Mg and O with weight percentages of 21.80 % Mg and 77.58 % O. The BET surface area was 219 m²/g, with BJH specific surface area of 134 m²/g and average pore size of 15.43 nm. The electrochemical properties were evaluated using cyclic voltammetry (CV) galvanostatic charge discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques, revealing specific capacitance values ranging from 8.66 to 90.73 F g⁻¹, with a capacitance retention of 66 %.EIS results indicated a solution resistance of 0.87792 Ω cm² and charge transfer resistance of 3.077 Ω cm². Humidity sensing response was evaluated by measuring resistance changes through LCR (Q) meter. The humidity sensor demonstrated a response and recovery times of 52 s and 131 s respectively. Results of various physical parameters and applications proved that the prepared magnesium oxide could be successfully used as active materials for fine supercapacitance and humidity sensing applications.