  The gas sensitivity of Mg/CuO nanocomposite films, characterized by varying
mass ratios of Mg:CuO, was assessed under exposure to 1000 ppm of methanol
vapor. Films were fabricated by the doctor blade method on conductive and
nonconductive glass substrates. Structural and optical analyses were conducted
using XRD and UV-Visible spectrums. The XRD patterns facilitated the estimation
of crystallite size, dislocation density and strain. The optical band gap of
the samples was determined from UV-Visible spectrums. Despite variations in
crystallite size, dislocation density and strain in response to changing Mg
concentrations in nanocomposites, no discernible shift in the band gap was
observed. The mass percentage of Mg in nanocomposite was incrementally altered
from 10% to 20% in steps of 5%. Due to the adsorption of methanol vapor, the
resistivity of the sample decreased significantly. Gas sensitivity exhibited
variance ranging from 3.79 for pure CuO to 1.23 for nanocomposite with 20%Mg.
The sample with 10%Mg quickly responded to methanol vapor compared to pure CuO
and other nanocomposites.
  Keywords: CuO, nanocomposites, gas sensors, XRD, UV-Visible spectrums
