Enhanced CO₂ Sensing Performance of Ca-Doped ZnO Nanoparticles under UV Illumination

Pure and calcium-doped ZnO (CZO) nanopowders with an atomic ratio of 0.03 were produced by sol–gel synthesis. X-ray diffraction investigation results showed that both undoped and Ca-doped ZnO exhibited a hexagonal Wurtzite structure with no additional secondary phases and a small amount of ZnO lattice deformation. This implies that the ZnO network has good calcium ion substitution. The average crystallite size increased from 30 to 57 nm when the Ca ions were added. The produced powders are made up of grains and particles with both regular and irregular spherical forms, according to TEM images. Zn, O, and C were detected in both samples by XPS spectra, and the efficient incorporation of Ca ions into the ZnO network was verified by an extra Ca 2p peak in C3ZO. By screen-printing nanopowder paste onto alumina substrates, carbon dioxide gas sensors based on the previously recommended samples have been created. This article primarily addresses the effects of Ca ions and UV light on electric and CO₂ sensing properties.