Sensitivity of Nanostructured Mn-Doped Cobalt Oxide Films for Gas Sensor Application

Ehssan Salah Hassan, Kameran Yasseen Qader, Esraa Hassn Hadi, Sami Salman Chiad, Nadir Fadhil Habubi, Khalid Haneen Abass

Abstract

The effect of manganese doped  cobalt oxide (Co3O4:Mn) was investigated by two different ratios (1% and 3%), which were precipitated by spray pyrolysis technique (SPT), and was adopted using a laboratory designed glass atomizer. Glass substrates were used to deposit films on them, heated at a temperature of 420 ℃. The structural properties were studied through X-ray diffraction. The results showed that all deposit nanostructured films were polycrystalline and  there was a decrease in the preferred reflection intensity along (311) plane resulting in a decrease in the crystallite size. Surface properties were analyzed through atomic force microscopy (AFM), which showed a decrease in the roughness and the particle size growth was a vertical columnar rod. The optical characterization displayed  that the transmittance of pure Co3O4 nanostructured films was 48% and decreased to 35% for 1% of the Mn concentration, and continued to decrease to 33% with the increase of manganese concentration up to 3%. Optical energy bandgap of pure Co3O4 nanostructured films was 1.435 eV and decreased to 1.419 eV for 1% of Mn concentration, and continued to decrease to 1.367 eV with the increase of Mn concentration up to 3%. The highest percentage sensitivity was for the sample doped with 3% Mn, which was about 65%, for NO2 gas concentration of 600 ppm, at an operating temperature of 200 ℃.

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Nano Biomedicine and Engineering.

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