Synthesis and characterization of thermochemical spray nickel oxide- cobalt oxide Nano composite As a CO2 gas sensor

In this research, cobalt oxide's pure nano thin films of were prepared, and a mixture of cobalt oxide (Co3O4) and nickel oxide (NiO) was prepared in volumetric proportions of nickel oxide that included (10,20vol%) by thermal chemical spraying method, deposited on bases of glass at a temperature of (250 °C). The results of X-ray examinations of the prepared membranes showed that they have a polycrystalline composition, and that the prepared membranes formed a nanocomposite of cobalt and nickel. The formula Debye Scherer was used to calculate the crystal size. The nanoscale was decreasing with increasing(10,20%) the mixing ratio of nickel oxide for membranes deposited on glass bases Dimensions (2×2cm) , decreasing from (19.6 nm) for pure cobalt oxide to (8.45875 nm). Cobalt oxide mixed with 20% nickel. Use an atomic force microscope (AFM) to determine the grain size, roughness rate, and square root square mean, The images showed that the surface of the membranes is homogeneous, and that the average granular size of all membranes is nano-size and its value changes with the change of mixing ratio, the optical transmittance of the prepared membranes was calculated, using a spectrophotometer and the wavelength ranges between, (nm1100-nm3000). It was found that the increase in the mixing ratio leads to a decrease in the transmittance, while the optical energy gap also decreased with the increase in the mixing ratio. The results confirmed that the cobalt oxide membranes inlaid with nickel oxide have a high degree of sensitivity towards CO2 gas, as the sensitivity values depend on the mixing ratios, base temperature and gas concentration. It was found that the relative sensitivity values (S%) for Co3O4 – NiO) ,thin films deposited on glass bases towards (Co2) gas, have a sensitivity value of up to (70.7) at the highest concentration (242ppm) and at a temperature of (100C°), as sensitivity increases with increasing gas concentration. The study also proved that nanothinfilms mixed of Co3O4-NiO prepared by thermal chemical decomposition method give gas sensors with good properties towards CO2 even at room temperature.