Investigation of sensitivity of V2O5 MOS sensors to H2S gas in different periods by hydrothermal synthesis methods

In this thesis, V2O5 nanostructures, which serve as sensing surface in the gas sensor system to be used especially in mine, oil and natural gas sectors, were grown on glass substrates through Hydrothermal Synthesis Method. The structural, morphological, elemental, optical and H2S gas sensing properties of V2O5 nanostructures grown as three different species (coded SN, SO and HN-PVP) by changing the growth parameters (growth time, growth temperature, solutions, solution pH value and acids) were investigated through XRD, SEM, EDAX, UV-VIS spectrophotometer and gas measurement system, respectively. The XRD and SEM studies indicated that the nanostructures had polycrystalline nature with monoclinic phase of V2O5 and there were dense coating containing nanorod, nanowire, nanoball, nanoplate on glass substrates. EDAX analysis of V2O5 nanostructures confirmed stoichiometric growth of nanostructures and the presence of V, O elements on the surface of the nanostructures. The optical absorption measurements at room temperature showed that the band gap energy values of the nanostructures changed depending on the growth time and growth temperature.As a result of these measurements and of the optimization processes by changing the growth parameters, the sensor with HN-PVP coded V2O5 nanowire network structure was determined as the optimized sensor capable of sensing 10-50 ppm H2S at operating temperature below 50 oC (at 42 oC). Gas sensing measurement was performed for H2S gas at eight different humidity values for the optimized sensor. In addition, gas sensing measurement was also performed for control group gases for optimized sensor.