**Acknowledgements**

I would like to thank Emin Yakar and Sani Demiri for academic support. Also, I would like to thank Irmak Karaduman Er and Selim Acar for their help in the gas sensor performance measurements section.

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**Author details**

Physics Department, Çanakkale Onsekiz Mart University, Çanakkale, Turkey

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Address all correspondence to: fatmaozutok@comu.edu.tr

provided the original work is properly cited.

Fatma Sarf

*Metal Oxide Gas Sensors by Nanostructures DOI: http://dx.doi.org/10.5772/intechopen.88858*

Thank you to the Science and Technology Application and Research Center (ÇOBILTUM/ÇOMU) for supporting instrumental analysis.

*Metal Oxide Gas Sensors by Nanostructures DOI: http://dx.doi.org/10.5772/intechopen.88858*

*Gas Sensors*

target gas-oxygen species-nanoparticles.

Gas sensitivity was preferred main gas sensor parameter.

surface atoms Van der Waals. This phenomenon is reversible.

ultrahigh porosity have been also so attractive especially last years.

development metal oxide gas sensors.

sensor performance measurements section.

(ÇOBILTUM/ÇOMU) for supporting instrumental analysis.

**Acknowledgements**

Gas transfer via micro-, meso-, and nano-porous sensing films with their assembled hierarchical, hollow, and yolk-shell forms has an enormous effect on interaction of

In this study, metal oxide gas sensors by nanostructures were investigated comprehensively. ZnO nanoflower, Al:ZnO depending on Al-solution type and ZnO/ MWCNT films were investigated toward different gases from our previous studies.

The results show that there is an interaction between the gas molecules and the sample surface based on the exchange of charges. While there is no gas in the environment, O2 molecules adsorbed on the sample surface form an electron depletion zone. When the sample interacts with gas molecules, O2 molecules also interact with the gas, and O2 molecules begin to be dislocated from the surface. By separating O2 molecules from the surface, electrons are released according to the property of the gas (reducing or oxidizing), or an electron is ionized from the sample. Thus, the change in electrical conductivity is observed. The detection rates and return mechanisms of the samples have also been fairly quick. Return times indicate that the main mechanism between the gases and the sample surface is physical adsorption. In physical adsorption, gas molecules are held in structurally formed cavities on the surfaces of the container in which they are located, interacting with the

In MO and metal doping MO studies, film growth process must be under control to avoid agglomerative formations and un-expected ion positions in crystal structure, this causes gas adsorption process decreasing. Similar effect also occurs in C-based material/MO nanocomposites however having bonds of C-based materials and p- to n-type conversion/p-n junction have improvement effect on the gas sensitivity with expanded depletion region, indicating room temperature sensing. On the other hand, in improvement studies of gas sensors, metal oxide gas sensors based on micro-hotplates fabricated with micro-electro-mechanical system (MEMS) technology that needs to be developed due to being restrictions on material and design. Uniform mesoporous structures are also desirable because they allow more sensing regions for gas diffusion. Additionally, metal organic frameworks (MOFs) with

Considering the circumstances mentioned above, engineering control over the metal oxide structure and sensor design is so critical in order to obtain high stability as well as high gas sensitivity. Development of new metal oxide material compositions and their high stability/crystallinity will bring high performance gas sensors. New nanofabrication techniques and surface improved studies have contributed to

I would like to thank Emin Yakar and Sani Demiri for academic support. Also, I would like to thank Irmak Karaduman Er and Selim Acar for their help in the gas

Thank you to the Science and Technology Application and Research Center

**12**
