Local Structure and Surface Properties of CoxZn1−xO Thin Films for Ozone Gas Sensing

ACS Appl. Mater. Interfaces, 2016, 8 (39), pp 26066–26072

Comparison of the responses of the CoxZn1−xO thin films to different gases

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Writers: Ariadne C. Catto, Luís F. da Silva, Maria Inês B. Bernardi, Sandrine Bernardini, Khalifa Aguir, Elson Longo, and Valmor R. Mastelaro

Keywords: cobalt; gas sensor; ozone; XANES spectroscopy; XPS; zinc oxide

Abstract: A detailed study of the structural, surface, and gas-sensing properties of nanostructured CoxZn1–xO films is presented. X-ray diffraction (XRD) analysis revealed a decrease in the crystallization degree with increasing Co content. The X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopies (XPS) revealed that the Co2+ ions preferentially occupied the Zn2+ sites and that the oxygen vacancy concentration increased as the amount of cobalt increased. Electrical measurements showed that the Co dopants not only enhanced the sensor response at low ozone levels (ca. 42 ppb) but also led to a decrease in the operating temperature and improved selectivity. The enhancement in the gas-sensing properties was attributed to the presence of oxygen vacancies, which facilitated ozone adsorption.

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