Study of structural properties and sensing performance of high performance sol-gel synthesized CeTixOy sensing membranes

Abstract

In this paper, we developed a very simple sol-gel spin-coating method to fabricate high performance CeTixOy sensing membranes for a solid-state electrolyte-insulator-semiconductor (EIS) pH sensor. The surface morphologies, crystal structures, chemical compositions, and elemental depth profiles of the CeTixOy membranes treated with three different titanium concentrations (0.1, 0.3 and 0.5 M) were studied using a combination of atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, respectively. The structural properties of the CeTixOy membranes were corrected with the sensing performances of CeTixOy EIS pH sensors. The sol-gel synthesized CeTixOy EIS device prepared at the 0.3 M condition exhibited the best sensing characteristics (pH sensitivity, hysteresis voltage and drift rate) among these conditions. We attribute this behavior to the optimal titanium content in the sensing membrane enhancing the surface roughness CeTixOy film, increasing the Ce3+/Ce4+ ratio, and forming the stoichiometric Ce2TiO5 structure.