Gas sensors based on plasma-electrochemically oxidized titanium foils

Abstract. We have developed a preparation technique to form graphite/TiO₂/Ti and platinum–graphite/TiO₂/Ti solid-state sensors. It is based on plasma electrolytic oxidation (PEO) of titanium foils, whereby a porous titanium oxide layer is formed with well-defined phase composition and a reproducible microstructure. A printing method is used to deposit graphite or catalytically active graphite–platinum electrodes. Our design enables the application of a variety of different detection principles such as calorimetry, impedances and amperometry. This study reports results for H₂, H₂O, and CO sensing at room temperature with the most appropriate detection principle, electrode composition and titanium oxide microstructure.