Efficient CO sensing by a CuO:Au nanocomposite thin film deposited by PLD on a Pyrex tube

Abstract

Carbon monoxide gas is a highly toxic, poison gas in air that can lead to death, if inhaled by humans for a prolonged time. It is produced from incomplete various combustion processes (natural gas, gasoline of cars, outdoor fires, etc.), and circulates the same way as air as its density is close to air density. Moreover, it is a tasteless, colorless and odorless gas. Therefore, efficient CO sensors are necessary with high efficiency, low cost and easily production, low power consumption, simplicity and robustness in their operation. Such sensors can be realized by electrochemical, semiconducting metal oxide thin films. A p-type pure CuO and CuO:Au compound thin film sensor has been grown by Pulsed Laser Deposition on the surface of a Pyrex tube (Din = 8 mm, thickness 1 mm) and CO sensing has been performed with a concentration as low as ca. 60 ppm/air. A cheap, home-made and with low power consumption ceramic heater was inserted into the tube reaching operating temperature up to 450 °C. A granular film surface revealed by AFM and SEM measurements, indicating a large effective surface for gas sensing. EDS surface mapping indicated the Au existence on the CuO:Au compound film homogeneously covering the whole film surface. CO sensing measurements were performed for 305, 325, 345 °C operating temperatures and for a large number of CO concentrations in air.