Investigation of low temperature effects on work function based CO2 gas sensing of nanoparticulate CuO films

Abstract

The gas sensing behavior of semiconducting nanoparticulate copper oxide (CuO‐NPs) towards CO2 with respect to different conditions affecting the signal response is investigated with the help of adsorption induced work function changes. Work function measurements have been carried out with the help of Kelvin probe. The analysis of cross‐sensitivities to humidity is conducted in the low temperature range between 25°C and 110°C and it is shown that for CuO‐NPs, optimization of work function based CO2 sensing is possible by using a combined effect of humidity and temperature. Furthermore, the temperature induced effects during CO2 sensing are explained using considerations of kinetics and thermodynamics of the process. We show that moderate temperatures of about 65°C exert a positive influence on the kinetics of chemical processes occurring on the CuO‐NPs surface in the presence of water and CO2 as well as counterbalance the negative impact of high humidity dependence on CO2 gas sensing. However starting from 65°C, CO2 response decreases owing to a negative effect of temperature on the thermodynamics of the sensing reaction. Compared to other metal oxide based materials for CO2 sensing, CuO‐NPs show promising results and enables the prospect towards the development of new CO2 gas sensor operable at low temperatures.