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

• Published in: Sensors and actuators. B, Chemical Vol. 247; pp. 968 - 974
• Main Authors: Tanvir, N.B., Yurchenko, O., Laubender, E., Urban, G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2017
• Subjects: CO2 sensing; Copper oxide; Kelvin probe; Temperature dependence; Work function; Temperature dependence; Kelvin probe; Work function; CO2 sensing; Copper oxide
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2016.11.020

•The chemical activity of p‐type CuO nanoparticles is investigated at low temperatures (T≤110°C) for work function readout based CO2 gas sensors.•Highest work function change is detected at the temperature of 50°C (ΔΦpCO2=4000/r.h.=45%=127 mV).•The decrease in the response at the temperatures (50C<T≤100°C) is explained in terms of affecting the thermodynamics of the CO2 sensing process.•An optimized response by combining temperature and humidity is proposed at 65°C, where the humidity dependence is lowest on the reaction kinetics. 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.