Zinc peroxide combustion promoter in preparation of CuO layers for conductometric CO2 sensing

Abstract

The detection of CO2 has applications for both industrial and domestic use due to its high exposure effects on the human health. Conductivity sensors on the other hand, present a cost-effective approach that can be successfully utilized for the detection of CO2. However, the integration of metal oxide based nanoparticles layers for conducometric sensing is complicated and requires improvement in the layer quality to achieve effective and stable gas sensing properties. Addressing this challenge, we present in this work, p-type semiconducting CuO nanoparticles as a CO2 gas sensitive material and introduce a combination of organic binder and peroxide such as ZnO2 for improved gas sensitive layer quality. The addition of ZnO2 to CuO nanoparticles enables the layers annealing at 300°C which makes the preparation method compatible to silicon based gas sensing devices. For the characterization of layers, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and Fourier transform infrared measurements are employed. The CO2 gas sensing measurements show a reversible change in resistance suggesting hybrid nanoparticles layers as an efficient gas sensitive material. The measurements performed at different humidity levels for CuO-ZnO2 (10:1) layer indicate different sensing mechanism for dry conditions in comparison to the measurements performed under humid atmosphere. The Lewis acid-base reaction between oxide oxygen and CO2 has been proposed as sensing mechanism for the measurements in dry air, whereas the formation of surface barriers between nano-grains due to the reaction with CO2 has been suggested for the CO2 response under humid conditions.