Novel Electronic Conductance CO2 Sensors Based on Nanocrystalline Semiconductors

Abstract

AbstractWe have recently demonstrated that screen-printed sensors using a 20 nm- instead of microsized BaTiO3-CuO-additives powder exhibit up to one order of magnitude higher sensitivity to CO2. In this paper, we focus on both the surface chemistry of the nano-BaTiO3- CuO-additives powder (mix-BaTiO3) and electrical changes during O2 and CO2 adsorptions. We show by Fourier transform infrared (FTIR) spectrometry, thus without using electrodes, that the mix-BaTiO3 system behaves like a p-type semiconductor at the operating temperature. The variations of the electrical conductivity versus CO2 concentrations are followed in situ by FTIR spectrometry and prove to be dependent on the surrounding oxygen. These IR results are then correlated to the electrical measurements performed on the sensor. Preliminary electrical response modelling shows a good agreement with the surface barrier layer theory.