In2O3/TiO2 sensor sensitivity to triethylamine gas: effects of temperature, humidity, composite ratio

Purpose The purpose of this study is to use a titanium oxide composite containing indium oxide as a gas sensor for triethylamine (TEA). Design/methodology/approach The use of density functional theory (DFT) to interpret experimental gas sensing results led to limited results that correlated theory and experiment. However, the use of transition state theory (TST) in combination with DFT led to the theoretical prediction of the most important experimental results in gas sensor experiments. Findings The method begins with the evaluation of the Gibbs energy of adsorption and transition of TEA with different composite ratios of the sensing material In2O3/TiO2. The change in the number of vacancies was calculated, which is proportional to the gas response. A 33% In2O3/TiO2 (molar) ratio was found to be optimum. The optimum temperature for the 33% In2O3/TiO2 was 280°C, which is close to the TEA autoignition temperature of 312°C. Logistic functions were incorporated for both the autoignition temperature and relative humidity. Originality/value The present method has several advantages over the use of DFT alone. Novelty includes the matching between theory and experiment, which encompasses the optimum composite ratio, sensor response with temperature, response versus TEA concentration, response time with temperature, response versus relative humidity and sensor response stability over time.