GaxIn2-xO3 surface pyramids interaction with formaldehyde: thermodynamic and sensing analysis

GaxIn2-xO3 surface pyramids' electronic structures are investigated using density functional theory, including dispersion corrections. Application of GaxIn2-xO3 surface pyramids as a gas sensor for formaldehyde is also performed and compared with experimental findings. These findings show that the energy gap of these pyramids follows closely with the bulk values. The energy gap increases between the two limits, In2O3 and Ga2O3. Applying GaxIn2-xO3 surface pyramids as a gas sensor uses transition state theory formalism. Thermodynamic quantities such as activation Gibbs energy, enthalpy, and entropy are needed for temperature-dependent calculations. A comparison of sensor response which is proportional to reaction rate as a function of temperature and formaldehyde concentration, reveals the quality of the theory. Response time and recovery time also show good agreement with the experiment. Formaldehyde burning (flash point and autoignition) in atmospheric oxygen is considered in calculations using a logistic function.