Transition state application to simulate CO gas sensor of pristine and Pt doped tin dioxide clusters

Carbon monoxide sensitivity of pristine and Pt doped tin dioxide (SnO2) is investigated in the present work using transition state theory. The use of transition state theory leads to a double exponent function formula for the concentration and sensitivity of the material. The method uses Gibbs free energy, enthalpy, and entropy of activation to formulate sensitivity, response time, and recovery time. The results showed that the activation energy of Pt doped SnO₂ nanocluster is lower than the pristine SnO₂ nanocluster. The Pt doped clusters promote higher reaction rates than pristine clusters. However, the activation energy of recovery with oxygen reaction is lower for the pristine cluster. The results also showed that the activation energy and reaction rates increase with temperature. The concentration of oxygen-deficient molecules in pristine and doped tin oxide as a function of temperature that represents the sensitivity of the sensor has the highest value at 225 °C. The theoretical results also show that response time decreases while recovery time increases with the increase of CO concentration. The results agree with experimental results.