NO properties that affect its reaction with pristine and Pt-doped SnS: a gas sensor study.

CONTEXT

The reaction of NO with pristine and Pt-doped SnS surfaces is investigated theoretically and compared with the experiment. Transition state theory formalism for gas sensors is adopted to present NO gas sensing. The dissociation temperature at approximately 150 °C is found to be of great importance in NO reactions. The adsorption and transition states of NO with pristine and Pt-doped SnS are calculated. Pt doping includes 0.5, 1, and 1.5% in accordance with available experimental results. The variation of thermodynamic quantities such as Gibbs free energy with Pt concentration and temperature is calculated. Transition state theory parameters that are suitable for the present sensor are determined. The results include the variation in response time with temperature, Pt concentration, and NO concentration. Response and response time as a function of temperature are rarely investigated in theoretical calculations, which is one of the advantages of the present study. Optimum response temperature and Pt concentration are found. The results agree with available experimental results.

METHODS

Density functional theory at the B3LYP level optimize molecular structures. 6-311G** basis set is used for all elements except Sn and Pt treated using SDD basis set. Gaussian 09 program and its facilities are used to perform present optimizations.