Mechanical–chemical coupling in gas–surface interaction: A study of strain effects on the catalytic properties of SiO2

In actual flight conditions, the surface of thermal protection materials may experience stress, and the impact of surface strain on catalytic reaction and mechanical–chemical coupling has not been fully explored. In this study, a surface gas–solid interaction model was constructed using reaction molecular dynamics and density functional theory methods. The surface catalytic reaction characteristics of α-SiO2 (001) under up to 2% uniaxial and biaxial tensile strain were investigated. Results indicate that both uniaxial stretching along the X axis and biaxial stretching along the X and Y axes inhibit the catalytic recombination reaction at higher surface temperatures. For the uniaxial stretching model, when the strain reaches 2%, the catalytic coefficient decreases by 21.2%, whereas for the biaxial stretching model, it decreases by 34.3%. From the perspectives of surface morphology and energy, the study reveals that tensile strain reduces the undercoordination degree of Si atoms on the surface, reduces the surface energy of α-SiO2 (001), increases the activation energy of the atomic oxygen recombination reaction, alters the recombination pathways of oxygen atoms, strain-induced selective desorption of oxygen atoms reduces the recombination probabilities of both Eley–Rideal and Langmuir–Hinshelwood pathways, ultimately decreasing the catalytic recombination coefficient.