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.