Fig. 1.

Generation of ROS during the contact between water vapor and SiO₂ nanoparticles. (A) Schematic image of the experimental setup of water vapor–solid interface in a sealed chamber. (B) The ROS concentration at the inlet of the sealed chamber. (C) The ROS concentration in the leaving gas after the contact between water vapor and SiO₂ nanoparticles. (D) The relationship between ROS concentration at the surface of SiO₂ nanoparticles and reaction time during the contact process. (E) The ESR spectrum of hydroxyl radicals at SiO₂ nanoparticles before contact occurred. (F) The corresponding ESR spectrum of hydroxyl radicals at SiO₂ nanoparticles after contact occurred.