Abstract

Solar radiation modification via stratospheric aerosol injection (SAI) has been proposed as a potential approach to partially offset anthropogenic climate warming. However, its feasibility is constrained by uncertainties associated with heterogeneous interactions between aerosol particles and trace gases relevant to stratospheric ozone chemistry.

Here, we develop and experimentally evaluate engineered amorphous silica particles designed for SAI-relevant functionality, with particular emphasis on minimizing heterogeneous uptake behavior under stratospheric conditions. Controlled synthesis, thermal treatment, and surface functionalization yield dense, spherical particles with reduced densities of accessible surface silanol groups, substantial hydrophobic surface functionalization, and stable hydrophobic characteristics under ultraviolet (UV) irradiation and exposure to acidic species.

Heterogeneous uptake of key trace gases, including HCl, HNO3, N2O5, and O3, was measured under low-temperature conditions relevant to the lower stratosphere. The engineered particles exhibit substantially reduced uptake compared with crystalline quartz, which is used here as a low-uptake benchmark surface, with uptake coefficients approaching experimental detection limits and interactions dominated primarily by weak surface association.

These findings extend benchmark measurements identifying amorphous silica as a low-uptake reference material and demonstrate that heterogeneous uptake behavior can be further suppressed through controlled surface engineering. The consistently low uptake observed across multiple trace gases suggests a substantially reduced potential for sustained heterogeneous gas–surface processing under representative stratospheric conditions, supporting the potential compatibility of such particles with ozone-relevant atmospheric chemistry.