Understanding the mechanisms of anisotropic dissolution in metal oxides by applying radiolysis simulations to liquid-phase TEM

Significance Dissolution of redox-active metal oxides plays a fundamental role in the environment and technological applications. However, dissolution mechanisms remain poorly understood at nanoscale, particularly the interplay between acidic and reductive processes. Using akaganeite (β–FeOOH) nanorods in liquid-phase-transmission electron microscopy, combined with deterministic simulations of dose rate–dependent radiolytic speciation, we exploit a quantitative connection between observed dissolution rate and behavior to modeled solution speciation at steady state to delineate underlying mechanisms. Gaining quantitative control of the balance between acidic and reductive dissolution, which can be varied by using pH buffers, chloride anions, and electron beam dose, enabled us to understand and tune resulting dissolution behaviors. The findings provide insights into processes controlling the dissolution of minerals in natural environments.