Diffusive Formation of Hollow Mesoporous Silica Shells from Core-Shell Composites: Insights from the Hydrogen Sulfide Capture Cycle of CuO@mSiO Nanoparticles.

Mesoporous silica is often employed as a coating material in core-shell nanoparticles to decrease the possibility of sintering or aggregation of the core particles. In this work, we discovered a surprising morphological transformation during the sulfidation and regeneration (oxidation) of core-shell CuO@mSiO materials designed for HS capture. Although CuS cores were still encapsulated within the silica shells after in situ sulfidation, hollow silica shells formed during the regeneration step as CuO leached out of the shell and aggregated into larger particles.