Porous
silica is a well-established material for industrial-scale
chromatographic separations and as catalyst supports because of its
precisely defined and open pore structure. The Achilles heel of porous
silica is poor caustic stabilitythis limits its usage to neutral
and weakly acidic environments. In this study, we present a new approach
for the fabrication of particles with exceptional porosity and caustic-stable
characteristics. A key design feature is the formationvia
controlled nucleation and growthof two coexisting crystal
phases, one of which is a sacrificial phase, easily and rapidly removed
in weak acid, to leave behind a porous silica-rich glass-ceramic skeleton.
Unimodal pore size distributions tunable in the range of 20–300 nm are achievable, with high percentage
porosity (>80%). The methods used are cost-effective and scalable.
While a silica-rich (diopside) skeleton phase was developed here,
the glass chemistry can be adapted to generate a range of interesting
and useful skeleton phases, with specific chemical properties and
functional ions for specific applications.