Porous silica has numerous existing and emerging applications.
It is a potential drug carrier [1,2], a catalyst support [3,4], and a
metal adsorbent [5,6]. Two key properties that affect the use of
porous silica are its specific surface area and specific pore volume.
Typical mesoporous silica is known for its unimodal small pore size
and therefore a high surface area with in turn provides a high
adsorption capacity but limits mass transfer into the pores [7,8].
This limitation of mesoporous silica is overcome by using hierarchical
porous silica (HPS) which has a network of large pores
connected to smaller pores