Many approaches have been developed to synthesize porous
silica and silica nanoparticles. Usually, a silica precursor, such as
silicon alkoxide (typically silicon tetraethoxysilane) is used as
the silicon source.7−10 While such methods are effective to
synthesize various silicas with controlled particle size,
morphology, and porosity, their main disadvantages are the
cost and sustainability issues associated with the silica
precursors. Silicon alkoxides are typically synthesized from a
multistep reaction route starting from the carbothermal
reduction of raw silica, such as sand.10−12 Such chemical
processes are energy intensive and associated with high
temperature, high pressure, and strong acidity, and are thus
eco-hazardous.