Aerosol synthesis of porous particles using simple salts as a pore template.

Ultrasonic spray pyrolysis has been used as a facile aerosol route to macroporous SiO(2) particles using simple inorganic salts as a pore template and colloidal SiO(2) as building blocks to the larger porous particles. As we found, the use of template salts with low melting points was vital to macroporous particle synthesis, as a dynamic droplet phase can be maintained throughout product formation. Otherwise, relatively compact particles are produced. Significantly, this approach avoids the need for post-isolation elimination of the template, instead permitting aqueous removal during product collection. Produced particles were characterized by SEM, TEM, and surface area and pore size measurements, while the influence of the selected salts on the reactivity between the building block SiO(2) colloids is discussed.