A Versatile Method for Controlled Synthesis of Porous Hollow Spheres

A versatile method was developed to synthesize nickel silicate, silica, and silica-nickel composite porous hollow spheres by using silica spheres as templates In the preparation, silica spheres were treated with a mixture of NiSO4 center dot 6H(2)O and NH3 center dot H2O The nickel-based ingredient reacted with the silica to form a shell while the alkaline solution could remove the silica core, thus forming the nickel silicate hollow spheres After these spheres were further treated with hydrogen in reduction or with HCl in etching, they became silica-nickel hollow spheres or silica hollow spheres, respectively The sizes of these hollow spheres depended on the concentration of the precursor. Our investigation also found that their sui face pi perms or magnetic properties could be tailored by adjusting the fabrication parameters