ZrO₂, CaCO₃, and Fe₄[Fe(CN)₆]₃ Hollow Nanospheres via Gelatin‐stabilized Microemulsions

Abstract

ZrO 2 , CaCO 3 , and Fe 4 [Fe(CN) 6 ] 3 hollow nanospheres are prepared via gelatin-stabilized microemulsions. ZrO 2 and CaCO 3 hollow spheres exhibit outer diameters of 10-20 nm, a thickness of the sphere wall of 4 nm and an inner cavity diameter of 6-12 nm; Fe 4 [Fe(CN) 6 ] 3 is with outer diameters of 50-60 nm, a wall thickness of 15 nm, and an inner cavity diameter of 25-30 nm. The hollow nanospheres turn out as readily crystalline although prepared at roomtemperature. Gelatin increases the viscosity of the polar micelle phase and thereby reduces the diffusion in the water phase. This measure is essential to obtain hollow spheres and to avoid the formation of massive nanoparticles. All as-prepared hollow nanospheres are charac-* Prof. Dr. C. Feldmann E-Mail: claus.feldmann@kit.edu [a]

Microemulsions: Options To Expand the Synthesis of Inorganic Nanoparticles

“…[68] Although successful for obtaining hollow nanospheres,t he gelatin-modified MEs-similar to the hard-template approach based on polymer templates (see Figure 9)-have the disadvantage that the removal of gelatin requires sintering at elevated temperatures of up to 600 8 8Ca fter synthesis.S uch ah eat treatment, however, destroys the hollow nanosphere structures.O nly in the case of ZrO 2 was the hollow-sphere structure retained after thermal removal of gelatin, even at 600 8 8C. [68] Besides the synthesis of hollow nanospheres,the relevant characterization and proving the presence of the inner cavity, in particular, is also ac hallenge.H ere,s tate-of-the-art electron microscopy,w ithout doubt, represents the most powerful tool. [68] Besides the synthesis of hollow nanospheres,the relevant characterization and proving the presence of the inner cavity, in particular, is also ac hallenge.H ere,s tate-of-the-art electron microscopy,w ithout doubt, represents the most powerful tool.…”

“…Au [47] 20-40/25-50 dodecane [b] n-C 12 H 25 SH water [b] HAuCl 4 4H 2 O Ag [61] 10-15/15-20 water NaBH 4 dodecane [Ag(PPh 3 ) 4 ]NO 3 AlO(OH) [62] 20-25/30-35 water dodecane Al(O s C 4 H 9 ) 3 La(OH) 3 [63] 2-17/10-30 water/KF [c] dodecane La(Cp) 3 ZnO [64] 2-4/6-8 water/NH 3 toluene Zn(Cp*) 2 Fe 2 O 3 [65] water/ gelatin [c] dodecane TiCl 4 ZrO 2 [68] 6-12/10-20 water/ gelatin [c] dodecane Zr(O t C 4 H 9 ) 4 Cu 2 S [69] 8…”

“…Reviews cavity diameter of 25-30 nm (Figure 13). [68] Although successful for obtaining hollow nanospheres,t he gelatin-modified MEs-similar to the hard-template approach based on polymer templates (see Figure 9)-have the disadvantage that the removal of gelatin requires sintering at elevated temperatures of up to 600 8 8Ca fter synthesis.S uch ah eat treatment, however, destroys the hollow nanosphere structures.O nly in the case of ZrO 2 was the hollow-sphere structure retained after thermal removal of gelatin, even at 600 8 8C. TheZrO 2 hollow nanospheres still exhibited aspecific surface area of about 98 m 2 g À1 ,a nd they showed aC O 2 uptake of 96 mg g À1 .…”

“…TheZrO 2 hollow nanospheres still exhibited aspecific surface area of about 98 m 2 g À1 ,a nd they showed aC O 2 uptake of 96 mg g À1 . [68] Besides the synthesis of hollow nanospheres,the relevant characterization and proving the presence of the inner cavity, in particular, is also ac hallenge.H ere,s tate-of-the-art electron microscopy,w ithout doubt, represents the most powerful tool. Thet ransfer of the fragile hollow nanosphere structures and observation under high-energy electron bombardment, however, needs special attention since the hollow nanospheres can be destroyed within aminute upon evacuation and/or electron bombardment.…”

“…Fe(CN) 6 ] 3 [68]. ZrO 2 and CaCO 3 were obtained with an outer diameter of 10-20 nm, awall thickness of 4nm, and an inner cavity diameter of 6-12 nm.…”