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Controlled Synthesis of Monodisperse SiO 2 TiO 2 Microspheres with a Yolk–Shell Structure as Effective Photocatalysts
Author(s) -
Yoo Jung Bo,
Yoo Hyo Jin,
Lim Byung Wook,
Lee Kang Hyuk,
Kim Mi Hyun,
Kang Donghyeon,
Hur Nam Hwi
Publication year - 2012
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200463
Subject(s) - dispersity , materials science , photocatalysis , chemical engineering , mesoporous material , shell (structure) , nanoreactor , template , mesoporous silica , nanotechnology , catalysis , microsphere , nanoparticle , composite material , chemistry , polymer chemistry , organic chemistry , engineering
Monodisperse yolk–shell SiO 2 –TiO 2 microspheres were synthesized using core–shell silica microspheres as templates. In the absence of prior surface modifications, a uniform coating of the TiO 2 layer on the core–shell silica was achieved through a sol–gel route. Mesoporous silica shells between the outer TiO 2 shell and the SiO 2 core were selectively removed by using a weak base, yielding yolk–shell SiO 2 –TiO 2 microspheres (ys‐SiO 2 @TiO 2 ). Using the same templates, we synthesized Pt‐encased microspheres (SiO 2 @Pt‐TiO 2 ), in which Pt nanoparticles are embedded between the SiO 2 core and the TiO 2 shell. Selective etching of the silica shells in SiO 2 @Pt‐TiO 2 yields Pt‐encased yolk–shell SiO 2 –TiO 2 microspheres (ys‐SiO 2 @ ${ \char60 {\rm{Pt}} \char62 }$ TiO 2 ), which contain void spaces suitable for use as nanoreactors. The ys‐SiO 2 @ ${ \char60 {\rm{Pt}} \char62 }$ TiO 2 catalyst shows enhanced hydrogen production from water under UV‐light irradiation presumably as a result of multiple reflections within the void spaces and can be reused without losing their activity. Moreover, this core–shell template method is effective for the synthesis of other yolk–shell microspheres with different metal oxides.