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Nano Lett. 2018 Jul 11;18(7):4257-4262. doi: 10.1021/acs.nanolett.8b01245. Epub 2018 Jun 27.

Multiple Heterojunction in Single Titanium Dioxide Nanoparticles for Novel Metal-Free Photocatalysis.

Author information

1
Department of Chemical and Biomolecular Engineering , Yonsei University , 50 Yonsei-ro, Seodaemun-gu , Seoul 120-749 , Republic of Korea.
2
Department of Materials Science and Engineering , Pohang University of Science and Technology , Pohang 790-784 , Republic of Korea.
3
Department of Energy Science , Sungkyunkwan University , Suwon 16419 , Republic of Korea.
4
Department of Physics, Center for Nanotubes and Nanostructured Composites (CNNC) , Sungkyunkwan University , Suwon 16419 , Republic of Korea.
5
Advanced Photonics Research Institute (APRI) , Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712 , Republic of Korea.
6
School of Chemical Engineering , Sungkyunkwan University , Suwon 16419 , Republic of Korea.
7
Beamline Division , Pohang Accelerator Laboratory , Pohang 790-834 , Republic of Korea.
8
College of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , People's Republic of China.

Abstract

Despite a longstanding controversy surrounding TiO2 materials, TiO2 polymorphs with heterojunctions composed of anatase and rutile outperform individual polymorphs because of the type-II energetic band alignment at the heterojunction interface. Improvement in photocatalysis has also been achieved via black TiO2 with a thin disorder layer surrounding ordered TiO2. However, localization of this disorder layer in a conventional single TiO2 nanoparticle with the heterojunction composed of anatase and rutile has remained a big challenge. Here, we report the selective positioning of a disorder layer of controlled thicknesses between the anatase and rutile phases by a conceptually different synthetic route to access highly efficient novel metal-free photocatalysis for H2 production. The presence of a localized disorder layer within a single TiO2 nanoparticle was confirmed for the first time by high-resolution transmission electron microscopy with electron energy-loss spectroscopy and inline electron holography. Multiple heterojunctions in single TiO2 nanoparticles composed of crystalline anatase/disordered rutile/ordered rutile layers give the nanoparticles superior electron/hole separation efficiency and novel metal-free surface reactivity, which concomitantly yields an H2 production rate that is ∼11-times higher than that of Pt-decorated conventional anatase and rutile single heterojunction TiO2 systems.

KEYWORDS:

Photocatalysts; charge separation; disorder engineering; multiple-heterojunction; surface reactivity; water splitting

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