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The pore wall structure of porous semi‐crystalline anatase TiO 2
Author(s) -
Kim ManHo,
Doh JeongMann,
Han Seong Chul,
Chae Keun Hwa,
Yu ByungYong,
Hong Kyung Tae,
Jackson Andrew,
Anovitz Lawrence M.
Publication year - 2011
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889811037447
Subject(s) - materials science , neutron scattering , anatase , scattering , small angle neutron scattering , porosity , electrolyte , coaxial , analytical chemistry (journal) , crystallography , composite material , optics , chemistry , chromatography , catalysis , biochemistry , physics , electrical engineering , electrode , photocatalysis , engineering
The structure of porous TiO 2 prepared by electrochemical anodization in a fluoride‐containing ethylene glycol electrolyte solution was quantitatively studied using small‐angle neutron scattering (SANS) and ultra‐small‐angle neutron scattering (USANS). The cylindrical pores along the coaxial direction were somewhat irregular in shape, were widely distributed in diameter, and seemed to have a broadly pseudo‐hexagonal arrangement. The scattering from the pore wall showed a negative deviation from Porod scattering, indicating that the interface between TiO 2 and the pore was not sharp. A density gradient of around 40–60 Å at the pore wall ( i.e. the interface between the pore and the TiO 2 matrix) was estimated using both constant and semi‐sigmoidal interface models. This gradient may be due to the presence of fluorine and carbon partially absorbed by the pore wall from the fluoride‐containing electrolyte or to sorbed water molecules on the wall. The neutron contrast‐matching point between the TiO 2 matrix and the pores filled with liquid H 2 O/D 2 O mixtures was 51/49%( v / v ) H 2 O/D 2 O, yielding an estimated mass density of 3.32 g cm −3 . The specific surface area of the sample derived from the (U)SANS data was around 939–1003 m 2 cm −3 (283–302 m 2 g −1 ).