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Monitoring the Structure Evolution of Titanium Oxide Photocatalysts: From the Molecular Form via the Amorphous State to the Crystalline Phase
Author(s) -
Onur Şahin Ezgi,
Dai Yitao,
Chan Candace K.,
Tüysüz Harun,
Schmidt Wolfgang,
Lim Joohyun,
Zhang Siyuan,
Scheu Christina,
Weidenthaler Claudia
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202101117
Subject(s) - anatase , amorphous solid , nanocrystalline material , materials science , crystallization , photocatalysis , alkoxide , chemical engineering , titanium , phase (matter) , titanium oxide , oxide , chemical physics , crystallography , nanotechnology , chemistry , catalysis , organic chemistry , engineering , metallurgy
Amorphous Ti x O y with high surface area has attracted significant interest as photocatalyst with higher activity in ultraviolet (UV) light‐induced water splitting applications compared to commercial nanocrystalline TiO 2 . Under photocatalytic operation conditions, the structure of the molecular titanium alkoxide precursor rearranges upon hydrolysis and leads to higher connectivity of the structure‐building units. Structurally ordered domains with sizes smaller than 7 Å form larger aggregates. The experimental scattering data can be explained best with a structure model consisting of an anatase‐like core and a distorted shell. Upon exposure to UV light, the white Ti x O y suspension turns dark corresponding to the reduction of Ti 4+ to Ti 3+ as confirmed by electron energy loss spectroscopy (EELS). Heat‐induced crystallisation was followed by in situ temperature‐dependent total scattering experiments. First, ordering in the Ti−O environment takes place upon to 350 °C. Above this temperature, the distorted anatase core starts to grow but the structure obtained at 400 °C is still not fully ordered.