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Sulfur and Ti 3+ co‐Doping of TiO 2 Nanotubes Enhance Photocatalytic H 2 Evolution Without the Use of Any co‐catalyst
Author(s) -
Ji Lei,
Zhou Xuemei,
Schmuki Patrik
Publication year - 2019
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201900532
Subject(s) - photocatalysis , materials science , catalysis , x ray photoelectron spectroscopy , doping , hydrogen production , band gap , sulfur , visible spectrum , annealing (glass) , electron paramagnetic resonance , nanotechnology , chemical engineering , photochemistry , optoelectronics , chemistry , organic chemistry , nuclear magnetic resonance , physics , engineering , metallurgy , composite material
TiO 2 nanotubes were successfully co‐doped with sulfur and Ti 3+ states using a facile annealing treatment in H 2 /H 2 S gas mixture. The obtained nanotubes were investigated for their photocatalytic performance and characterized by SEM, XRD, XPS, EPR, IPCE, IMPS and Mott‐Schottky measurements. The synthesized co‐doped TiO 2 nanotubes show an enhanced photocatalytic hydrogen production rate compared to tubes that were treated only in pure H 2 or H 2 S atmosphere—this without the presence of any co‐catalyst. It was found that sulfur in co‐doped TiO 2 exists in the form of S 2− and a small quantity of S 4+ /S 6+ , which leads to a narrowing of the band gap. However, the enhanced absorption of light in the visible range is not the key reason for the improved photocatalytic performance. We ascribe the enhanced photocatalytic activity to a synergetic effect of S mid‐gap states and disordered Ti 3+ defects that facilitate photo generated electron transfer.