Abstract
To design a high-performance photocatalytic system with TiO2, it is necessary to reduce the bandgap and enhance the absorption efficiency. The reduction of the bandgap to the visible range was investigated with reference to the surface distortion of anatase TiO2 nanoparticles induced by varying Fe doping concentrations. Fe-doped TiO2 nanoparticles (Fe@TiO2) were synthesized by a hydrothermal method and analyzed by various surface analysis techniques such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, scanning transmission X-ray microscopy, and high-resolution photoemission spectroscopy. We observed that Fe doping over 5 wt.% gave rise to a distorted structure, i.e., Fe2Ti3O9, indicating numerous Ti3+ and oxygen-vacancy sites. The Ti3+ sites act as electron trap sites to deliver the electron to O2 as well as introduce the dopant level inside the bandgap, resulting in a significant increase in the photocatalytic oxidation reaction of thiol (–SH) of 2-aminothiophenol to sulfonic acid (–SO3H) under ultraviolet and visible light illumination.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1263-6) contains supplementary material, which is available to authorized users.
Highlights
Titanium oxide (TiO2) is one of the most promising materials for various applications such as solar cells, gas sensors, photocatalysis, and corrosion protection due to its chemical stability, nontoxicity, and low cost [1, 2]
We introduced Fe ions into the TiO2 substrate using a hydrothermal method and systematically investigated the photocatalytic activities of Fe-doped TiO2 nanoparticle (Fe@TiO2) at various Fe doping concentrations
We found that 5 wt.% of Fe dopants in TiO2 nanoparticles form a new distorted phase in which catalytic performance is significantly enhanced by bandgap narrowing
Summary
Titanium oxide (TiO2) is one of the most promising materials for various applications such as solar cells, gas sensors, photocatalysis, and corrosion protection due to its chemical stability, nontoxicity, and low cost [1, 2]. The problems caused by the large bandgap (3.0–3.2 eV) result in poor efficiency and limited light absorption in the visible region, which makes a practical application difficult [6, 7]. To solve these chronic problems and enhance catalytic properties, narrowing the bandgap is necessary. One strategy is co-deposition of a noble metal such as Pt, Ag, Au, or Pd onto the TiO2 surface This strategy has little effect on narrowing the bandgap, it does improve the separation of holes and electrons significantly [8,9,10,11,12,13].
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