Effects of reaction medium and crystallite size on Ti3+ surface defects in titanium dioxide nanoparticles prepared by solvothermal method

Sirisuk, Akawat; Klansorn, Ekkachai; Praserthdam, Piyasan

doi:10.1016/j.catcom.2008.01.035

Cited by 46 publications

(38 citation statements)

References 20 publications

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“…In recent years, the role of oxygen vacancies and Ti 3+ in the photocatalytic activity of TiO2 has been of great interest [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] . While characterisation of TiO2-based photocatalysts uses standard techniques such as UV-vis spectroscopy, valence band XPS, dye degradation insights into the dynamics of electrons and holes and defects can be obtained from Transient Absorption Spectroscopy (TAS) [51][52][53][54][55] and photoluminescence (PL) [56][57][58] .…”

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confidence: 99%

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

et al. 2016

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Type of publicationArticle (peer-reviewed) AbstractThis progress review describes our work on the design of new TiO2 based photocatalysts. The key concept is the formation of composite structures through the modification of anatase and rutile TiO2 with molecular-sized nanoclusters of metals oxides. Our density functional theory (DFT) level simulations have been compared with experimental work synthesizing and characterizing surface modified TiO2. We use DFT to show that nanoclusters of metal oxides such as TiO2, SnO/SnO2, PbO/PbO2, ZnO and CuO are stable when adsorbed at rutile and anatase surfaces and can lead to a significant red shift in the absorption edge which will induce visible light absorption; this is the first requirement for a useful photocatalyst. We determine the origin of the red shift and the fate of excited electrons and holes. For p-block metal oxides the oxidation state of Sn and Pb can be used to modify the magnitude of the red shift and its mechanism. We describe comparisons of recent experimental studies of surface modified TiO2 that validate our DFT simulations. These nanocluster-modified TiO2 structures 2 form the basis of a new class of photocatalysts which will be useful in oxidation reactions and with a correct choice of nanocluster modified can be applied to other reactions.

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Section: Figure 1: Schematic Cartoon Of the Processes Involved In Phomentioning

confidence: 99%

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

et al. 2016

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“…Especially, active sites on the TiO 2 surface should play an essential role in the catalytic reactions. Surface defects of TiO 2 such as oxygen vacancies, steps, and kinks are known to be photocatalytic active sites [2,3]. Hence, it is very important to clarify the structures and electronic states of the surface imperfections.…”

Section: Introductionmentioning

confidence: 99%

Optical Second Harmonic Generation from Periodic Steps on Rutile TiO2(110)

Takahashi

Watanabe

Mizutani

2010

e-J. Surf. Sci. Nanotechnol.

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We have succeeded in observing optical second harmonic generation (SHG) from steps on the TiO2 surfaces adsorbed with HCOOH. The samples were single crystals of rutile TiO2 with (110), (15 15 4), (13 9 0), and (671) faces. These samples underwent annealing in O2 gas, HF etching, and immersion into HCOOH aqueous solution to adsorb HCOOH molecules on their surfaces. Their surfaces were characterized by reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM), and were confirmed to have regularly aligned steps created by the miscut of the samples. SH intensity as a function of the sample rotation angle was measured in air with the incident angle of 2• at the SH photon energy of 2ω = 4.66 eV. The SH intensity from the surfaces with steps were 2 to 3 orders of magnitude stronger than that from the (110) surface. The SH intensity patterns from these stepped surfaces were anisotropic. The result indicates that the contribution of the surface steps was observed selectively.

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“…However, the differential frictional coefficients are reduced from 28.0% to 22.7% for static friction testing and reduced from 12.5% to 11.8% for dynamic friction testing, respectively. Because felting effect of wool fibers are determined by directional frictional effect, the smaller the differential frictional coefficient is, the less felting effect the wool fiber has [41]. It is thus anticipated that the felting phenomenon of the N-doped TiO2 coated wool fibers will be alleviated during wet processing including laundering and scouring owing to a reduction of these frictional difference ( a − w).…”

Section: Friction Propertiesmentioning

confidence: 99%

“…While it is known that titanium trivalent (Ti 3+ ) on the surface of TiO2 particles is very reactive [41] and plays an essential role in photocatalytic process over TiO2 photocatalyst [42], and that it can be generated by using UV irradiation and thermal annealing on the surface of anatase TiO2 particles, we thus propose that the stable bonding between TiO2 particles and wool fibers are C-Ti 4+ , S-Ti 4+ (Ti 2+ ), O-Ti 4+ , and N-Ti 4+ , and the reaction mechanism between TiO2 nanoparticles and wool fibers is summarized in Figure 4.…”

Section: Xps Analysismentioning

confidence: 99%

Photocatalytic effects of wool fibers modified with solely TiO2 nanoparticles and N-doped TiO2 nanoparticles by using hydrothermal method

Zhang

Yang

Zhang

et al. 2014

Chemical Engineering Journal

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Abstract:The surfaces of wool fibers are modified with N-doped TiO2 nanoparticles by treating the fibers with tetrabutyl titanate and ammonium chloride under low temperature hydrothermal conditions to obtain wool fibers with photocatalytic functions in the visible light spectrum. The effects of nitrogen and sulfur in amino acids in keratin on the photocatalytic activity of TiO2 particle coated wool fibers are investigated. Changes of various fiber properties such as tensile strength, surface friction, photocatalytic activity, and self-cleaning performance of untreated, TiO2-coated and N-doped TiO2-coated wool fibers are studied. It is found that N-doped anatase TiO2 nanoparticles with an average grain size of 11.2 nm are synthesized and simultaneously grafted onto the wool fibers. After treatments, the crystallization index of the wool fibers is slightly reduced. The capability to protect against ultraviolet radiation is much enhanced. The performances of photocatalytic degradation of methylene blue dye and self-cleaning of red wine under both UV and visible light irradiation are endowed. It is also found that wool fibers coated with TiO2 particles without being doped by nitrogen still have apparent photocatalytic reactions and self-cleaning effects under visible light irradiation due to the formation of C-Ti 3+ , O-Ti 3+ , and N-Ti 3+ bonds between TiO2 and wool keratin on the wool fiber surfaces. Thus wool fabrics might not need to be coated with N-doped TiO2 nanoparticles to realize its self-cleaning effect under visible light. Such important conclusions would provide wool materials with wide applications in clothing and 3 technical products such as wastewater treatment.

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Effects of reaction medium and crystallite size on Ti3+ surface defects in titanium dioxide nanoparticles prepared by solvothermal method

Cited by 46 publications

References 20 publications

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Optical Second Harmonic Generation from Periodic Steps on Rutile TiO2(110)

Photocatalytic effects of wool fibers modified with solely TiO2 nanoparticles and N-doped TiO2 nanoparticles by using hydrothermal method

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Effects of reaction medium and crystallite size on Ti3+ surface defects in titanium dioxide nanoparticles prepared by solvothermal method

Cited by 46 publications

References 20 publications

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO2

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO2

Optical Second Harmonic Generation from Periodic Steps on Rutile TiO2(110)

Photocatalytic effects of wool fibers modified with solely TiO2 nanoparticles and N-doped TiO2 nanoparticles by using hydrothermal method

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Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂

Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO₂