Water-plasma-assisted synthesis of black titania spheres with efficient visible-light photocatalytic activity

Panomsuwan, Gasidit; Watthanaphanit, Anyarat; Ishizaki, Takahiro; Saito, Nagahiro

doi:10.1039/c5cp00171d

Cited by 100 publications

(70 citation statements)

References 47 publications

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“…As shown in Figure 11, black TiO 2 nanotubes demonstrated the highest photocatalytic activity in rhodamine B degradation experiment, though the asanodized TiO 2 nanotubes were rich in oxygen vacancies [91]. [44]. Under visible-light irradiation for 180 min, the methylene blue is almost completely degraded in the presence of H-TiO 2−x (90%), whereas it is degraded only by 18% in the presence of P25 [44].…”

Section: Magnesium Reductionmentioning

confidence: 91%

“…[44]. Under visible-light irradiation for 180 min, the methylene blue is almost completely degraded in the presence of H-TiO 2−x (90%), whereas it is degraded only by 18% in the presence of P25 [44].…”

Section: Magnesium Reductionmentioning

confidence: 95%

“…Color change from white to black for TiO 2 nanomaterials reflects the change in optical properties and thus suggests the structural change after modification, at least the surface structural change. High-resolution transmission electron microscope (HRTEM) has revealed that a number of black TiO 2 nanomaterials have a crystalline/ amorphous core/shell structure, while white ones have clear lattice fringes throughout the crystals [22,23,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44]. The amorphous or disordered surface layer has been considered the typical feature of black TiO 2 nanomaterials.…”

Section: Basic Properties Of Black Tio 2 Versusmentioning

confidence: 99%

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Black Titanium Dioxide Nanomaterials in Photocatalysis

Yan

Xia

2017

International Journal of Photoenergy

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Titanium dioxide (TiO 2 ) nanomaterials are widely considered to be state-of-the-art photocatalysts for environmental protection and energy conversion. However, the low photocatalytic efficiency caused by large bandgap and rapid recombination of photoexcited electrons and holes is a challenging issue that needs to be settled for their practical applications. Structure engineering has been demonstrated to be a highly promising approach to engineer the optical and electronic properties of the existing materials or even endow them with unexpected properties. Surface structure engineering has witnessed the breakthrough in increasing the photocatalytic efficiency of TiO 2 nanomaterials by creating a defect-rich or amorphous surface layer with black color and extension of optical absorption to the whole visible spectrum, along with markedly enhanced photocatalytic activities. In this review, the recent progress in the development of black TiO 2 nanomaterials is reviewed to gain a better understanding of the structure-property relationship with the consideration of preparation methods and to project new insights into the future development of black TiO 2 nanomaterials in photocatalytic applications.

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Section: Magnesium Reductionmentioning

confidence: 91%

Section: Magnesium Reductionmentioning

confidence: 95%

Section: Basic Properties Of Black Tio 2 Versusmentioning

confidence: 99%

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Black Titanium Dioxide Nanomaterials in Photocatalysis

Yan

Xia

2017

International Journal of Photoenergy

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“…[ 90 ] In addition, the color of fi nal product could be variable depending on the temperature and time of Arannealling. [ 85 ] The water plasma was generated in liquid water between a pair of metallic Ti electrodes by applying microsecond bipolar high-voltage pulses with high frequency. [ 85 ] The water plasma was generated in liquid water between a pair of metallic Ti electrodes by applying microsecond bipolar high-voltage pulses with high frequency.…”

Section: Oxidation Approachesmentioning

confidence: 99%

Progress in Black Titania: A New Material for Advanced Photocatalysis

Liu

Zhu

Wang

et al. 2016

Advanced Energy Materials

278

190

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excited charges should separate from each other and migrate to the surface to perform photocatalytic reactions, before they are annihilated in the recombination process. [ 3,17,18 ] Nevertheless, TiO 2 has a wide bandgap of 3.0−3.2 eV for the three common natural polymorphs -anatase, rutile and brookite. [ 8 ] That limits the optical absorption of TiO 2 in the ultraviolet (UV) region of the solar spectrum, resulting in insuffi cient utilization of solar energy (less than 5%). Another hurdle for TiO 2 material in the photo-chemical applications is its low quantum effi ciency that results from its high recombination of photo-generated electron-hole pairs. [ 16,18 ] Therefore, improving the optical absorption properties and reducing electron-hole recombination of TiO 2 are expected to be signifi cant for superior photoactivity.Various strategies have been adopted to tune TiO 2 's optical and electronic properties to improve its visible-light photoactivity. For example, metal ions (Co, Ni, Mn, Fe, Cr, …) or non-metal ions (N, S, C, I, …) are doped in the titania matrix to induce mid-gap states or to narrow the bandgap of TiO 2 , aiming to enhance its visible-light response. [ 3,17 ] Doping with open-shell metals is claimed to be benefi cial for red-shifting TiO 2 photochemistry into the visible, while closed shell cation dopants have no photochemical benefi t. Some d -block transition metal doping often generates deeply localized d -states in the forbidden bandgap of TiO 2 and results in recombination centers for carriers. [ 3,19 ] For the incorporation of non-metal ions, heavy doping is always diffi cult due to the large differences in chemistry between the alien ions and O 2− in titania, thus the visible light absorption is not signifi cantly enhanced. [ 20 ] Dye-sensitized or noble metal nanodots decorated TiO 2 nanostructures have been largely designed to enhanced its optical properties and to improve the charge separation effi ciency. [ 6,9,15,17,21 ] Additionally, charge separation in TiO 2 is believed to be effi ciently improved by forming heterojunctions with other semiconductors, such as metal oxides and chalcogenides. [ 6,22 ] In 2011, a hydrogenated black titania with a narrowed bandgap of ≈1.5 eV was reported to boost the full spectrum sunlight absorption and the photocatalytic activity. [ 23 ] This discovery has triggered world-wide scientifi c interests in black TiO 2 nanomaterials. [ 8 ] Black TiO 2 is featured by selfstructural modifi cations, involving self-doped Ti 3+ /oxygen vacancy, or incorporation of H-doping. [ 5,8 ] Owing to these modifi cations, their crystal and electronic structures as well as the surface property are signifi cantly changed, and the most marked effect is the color changing. The intrinsic TiO 2The photocatalytic activity of TiO 2 has aroused a broad range of research effort since 1972. Although TiO 2 has a very high effi ciency in utilizing ultraviolet light, its overall solar activity is very limited due to its wide bandgap (≈3.0−3.2 eV). This is a bottleneck for TiO 2 to...

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“…Unique reactions can thereby occur at the interface under room temperature. Various researchers have used the solution plasma to synthesize Au, Pt28, AuPt29, Pd30, PdAu31, Ag32, Au alloys3334, metal oxide nanoparticles35363738, and nanosheets394041. It has also been used to modify the surface of carbon materials to achieve monodispersion42, to prepare metal nanoparticles on carbon43444546, and to degrade gelatin47, among other applications484950515253545556575859.…”

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confidence: 99%

Fastest Formation Routes of Nanocarbons in Solution Plasma Processes

Morishita

Ueno

Panomsuwan

et al. 2016

Sci Rep

Self Cite

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Although solution-plasma processing enables room-temperature synthesis of nanocarbons, the underlying mechanisms are not well understood. We investigated the routes of solution-plasma-induced nanocarbon formation from hexane, hexadecane, cyclohexane, and benzene. The synthesis rate from benzene was the highest. However, the nanocarbons from linear molecules were more crystalline than those from ring molecules. Linear molecules decomposed into shorter olefins, whereas ring molecules were reconstructed in the plasma. In the saturated ring molecules, C–H dissociation proceeded, followed by conversion into unsaturated ring molecules. However, unsaturated ring molecules were directly polymerized through cation radicals, such as benzene radical cation, and were converted into two- and three-ring molecules at the plasma–solution interface. The nanocarbons from linear molecules were synthesized in plasma from small molecules such as C2 under heat; the obtained products were the same as those obtained via pyrolysis synthesis. Conversely, the nanocarbons obtained from ring molecules were directly synthesized through an intermediate, such as benzene radical cation, at the interface between plasma and solution, resulting in the same products as those obtained via polymerization. These two different reaction fields provide a reasonable explanation for the fastest synthesis rate observed in the case of benzene.

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Water-plasma-assisted synthesis of black titania spheres with efficient visible-light photocatalytic activity

Cited by 100 publications

References 47 publications

Black Titanium Dioxide Nanomaterials in Photocatalysis

Black Titanium Dioxide Nanomaterials in Photocatalysis

Progress in Black Titania: A New Material for Advanced Photocatalysis

Fastest Formation Routes of Nanocarbons in Solution Plasma Processes

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