Yolk-porous shell nanospheres from siliver-decorated titanium dioxide and silicon dioxide as an enhanced visible-light photocatalyst with guaranteed shielding for organic carrier (original) (raw)
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Semiconductor Photocatalysis [Working Title]
Supporting a photocatalyst, such as titania nanoparticles (TiO 2 NPs), is a good strategy to improve its performance since it can facilitate the photocatalyst recovery from the aqueous media and provides a high surface area for pollutant adsorption. Among the several advanced functional materials used as TiO 2 NP support, the hierarchical meso/macroporous SiO 2 spheres not only show the advantages associated to its chemical nature but also the dendritic fibrous structure provides a porous network that offers many benefits to be exploited in optical and catalytic devices. In this chapter, different synthetic approaches to design hierarchical meso/macroporous silica and the strategies to support TiO 2 NPs regarding the photocatalytic performance of these materials are shown.
Applied Catalysis A: General, 2018
In synthetic TiO 2 , anatase to rutile transformation usually occurs at a temperature over 550 ºC. Here, we report a silica-protection method that can extend the phase transformation temperature to 800 ºC. This approach involves the deposition of silica shells on TiO 2 microspheres and subsequent calcination in either air or ammonia, yielding core-shell microspheres. Nitridation of the silica-coated TiO 2 using ammonia gas transformed the amorphous TiO 2 core into crystalline N-doped TiO 2 (TiO 2-x N x), while rendering the silica shell mesoporous. The anatase TiO 2-x N x phase could be retained at 800 °C due to the silica shell. The nitrided microspheres with anatase phase exhibited excellent photocatalytic activities for the degradation of organic pollutants and high photoelectrochemical performance in producing photocurrents under visible-light irradiation. Moreover, the nitrided anatase TiO 2-x N x retained its high photocatalytic activities even after one and half years of exposure to air. Thus, the silica-protection method is a simple and effective strategy for the synthesis of high-temperature stable N-doped anatase TiO 2 photocatalysts with sustainable photocatalytic activities.
Journal of Sol-Gel Science and Technology, 2010
Nanosized TiO 2 and nano-anatase TiO 2 decorated on SiO 2 spherical core shells were synthesized by using a sol-gel method. The synthesized pure TiO 2 nano particle and TiO 2 grafted on SiO 2 sphere with various ratios have been characterized for their structure and morphologies by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrophotometry (FTIR) and transmission electron microscopy (TEM). Their surface areas were measured using the BET method. The photocatalytic activity of all nanocomposites was investigated using methylene blue as a model pollutant. The synthesized TiO 2 /SiO 2 particles appeared to be more efficient in the degradation of methylene blue pollutant, as compared to pure TiO 2 particles.
Journal of Nanoparticle Research, 2011
The facile bulk synthesis of silica nanospheres makes them an attractive support for the transport of chemical compounds such as nanocrystalline titanium dioxide. In this contribution we present a promising route for the synthesis of mesoporous silica nanospheres (m-SiO 2) with diameter in range 200 nm, which are ideal supports for nanocrystalline titanium dioxide (TiO 2). The detailed microscopic and spectroscopic characterizations of core/shell structure (m-SiO 2 /TiO 2) were conducted. Moreover, the photocatalytic potential of the nanostructures was investigated via phenol decomposition and hydrogen generation. A clear enhancement of photoactivity in both reactions as compared to commercial TiO 2-Degussa P25 catalyst is detected.
SiO2/TiO2 double-shell hollow particles: Fabrication and UV–Vis spectrum characterization
Advanced Powder Technology, 2015
Well-defined SiO 2 /TiO 2 double-shell hollow particles (STDSHPs) were successfully fabricated by a sol-gel method with avoiding the particle aggregations and the generation of freestanding TiO 2 particles. Comparing with the conventional solid TiO 2 particles, STDSHPs showed a novel hollow structure, a much smaller TiO 2 grain size (9nm), and a larger specific surface area (113m 2 /g). In the UV-vis spectrum characterizations, STDSHPs showed significant light harvesting capability in both UV-and visible-light range. STDSHPs also showed stronger per-weight UV absorbance capability than solid TiO 2 particles and commercial TiO 2 photocatalyst P25, which could be attributed to their novel hollow structure-and thus the absence of light-inaccessible TiO 2 particles. Moreover, we analyzed the narrowed band-gap of STDSHPs by the Brus' effective-mass model (EMM).
Visible-light-driven photocatalytic S- and C- codoped meso/nanoporous TiO2
Energy & Environmental Science, 2010
The first facile and efficient soft synthesis for fabricating S-and C-co-doped hierarchically meso/nanoporous TiO 2 is hereby presented. The doping of sulfur is achieved through a counter strategy, in which the precursor of TiO 2 is added to the sulfur hydrosol. The sulfur nanoparticles in the sulfur hydrosol serve as the seeds for the formation of bimodal meso/nanopores TiO 2 upon calcination treatment. The prepared anatase TiO 2 exhibited excellent thermal stability and photocatalytic activity. In comparison to commercial P25 TiO 2 , our S-and C-codoped meso/ nanoporous anatase TiO 2 exhibits remarkably enhanced visible light-driven photocatalytic activity on the decomposition of methylene blue (MB). The samples also showed excellent cyclic stability in the photocatalytic activity of degrading MB. The formation mechanism of these S-, C-codoped hierarchically meso/nanoporous TiO 2 spheres is also discussed. The high photocatalytic activity in the visible light region is attributed to numerous oxygen vacancies, acidic sites on the surface of TiO 2 , and large specific surface area. is envisioned as the most promising photocatalyst for environmental purification due to its excellent photochemical stability and intense photo-oxidative properties. The photogenerated holes in TiO 2 is approximately À7.4 eV vs. vacuum, below the highest occupied molecular orbitals (HOMO) of most organic molecules. Thus, it can aggressively oxidize (rip off electrons from) organic pollutants. However, because of its large band gap of 3.20 eV, only the UV fraction of solar light (about 2-3% energy of the total solar spectrum) can be utilized to generate electron-hole pairs. To enhance the energy efficiency, therefore, photosensitization of TiO 2 by doping of hetero elements that can lead to high photocatalytic activity in visible light region becomes the current topic of interest. We present here an efficient soft synthesis for fabricating S-and C-codoped hierarchically meso/nanoporous TiO 2 . The doping of sulfur is achieved through a counter strategy, in which the precursor of TiO 2 is added to the sulfur hydrosol. The sulfur nanoparticles in the sulfur hydrosol serve as the seeds for the formation of bimodal meso/nanopores TiO 2 upon calcination treatment. The prepared anatase TiO 2 exhibits excellent thermal stability and photocatalytic activity in comparison to commercial P25 TiO 2 .
Transactions of Nonferrous Metals Society of China, 2012
Using Ti powder as reagent, TiO 2 nanoneedle/nanoribbon spheres were prepared via hydrothermal method in NaOH solution. The samples were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), X-ray diffraction (XRD), and UV-visible light absorption spectrum. The results indicate that the growth orientations of the crystals are influenced by the hydrothermal temperature and NaOH concentration. The diameter of the nanoneedle spheres and nanoribbon spheres (40í50 ȝm) are almost the same as that of Ti powders. TiO 2 nanoneedle/nanoribbon sphere powders are anatase after heat treatment at 450 °C for 1 h. Furthermore, methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens. Under the same testing conditions, the photocatalytic activities of the products decrease in the following order: TiO 2 nanoneedle sphere, TiO 2 nanoribbon sphere and P25.
Shell TiO 2 architectures : towards advanced room temperature visible light selective photocatalysts
2018
Pleased to contact you, I hope this message finds you well. We are delighted to submit the manuscript entitled "Designer hydrogenated wrinkled Yolk@Shell TiO2 nanoarchitectures: towards advanced room temperature visible light selective photocatalysts" to be considered for publication in Journal of Materials Chemistry A. The manuscript discloses the preparation of an unprecedented yolk/shell wrinkled TiO2 architectures with excelling photocatalytic activities under visible light irradiation. This method includes solvothermal, partial etching and hydrogen treatment sequential preparation steps. The resultant yolk@hydrogenated wrinkled shell TiO2 architectures exhibited a high efficiency in visible light oxidation of alcohols to the corresponding aldehydes (up to 90 in conversion, 97% in selectivity).