Cu-grafted TiO2 photocatalysts: effect of Cu on the action spectrum of composite materials

Different TiO2 photocatalysts, i.e., commercial samples (ST-01 and P25 with minority of rutile phase), nanotubes, well-crystallized faceted particles of decahedral shape and mesoporous spheres, were used as supports for deposition of Pt nanoparticles (NPs). Size-controlled Pt NPs embedded in TiO2 were successfully prepared by microemulsion and wet-impregnation methods. Obtained photocatalysts were characterized using XRD, TEM, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) specific surface area, DR/UV-vis and action spectrum analysis. The effect of deposition method, amount of Pt precursor and TiO2 properties on size, distribution, and chemical states of deposited Pt NPs were investigated. Finally, the correlations between the physicochemical properties and photocatalytic activities in oxidation and reduction reactions under UV and Vis light of different Pt-TiO2 photocatalysts were discussed. It was found that, regardless of preparation method, the photoactivity mainly depended on platinum and TiO2 morphology. In view of this, we claim that the tight control of NPs’ morphology allows us to design highly active materials with enhanced photocatalytic performance. Action spectrum analysis for the most active Pt-modified TiO2 sample showed that visible light-induced phenol oxidation is initiated by excitation of platinum surface plasmon, and photocatalytic activity analysis revealed that photoactivity depended strongly on morphology of the obtained Pt-modified TiO2 photocatalysts.

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Comparative Microstructures of Ion Milled and Electrochemically Thinned Composite Materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052742 ◽

1974 ◽

Vol 32 ◽

pp. 546-547

Author(s):

R.R. Russell

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Composite Materials ◽

Great Difficulty ◽

Ion Milling ◽

Transmission Electron ◽

Ion Damage ◽

Intermetallic Composite

Transmission electron microscopy of metallic/intermetallic composite materials is most challenging since the microscopist typically has great difficulty preparing specimens with uniform electron thin areas in adjacent phases. The application of ion milling for thinning foils from such materials has been quite effective. Although composite specimens prepared by ion milling have yielded much microstructural information, this technique has some inherent drawbacks such as the possible generation of ion damage near sample surfaces.

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Transmission electron microscopy of composite materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107125 ◽

1988 ◽

Vol 46 ◽

pp. 1012-1015

Author(s):

K.P.D. Lagerlof

Keyword(s):

Composite Materials ◽

Physical Properties ◽

Structural Defects ◽

Structural Composites ◽

Multiphase Materials ◽

Structural Reinforcement ◽

Transmission Electron ◽

Reinforced Fiber ◽

Particulate Reinforced Composites ◽

Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

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