XPS Results (xp + result)

Distribution by Scientific Domains

Selected Abstracts

Electrochemical polymerization of chiral pyrrole derivatives in electrolytes containing chiral camphor sulfonic acid

GY Han
Abstract N -Substituted pyrrole derivatives with chiral side groups have been synthesized and electrochemically polymerized in acetonitrile containing tetrabutylammonium perchlorate (TBAClO4) and (S)-(+)-camphor-10-sulfonic acid ((S)-(+)-CSA) or (R)-(,)-camphor-10-sulfonic acid ((R)-(,)-CSA). The resulting N -substituted polypyrrole films were characterized by cyclic voltammetry, infrared, Raman and X-ray photoelectron (XPS) spectroscopies. XPS results demonstrated that the as-grown polymer films are preferably doped by CSA anions when the monomer and the CSA anion have the same optical rotation dispersion (ORD). Furthermore, the conductivities of the polymers synthesized in the media containing CSA with the same ORD of the corresponding monomers were measured to be about 2,10 times higher than those of polymers obtained from electrolytes without CSA. Copyright 2004 Society of Chemical Industry [source]

Sm3+ -Doped Bi2O3 Photocatalyst Prepared by Hydrothermal Synthesis

CHEMCATCHEM, Issue 4 2009
Jakkidi Krishna, Reddy
Abstract Bi2O3 and Sm3+ -doped Bi2O3 visible-light-active photocatalysts with different Sm3+ loadings (0.5, 1.0, and 2.0,wt,%) were synthesized by a hydrothermal method. The structural properties of the prepared catalysts were studied by X-ray diffraction (XRD), BET surface area, UV/Vis diffuse reflectance (DRS), FTIR, and X-ray photoelectron (XPS) spectroscopic techniques. The XRD spectra of the Sm-doped Bi2O3 catalysts calcined at 550,C show only the characteristic peaks of Bi2O3. A high red shift in the range 450,600,nm was detected in the DRS band, leading to a large decrease in the band-gap energy from 2.82 to 2.0,eV. This red shift increased with increasing Sm content. XPS results revealed that Sm interacted with Bi2O3, wherein both Bi and Sm were in the +3 oxidation state. The photocatalytic activities of the catalysts were evaluated for the degradation of methylene blue and phenol under solar irradiation. Of all of the catalysts prepared, the Sm3+ -doped Bi2O3 with a Sm loading of 1,wt,% gave the best photocatalytic activity. [source]

Analysis of Al2O3 Atomic Layer Deposition on ZrO2 Nanoparticles in a Rotary Reactor,

A. McCormick
Abstract Al2O3 atomic layer deposition (ALD) is analyzed on ZrO2 nanoparticles in a rotary reactor. This rotary reactor allows for static exposures and efficiently utilizes the reactants for ALD on high surface area nanoparticles. The Al2O3 ALD is performed using exposures to Al(CH3)3 and H2O reactants. The pressure transients during these exposures are examined using a sequence of reactant micropulses. These micropulses are less than the required exposures for the ALD surface chemistry to reach completion. The pressure transients during identical sequential Al(CH3)3 and H2O micropulses change as the surface chemistry progresses to completion. These pressure transients allow the required saturation reactant exposure to be determined to maximize reactant usage. The ZrO2 nanoparticles are coated using various numbers of Al(CH3)3 and H2O reactant exposures. The Al2O3 ALD-coated ZrO2 nanoparticles are subsequently analyzed using a number of techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES), scanning AES (SAES), and X-ray photoelectron spectroscopy (XPS). The TEM images reveal very conformal Al2O3 ALD on the ZrO2 nanoparticles. The Al2O3 ALD thicknesses versus number of Al(CH3)3 and H2O reactant exposures yielded an Al2O3 ALD growth rate of 2.0, per reactant cycle. The AES and XPS results are consistent with an Al2O3 ALD film that completely and conformally covered the underlying ZrO2 nanoparticle. The SAES measurements show that the Al2O3 ALD films are continuous and homogeneous on the ZrO2 nanoparticles. These results demonstrate that a rotary reactor can successfully perform ALD with high reactant efficiency on high surface area nanoparticles. [source]

Fullerene-like Mo(W)1,xRexS2 Nanoparticles

Francis, Leonard Deepak Dr.
Abstract Inorganic fullerene-like (IF) Mo1,xRexS2 and W1,xRexS2 nanoparticles have been synthesized by a gas-phase reaction involving the respective metal halides with H2S. The IF-Mo(W)1,xRexS2 nanoparticles, containing up to 5,% Re, were characterized by a variety of experimental techniques. Analyses of the X-ray powder diffraction and different electron microscopy techniques show that the Re is doped in the MoS2 host lattice. Interestingly, Re-doped MoS2 nanotubes are present as well, although in small quantities (,5,%). XPS results confirm the nanoparticles to be more n-type arising from the effect of Re doping. Additionally, density-functional tight-binding (DFTB) calculations support the observed n-type behavior. [source]

Controlled Grafting of Poly(methyl methacrylate) Brushes on Poly(vinylidene fluoride) Powders by Surface-initiated Atom Transfer Radical Polymerization

Zhaoqi TANG
Abstract Controlled grafting of well-defined polymer brushes of methyl methacrylate (MMA) on the poly(vinylidene fluoride) (PVDF) powders was carried out by the surface-initiated atom transfer radical polymerization (ATRP). The ATRP initiator was anchored on the PVDF surface by alkaline treatment, followed by UV-induced bromination; then methyl methacrylate (MMA) was grafted onto the brominated PVDF by the ATRP technique. The chemical composition changes of PVDF were characterized by Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS results clearly indicated the successful graft of poly(methyl methacrylate) onto the PVDF surface. [source]