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In this study, graphene foam/hematite (GF/alpha-Fe2O3) nanowire arrays hetero-structured nanocomposite (HNC) electrode was synthesized in a hierarchical manner where each constituent had its own function. The synthesis of continuous, high crystallinity and intact graphene layers on the surface of Ni foam was carried out via chemical vapor deposition (CVD) and there was no significant deterioration after Ni removal. Acting as an active backing layer, the GF provided a large surface area with high charge transfer capacity, thus facilitating the high electron transfer rate and increased electrochemical response. Hydrothermal synthesis yielded alpha-Fe2O3 nanowires with an average length of 400-450 nm. XPS results showed that the HNC sample was mostly composed of alpha-Fe2O3 phase. Finally, HNC electrode was applied for the construction of an electrochemical glucose biosensor. The increased surface area of the electrode facilitated immobilization of large amounts of glucose oxidase (GOx). Based on the active surface area of the electrode, the limit of detection and sensitivity of the biosensor were calculated to be 71.6 mu M and 20.03 mu AmM(-1)cm(-2), respectively. The high sensitivity and selectivity of HNC for the detection of glucose demonstrated that the synthesized nanocomposite material is a promising material to construct high sensitive biosensors for the detection of biologically relevant molecules. (C) 2021 Elsevier B.V. All rights reserved., Scientific and Technical Research Council of Turkey [TUBITAK] [118M621], This work was supported by the The Scientific and Technical Research Council of Turkey [TUBTAK; grant number: 118M621] .

International audience; Under in situ UV illumination, some materials present evolution of their opto-electronic properties that can be monitored by spectroscopy. We present here a mathematical method which can be applied to spectroscopic measurements when an evolving set of data is recorded: the vectorial method. The investigations and quantifications are performed by Infrared spectroscopy and XPS on organic-inorganic thin films prepared by sol-gel. The inorganic part of these hybrid thin films contains Ti oxide-network based whereas the organic part is composed of N,N-dimethylformamide and its hydrolysis products. Under UV illumination, those films exhibit intermediate bandgap behavior due to the photoreduction of Ti(IV) in Ti(III). The role of the solvent in the thin film is underlined during the process of photoreduction together with an understanding of the condensation of the Ti oxide-based network, as these evolutions are critical for the opto-electronic properties of those thin films.

TiO2-SiO2 mixed oxides have been prepared by the sol–gel technique from tetrabutyl orthotitanate and tetraethyl orthosilicate. The prepared materials were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, nitrogen physisorption, Fourier-transform infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS). The results indicate that the TiO2-SiO2 mixed oxides have a large surface area and a nanoscale size. FT-IR spectra show that Ti atoms are bonded to silica by oxygen bridging atoms in Ti-O-Si bonds. The titanium valence states in TiO2-SiO2 mixed oxides were investigated by XPS, and their spectra report the presence of Ti2+ and Ti3+ cations for high silica concentration, suggesting the formation of oxygen vacancies. The photocatalytic activity of the prepared materials has been evaluated for the photodegradation of methylene blue (MB). The mixed oxides were activated by means of a UV light source, and the concentration of MB was monitored by UV–Vis spectroscopy. The synthesized TiO2-SiO2 shows significantly higher MB removal efficiency in comparison with that of the commercial TiO2 Degussa, P25. In this paper, we observed three valence states of titanium: Ti4+, Ti3+ and Ti2+ in TiO2-SiO2 40%. This issue has not yet been reported. XPS analysis show that the content of Ti2+ and Ti3+ amounts to 25.26 at.% and 13.08 at.%, respectively, while the concentration of Ti4+ is 61.72 at.%, much lower than in the TiO2-SiO2 9% sample. This behavior is explained observing that in TiO2-SiO2 40%, Ti4+ is reduced to Ti3+ and Ti2+ to a larger extent with respect to TiO2-SiO2 9%.

The Near-Edge X-ray-Absorption Fine-Structure (NEXAFS) and X-ray Photoemission Spectroscopy (XPS) of short-chain oligothiophenes (thiophene, 2,2'-bithiophene, and 2,2':5',2 ''-terthiophene) in the gas phase have been measured in the sulfur L-2,L-3-edge region. The assignment of the spectral features is based on the relativistic two-component zeroth-order regular approximation time dependent density functional theory approach. The calculations allow us to estimate both the contribution of the spin-orbit splitting and of the molecular-field splitting to the sulfur binding energies and give results in good agreement with the experimental measurements. The deconvolution of the calculated S2p NEXAFS spectra into the two manifolds of excited states converging to the L-III and L-II edges facilitates the attribution of the spectral structures. The main S2p NEXAFS features are preserved along the series both as concerns the energy positions and the nature of the transitions. This behaviour suggests that the electronic and geometrical environment of the sulfur atom in the three oligomers is relatively unaffected by the increasing chain length. This trend is also observed in the XPS spectra. The relatively simple structure of S2p NEXAFS spectra along the series reflects the localized nature of the virtual states involved in the core excitation process. Published by AIP Publishing.

Intercalation of 9-aminoacridine (9AA: C 13 H 10 N 2 ) in thin films of exfoliated Li 2 x − y Mn 1− x PS 3 has been performed by means of a solution approach starting from the hydrochloride salt of the organic species (9AAHCl: C 13 H 10 N 2 ·HCl). The resulting nanocomposite Li 2 x − y Mn 1− x PS 3 (C 13 H 11 N 2 ) y films have been investigated by X-ray photoemission spectroscopy (XPS), at room temperature, in the regions of the Mn, P, S and Cl 2p, Li, C and N 1s and Mn 3p core levels. The XPS analysis has been also carried out on the 9-aminoacridine hydrochloride films whose XPS spectra have been compared with those of the Li 2 x − y Mn 1− x PS 3 (C 13 H 11 N 2 ) y films to obtain information about the nature of the interaction between the guest species (9AAH + ) and the matrix (Li 2 x − y Mn 1− x PS 3 − ).

The current interest in functionalized calixarenes with phosphorylated pendant arms resides in their coordination ability towards f elements and capability towards actinide/rare earth separation. Uranyl cation forms 1:1 and 1:2 (M:L) complexes with a tetra-phosphinoylated p-tert-butylcalix[4]arene, B4bL4: UO2(NO3)2(B4bL4) n · xH2O (n = 1, x = 2, 1; n = 2, x = 6, 2). Spectroscopic data point to the inner coordination sphere of 1 containing one monodentate nitrate anion, one water molecule and the four phosphinoylated arms bound to UO2 2+ while in 2, uranyl is only coordinated to calixarene ligands. In both cases the U(VI) ion is 8-coordinate. Uranyl complexes display enhanced metal-centred luminescence due to energy transfer from the calixarene ligands; the luminescence decays are bi-exponential with associated lifetimes in the ranges 220 μs <τ s τ L < 640 μs, pointing to the presence of two species with differently coordinated calixarene, as substantiated by a XPS study of U(4f 5/2,7/2), O(1s) and P(2p) levels on solid state samples. The extraction study of UO2 2+ cation and trivalent rare-earth (Y, La, Eu) ions from acidic nitrate media by B4bL4 in chloroform shows the uranyl cation being much more extracted than rare earths.

A novel 5,10,15,20-tetra[4-(3,5-dioctoxybenzamide)phenyl]porphyrin and its transition metal complexes are reported in this paper. Their molecular structures were characterized by elemental analysis, IR spectra, 1HNMR spectra and UV-Vis spectra. Their spectroscopic properties were studied by Raman spectra, fluorescence spectra and X-ray photoelectron spectra (XPS). The fluorescence quantum yields have been measured at room temperature. The fluorescence intensity of porphyrin ligand was stronger than that of the complexes. In Raman spectra, there was much difference between porphyrin ligand and its metal complexes due to changes of the symmetry of porphyrin plane. In the XPS spectra, the replacement of the free-base protons by a metal ion to form the metalloporphyrin increases the symmetry of the molecule also introduces an electron with-drawing group into the center of the porphyrin ligand which increases the N1s binding energy.

Thin PMMA films with and without gold nanoparticles were subjected to +/-10V d.c. and a.c. (square wave) excitations in various frequencies while recording their XPS spectra, and the resulting differences due to charging were examined. Both pure PMMA films and films containing gold nanoparticles showed charging shifts, but those of pure PMMA were more extensive than of PMMA containing gold nanoparticles, suggesting enhanced conductivity, induced by the incorporated gold nanoparticles. Non-charging behavior for these films was also observed with the increase of gold nanoparticle concentration. Gold nanoparticles were in situ synthesized and photo-patterned within the polymer films by UV irradiation. (C) 2010 Elsevier B.V. All rights reserved.

X-ray photoelectron spectroscopy (XPS), magnetization and magnetic susceptibility of Mn1−x Alx (x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.7) alloys are reported. X-ray diffraction measurements showed that all investigated samples have the same crystallographic structure as the parent compound (AuCu3-structure type). The alloys are disordered for x ≤ 0.5, but become almost crystallographically ordered for higher Al concentration. This change in the crystallographic order is reflected both in the magnetization and Curie temperature values. The exchange interaction is ferromagnetic between the pairs of the near-neighbour Mn-Ni and Ni-Ni magnetic moments and antiferromagnetic for Mn-Mn pairs. The last one is present only in the disordered alloys, which leads to smaller values of the magnetization of these alloys in comparison with the ordered ones. The Mn magnetic moment has the fully ordered value of 3.2 μB in all investigated alloys. The decrease of the Ni magnetic moment as the Al concentration increases may be explained by the hybridization of the Ni 3d and Al 3sp states, which leads to a partial filling of the Ni 3d band. The magnetic susceptibility measurements pointed out the existence of spin fluctuations on Ni sites.