Al 2p Binding Energy Research Articles

Facile fabrication of amorphous Al/Fe based metal-organic framework as effective heterogeneous fenton catalyst for environmental remediation.

This study presents a facile preparation and durable amorphous Fe and Al-based MOF nanoplate (AlFe-BTC MOFs) catalyst with notable stability in Fenton reactions. Rigorous characterization using XRD, HR-TEM, and BET confirms the amorphous nature of the synthesized AlFe-BTC MOFs, revealing mesopores (3.4nm diameter), a substantial surface area (232 m2/g), and a pore volume of 0.69cc/g. XPS analysis delineates distinct Al2p and Fe2p binding energy values, signifying specific chemical bonding. FE-SEM elemental mapping elucidates the distinctive distribution of Fe and Al within the framework of AlFe-BTC MOFs. In catalytic activity testing, the amorphous AlFe-BTC MOFs exhibited outstanding performance, achieving complete degradation of Methylene blue (MB) dye and 78% TOC removal over 45min of treatment under mild reaction conditions. The catalyst's durability was assessed, revealing about 75% TOC removal and complete dye decomposition over five successive recycles, with less than 1mg/L of Fe and Al leaching. UV-Vis spectra revealed the destruction of MB dye over multiple recycling studies. Based on this finding, the amorphous AlFe-BTC MOF nanoplates emerge as a promising solution for efficient dye removal from industrial wastewater, underscoring their potential in advanced environmental remediation processes.

Mechanochemical Synthesis of Non-Solvated Dialkylalumanyl Anion and XPS Characterization of Al(I) and Al(II) Species.

A non-solvated alkyl-substituted Al(I) anion dimer was synthesized by a reduction of haloalumane precursor using a mechanochemical method. The crystallographic and theoretical analysis revealed its structure and electronic properties. Experimental XPS analysis of the Al(I) anions with reference compounds revealed the lower Al 2p binding energy corresponds to the lower oxidation state of Al species. It should be emphasized that the experimentally obtained XPS binding energies were reproduced by delta SCF calculations and were linearly correlated with NPA charges and 2p orbital energies.

Use of CO2 to Cure Steel Slag and Gypsum-Based Material

To improve the utilization of steel slag (SS) in CO2 capture and making building materials, the paper mainly discussed the effects of desulphurization gypsum (DG) and w/s ratio on strength development and CO2 capture capability of high Al content SS. It showed that 10 wt% DG enhanced the strength of hydration-curing SS by 262% at 28 days. Similarly, adding 6 wt% DG in carbonation-curing SS contributed to increases in strength and CO2 uptake by 283% and 33.54%, reaching 42.68 MPa and 19.12%, respectively. Strength decreases and CO2 uptake increases with w/s. Microanalysis (QXRD, SEM-EDS, TG-DTG, FTIR, XPS, and MIP) revealed that the main hydration products of SS were C-S-H gel and C4AH13, which transformed to ettringite with DG addition. The carbonation products were mainly calcite and aragonite. Additionally, the amount of aragonite, mechanically weaker than calcite, decreased and calcite increased significantly when DG was added in carbonation-curing samples, providing a denser structure and higher strength than those without DG. Furthermore, high Al 2p binding energies revealed the formation of monocarboaluminate in the DG-added carbonation samples, corresponding to higher CO2 uptake. This study provides guidance for the preparation of SS-DG carbide building materials.

Synthesis of new Ln4(Al2O6F2)O2 (Ln = Sm, Eu, Gd) phases with a cuspidine-related structure.

The first fluorination of the cuspidine-related phases of Ln4(Al2O7□)O2 (where Ln = Sm, Eu, Gd) is reported. A low-temperature reaction with poly(vinyl-idene difluoride) lead to the fluorine being substituted in place of oxygen and inserted into the vacant position between the dialuminate groups. X-ray photoelectron spectroscopy shows the presence of the F 1s photoelectron together with an increase in Al 2p and rare-earth 4d binding energies supporting F incorporation. Energy-dispersive X-ray spectroscopy analyses are consistent with the formula Ln4(Al2O6F2)O2, confirming that substitution of one oxygen by two fluoride atoms has been achieved. Rietveld refinements show an expansion in the cell upon fluorination and confirm that the incorporation of fluoride in the Ln4(Al2O7□)O2 structure results in changes in Al coordination from four to five. Thus, the isolated tetrahedral dialuminate Al2O7 groups are converted to chains of distorted square-based pyramids. These structural results are also discussed based on Raman spectra.

Systematic XPS study of gallium-substituted boehmite

Abstract: Ga-substituted boehmites were synthesized using a soft-chemistry route in the presence of poly(ethylene oxide) surfactant under hydrothermal conditions. The effect of Ga-substitution was studied by X-ray diffraction and X-ray photoelectron spectroscopy. Initial precipitates were amorphous (minor bayerite). After hydrothermal treatment, XRD showed broad reflections at low Ga-substation indicating low crystallinity and formation of pseudoboehmite. This was confirmed by high-resolution XPS of Al 2p, Ga 2p, and O 1s. The Al 2p binding energy of 74.03 eV was closer to boehmite than pseudoboehmite, probably caused by the Ga-substitution in the structure. The O 1s showed the presence of O, OH, and H2O. The ratio of (total O)/(Al + Ga) showed an excess of O as expected for pseudoboehmite. The ratio of (O + OH)/Al + Ga) was also slightly larger than the theoretical value of 2 for boehmite. High concentrations of added Ga (10, 20 %) resulted in amorphous material after hydrothermal treatment. Graphical Abstract: [Figure not available: see fulltext.]

On electrochemistry of Al2O3-coated LiCoO2 composite cathode with improved cycle stability

LiCoO2-based cathode does still have a powerful competition in high-end mobile electronics due to its relatively high true density (about 5.2 g/cm3). When the operation potential range is extended, the improvement in its cycle stability has attracted more attention. The extension of its operation potential can be realized by partial replacement of Co by Ni and Mn or by surface modification. However, Ni and Mn replacing partial Co results in decreased true density; for example, the true density of LiNi0.5Mn0.3Co0.2O2 is about 4.6 g/cm3. In this case, the increase in its practical energy density is impossible. As a result, the surface modification technology becomes very important to extend its operation potential range. In this article, an Al2O3-coated LiCoO2 cathode was synthesized. X-ray diffraction test did not show any impurity. Scanning electron spectroscopy measurements showed that the basic microstructure of pristine LiCoO2 grain is sustained after coating Al2O3. The surface characteristic of pure and Al2O3-coated LiCoO2 was also analyzed using an X-ray photoelectron spectroscopy (XPS) technique. Unusual XPS peaks of O 1s, Al 2p, and Co 2p binding energy were found and may be caused by the possible H existence in crystal structure. The electrochemical behavior was systematically investigated, and the cathode was cycled at different charge cutoff voltages (4.30∼4.60 V). The charge-discharge and cyclic voltammetry measurements showed an obviously improved cyclic performance after coating Al2O3. The electrocatalytic activity is not clearly changed before and after coating Al2O3. From our systematical investigation, it could be concluded that the Al2O3-coated LiCoO2 cathode is suitable for practical application in the potential range of 3.70∼4.50 V vs. Li/Li+.

Al-O-Si Bond Formation in Boehmite-Fumed Silica Mixtures during Mechanochemical Activation

Al-O-Si bond formation in boehmite-fumed silica mixtures during mechanochemical activation was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), magic angle spinning nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopy (XPS). The intrinsic structure deformation of the boehmite was examined with XRD. Formation of new Al-O-Si bonds was illustrated by the incorporation of Al3+ in Si-O-Si linkages, the change in the Al coordination number of boehmite, and the appearance of new resonance in the 29Si NMR spectrum of the ground mixture. The presence of Al-O units in silica frameworks was verified by the increase of Al 2p binding energy and the decrease of Si 2p binding energy.

Surface chemistry of metal oxide coated lithium manganese nickel oxide thin film cathodes studied by XPS

The effect of coating the high voltage spinel cathode LiMn1.5Ni0.5O4 with three metal oxide thin layers is discussed. Instead of the typical powder electrodes with poorly defined surface coatings, thin film electrodes were prepared with well-defined oxide coating thicknesses to investigate the influence of coating on surface reactivity via X-ray photoelectron spectroscopy (XPS). ZnO is found to decompose during the first charge whereas Al2O3 and ZrO2 are stable for more than 100 cycles. ZrO2, however, importantly limits the available Li storage capacity of the electrochemical reaction due to poorer kinetics. Al2O3 offers the best results in term of capacity retention. Upon cycling, the evidence of a signal at 75.4eV in the Al2p binding energy spectrum indicates the partial fluorination of Al2O3 into, perhaps, Al2O2F2. Moreover, the continuous formation of ethers, esters and LixPOyFz compounds on the surface of the electrodes is found for all coating materials.

Chemical bond change of gibbsite and fumed silica mixture during mechanical activation

Chemical bond changes of gibbsite and fumed silica mixture during mechanical activation were investigated by X-ray powder diffraction (XRD), magic angle spinning nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopy (XPS). Crystallinity and intrinsic structural change of the mixture during high-energy milling were examined by XRD. Formation of new AlOSi chemical bonds was detected by the changes in Al coordination number of gibbsite in the mixture during milling, and the appearance of new resonance in 29Si NMR spectrum of the ground mixture. The presence of AlO units in silica framework was demonstrated by the increase of Al 2p binding energy and the decrease of Si 2p binding energy.

Thermal plasma-sintered Ti-doped Al—Zr oxide composites: X-ray photoelectron spectroscopy studies

Ti-doped Al—Zr oxide composites (Zr1− x–Al1+ x–Ti x–O y with x = 0.05, 0.1, 0.15) were sintered to high density end products by an extended arc DC thermal plasma heating technique within a short sintering time as compared with a conventional long range resistive heating schedule. Thermal plasma-sintered samples showed conducting behaviour at room temperature whereas conventional-sintered samples became highly resistive. Specimens were analysed by X-ray photoelectron spectroscopy, X-ray diffraction, and Electron Probe Micro Analyzer studies. Higher binding energy of Zr 3d lines in a plasma-sintered sample showed that ZrO2 has strongly reacted with TiO2, thereby enhancing the possibility of ZrTiO4 phase formation. The increase in Al 2p binding energy for a conventional-sintered sample indicated the reaction of Al2O3 with TiO2, which was likely to enhance Al2TiO5 phase formation. XRD and scanning electron microscope analysis along with density studies corroborated this finding. The existence of elemental Ti at 453.3 eV and the presence of TiC at 455.2 eV were found to be responsible for conducting behaviour of plasma-sintered composites.

A new method to evaluate the hydraulic activity of Al-Si materials

Slag, fly ash, gangue and 500°C calcined gangue are analyzed by using identical coupled plasma optical emission spectroscopy (ICP), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and magnetic angle spinning nuclear magnetic resonance (MAS NMR). Research results show that there is a negative linear relationship between the Si 2p and Al 2p binding energies of Al-Si materials and the compressive strength of aluminosilicate based cementitious materials prepared with these Al-Si materials, i.e. the lower the binding energies, the higher the compressive strength. Indeed, the Si 2p and Al 2p binding energies of Al-Si materials can be used to indicate their hydraulic activity. The binding energies of the four examined materials increase in the order of slag, fly ash, 500°C calcined gangue and untreated gangue. Moreover, the binding energies of Si 2p, Al 2p and O 1s of every Al-Si material have excellent correlation. By using the Al 2p binding energy and 27Al MAS NMR spectra, the coordination number of aluminum in slag is determined to be four, while that in gangue, is six. Based on the aforementioned discoveries, this paper presents a new effective method to evaluate the hydraulic activity of Al-Si materials by using the surface binding energies of silicon and aluminum of Al-Si materials.

Optimization of sol–gel coatings on the surface of aluminum pigments for corrosion protection

Encapsulated aluminum pigments were prepared by sol–gel method using tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) as precursors. The reaction conditions were optimized and the aluminum pigments prepared under the optimum conditions were characterized by Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Subsequently the stability of the aluminum pigments in acid and alkaline aqueous media was examined. It was found that both TEOS and VTES hydrolyze and condense to form a dense netlike layer on the surface of aluminum pigments. XPS analysis shows that TEOS–VTES successfully bonded to Al surface. The 0.64 eV shift of Al 2p binding energy indicates a new Si–O–Al bond formed on Al surface. The corrosion protection efficiencies of the TEOS–VTES-coated aluminum pigments prepared under the optimum experimental conditions reach 99.8% and 99.9% in acid media of pH 1 and alkaline media of pH 11, respectively, suggesting that TEOS–VTES sol–gel coatings can protect aluminum pigments well in corrosion media.

X-ray photoelectron spectroscopy of aluminium-substituted tobermorite

We have synthesised 11-Å tobermorite hydrothermally, both pure and with increasing isomorphic substitution of aluminium for silicon. The samples were analysed by X-ray photoelectron spectroscopy (XPS). Aluminium was found, on the basis of its Al 2p binding energies, to be tetrahedrally coordinated. We observed no changes in Ca/(Si+Al) ratio upon aluminium substitution, implying that charge balancing does not occur via the incorporation of additional calcium into the tobermorite structure. Aluminium substitution into the silicate structure led to a decrease in Si 2p binding energies. This implies one of two alternatives. Firstly, that charge balancing occurs via substitution of OH − for O 2− in the tobermorite structure. Secondly, the presence of aluminium in the tobermorite structure may negatively influence the degree of silicate polymerisation. Further work is required to determine which of these possibilities is the case.

Acid−Base Characterization of Aluminum Oxide Surfaces with XPS

The localized acid−base properties of different, aluminum oxide thin layer surfaces have been evaluated with X-ray photoelectron spectroscopy (XPS). Five types of oxide layers were studied, which were produced by oxidizing aluminum in a vacuum, with an alkaline and acidic pretreatment, and in boiling water. The photoelectron core level binding energies, as measured with XPS, are evaluated for this purpose, while taking into consideration the initial and final state effects. For the structurally comparable oxides, the shifts in the O 1s binding energies are determined by their initial state chemistry. The values of the O 1s binding energy can be directly related to the surface-averaged charge on the O anions. For the Al cations, a correlation between the photoelectron core level binding energy shift and changes in the initial state chemistry was observed, but the Al 2p binding energy shifts were found to be partially due to changes in extra-atomic relaxation. The measured Al 2p binding energies and the binding energies of the resolved OH and O components in the O 1s peak showed that the studied aluminum oxides have OH sites with the same Brönsted/Lewis acid−base properties, O sites with the same Lewis base properties, and Al sites with very similar Lewis acid properties. The pseudoboehmite oxide, obtained by boiling aluminum in water, exhibits more basic O, OH, and Al sites. This oxide deviates structurally from the other oxides studied, resulting in a lower extra-atomic relaxation and Madelung potential contribution to the binding energies.

Nondestructive depth profile of the chemical state of ultrathin Al2O3/Si interface

We investigated a depth profile of the chemical states of an Al2O3/Si interface using nondestructive photon energy-dependent high-resolution x-ray photoelectron spectroscopy (HRXPS). The Si 2p binding energy, attributed to the oxide interfacial layer (OIL), was found to shift from 102.1 eV to 102.9 eV as the OIL region closer to Al2O3 layer was sampled, while the Al 2p binding energy remains the same. This fact strongly suggests that the chemical state of the interfacial layer is not Al silicate as previously believed. We instead propose from the HRXPS of Al 2p and Si 2p depth-profile studies that the chemical states of the Al2O3/Si interface mainly consist of SiO2 and Si2O3.

Alloying mechanism of beta stabilizers in a TiAl alloy

The effects of beta stabilizers such as Fe, Cr, V, and Nb on the microstructures and phase constituents of Ti52Al48-xM (x=0, 1.0, 2.0, 4.0, or 6.0 at. pct and M=Fe, Cr, V, and Nb) alloys were studied. The dependence of the tensile properties and creep resistance of TiAl on the alloying elements, especially the formation of B2 phase, was investigated. Fe is the strongest B2 stabilizer, Cr is second, V is an intermediate stabilizer, and Nb is the weakest stabilizer. The composition partitioning of Fe, Cr, V, and Nb in the γ phase is affected by the formation of B2 phase. The peaks of the tensile strengths and creep rupture life of Ti52Al48-xM generally occur at the maximum solid solution of these elements in the γ phase, which is just before the formation of B2 phase. Ti52Al48-0.5Fe shows an attractive elongation of 2.5 pct at room temperature, and the Ti52Al48-1V, Ti52Al48-Cr, and Ti52Al48-2Nb alloys have about 1.1 to 1.3 pct elongation at room temperature. The increase of tensile strengths and creep resistance with increasing Fe, Cr, V, and Nb contents is chiefly attributed to the solid-solution strengthening of these elements in the γ phase. The appearance of B2 phase deteriorates the creep resistance, room-temperature strengths, and ductility. With respect to the maximum solid-solution strengthening, an empirical equation of the Cr equivalent [Cr] is suggested as follows: [Cr]=Cr+Mn+3/5V+3/8Nb+3/2 (W+Mo)+3Fe=1.5 to 3.0. The solid-solution strengthening mechanism of Fe, Cr, V, and Nb at room temperature arises from the increase of the Ti 3s and Al 2s binding energies in Ti-Ti and Al-Al bonds, and the retention of the strength and creep resistance at elevated temperatures in Ti52Al48-xM is mainly attributed to the increase of the Ti 3s and Al 2s binding energies in Ti-Al bonds in γ phase. The decrease of the Ti 3p and Al 2p binding energies in Ti-Ti, Ti-Al, and Al-Al bonds benefits the ductility of TiAl.

Growth and characterization of cathodic arc evaporated CrN, (TiAl)N and (TiZr)N films

Nitride films have been grown using newly developed chromium, titanium-aluminum and titanium-zirconium targets by the cathodic arc evaporation process. Special alloy processing produced cathodes that overcame conventional problems associated with evaporation of multicomponent cathodes. Single and multilayer films of the various nitride compositions were analysed using X-ray photoelectron spectroscopy (XPS) and their electrochemical polarization behaviour was tested using polarization corrosion methods. From the XPS data, it was determined that the atomic ratio of the metallic constituents in the alloy cathodes was unity and the ratio of the cations to the anions in the nitride films was also unity. The Ti 2p, Al 2p and Zr 3d binding energies from the nitride films were 0.8–1.0 eV higher than in the corresponding target material. The XPS results strongly suggest that the (TiAl)N films are made up of distinct TiN and AlN phases and the (TiZr)N films of similarly distinct TiN and ZrN phases. In addition, electrochemical studies showed that the rest potential and polarization behaviour of the nitride films were influenced by the composition and integrity of the surface film.

Temperature-dependent line broadening in core-level photoemission spectra from aluminum.

The temperature dependence of the Al 2p line width and binding energy has been studied in the range from 80 K up to and beyond the Al bulk melting point (${\mathit{T}}_{\mathit{m}}$=933.5 K). By comparing the experimental data with results from calculations based on a nearest-neighbor force constant model, we find the phononic coupling to be of quadratic rather than linear nature as previously assumed. The temperature dependence of the Al 2p binding energy is interpreted on the basis of thermal expansion and phononic coupling.

Photodissociation of dimethylaluminum hydride on Si(100) at 193 nm studied by x-ray photoelectron spectroscopy

By irradiation of 193 nm photons on the molecularly adsorbed species of dimethylaluminum hydride on Si(100) at 150 K, the [C]/[Al] atom ratio decreased and the Al2p binding energy was lowered. This change is due to the Al—C bond cleavage by direct photoabsorption of the adsorbed species. Irradiation at 351 nm induces no appreciable dissociation of the adsorbed species. When dimethylaluminum hydride was adsorbed on the Si substrate at room temperature, the 193 nm irradiation induced only a small change in the x-ray photoelectron spectra of the dissociatively adsorbed species. Variation of the photodissociation quantum yield is discussed in terms of dissociative adsorption mechanisms.

XPS studies on intermetallic phases formed in AlNi and AlMn thin films

AbstractThin films of AlNi and AlMn alloys were prepared by high‐temperature successive vapour deposition (HTSVD). In the case of AlNi a pronounced shift (∼0.5 eV) of the Ni Auger parameter [combined Ni 2p binding energy (BE) and Ni L3 VV kinetic energy (KE) values] to lower values can be detected for the Al3Ni compound, the structure of which was determined by x‐ray diffraction. In the AlMn system a quasi‐crystalline Al4Mn phase was formed and its structure was determined by selected area electron diffraction as well as by TEM and cross‐sectional TEM. XPS measurements show that for this AlMn phase only a small peak shift (∼0.3 eV) of the Mn 2p core level can be related to the compound formation as compared to the pure metallic state of the components. The same shift to lower values was also obtained for the Auger parameter (Mn 2p BE + Mn L3M23M23). The small peak observed by others at 2.4 eV higher than the Al 2p BE is unambiguously related to the oxygen content in our samples. On the basis of the results we can conclude that the observed core level and Auger line shifts; the small linewidths and especially the Auger parameter shift to lower values are all indicative of the formation of intermetallic compounds in these systems.