High-resolution X-ray Photoelectron Spectroscopy Spectra Research Articles

Innovative synthesis technique for high-performance dielectric resonator antennas: laser-induced shockwave sintering of potassium sodium niobate (KNN)

This study explored the synthesis and sintering of potassium sodium niobate (KNN) nanoparticles, emphasizing morphology, crystal structure, and sintering methods. The as-synthesized KNN nanoparticles exhibited a spherical morphology below 200 nm. Solid state sintering (SSS) and laser-induced shockwave sintering (LISWS) were compared, with LISWS producing denser microstructures and improved grain growth. Raman spectroscopy and x-ray diffraction confirmed KNN perovskite structure, with LISWS demonstrating higher purity. High-resolution x-ray photoelectron spectroscopy spectra indicated increased binding energies in LISWS, reflecting enhanced density and crystallinity. Dielectric and loss tangent analyses showed temperature-dependent behavior, with LISWS-3 exhibiting superior properties. Antenna performance assessments revealed LISWS-3’s improved directivity and reduced sidelobe radiation compared to SSS, attributed to its denser microstructure. Overall, LISWS proved advantageous for enhancing KNN ceramics, particularly in antenna applications.

Influence of light, heat and humidity on MAPbI3/Si interface stability

X-ray photoelectron spectroscopy (XPS) was used to examine the MAPbI3/Si interface (MA = methylammonium) before and after 45 days of exposure to light, heat stress at 85 °C or 50% relative humidity (RH). From the survey XPS spectra it follows that under these external influences, changes in the I/Pb ratio, indicating the presence of the PbI2 phase as a degradation product, do not go beyond 12%. These results were confirmed by measurements of high-resolution XPS spectra in the energy ranges of Pb 4f, I 3d and valence band signals, which do not show significant high-energy shifts towards the energy position of the PbI2 reference spectra.

Plasma-Activated Solutions Regulate Surface-Terminating Groups Enhancing Pseudocapacitive Ti3 C2 Tx Electrode Performance.

2D transition metal carbides and nitrides (MXenes) are actively pursued as pseudocapacitive materials for supercapacitors owing to their advantages in electronic conductivity and surface reactivity. Increasing the fraction of ─O terminal groups in Ti3 C2 Tx is a promising approach to improve the pseudocapacitive charge storage in H2 SO4 electrolytes, but it suffers from a lack of effective functionalization methods and stability of the groups in practical operation. Here a low-temperature and environment-friendly approach via the interaction of nonequilibrium plasmas with Ti3 C2 Tx dispersion is demonstrated to generate abundant and stable surface-terminating O groups. The impact of the discharge environment (Ar, O2 , and H2 ) on the structural characteristics and electrochemical performance of Ti3 C2 Tx nanosheets is studied. The Ti3 C2 Tx modified in Ar and H2 maintains their original morphology but a significantly lower F content. Consequently, an extraordinarily high content (78.5%) of surface-terminating O groups is revealed by the high-resolution X-ray photoelectron spectroscopy spectra for the Ti3 C2 Tx samples modified in H2 plasma-treated solutions. Additionally, the Ti3 C2 Tx treated using H2 plasmas exhibits the best capacitive performance of 418.3 F g-1 at 2mV s-1 , which can maintain 95.88% capacity after 10000 cycles. These results contribute to the development of advanced nanostructured pseudocapacitive electrode materials for renewable energy storage applications.

Investigation of electrophysical, photo- and gas-sensitive properties of ZnO–SnO2 sol–gel films

Thin nanocomposite films based on tin dioxide with a low content of zinc oxide (0.5–5[Formula: see text]mol.%) were obtained by the sol–gel method. The synthesized films are 300–600[Formula: see text]nm thick and contains pore sizes of 19–29[Formula: see text]nm. The resulting ZnO–SnO2 films were comprehensively studied by atomic force and Kelvin probe force microscopy, X-ray diffraction, scanning electron microscopy, and high-resolution X-ray photoelectron spectroscopy spectra. The photoconductivity parameters on exposure to light with a wavelength of 470[Formula: see text]nm were also studied. The study of the photosensitivity kinetics of ZnO–SnO2 films showed that the film with the Zn:Sn ratio equal to 0.5:99.5 has the minimum value of the charge carrier generation time constant. Measurements of the activation energy of the conductivity, potential barrier, and surface potential of ZnO–SnO2 films showed that these parameters have maxima at ZnO concentrations of 0.5[Formula: see text]mol.% and 1[Formula: see text]mol.%. Films with 1[Formula: see text]mol.% ZnO exhibit high response values when exposed to 5–50[Formula: see text]ppm of nitrogen dioxide at operating temperatures of [Formula: see text]C and [Formula: see text]C.

2H-MoS 2 Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

2H-MoS ₂ Modified Nitrogen-Doped Hollow Mesoporous Carbon Spheres as the Efficient Catalytic Cathode Catalyst for Aprotic Lithium-Oxygen Batteries

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N 5 Site for Enhanced Electrocatalytic Reaction

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N ₅ Site for Enhanced Electrocatalytic Reaction

Modification of conventional peak shapes to accurately represent spectral asymmetry: High-Resolution X-ray photoelectron spectra of [C4C1Pyrr][NTf2] and [C8C1Im][NTf2] ionic liquids

X-ray photoelectron spectroscopy (XPS) is one of the most widely used techniques for surface characterization. Analysis of XPS data is challenging and requires the analyst to fit the data with synthetic line shapes to reach physically meaningful interpretations. Experimental spectral envelopes, however, are complex and display asymmetric features that are often ignored or attributed to additional chemical components. The high-resolution XPS spectra of [C4C1Pyrr][NTf2] and [C8C1Im][NTf2] all exhibit a degree of asymmetry which is systematically observed at the higher binding energy side of photoemission envelopes. We present the development of a refined fitting procedure for XPS spectra of these ionic liquid-based systems which include (a) Shirley background offset necessary to account for the insulator-like region and (b) spectral asymmetry in C 1s and N 1s regions. Further, Shirley and trapezoid components are applied to compensate for inelastic scattering taking place during electron transitions as high as 7.8 eV above the start of the fitting region in C 1s high-resolution spectrum. To demonstrate the fitness of this model, we present an analysis of a 2:1 mixture of [C4C1Pyrr][NTf2]: [C8C1Im][NTf2].

Decoration of Reduced Graphene Oxide with Magnesium Oxide during Reflux Reaction and Assessment of Its Antioxidant Properties

The aim of this work is the reduction and decoration of graphene oxide (GO) with magnesium oxide (MgO). In this work, GO was synthesized using modified Hummers’ protocol with (1:2), (1:3) and (1:4) graphite:potassium permanganate mass ratios. Subsequently, all GO samples (GO1:2, GO1:3, GO1:4) were reduced and decorated with magnesium oxide nanoparticles using a reflux technique at 100 °C for 2 h. Sample characterization using X-ray diffraction (XRD) reveals the presence of peaks relative to two different magnesium (Mg) phases: magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)2). The presence of these spectral features, although characterized by a remarkable broadening, confirms the successful synthesis of Mg(OH)2-rGO-MgO nanocomposites. X-ray photoelectron spectroscopy (XPS) spectra indicate the presence of peaks assigned to C, O and Mg. The analysis of the high-resolution XPS spectra of these elements confirms once again the presence of Mg(OH)2-rGO-MgO compounds. The low temperature synthesis of Mg(OH)2-rGO-MgO nanocomposite exhibiting superior catalytic properties compared to MgO–rGO nanoparticles is an important step forward with respect to the current state of the art. The antioxidant activity of six nanocomposites, namely GO1:2, GO1:3, GO1:4, MgO–rGO1:2, MgO–rGO1:3 and MgO–rGO1:4, was determined using standard protocols based on a DPPH radicals scavenging assay, an H2O2 scavenging assay, and a phosphomolybdate assay. All our samples exhibited dose-dependent antioxidant activity. Interestingly, among the different synthesized nanoparticles, GO1:4 and MgO–rGO1:4 showed the best performances.

Valence State Tuning of Gold Nanoparticles in the Dewetting Process: An X-ray Photoelectron Spectroscopy Study.

Gold nanoparticles (AuNPs) are commonly synthesized using the citrate reduction method, reducing Au3+ into Au1+ ions and facilitating the disproportionation of aurous species to Au atoms (Au0). This method results on citrate-capped AuNPs with valence single states Au0. Here, we report a methodology that allows obtaining AuNPs by the dewetting process with three different valence states (Au3+, Au1+, and Au0), which can be fine-tuned with ion bombardment. The chemical surface changes and binding state of the NPs were investigated using core-level X-ray photoelectron spectroscopy (XPS). This is achieved by recording high-resolution Au 4f XPS spectra as a function of ion dose exposure. The results obtained show a time-dependent tuning effect on the Au valence states using low-energy 200 V acceleration voltage Ar+ ion bombardment, and the valence state conversion kinetics involves the reduction from Au3+ and Au1+ to Au0. Proper control of the reduction in the valence states is critical in surface engineering for controlling catalytic reactions.

Study of optical, morphological, structural, and chemical properties of CdO thin films synthesized by thermal annealing transformation of CdCO3 thin films

Considering the potential applications of cadmium oxide (CdO) thin films in optoelectronics, this work aims to investigate the structural, optical, compositional, and morphological properties of CdO thin films obtained by converting CdCO3 thin films into CdO by thermal annealing. The established method consists of thermal treatment for 2 h at different temperatures for CdO thin film obtention. The CdO thin films were characterized by ultraviolet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetry (TGA). The direct band gap of the CdO thin films obtained was 2.39 and 2.43 eV. These values are in the range reported in the literature for CdO thin films and are related to direct transitions of electrons between valence and conduction bands. Furthermore, the HR-TEM and XRD analysis confirmed a cubic crystalline structure for CdO thin films. The low-resolution and high-resolution XPS spectra further confirm the expected chemical composition of CdO thin films.

BiO 2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO 2 Reduction to Formate

BiO _2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO ₂ Reduction to Formate

Boosting Electrocatalytic CO 2 Reduction with Conjugated Bimetallic Co/Zn Polyphthalocyanine Frameworks

Boosting Electrocatalytic CO ₂ Reduction with Conjugated Bimetallic Co/Zn Polyphthalocyanine Frameworks

Effect of Fe on Bi2Te3: Structure, magnetic properties, and XPS valence band

The crystal structure and magnetic properties of Fe doped Bi2Te3 are presented. The samples were studied by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetization measurements. Rietveld refinement results show a decrease in volume due to the decrease in c lattice parameter as iron is introduced. By XPS measurements, the Te 3d, Bi 4f, Bi 5d, Te 4d, and Fe 3d core levels were identified, and the XPS valence band (VB) was measured. The deconvolution process of high resolution XPS spectra in Fe 3d orbital shows that the Fe3+ ion is present in the samples. Theoretical calculations by DFT reveal that the Bi2Te3 compound is a semiconductor with a narrow energy band gap in agreement with experimental results. DOS analysis shows that the main contributions to the valence band are the Te 5p, Bi 6p, and Fe 3d states. XPS VB shows a decrease in the intensity at zero eV due to increased Fe 3d states and good correspondence with DOS calculated for Bi2Te3. Finally, magnetic susceptibility measurements on Bi2Te3 do not show a magnetic behavior; however, for the doped sample with x = 0.2, a weak ferromagnetic behavior (WFM) below 14 K is observed.

Structural, surface electronic bonding, optical, and mechanical features of sputtering deposited CrNiN coatings with Si and Al additives

Herein, the closed field unbalanced magnetron sputtered CrNiN, CrNiSiN, and CrNiAlN coatings are studied to gain insights into their structural, morphological, optical, and mechanical properties. Detailed characterizations of the thin films have been carried out through X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible–near infrared (UV–Vis) spectroscopy, nanoindentation, finite element modeling (FEM), and water contact angle measurements. XRD confirmed the hexagonal close-packed hcp-Cr2N (211) phase and face-centered cubic fcc-CrN (200) phase. The SEM images confirmed the compact, dense, and uniform distribution of gains in the coating structures. The average crystallite size of CrNiN coatings was 515 nm. The addition of substituents (Si and Al) to the CrNiN coatings resulted in increasing the crystallite sizes to 605 nm (for CrNiSiN) and 811 nm (for CrNiAlN) as well as grain size from 1.32 to 2.335 μm. XPS analysis was conducted to estimate the atomic constituents and measure the high-resolution XPS spectra of Ni2p photoelectron lines. The elastic modulus and hardness of the coatings are between 361 and 459 GPa, and 23.1–26.8 GPa, respectively. The Si, and Al additions enhanced both Young's modulus and the hardness of the coatings. Results of FEM modeling demonstrated the stress distribution within the coatings on steel and silicon substrates at different film thicknesses. The maximum stress level was increased by 30% at the coatings' upper portion, while that of the interface was reduced by 60%. The water contact angle values lay within the range of 102.4°–112.4°.

Hydroxyapatite and lead-substituted hydroxyapatite near-surface structures: Novel modelling of photoemission lines from X-ray photoelectron spectra

X-ray photoelectron spectroscopy (XPS) is one of the main tools for hydroxyapatite (HA) surface characterization in developing materials for biomedical and heterogeneous catalysis. Despite the XPS technique's potential to correlate binding energies with existing photo-emitter sites on near-surfaces, few previous studies analyzed this aspect for HA and metal-substituted HA surfaces. In this work, we theoretically reconstructed the XPS spectra of stoichiometric HA and lead-substituted hydroxyapatite (PbCaHA, Ca10-xPbx(PO4)6(OH)2; x = 2, 10) using a first-principles linear combination of atomic orbitals embedded cluster approach and periodic supercell band structures within the framework of Density Functional Theory (DFT). We take into account photoemission lines contributions from Ca(1), Ca(2), Pb(1) and Pb(2) sites located on surface and near-surface depths (up to ∼15 Å) along the (001) and (100) surfaces. The calculated DFT spectra of HA and PbCaHA were compared with high-resolution XPS spectra previously characterized by synchrotron X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS). A combined theoretical and experimental approach enables decoding of the complex structure of HA and PbCaHA in XPS spectra. It was found that XPS binding energies profiles depend significantly on photo-emitters from near-surface sites and surface crystallographic orientation. The main Ca 2p3/2 envelope peak in HA is predominantly from Ca(1) and Ca(2) sites (∼347.4 eV), while the weaker peak is due to the Ca(2) site only (∼345.0 eV). Variations on HA nanoparticle morphology could be a critical factor for changes in XPS binding energies' profile.

Intermediate Cu-O-Si Phase in the Cu-SiO2/Si(111) System: Growth, Elemental, and Electrical Studies.

We investigate here the strain-induced growth of Cu at 600 °C and its interactions with a thermally grown, 270 nm-thick SiO2 layer on the Si(111) substrate. Our results show clear evidence of triangular voids and formation of triangular islands on the surface via a void-filling mechanism upon Cu deposition, even on a 270 nm-thick dielectric. Different coordination states, oxidation numbers, and chemical compositions of the Cu-grown film are estimated from the core level X-ray photoelectron spectroscopy (XPS) measurements. We find evidence of different compound phases including an intermediate mixed-state of Cu–O–Si at the interface. Emergence of a mixed Cu–O–Si intermediate state is attributed to the new chemical states of Cux+, Ox, and Six+ observed in the high-resolution XPS spectra. This intermediate state, which is supposed to be highly catalytic, is found in the sample with a concentration as high as ∼41%. Within the Cu–O–Si phase, the atomic percentages of Cu, O, and Si are ∼1, ∼86, and ∼13%, respectively. The electrical measurements carried out on the sample reveal different resistive channels across the film and an overall n-type semiconducting nature with a sheet resistance of the order of 106 Ω.

2-Phenylimidazole Corrosion Inhibitor on Copper: An XPS and ToF-SIMS Surface Analytical Study

This work presents a surface analytical study of the corrosion inhibitor 2-phenylimidazole (2PhI) adsorbed on a Cu surface from 3 wt.% NaCl solution. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to investigate the surface phenomena. Various XPS experiments were performed, i.e., survey- and angle-resolved high-resolution XPS spectra measurements, gas cluster ion beam sputtering in conjunction with XPS measurements, and XPS imaging in conjunction with principal component analysis. These measurements were used to detail the composition of the surface layer at depth. In addition, various ToF-SIMS experiments were performed, such as positive ion ToF-SIMS spectral measurements, ToF-SIMS imaging, and cooling/heating in conjunction with ToF-SIMS measurements. This study shows that organometallic complexes were formed between 2PhI molecules and Cu ions, that the surface layer contained entrapped NaCl, that the surface layer contained some Cu(II) species (but the majority of species were Cu(I)-containing species), that the surface was almost completely covered with a combination of 2PhI molecules and organometallic complex, and that the temperature stability of these species increases when 2PhI is included in the organometallic complex.

Atomically Dispersed Manganese Lewis Acid Sites Catalyze Electrohydrogenation of Nitrogen to Ammonia

Atomically Dispersed Manganese Lewis Acid Sites Catalyze Electrohydrogenation of Nitrogen to Ammonia

Rare-Earth Doping Graphitic Carbon Nitride Endows Distinctive Multiple Emissions with Large Stokes Shifts

Rare-Earth Doping Graphitic Carbon Nitride Endows Distinctive Multiple Emissions with Large Stokes Shifts