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The transformation of 2 ¯ 01 β - Ga 2 O 3 to h- GaN under exposure to RF nitrogen plasma was monitored in situ by reflection high-energy electron diffraction. Analysis of the reaction kinetics reveals that the nitridation process is initiated by the formation of an oxynitride phase and proceeds via two-dimensional nucleation and growth of wurtzite GaN grains. X-ray photoelectron spectra suggest a Ga − (N x O 1 − x) type configuration dominates the surface early in the nitridation process. The surface restructuring is followed by a diffusion-fed phase transformation, which propagates the wurzite GaN structure into the substrate upon reaching 70 % nitrogen anion site occupation, corresponding to the oxygen solubility in h - GaN. A direct correlation is observed between the nitridated film morphology and the epitaxial film crystallinity, demonstrating control of the residual strain, lateral coherence, and mosaicity in subsequent GaN epitaxy by the nitridation conditions. This study provides mechanistic details of the nitridation reaction of 2 ¯ 01 β - Ga 2 O 3 facilitating the optimization of the nitridation process toward improving GaN - 2 ¯ 01 β - Ga 2 O 3 heterojunctions. [ABSTRACT FROM AUTHOR]

We present a comprehensive, combined experimental and theoretical study of the core-level photoelectron and near-edge x-ray absorption fine structure (NEXAFS) spectra of 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil at the oxygen 1s, nitrogen 1s, carbon 1s, and the sulfur 2s and 2p edges. X-ray photoelectron spectra were calculated using equation-of-motion coupled-cluster theory (EOM-CCSD), and NEXAFS spectra were calculated using algebraic diagrammatic construction and EOM-CCSD. For the main peaks at O and N 1s as well as the S 2s edge, we find a single photoline. The S 2p spectra show a spin–orbit splitting of 1.2 eV with an asymmetric vibrational line shape. We also resolve the correlation satellites of these photolines. For the carbon 1s photoelectrons, we observe a splitting on the eV scale, which we can unanimously attribute to specific sites. In the NEXAFS spectra, we see very isolated pre-edge features at the oxygen 1s edge; the nitrogen edge, however, is very complex, in contrast to the XPS findings. The C 1s edge NEXAFS spectrum shows site-specific splitting. The sulfur 2s and 2p spectra are dominated by two strong pre-edge transitions. The S 2p spectra show again the spin–orbit splitting of 1.2 eV. [ABSTRACT FROM AUTHOR]

By manipulating the work function, the dissipation of thermal energy on the material surface can be regulated through Electron Transpiration Cooling (ETC) mechanism. The doping of rare-earth oxide serves as an effective approach for reducing the work function, whereas there is still a lack of comprehensive research into the microstructural morphology of the rare-earth oxides and their correlations with the modifications of the work functions. This study investigates the detailed microscopical structure of Gd 2 O 3 in the ultrahigh-temperature ceramic system (ZrB 2 -20 vol%SiC). Semi-quantitative composition analyses based on X-ray photoelectron spectra indicate that an increased doping concentration of Gd 2 O 3 is beneficial for the formation of a single solid-state Gd 0.18 Zr 0.82 O 1.91 phase of ZrB 2 -SiC system. Atomic-scale scanning transmission electron microscopy (STEM) analyses suggest that Gd 2 O 3 is enriched at the interfaces between SiC and ZrB 2 matrix with a nanoscale fibrous morphology composed of alternated Gd 2 O 3 crystals and pores, rendering a continuous microstructure throughout the entire system. This peculiar microstructural morphology is anticipated to facilitate its diffusion along the grain boundary and the formation of Gd 2 O 3 nanolayers at the surface region below the melting points of the ceramic matrix, which can efficiently lower the material work function and reduce the emission energy of the surface electrons during thermal emission through ETC mechanism. The composite with 10 vol% Gd 2 O 3 induces a reduction of the averaged work function of ∼0.49 eV before preforming the thermionic emission experiments. Our results provide valuable insights into the impacts of rare-earth oxide on the ZrB 2 -SiC matrix, as well as shed light on the feasibility of the ETC mechanism through the efficient design of thermal protection materials. [ABSTRACT FROM AUTHOR]

A series of Lu 2(1- x) Tb 2 x (WO 4) 3 (x = 0.00–1.00) white powder materials were prepared by a high-temperature solid-phase method. The crystal structure, microscopic morphology, elemental composition, bandgap energy, photoluminescence properties, and thermal stability of luminescence of the prepared materials were analyzed and studied through room and high temperature X-ray diffraction patterns, field emission scanning electron microscopy images, energy energy-dispersive spectra and X-ray photoelectron spectra, diffuse reflectance spectra, room and high temperature photoluminescence spectra. Under 260 nm excitation, the green emitting Lu 2(1- x) Tb 2 x (WO 4) 3 samples exhibited an optimum Tb3+ doping concentration at x = 0.30. Calculated results illustrate that the concentration quenching was mainly caused by dipole-dipole interaction. Lu 1.98 Tb 0.02 (WO 4) 3 phosphor exhibited thermally enhanced luminescence at 120 °C, with a maximum luminescence intensity of 254 % of the initial room temperature intensity. Lu 1.4 Tb 0.6 (WO 4) 3 phosphor exhibited thermally enhanced luminescence at 150 °C, with a maximum luminescence intensity of 109 % of the initial room temperature intensity. The mechanism of the thermally enhanced luminescence phenomenon is further discussed to be the adsorbed crystal water and the negative thermal expansion of the material. Thermally enhanced luminescence is of great significance in overcoming luminescent thermal quenching phenomenon, improving the luminescence efficiency, optimizing the material design, and so forth. It has potential applications in high-temperature lighting, display technology, temperature sensing, and optical anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Cu/Mo codoped NiO semiconductors exhibited a visible light efficient photo-removal performance for diclofenac sodium and methylene blue waste. A simple and low-cost methodology was used to synthesize NiO, Ni0.95Cu0.03Co0.02O, and Ni0.95Cu0.03Mo0.02O nanocatalysts. The crystal structure verified the formation of a cubic NiO single phase. The scanning electron microscopy (SEM) micrographs of all samples have shown a homogenous spherical particle distribution. The harvesting of visible light from NiO semiconductors was significantly enhanced after the addition of Cu/Co and Cu/Mo ions. The X-ray photoelectron spectra confirmed that Cu dopant has a +2-oxidation state while Mo dopant has +3 and +4 as mixed oxidation states. Ni0.95Cu0.03Co0.02O and Ni0.95Cu0.03Mo0.02O have shown high dielectric constant values at low frequencies. For purification of wastewater, the visible light photocatalytic efficiencies of Cu/Mo codoped NiO catalyst for the removal of 20 mg/L methylene blue (MB) and 20 mg/L diclofenac sodium (DS) were 98 and 95% after 50 min, respectively. The MB and DS molecules were converted to CO2 and H2O as confirmed by total organic carbon and chemical oxygen demand analyses. Besides, this nanocatalyst showed a high reusability for MB and DS pollutants until four cycles. [ABSTRACT FROM AUTHOR]

The present work emphases on the post-mortem study of silica/carbon composite as functional anode in Li-ion batteries (LIBs). Herein, the silica/carbon composite is synthesized by facile in-situ hydrothermal technique. The x-ray diffraction (XRD) pattern indicates the amorphous nature of silica/carbon composite. The stacked sheet-like morphology of silica/carbon composite is seen in the high-resolution transmission electron microscopy (HR-TEM) & scanning electron microscopy (SEM) images. In addition, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy dispersive x-ray analysis (EDAX), and x-ray photoelectron spectra (XPS) characterizations of silica/carbon composite has been studied in detail. The rate capability of silica/carbon composite anode in LIB indicates 99% capacity retention after applying current density ranging from 50 mA g−1 to 1000 mA g−1, successively. The composite anode delivers a stable specific capacity ∼300 mAh g−1 at a current density of 100 mA g−1 for 500 cycles. Electrochemical impedance spectroscopy (EIS) study analyzed the faster Li-ion diffusion and increment in the diffusion coefficient by a factor of 1000 after 500 cycles. To the best of our knowledge, this is the first work on the post-mortem study of silica/carbon composite as anode in LIB. Post-cycling characterizations including XRD, FTIR, and SEM reveal the absence of any impurity phases and negligible volumetric expansion after prolonged cycling. It further confirms that the carbon present in the silica/carbon composite helps to accommodate the volumetric expansion of silica and prevents cracking of the anode over 500 cycles. [ABSTRACT FROM AUTHOR]

This study compares the surface patina of ancient tin rich bronze with pure hydrothermally synthesized SnO2 nanoparticles using various analytical techniques, including metallographic microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy. The primary crystalline component of the patina consists of approximately 5 nm SnO2 nanoparticles, which closely resemble pure SnO2, indicating their comparability. Cu was also detected in the patina; however, it did not form crystalline structures. The X-ray diffraction results showed a shift in the patina's peak, suggesting the infiltration of Cu into the SnO2 lattice, which compromises its crystallinity. In comparison to synthetic SnO2, the X-ray photoelectron spectroscopy spectra of the patina revealed novel peaks corresponding to both Cu and O, indicating the presence of Cu−O−Sn bonding—a characteristic feature of type-I patina. This suggests that the primary structure of type-I patina consists of crystalline SnO2 nanoparticles, with a limited amount of Cu integrated into its lattice configuration. The concentration of Cu within the SnO2 crystal units is restricted, leading primarily to the formation of amorphous Cu2O in conjunction with Sn. The presence of Sn enhances the structural stability of Cu2O, facilitating its incorporation while inhibiting the crystallization of Cu2O. However, when the Sn concentration is insufficient, an inadequate Cu–O−Sn amorphous phase may form, allowing for the potential crystallization of Cu2O. [ABSTRACT FROM AUTHOR]

Fe(III) oxides were prepared as free nanoparticles and on DNA templates via the precipitation of Fe(III) salts with NaOH in the presence/absence of DNA. Through control of the pH and temperature, FeOOH and Fe2O3 were synthesised. The formation of templated materials FeOOH/DNA and Fe2O3/DNA was confirmed using UV-Vis absorption and FTIR spectra. The direct optical gap of Fe2O3/DNA was estimated as 3.2 eV; the absorption by FeOOH/DNA and Fe2O3/DNA at longer wavelengths is weaker, but consistent with indirect gaps near 2 eV. X-ray photoelectron spectra confirmed the presence of Fe(III) and DNA in the templated samples. Analysis of the X-ray diffraction patterns of both templated and non-templated FeOOH and Fe2O3 demonstrated that the materials were the α-FeOOH and α-Fe2O3 polymorphs with crystallite diameters of the DNA-templated materials estimated as 7.6 nm and 6.8 nm. Transmission electron microscopy showed needle-like crystals of both FeOOH and Fe2O3, but the Fe2O3 contains some globular structures. In contrast, the morphology of FeOOH/DNA and Fe2O3/DNA consists of needle-like crystallites of the respective oxides organised into complex dendritic structures with a length on the 10 μm scale formed by the DNA molecules. Finally, scanned conductance microscopy provided evidence for the conductivity of the FeOOH/DNA after alignment via molecular combing on an Si/SiO2 substrate. Fe2O3/DNA did not exhibit any detectable conductivity. [ABSTRACT FROM AUTHOR]

A series of Zr4+-Co2+ substituted U-type hexaferrites (Ba 4 Zn 2 Fe 36-2x Zr x Co x O 60 (0.0 ≤ x ≤ 1.0, having Δx = 0.25)) were synthesized via sol-gel auto-combustion method. The samples were sintered at 1200 ° C for 6 h. The impact of Zr–Co substitution on phase, structure, morphology, and dielectric behavior were investigated through XRD, FTIR, SEM, XPS and VNA. XRD studies shows that the U-type hexaferrite phase has been developed and the increase in lattice constants (a & c), cell volume, c/a ratio, and percentage porosity was observed. Sample with x = 0.25 exhibited the smallest crystallite size (34.5 nm). The existence of signature metal-oxygen vibrational bands for hexaferrites was observed by FTIR spectra. SEM analysis reflects that the substitution produces a significant effect on morphology and grain size of the samples. X-ray photoelectron spectra (XPS) of sample x = 1.0 confirmed the chemical and elemental composition. The dielectric constant, dielectric loss, and ac conductivity increases with increasing frequency and decreases with Zr–Co substitution. The lowest reflection loss of R L = −64.5 dB (with MW absorption >99.9 %) was observed for the composition x = 0.5 with pellet thickness of 1.73 mm at 1.05 GHz frequency. Due to the improved bandwidth and better absorption, these hexaferrites can be used in microwave and high frequency applications. [ABSTRACT FROM AUTHOR]

Diamond films possess numerous extraordinary physical and chemical properties, but their high-temperature applications are limited by its poor thermal stability. Herein, we fabricated the undoped microcrystalline diamond (MCD) film and heavy boron-doped diamond (h-BDD-1, 2.94 × 1021 atoms·cm−3; h-BDD-2, 9.10 × 1021 atoms·cm−3) films to investigate the effect of boron doping on the thermal stability of diamond films. A series of evidences, including air annealing experiments, thermogravimetric-differential scanning calorimetry (TG-DSC) analysis, and in-situ ultra-high-temperature confocal laser-scanning microscope (CLSM), demonstrated that the thermal stability of diamond films was obviously enhanced by boron doping. Consequently, the h-BDD-2 film exhibited the best thermal stability with an initial oxidation temperature above 900 °C, which was much higher than that of MCD film (709 °C). By deconvolving the X-ray photoelectron spectra, we believed that the transition of B–C bonds to stable oxy-boron carbide complexes (B 4 O–C, B 3 O–C) is the key to improving the thermal stability. These results not only reveal a new antioxidant mechanism of boron-doped diamond films but also pave a way for the application of diamond in high-temperature environments. [ABSTRACT FROM AUTHOR]

The electronic structure of NoO2 and the valence-band X-ray photoelectron spectrum (XPS) in the energy range from 0 eV to ~40 eV are calculated by the relativistic discrete variation method. Significant covalency effects are observed in NoO2, which are due to a considerable overlap of not only No 6d AO but also No 6p and No 5f AOs with oxygen orbitals. The MO histogram and scheme are derived, which enable the comprehension of features of the chemical bond nature and the structure of the XPS spectrum of valence electrons in NoO2. [ABSTRACT FROM AUTHOR]

The surface recrystallization model of the fully amorphized C3H5-molecular-ion-implanted silicon (Si) substrate is investigated. Transmission electron microscopy is performed to observe the amorphous/crystalline interface near the C3H5-molecular-ion-implanted Si substrate surface after the subsequent recovery thermal annealing treatment. At a depth of high-concentration carbon of approximately 4.8 × 1020 atoms/cm3, recrystallization from the crystalline template to the surface by solid-phase epitaxial growth is partially delayed, and the activation energy was estimated to be 2.79 ± 0.14 eV. The change in the crystalline fraction of the fully amorphized C3H5-molecular-ion-implanted Si substrate surface is quantitatively evaluated from the binding energy of Si 2p spectra by X-ray photoelectron spectroscopy. Using the Kolmogorov–Johnson–Mehl–Avrami equation, the surface recrystallization of the fully amorphized C3H5-molecular-ion-implanted Si substrate is assumed to proceed two-dimensionally, and its activation energy is obtained as 2.71 ± 0.28 eV without the effect of carbon. Technology computer-aided design (TCAD) process simulations calculate recrystallization under the effect of high-concentration carbon and demonstrate the reach of some crystalline regions to the surface first. In the fully amorphized C3H5-molecular-ion-implanted Si substrate, it is considered that recrystallization is partially delayed due to high-concentration carbon and surface recrystallization proceeds two-dimensionally from some crystalline regions reaching the surface first. [ABSTRACT FROM AUTHOR]

The electronic structure of NoO2 and the valence-band X-ray photoelectron spectrum (XPS) in the energy range from 0 eV to ~40 eV are calculated by the relativistic discrete variation method. Significant covalency effects are observed in NoO2, which are due to a considerable overlap of not only No 6d AO but also No 6p and No 5f AOs with oxygen orbitals. The MO histogram and scheme are derived, which enable the comprehension of features of the chemical bond nature and the structure of the XPS spectrum of valence electrons in NoO2. [ABSTRACT FROM AUTHOR]

In order to improve dispersibility, polymerization characteristics, chemical stability, and magnetic flocculation performance, magnetic Fe3O4 is often assembled with multifarious polymers to realize a functionalization process. Herein, a typical three-dimensional configuration of hyperbranched amino acid polymer (HAAP) was employed to assemble it with Fe3O4, in which we obtained three-dimensional hyperbranched magnetic amino acid composites (Fe3O4@HAAP). The characterization of the Fe3O4@HAAP composites was analyzed, for instance, their size, morphology, structure, configuration, chemical composition, charged characteristics, and magnetic properties. The magnetic flocculation of kaolin suspensions was conducted under different Fe3O4@HAAP dosages, pHs, and kaolin concentrations. The embedded assembly of HAAP with Fe3O4 was constructed by the N–O bond according to an X-ray photoelectron energy spectrum (XPS) analysis. The characteristic peaks of –OH (3420 cm−1), C=O (1728 cm−1), Fe–O (563 cm−1), and N–H (1622 cm−1) were observed in the Fourier transform infrared spectrometer (FTIR) spectra of Fe3O4@HAAP successfully. In a field emission scanning electron microscope (FE-SEM) observation, Fe3O4@HAAP exhibited a lotus-leaf-like morphological structure. A vibrating sample magnetometer (VSM) showed that Fe3O4@HAAP had a relatively low magnetization (Ms) and magnetic induction (Mr); nevertheless, the ferromagnetic Fe3O4@HAAP could also quickly respond to an external magnetic field. The isoelectric point of Fe3O4@HAAP was at 8.5. Fe3O4@HAAP could not only achieve a 98.5% removal efficiency of kaolin suspensions, but could also overcome the obstacles induced by high-concentration suspensions (4500 NTU), high pHs, and low fields. The results showed that the magnetic flocculation of kaolin with Fe3O4@HAAP was a rapid process with a 91.96% removal efficiency at 0.25 h. In an interaction energy analysis, both the UDLVO and UEDLVO showed electrostatic repulsion between the kaolin particles in the condition of a flocculation distance of <30 nm, and this changed to electrostatic attraction when the separation distance was >30 nm. As Fe3O4@ HAAP was employed, kaolin particles could cross the energy barrier more easily; thus, the fine flocs and particles were destabilized and aggregated further. Rapid magnetic separation was realized under the action of an external magnetic field. [ABSTRACT FROM AUTHOR]

In this paper, a porous zirconium‐based metal–organic framework (NH2‐UiO‐66) and functionalized carbon black (FCB) composite was prepared through a one‐pot hydrothermal method, and a novel electrochemical sensor based on NH2‐UiO‐66@FCB modified glassy carbon electrode (NH2‐UIO‐66@FCB/GCE) was developed for the simultaneous sensoring of butylhydroxyanisole (BHA) and tert‐butylhydroquinone (TBHQ). The morphology and structure of NH2‐UiO‐66@FCB were characterized through scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectrum. The electrochemical behaviors of the NH2‐UiO‐66@FCB/GCE were investigated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Under optimized experimental conditions, the linear ranges for TBHQ and BHA detection were determined to be 0.12–460 μM and 0.7–420 μM, respectively, with their corresponding detection limits of 0.072 μM and 0.29 μM. Furthermore, the sensor exhibited excellent selectivity, repeatability and stability, and successfully used for the simultaneous detection of TBHQ and BHA in food samples. [ABSTRACT FROM AUTHOR]

To further improve the sealing effect of electrochemical polarization (EP) on the CrN coatings, the EP treatment at different cycle numbers was conducted. The microstructure, mechanical, and tribological properties of CrN coatings were investigated. Findings indicated an elevation in oxygen content from 6.32% to 12.35% with increasing cycle number from 10 to 60 times, yet the crystal structure of CrN (111) and CrN (200) persisted. The X-ray photoelectron spectrum (XPS) and transmission electron microscope (TEM) revealed that a minimal quantity of oxides was produced. This led to a decrease in the coatings porosity from 16.79% to 5.83%. For this reason, the hardness of CrN coatings increased with a maximum degree of 18.3%, whilst the wear rate decreased with a maximum degree of 37.5% at the cycle number of 20 times. [ABSTRACT FROM AUTHOR]

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Gallium oxide (β-Ga2O3) is a well-known extra-wide bandgap semiconductor and one of the promising materials used for power photoelectric devices, gas sensors, catalytic agents, etc. This work presents the suppression of self-trapped holes (STHs) and increase of oxygen vacancies (VO) in β-Ga2O3 microspindles by doping of Zn ions as well as the electrocatalytic activity of these microspindles. Undoped and Zn-doped β-Ga2O3 microspindles were prepared by a hydrothermal method followed by high-temperature calcination. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results show that the morphology and structure of the samples did not change after low dose of Zn doping. The analyses of temperature-dependent photoluminescence (PL) spectra and X-ray photoelectron spectroscopy (XPS) indicate that incorporation of divalent Zn ions as deep acceptors can increase VO concentration and effectively suppress the formation of STHs. Enhanced electrocatalytic activity was observed in Zn-doped β-Ga2O3 microspindles compared with undoped β-Ga2O3 microspindles. The new active sites introduced by Zn doping, higher VO concentration, and suppressed STHs are believed to be responsible for the enhanced electrocatalytic performance of Zn-doped β-Ga2O3 microspindles. This work is expected to expand the application of β-Ga2O3 based microstructures in electrocatalysis and provide innovative ideas for energy and environmental issues. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) are an interesting nanomaterial due to their tunable photoluminescence and other functional properties. Herein, by introducing amine‐functionalized CDs nanoparticles onto macromolecular chains of maleic anhydride grafted styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MA) via a possible ring‐opening reaction of anhydride with amine, a mechanically robust and ultrastretchable thermoplastic elastomeric materials with fluorescence and dielectric functionality was developed. The amine‐functionalized CDs nanoparticles were synthesized from pyrene precursor by hydrothermal treatment. The transmission electron micrograph, Raman, Fourier transform infrared, and x‐ray photoelectron spectra confirmed the formation of highly crystalline graphitized structure of the CDs nanoparticles. Fluorescence and UV–Vis spectroscopy were used to evaluate the optical properties of the developed materials. The developed CDs/SEBS‐g‐MA nanocomposites exhibited strong intense green fluorescence compared with the pure SEBS‐g‐MA film. The thermal stability of the developed nanocomposites was improved by an increase of the Tmax by about 18°C. In addition, the developed composite showed high stretchability (strain at break ~1000%), good mechanical strength, and dielectric properties (room temperature dielectric constant ~5.2). The enhanced dielectric property of the developed composites may be due to the space charge accumulation and induced interfacial polarization at the filler–matrix interface. [ABSTRACT FROM AUTHOR]

NaBH4 is an attractive candidate for closed-loop hydrogen generation in small practical applications owing to its ambient condition hydrogen release mechanism, non-toxic byproduct, ability to regenerate, and stability at ambient conditions. The hydrolysis of NaBH4 requires a catalyst to accelerate the hydrogen generation process and cobalt oxide is one such promising catalyst in this reaction. The surface species and crystalline phases of cobalt oxide catalysts play an important role in determining the hydrogen generation rate and overall hydrolysis process. In this study, cobalt oxide nanoparticles are synthesized by a thermal plasma route. The two crystalline phases, namely c-CoO and Co3O4, are tuned using thermal plasma operating conditions. The catalysts so obtained have been thoroughly characterized using analytical techniques like XRD, XPS, HR-TEM, etc. Furthermore, the catalyst was used for hydrogen production in the hydrolysis process of NaBH4. The ex situ X-ray photoelectron spectra recorded at different stages of the hydrolysis process have been extensively used to understand surface modifications occurring at the surface of the catalyst. The Co+3/Co+2 ratio and attachment of other species during hydrolysis analyzed using XPS are correlated with the overall hydrolysis reaction before and after catalysis. It was concluded that the presence of the c-CoO (i.e. initial Co+2 species presence) phase brings stability to hydrogen production in that cycle. [ABSTRACT FROM AUTHOR]

NaBH4 is an attractive candidate for closed-loop hydrogen generation in small practical applications owing to its ambient condition hydrogen release mechanism, non-toxic byproduct, ability to regenerate, and stability at ambient conditions. The hydrolysis of NaBH4 requires a catalyst to accelerate the hydrogen generation process and cobalt oxide is one such promising catalyst in this reaction. The surface species and crystalline phases of cobalt oxide catalysts play an important role in determining the hydrogen generation rate and overall hydrolysis process. In this study, cobalt oxide nanoparticles are synthesized by a thermal plasma route. The two crystalline phases, namely c-CoO and Co3O4, are tuned using thermal plasma operating conditions. The catalysts so obtained have been thoroughly characterized using analytical techniques like XRD, XPS, HR-TEM, etc. Furthermore, the catalyst was used for hydrogen production in the hydrolysis process of NaBH4. The ex situ X-ray photoelectron spectra recorded at different stages of the hydrolysis process have been extensively used to understand surface modifications occurring at the surface of the catalyst. The Co+3/Co+2 ratio and attachment of other species during hydrolysis analyzed using XPS are correlated with the overall hydrolysis reaction before and after catalysis. It was concluded that the presence of the c-CoO (i.e. initial Co+2 species presence) phase brings stability to hydrogen production in that cycle. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Inspired by a three‐dimensional (3D) structure, we demonstrate 3D aluminum nitride (AlN) nanofibers fabricated by a freeze‐drying technique using polyvinyl alcohol (PVA)/boehmite precursor nanofibers. After applying hot pressing, a series of PVA/boehmite precursor nanofibers were prepared with varying PVA‐to‐boehmite ratios (30/70 wt%, 50/50 wt%, and 70/30 wt%). Our findings reveal that the thermal conductivity of the AlN composite nanofibers is significantly affected by the relative proportions of PVA and boehmite, where the ratio of PVA should be more significant than that of boehmite. We produced AlN nanofibers at a lower temperature (1500°C) than the theoretical formation temperature of AlN (1664°C). The minimum specific surface area and pore volumes were 8.39 m2/g and 0.0166 cm3/g, respectively, at 1500°C. X‐ray photoelectron spectroscopy spectra measured 38.27% aluminum and 23.55% nitrogen in AlN nanofibers. The aligned AlN nanofibers mat was impregnated with polyurethane (PU), which showed good thermal conductivity in the planar (4.1–13.6 W/(m·K)) and thickness (1.5–4.9 W/(m·K)) directions at 18–56 vol% AlN nanofibers content. The heat‐dissipating sheet also showed superior electrical insulating (1.2 × 1012 Ω/cm2) properties. In this study, the author sought to develop a heat‐spreading material made of thermally conductive, but electrically insulating PU/AlN nanofibers that could efficiently dissipate heat from electric devices. [ABSTRACT FROM AUTHOR]

The effect of niobium ion implantation on the surface and scratch properties of a WC-5wt.%Ni cold sprayed coating was investigated with accelerating energies of 60 and 170 keV and fluences of 5 × 1016 and 8 × 1016 ions cm−2, respectively. High-resolution Rutherford backscattering spectroscopy spectra revealed that Ni-Nb and WC-Nb amorphous layers had likely formed. Using ion implantation parameters of 60 keV with a fluence of 8 × 1016 ions cm-2 (coating 608-NB), higher Nb peak intensities were found. Oxide formation in the form of NbO, NbO2, and Nb2O5 was detected with high-resolution x-ray photoelectron spectroscopy spectra analyses on the 608-NB coating, in conjunction with the intermetallic, thereby having the best coating properties: higher hardness, low roughness, and scratch properties compared to the other ion-doped samples. The failure mechanisms of all the coatings were found to be similar, showing angular cracks, cone cracking, and primary delamination. [ABSTRACT FROM AUTHOR]

In this work, conventional sintering, hot-pressing sintering, and spark plasma sintering techniques were utilized to simulate the thermal field, thermal-stress field, and thermal-stress-electric field, respectively. The effects of these fields on the microstructure and cation distribution of the (Mg 0.1 Mn 0.1 Co 0.1 Ni 0.2 Ti 0.1 Cu 0.1 Zn 0.2)Fe 2.1 O 4 ferrite (HEF) material were comprehensively analyzed. The results indicate that in the temperature range of 1000–1100 °C, the thermal field provides the driving force for sintering, promotes grain growth (average particle size: 2→7 μm), and increases crystallinity degree. The stress field brings the particles into close contact with each other, facilitates diffusion, and delays grain growth (0.5→5 μm). The electric field reduces grain boundary energy, causes mass transfer, and makes the grains finer (0.5→0.7 μm) and more uniform. Mathematical model analysis reveals that the thermal field is beneficial to the random distribution of cations, which yields an inversion degree (γ) of about 2/3 and increases the configuration entropy of HEF. The stress field leads to lattice distortion, permits ions with larger radius to occupy tetrahedral positions, and changes the cell parameters and oxygen position parameter of HEF. Finally, the interaction between electric field and crystal charges increases the electrostatic field energy, which promotes the formation of positive spinel structure and maximizes the crystal field stability energy. X-ray photoelectron spectra, Raman spectra, and change in lattice constant confirm the rationality of the mathematical model, and can be used to establish the model of the crystal structure under field effects. [ABSTRACT FROM AUTHOR]

We evaluated the effect of O atoms on the postannealed BaSi2 films grown by molecular beam epitaxy. Postannealing (PA) in an Ar atmosphere at a pressure of 1.9 × 105 Pa increased the O concentration to 7 × 1020 cm−3 in the bulk region and further increased to ∼1022 cm−3 at the BaSi2/Si interface. Cracks formed during the PA process, allowing O to enter more easily to the BaSi2 films. In the x-ray photoelectron spectroscopy spectrum of the Si 2s core level measured at 10 nm from the surface, a shift of the peak related to SiOx was detected, indicating a change in the bonding state of Si and O in this region. When PA was performed in vacuum at 10−3 Pa, the photoresponsivity in the short wavelength region was enhanced, with a maximum value of 6.6 A W−1 at 790 nm. The O concentration in the film decreased in the sample annealed in vacuum, and the PL peak intensity at 0.85 eV decreased, suggesting that this was due to a decrease in O-related defects compared to the Ar atmosphere. However, agglomeration of BaSi2 caused significant surface roughness, indicating the importance of PA conditions that minimize O uptake and keep the surface smooth for improved performance of BaSi2 solar cells. [ABSTRACT FROM AUTHOR]

It is usually difficult to realize high mobility together with a low threshold voltage and good stability for amorphous oxide thin-film transistors (TFTs). In addition, a low fabrication temperature is preferred in terms of enhancing compatibility with the back end of line of the device. In this study, α-IGZO TFTs were prepared by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The channel was prepared under a two-step deposition pressure process to modulate its electrical properties. X-ray photoelectron spectra revealed that the front-channel has a lower Ga content and a higher oxygen vacancy concentration than the back-channel. This process has the advantage of balancing high mobility and a low threshold voltage of the TFT when compared with a conventional homogeneous channel. It also has a simpler fabrication process than that of a dual active layer comprising heterogeneous materials. The HiPIMS process has the advantage of being a low temperature process for oxide TFTs. [ABSTRACT FROM AUTHOR]

First‐principles calculations on titania clusters (TiO2)n (n=5 and 10) supported on the pristine Ti2C (0001) surface were carried out to understand the properties of semiconductor/MXene composites with implications in (photo)‐catalysis. The reported results reveal a high exothermic interaction accompanied by a substantial charge transfer with a concomitant, notorious, deformation of the titania nanoclusters. The analysis of the density of states analysis of the composite systems evidences a metallic character with titania related states crossing the Fermi level. The picture of the chemical bonds is completed by the analysis of X‐Ray Photoelectron Spectra (XPS) features, evidencing clear shifts of the C(1s) and O(1s) related peaks relative to the isolated systems that have a quite complex origin. This detailed analysis provides insights to experimentalists interested in the design and synthesis of these systems with possible applications in catalysis. [ABSTRACT FROM AUTHOR]

Thermochemical models of detonation are widely used to estimate energy delivery, but they are based on the assumption that the carbon-rich condensates (soot) formed during detonation are very similar to bulk carbon. We present an analytic equation of state (EOS) based on experimental detonation data for soot formed during the detonation of triaminotrinitrobenzene (TATB)-based high explosives. X-ray photoelectron spectra of several detonation soots are used to determine the elemental nitrogen abundance, with surprisingly high values for TATB. The proposed TATB soot EOS is highly compressible at low pressures and shares some features of glassy carbon, exhibiting graphite- and diamond-like behavior as a function of pressure. We demonstrate the influence of formed soot on detonation performance, including a lowering of the detonation velocity at typical charge densities, and a more compressive product Hugoniot at overdriven conditions. The soot model improves the accuracy of thermochemical calculations for TATB-based explosives across a wide range of states. Detonation velocity predictions for HMX (cyclotetramethylene-tetranitramine)-TATB blends with 80% or more TATB content, as well predictions for 1,3-diamino-2,4,6-trinitrobenzene (DATB) and 3-nitro-1,2,4-triazol-5-one (NTO), which share some features with TATB, are also improved. [ABSTRACT FROM AUTHOR]

High performance wide bandgap perovskite solar cells (WB-PSCs) have found widespread applications in tandem solar cells. In WB-PSCs, achieving a high conversion efficiency relies on the effective utilization of light absorption and minimization of electronic defects. In this work, electronic defects at the surface and grain boundaries of perovskite materials have been passivated by n-butylammonium bromide (BABr) to suppress carrier non-radiative recombination. Confirmed through x-ray powder diffraction and x-ray photoelectron spectroscopy spectra, ultra-thin two-dimensional (2D) perovskite layers were successfully generated on a perovskite surface. The BABr-treated devices exhibited an increased fill factor and open circuit voltage (VOC) compared to the references. Furthermore, a nanotextured electrode with a roughness of 22.98 nm was employed to trap light. The nanotextured buried interface not only promoted light utilization but also alleviated residual stress and micro-strain in the perovskite film compared to the smooth substrate. Finally, the champion WB-PSC achieved a power conversion efficiency of 20.46% in the reverse scan. These findings pave a promising path for the development of solution-processed perovskite films on nanotextured silicon substrates to improve the performance of monolithic tandem solar cells. [ABSTRACT FROM AUTHOR]

The convolution of two physical entities, denoted as f and g, delineates the manner in which one entity undergoes modification in response to the other. This transformative process is mathematically represented by the expression f ⨂ g, symbolizing the convolution of the two entities in a resultant function h. Frequently, it becomes imperative to comprehend the magnitude of the induced modifications. From the derived function h, a crucial step involves the separation of the two original signals, a process commonly referred to as deconvolution. Various techniques have been proposed to facilitate the calculation of the deconvolution, with one notable approach originating in 1931 by van Cittert. The algorithm, based on an iterative method, has been scrutinized over time, notably by Bracewell and, more recently, by Jansson. This work represents the current state-of-the-art, focusing specifically on the analysis of Auger spectra obtained through XPS. Emphasis is placed on delineating the procedural aspects of the analysis, and the algorithm utilized in the open-source software RxpsG is comprehensively described. [ABSTRACT FROM AUTHOR]

In the presented study, X-ray photoelectron spectroscopy and total reflection X-ray photoelectron spectroscopy methods were applied to analyze the Ti (75 nm) and Pd (100 nm) nanolayers deposited on the Si substrate using magnetron sputtering. The aim of the research was to determine the elemental composition and surface homogeneity of the analyzed nanolayers before their irradiation with highly charged xenon ions and to estimate the detection limit of the X-ray photoelectron spectroscopy technique for various glancing angles. The measurements were conducted using the SPECS mono-XPS system in the Institute of Physics at the Jan Kochanowski University (Kielce, Poland). The experimental setup and measurement conditions for the studied Ti and Pd layers are described. The X-ray photoelectron spectroscopy spectra were registered both for the non-total (35° and 10° angles) and total reflection (2:2° for the Pd nanolayer and 1:5° for the Ti nanolayer) regimes. The position of the C 1s photoelectron peak was applied (C-C component, binding energy 284.8 eV) to calibrate energy. First, the homogeneity of the nanolayers was investigated. The analysis of spectra concentrated on investigating the photoelectron peaks and, consequently, on determining the following: the binding energy of electrons, the intensity and full width at half maximum of photoelectron peaks, the background level, and the elemental composition of the nanolayer surface. In this study, the detection limit of the X-ray photoelectron spectroscopy measurements for different photoelectron peaks was calculated in relation to the excitation angle. An improvement of the X-ray photoelectron spectroscopy detection limit by a factor of 3-6, depending on the type of photoelectron peak, was observed for the angles below the critical angle of the X-ray total reflection phenomenon. [ABSTRACT FROM AUTHOR]

Identification of similar and dissimilar spectra is an important part of analyzing X‐ray photoelectron spectroscopy (XPS) images. Cluster analysis (CA) is a commonly used exploratory data analysis (EDA) method that groups similar spectra in a data set. CA can be performed in either an agglomerative fashion, for example, using Ward's method, which involves successively linking together/clustering the most similar spectra in a data set, or in a divisive fashion, for example, using the K‐means approach, which involves partitioning all the data into a specified number of clusters. In this note, we show the application of CA to an XPS image dataset. The use of Ward's method identified two major clusters in the image, where one of the clusters appeared as two subclusters. The K‐means image based on two clusters agrees well with previous analyses of the same image. The average spectra corresponding to clusters helped confirm the assignments made by the CA algorithms, as did a multivariate curve resolution (MCR) analysis of the interior region identified in our cluster analysis. "Elbow" plots can help determine the number of clusters to keep in K‐means clustering. The combination of the agglomerative and divisive forms of CA, where the first informs the second, can be effective in revealing the structures of XPS image datasets. The Procrustean bed is a metaphor for overfitting and underfitting in EDA. [ABSTRACT FROM AUTHOR]

A Pd–Ni ellipsoidal nano-alloy catalyst with a long diameter of 5 ± 0.1 nm and short diameter of 3 ± 0.1 nm supported on carbon black (PdNi EN/CB) was successfully prepared via a facile one-pot synthesis route. During the synthetic process, cetyl trimethyl ammonium chloride (CTAC) was used as a structure-directing agent, which induced the ellipsoidal morphology. As compared with commercial Pt/C, Pd/C and Pd–Ni catalyst without special morphology supported on carbon black (PdNi NW/CB), PdNi EN/CB demonstrated both ultrahigh catalytic activity towards oxygen reduction reaction (ORR) and favorable long-term durability in alkaline solutions. According to X-ray photoelectron spectra (XPS) analysis and density functional theory (DFT) calculation results, a down-shift of the Pd d-band center, which weakens the adsorption strength for oxygen-containing species, along with a reaction path closer to the ideal free energy due to the small particle size and special morphology of Pd–Ni ellipsoidal nano-alloys contribute to the excellent activity of the PdNi EN/CB catalyst. [Display omitted] • A Pd–Ni ellipsoidal nano-alloy catalyst supported on carbon black was prepared. • Formation of ellipsoid is due to the addition of CTAC as a structure-directing agent. • PdNi EN/CB has superb catalytic activity for ORR and favorable durability in KOH. • A down-shift of d-band center owing to special morphology leads to the high activity. • The reaction path of PdNi EN/CB is closer to the ideal free energy. [ABSTRACT FROM AUTHOR]

Understanding the electronic properties of silicon semiconductors is important for the preparation of high‐performance semiconductor materials. We calculated the band entropies, electronic structures, and bonding properties of a silicon semiconductor using density functional theory and the binding‐energy and bond‐charge model. The relationship between Si energy and temperature was studied using the tight binding (TB) approximation and bond‐order‐length‐strength (BOLS) theory (BOLS‐TB), with the Si (111) surface as an example. The specific binding energies and bonding properties of Si atoms in different surface atomic layers are discussed by analyzing the X‐ray photoelectron spectra of the Si (111) surface at 953 and 1493 K. This study improves our understanding of how surface properties reflect local bonding states and deepens our understanding of how atomic‐relaxation‐derived Hamiltonian perturbations and temperature influence the binding energy of the surface region. It also contributes to the development of Si‐based semiconductor materials by providing new ideas and methods. [ABSTRACT FROM AUTHOR]

Mg2+ and silicate ions are important ionic species in bone formation. Previously, the authors' group reported a 15MgO–15CaO–8P2O5–4SiO2 glass (silicophosphate invert glass [spIG]) containing orthophosphate and orthosilicate structures. Mg2+ and Ca2+ ions in the glass preferentially formed Si–O–Mg and P–O–Ca bonds, respectively, suppressing the release amount of silicate ions in a tris–HCl buffer solution (TBS). In this study, a new 15MgO–15CaO–5P2O5–10SiO2 invert glass without a silicate 3D‐network structure was prepared via a melt‐quenching method. The new glass exhibits an improved silicate‐ion release ability that promotes bone formation. The dissolution amounts of Ca2+ and phosphate ions from the glass into a TBS were similar to those of spIG, but the amounts of Mg2+ and silicate ions increased by ∼2 and ∼5 times, respectively. 31P and 29Si magic‐angle spinning nuclear magnetic resonance spectroscopic analyses showed that the glass was composed of orthophosphate and chain silicate structures. Even when the silica content exceeded that of spIG, the formation of a silicate 3D‐network was suppressed. The O1s X‐ray photoelectron spectra indicated that (Si, P)–O–Mg bonds contribute to the glass formation. In a glass model based on classical molecular dynamics, the oxygen coordination numbers of Mg and Ca were determined as 4–7 and 5–8, respectively. Mg2+ ions are predominantly responsible for bridging the silicate/phosphate structures in this glass and play an important role in tuning the glass formation and the release amount of silicate ions. [ABSTRACT FROM AUTHOR]

In this work, nitrogen (N)‐doped graphene film is synthesized, as a photo‐catalyst, on one side of the copper foam by chemical vapor deposition and the copper foam is directly used as an electrode after porous Pd@rGO cathode loading to the other side of the foam for the photo‐assisted charging of the Li‐ion oxygen battery. The amount of urea (CO(NH2)2), which is used as N atom source, is optimized to get maximum photo‐anodic currents from the n‐type graphene films. The optical band gap and the valance band edge potential of the optimized N‐doped graphene film are determined as 2.00 eV and 3.71 VLi+/Li, respectively. X‐ray photoelectron spectra provided that the atomic percent of N atoms in the graphene film is 1.34% and the graphitic, pyrrolic and pyridinic N atom percentages are 54.01%, 42.20% and 3.79%, respectively. The photo‐assisted charging tests indicated that the N‐doped graphene film photo‐catalyst reduced the charging potential significantly even at 1000 mA g−1 (0.1 mA cm−2) current density and improved the cyclic discharge‐charge performance of the Li‐ion oxygen battery considerably. [ABSTRACT FROM AUTHOR]

Atomic layer deposition is a powerful technique for achieving atomic-level control in the deposition of thin films and nanoparticles. The ultrathin noble metal films can be applied in many functional devices, but it is a challenge to obtain such films since the island growth mode generally happens instead of the layer growth mode. In this work, the nucleation and growth of platinum on Si, Al2O3, Au, and Ni substrates were studied using (MeCp)PtMe3 and O2 plasma as a precursor and a co-reactant, respectively. The evolution of Pt coverage on different surfaces was observed and discussed based on the experimental results by x-ray photoelectron spectra. The chemical adsorption of the precursor and the following processes like metal atom diffusion on substrate surfaces and up-stepping onto the existing metal islands were considered to dominate the growth before continuous films formed. The chemisorption determined the metal coverage on bare substrate surfaces, and the total coverage was influenced by metal atom diffusion and up-stepping behaviors that are determined by surface energy relationships between the deposited metal and substrate surfaces. Pt films were easier to form on Al2O3 and Ni surfaces compared with on Si and Au surfaces, respectively. A model was proposed to help to understand the mechanisms in the nucleation and growth processes, involving the chemisorption, diffusion, and up-stepping, which contributed to prepare ultrathin continuous Pt films on different substrates. [ABSTRACT FROM AUTHOR]

A new method of X-ray photoelectron spectra processing based on a target model with a stochastic surface layer is proposed. On the basis of this model, X-ray photoelectron spectra of multilayer multicomponent metallic targets with an inhomogeneous surface layer are obtained for various probing angles considering surface shading effects. A layer-by-layer phase profile of metallic samples is obtained using the advanced method of surface analysis based on angle-resolved X-ray photoelectron spectroscopy. The results are validated by atomic force microscopy. [ABSTRACT FROM AUTHOR]

One of the main challenges potassium‐ion batteries (PIBs) face is the lack of structurally stable anodes with high reactivity and fast kinetics for reversible potassium insertion/extraction. Herein, nitrogen‐doped carbon nanotubes (N‐CNTs) are synthesized using a straightforward method assisted by a Co‐based catalyst. The as‐synthesized N‐CNTs possess interlayer distances up to 0.38 nm and nitrogen‐doping content of 2.2 at.%. Compared to the undoped CNTs (U‐CNTs), N‐CNTs exhibit a promising initial specific capacity of 568 mAh g−1 at 0.1 A g−1, as well as excellent long‐term cycling performance of 104, 82, and 76 mAh g−1 at a high current of 0.5, 1, and 2 A g−1 for 500 cycles. The cyclic voltammetry (CV) measurements reveal the potassium storage mechanism of N‐CNTs, which combines the major capacitive mechanisms and the secondary diffusion, and successfully avoids inconspicuous voltage plateau. The kinetic analysis of the galvanostatic intermittent titration technique and ex situ X‐ray photoelectron spectroscopy spectra show fast reaction kinetics and low side effects and degradation for the N‐CNTs anodes during the potassiation/de‐potassiation process. This study provides a straightforward method to synthesize heteroatom‐doped carbonaceous anode materials and achieves superior electrochemical properties with cost‐effectiveness and material sustainability. [ABSTRACT FROM AUTHOR]

This paper focuses on enhancing the performance of electrocatalytic CO2 reduction reaction (CO2RR) by improving the dispersion of cobalt phthalocyanine (CoPc), especially for the methanol formation with multi-walled carbon nanotubes (CNTs) as a support. The promising CNTs-supported CoPc hybrid was prepared based on ball milling technique, and the surface morphology was characterized by means of those methods such as scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectra (XPS). Then, the synergistic effect of CNTs and ball milling on CO2RR performance was analyzed by those methods of cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), gas chromatography (GC), and proton nuclear magnetic resonance spectroscopy (1HNMR). Subsequently, the reduction mechanism of CO2 on ball-milled CoPc/CNTs was revealed based on the DFT calculations. The results showed that the electrocatalyst CoPc/CNTs hybrid prepared with sonication exhibited a conversion efficiency of CO2 above 60% at -1.0 V vs. RHE, accompanied by the Faradaic efficiencies of nearly 50% for CO and 10% for methanol, respectively. The addition of CNTs as the support improved the utilization efficiency of CoPc and reduced the transfer resistance of species and electrons. Then the ball-milling method further improved the dispersion of CoPc on CNTs, which resulted in the fact that the methanol efficiency was raised by 6% and partial current density was increased by nearly 433%. The better dispersion of CoPc on CNTs adjusted the reduction pathway of CO2 and resulted in the enhancement of methanol selectivity and catalytic activity of CO2. The probable pathway for methanol production was proposed as CO2 → *CO2− → *COOH → *CO → *CHO → *CH2O → *OCH3 → CH3OH. This suggests the significance of the ball-milling method during the preparation of better supported catalysts for CO2RR towards those high-valued products. [ABSTRACT FROM AUTHOR]

The molecular complexes of Re(4,4′-dcbpy)(CO)3Cl (dcbpy = dicarboxylicacid-2,2'-bipyridyl) and [Ru(dcbpy)3]2+ are co-assembled into UiO-66 scaffolds as structural imperfects for CO2 photocatalytic reduction (named as Re-Ru@U). The prepared catalysts are characterized by XRD, Fourier-Transform infrared (FTIR) spectra, X-ray photoelectron spectra (XPS) and N2 adsorption–desorption isotherms. The intact structure of molecular complexes within the matrix are monitored by 1H nuclear magnetic resonance (NMR) spectra through a totally digesting catalyst. The optical properties are studied via absorption and photoluminescence spectra, and the single-electron reduction in Re and Ru complexes is detected by electron paramagnetic resonance (EPR) spectra. An excellent photocatalytic performance is obtained with steady and sustained CO evolution and a turnover number (TON) value of 15 (11 h). The CO activity irradiating by single wavelength presents the absorption-intensity-dependent changing tendency, where the absorption intensity is superposed by Re and Ru complexes. The two radicals related to Re and Ru, respectively, are simultaneously detected in the Re-Ru@U catalyst. It is suggested that the ReC2 component serves as both a photosensitizer and a catalyst, and the RuC2 component works as an additional photosensitizer to supply the second electron for CO2 reduction. The co-assembling of dual metals Re and Ru in the matrix promotes the electron transfer from the reductive Ru centres to one-electron-reduced Re centres and accounts for the superior activity of CO evolution. Our results demonstrate a strategy to develop the multimetallic catalysts via facile assembling into MOF scaffolds to promote photocatalytic performance. [ABSTRACT FROM AUTHOR]

Polymer-bonded explosives (PBXs) played a critical role in lethality and destruction as a vital military explosive in the world. Unfortunately, the current PBXs exhibit poor properties in safety performance and reliability for the weak interfacial surface, which cannot meet requirements of the high security and high reliability of weapons and ammunition in the harsh environment of modern battlefields. Herein, the neutral polymeric bonding agents (NPBAs) were successfully coated on the surface of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and proved to enhance the mechanical performance and reliability of PBXs. The scanning electron microscopy images indicated a slight aggregation of NPBAs coated in the HMX surface, the XRD spectra of HMX@NPBAs had an analogous spectrum of HMX, and the X-ray photoelectron spectroscopy spectrum confirmed that the NPBAs played a role on the surface of HMX by coating. Furthermore, the HMX coated with NPBAs had more excellent safety performance, thermal stability, and mechanical properties. The strategy is helpful to strengthen the interaction between HMX and binder matrix, which provides a brilliant idea in modifying for the weak interfacial surface of energetic crystals. [ABSTRACT FROM AUTHOR]

Our density functional theory calculations (by GAUSSIAN) on the Si4O104− moiety and Na4Si4O10 molecule reproduce the experimental Raman frequencies and relative intensities for the three A1 modes in the experimental Raman spectra of Na2Si2O5 and BaSi2O5 crystals and glasses. Taking the center of mass into consideration, accompanied by visualization using GaussView, these calculations provide a firm assignment of these three peaks: the 1060 cm−1 peak to the Si-NBO stretch (NBO = Si–O or Si–O–Na), the ∼600 cm−1 peak to the Si-BO stretch (BO = Si–O–Si), and the ∼500 cm−1 peak to the Si-BO-Si bend. Our GAUSSIAN calculations on modified "non-equilibrium" SiO44− tetrahedra, constrained to have the same Si–O bond lengths and O–Si–O bond angles as in the Si4O104− moiety, confirm the above-mentioned assignment and show reasonable agreement with the experimental Raman frequencies and relative intensities. We then examine the regular trends in the Si-NBO and Si-BO stretch frequencies for all Qn (n = 0–4) species in silicate glasses and crystals. The large systematic change in the differences between these frequencies (Δ1) is explained by electronic changes within the SiO4 tetrahedron. For example, the larger Δ1 for the Q3 tetrahedra than the Q2 tetrahedra is due to the changes in Si, BO, and NBO electron densities on the tetrahedral Si and O atoms, as measured by Si 2p and O 1s x-ray photoelectron spectra. This trend strongly suggests that the Si-BO stretch frequency for the Q4 species in v-SiO2 should be ∼500 cm−1, close to the A1 breathing mode frequency of 495 cm−1 for four membered rings previously assigned. [ABSTRACT FROM AUTHOR]

BACKGROUND: In this study, adsorption properties and photocatalytic activities of Cu‐BTC and ZIF‐8 are explored using an anionic dye, methyl orange (MO), and a cationic dye, methylene blue (MB). Effect of humidity on the stabilities and performances of Cu‐BTC and ZIF‐8 is controlled under 40%, 67% and 84% relative humidity (RH) conditions. Cu‐BTC, ZIF‐8 and humidified samples are characterized by various techniques. RESULTS: Humidified samples do not exhibit new X‐ray diffraction (XRD) peaks and significant variations in scanning electron microscopy images and UV–visible diffuse reflectance (UV–Vis DRS) spectra. After degradation experiments, XRD, X‐ray photoelectron spectra and UV–Vis DRS confirm the coexistence of Cu1+ and Cu2+ in Cu‐BTC and the formation of ZnO in ZIF‐8. Reduction in surface area measurements and detection of N and S signals in energy‐dispersive X‐ray analysis prove interaction of MO and MB. Adsorptions of MO and MB are proposed via electrostatic attraction, π–π interaction and hydrogen bonding and conform to pseudo‐second‐order kinetics. Langmuir and Freundlich models describe the adsorption isotherms of MO and MB. Ligand‐to‐metal charge transfer process is principally responsible for the photoactivities of Cu‐BTC and ZIF‐8. Cu‐BTC (84% RH) and ZIF‐8 (84% RH) exhibit the highest performances, following Langmuir–Hinshelwood kinetics. Stability tests of Cu‐BTC, ZIF‐8 and humidified samples imply their reuse abilities. CONCLUSION: This study correlates structural characteristics and adsorption abilities/photocatalytic performances of Cu‐BTC and ZIF‐8. Results may offer new ideas for the improvement of metal–organic frameworks as adsorbents and photocatalysts. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

We analyzed the X-ray photoelectron spectra (XPS) of carbon 1s states in graphene and oxygen-intercalated graphene grown on SiC(0001) using Bayesian spectroscopy. To realize highly accurate spectral decomposition of the XPS spectra, we proposed a framework for discovering physical constraints from the absence of prior quantified physical knowledge, in which we designed the prior probabilities based on the found constraints and the physically required conditions. This suppresses the exchange of peak components during replica exchange Monte Carlo iterations and makes possible to decompose XPS in the case where a reliable structure model or a presumable number of components is not known. As a result, we have successfully decomposed XPS of one monolayer (1ML), two monolayers (2ML), and quasi-freestanding 2ML (qfs-2ML) graphene samples deposited on SiC substrates with the meV order precision of the binding energy, in which the posterior probability distributions of the binding energies were obtained distinguishably between the different components of buffer layer even though they are observed as hump and shoulder structures because of their overlapping. [ABSTRACT FROM AUTHOR]

There is an urgent need to realize precise clinical ultrasound with ultrasound contrast agents that provide high echo intensity and mechanical index tolerance. Graphene derivatives possess exceptional characteristics, exhibiting great potential in fabricating ideal ultrasound contrast agents. Herein, we reported a facile and green approach to synthesizing reduced graphene oxide with ellagic acid (rGO-EA). To investigate the application of a graphene derivative in ultrasound contrast agents, rGO-EA was dispersed in saline solution and mixed with SonoVue (SV) to fabricate SV@rGO-EA microbubbles. To determine the properties of the product, analyses were performed, including ultraviolet–visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectrum (XPS), X-ray diffraction analysis (XRD) and zeta potential analysis. Additionally, cell viability measurements and a hemolysis assay were conducted for a biosafety evaluation. SV@rGO-EA microbubbles were scanned at various mechanical index values to obtain the B-mode and contrast-enhanced ultrasound (CEUS) mode images in vitro. SV@rGO-EA microbubbles were administered to SD rats, and their livers and kidneys were imaged in CEUS and B-mode. The absorption of rGO-EA resulted in an enhanced echo intensity and mechanical index tolerance of SV@rGO-EA, surpassing the performance of SV microbubbles both in vitro and in vivo. This work exhibited the application potential of graphene derivatives in the field of ultrasound precision medicine. [ABSTRACT FROM AUTHOR]

Highlights: KTiNbO5 and KTiNbO5/reduced graphene oxide (rGO) nanocomposites were successfully synthesised via solvothermal methods. Optimising the rGO wt% yielded a composite with 12 wt% (KTNO/rGO-12). KTNO/rGO-12 was tested for its potassium storage performance, achieving a first charge capacity of 128.1 mAh g−1 and retaining 76.1% over 500 cycles at 20 mAh g−1. The mechanism of intercalation was examined, suggesting a potentially low-strain material, with both titanium and niobium redox activity contributing to the charge storage. With graphite currently leading as the most viable anode for potassium-ion batteries (KIBs), other materials have been left relatively under-examined. Transition metal oxides are among these, with many positive attributes such as synthetic maturity, long-term cycling stability and fast redox kinetics. Therefore, to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5 (KTNO) and its rGO nanocomposite (KTNO/rGO) synthesised via solvothermal methods as a high-performance anode for KIBs. Through effective distribution across the electrically conductive rGO, the electrochemical performance of the KTNO nanoparticles was enhanced. The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g−1 and reversible capacity of 97.5 mAh g−1 after 500 cycles at 20 mA g−1, retaining 76.1% of the initial capacity, with an exceptional rate performance of 54.2 mAh g−1 at 1 A g−1. Furthermore, to investigate the attributes of KTNO in-situ XRD was performed, indicating a low-strain material. Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage, with the titanium showing greater redox reversibility than the niobium. This work suggests this low-strain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs. [ABSTRACT FROM AUTHOR]