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[Display omitted] • MD simulations reveal distinct SiC microstructure evolution under H+ and Cu2+ implantation. • Cu2+ ions reach higher atomic temperatures, while H+ affects a larger volume. • An incident angle of 0° maximizes sputtering yield and promotes amorphous structure formation. • Cu2+ ions exhibit lower sputtering yield and energy increase compared to H+ ions. • The channeling effect is more pronounced in H+ implantation models. The microstructure evolution of 4H-SiC under the implantation of hydron ions and copper ions was investigated using molecular dynamics (MD) simulations and experimental analysis. MD models were developed to simulate the implantation of single Cu2+ and H+ ions into SiC, analyzing lattice damage, amorphous defects, and temperature distribution. H+ ion implantation resulted in a higher number of amorphous atoms compared to Cu2+ ions. The maximum atomic temperature during Cu2+ ion implantation was significantly higher (1635 K) than during H+ ion implantation (950 K), although the volume of the temperature rise region was larger in the H+ model. Cu2+ ions induced more severe lattice vibrations than H+ ions. Atom movement along regions of weak lattice binding energy was observed. The study also examined overlapping multiple ion implantations, considering ion type, initial energy, and incident angle. Cu2+ ions exhibited smaller sputtering yield, projection range, number of amorphous atoms, and energy increment compared to H+ ions. A 0° incident angle resulted in higher sputtering yield and increased amorphous structure formation due to the channeling effect, which was more pronounced in the H+ model. The experimental results demonstrate that compared to Cu2+ ions, H+ ions have a greater impact on the surface peak roughness, sub-surface damage depth, and surface damage of SiC samples. It can provide a reliable guidance for selecting process parameters and the types of ions to implant. [ABSTRACT FROM AUTHOR]

[Display omitted] • A superior HOR electrocatalyst of Ru-Cr(OH) x /MXene was prepared via a facile one-step method. • The two-dimensional materials of MXene were firstly applied in the field of HOR. • The as-prepared Ru-Cr(OH) x /MXene exhibited high CO-tolerance, excellent HOR activity and stability. • The high-performance of Ru-Cr(OH) x /MXene is attributed to a weak HBE and strong OHBE. The development of high-performance non-platinum catalysts remains a key challenge for the practical application of anion-exchange membrane fuel cells due to the sluggish kinetics response of the hydrogen oxidation reaction (HOR) in alkaline electrolytes. Herein, we report an outstanding HOR electrocatalyst using a facile one-step method with the two-dimensional double transition metal MXene (Mo 2 TiC 2 T x) as a carrier mixed with metallic ruthenium and Cr(OH) x clusters (Ru-Cr(OH) x /MXene). Specifically, the as-prepared Ru-Cr(OH) x /MXene electrocatalyst exhibits a high apparent kinetic current (j k) of 18.32 mA cm−2 and exchange current (j 0) of 1.64 mA cm−2 at an overpotential of 50 mV, respectively, which are 4.74 and 1.46 times as high as those of Pt/C catalyst. Additionally, mechanism experiments indicated that the Ru-Cr(OH) x /MXene electrocatalyst could attenuate the adsorption of hydrogen intermediate (H ad) and enhance the adsorption of hydroxyl species (OH ad) to promote CO oxidation, which resulted in a significant increase in the HOR activity and enhanced tolerance to CO. Furthermore, combining theoretical studies via density functional theory calculations, our work confirm that the interaction effect of each components of Ru-Cr(OH) x /MXene can optimize the binding energy of the H ad and OH ad for the HOR. This work develops a new approach to design of HOR electrocatalyst with MXene-based materials. [ABSTRACT FROM AUTHOR]

The novel structural design of aqueous magnesium-ion batteries with PTCDA as the anode, MnO 2 /GO as the cathode and Li/Mg hybrid superconcentrated electrolyte makes full use of the low reduction potential of Mg2+ and the synergistic effect of hybrid ions, thus significantly enhancing the performance. [Display omitted] • An aqueous Mg2+ battery based on hybrid superconcentrated electrolyte is developed. • The discharge capacities of 200.6 mAh/g and energy density of 170.1 Wh Kg−1. • The synergistic effect of hybrid ions and the characteristics of superconcentrated electrolyte significantly enhance battery performance. Rechargeable aqueous magnesium ion batteries (AMIBs) are considered a promising energy storage system due to the relatively high energy density, excellent rate performance and reversibility, and absence of dendrite formation during cycling. However, the high surface charge density of Mg2+ ions results in slow diffusion kinetics, and high voltage leads to excessive electrolyte decomposition at the electrode/aqueous electrolyte interface, thereby limiting the development of high-energy–density MIBs. In this work, we extend the electrochemical stability window of the aqueous electrolyte to 2.1 V by using a hybrid ion superconcentrated electrolyte at concentrations not achievable with Mg2+ electrolytes alone. The AMIB with a water-in-salt (WIS) electrolyte delivers discharge capacities of up to 200.6 and 84.4 mAh g−1, and energy densities of 170.1 and 68.1 Wh Kg−1 at 0.5 and 20 A g−1, respectively, representing excellent rate performance, while retaining 85 % of the specific capacity after 2000 cycles. Additionally, we explore the corresponding electrochemical reaction mechanism, revealing the synergistic effect of Mg2+ and Li+ ions in the charge/discharge process, which supports the excellent electrochemical performance of AMIB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hf 4 f peaks identified for hafnia, hafnium silicate, and their nitrided forms. • The composition of nitrided hafnia is HfO 1.66 N 0.33. • A Si2+-2N1- dipole layer at the interface causes a shift of the spectra. • Saturation shows that excited N 2 + ions are the nitridation agent for hafnia. • Hafnium silicate nitrides sooner than hafnia in HfO 2 /Si structures. • Lower plasma pressure enhances the nitridation of hafnia. We report a comprehensive quantitative ARXPS study of 20-cycle ALD-grown HfO 2 films on Si (0 0 1) substrates with and without remote plasma nitridation. The films comprised a 0.6 nm HfO 2 layer atop a 1 nm hafnium-rich silicate interlayer. A detailed analysis of the Hf 4 f , Si 2 p , O 1 s , C 1 s , and N 1 s core level spectra is presented for samples with and without nitridation. The fitting of the Hf 4 f spectra reveals four contributing components associated with silicate, hafnia, and their respective nitrided species. The Hf 4 f , O 1 s , and C 1 s spectra exhibit a negative binding energy shift of about 0.2 eV upon nitridation induced by a Si2+-N dipole formed at the interface. Quantitative ARXPS analysis, employing the MultiLayer Model, enabled the determination of the thicknesses, and composition together with their associated uncertainties. The analysis showed that the composition of the nitrided hafnia is HfO 1.66 N 0.33. There is a higher degree of nitridation in the silicate interlayer compared to the overlying hafnia layer. The degree of nitridation is found to increase with plasma power; N 2 + is identified as the primary plasma species responsible for the nitridation of hafnia. [ABSTRACT FROM AUTHOR]

5cm×13cm (h×w) In non-Van-Der-Waals 2D Bi 2 O 2 Se Films, elcctrons in [Bi 2 O 2 ]2+ layer and holes in [Se]2- layer suffer large Coulomb interactions as the strong localization. From detailed study of electronic structures and excitons, a larger exciton binding energy (E b) was observed compared with typical multi-layer TMDCs. Opposite thickness-evolution tendency of E b along with photon energy are attributed to dispersive dielectric screening effects. [Display omitted] • Thickness dependent dielectric properties of Bi 2 O 2 Se films are investigated by spectroscopic ellipsometry. • Five critical points are determined and assigned into electronic band structure. • A large exciton binding energy (E b = 234 meV) is revealed in 3.54-nm Bi 2 O 2 Se. • Opposite evolution trend of E b with thickness exhibit in low and high energy region. Bi 2 O 2 Se, as a non-van-der-waals (non-vdW) interlayer coupling two-dimensional material, its electronic band structures and exciton behavior still merit further in-depth studies, especially in the consideration of thickness tuning degrees of freedom. Here, we reveal the broadband excitonic performance and critical point properties of Bi 2 O 2 Se films with different thicknesses (3.54–16.33 nm). Five critical points are determined and assigned to specific optical transitions. Moreover, we observe that electronic bandstructures in the Γ valley are stable with variable thicknesses, while the deeper electron levels received more pronounced thickness modulation. And we first report four excitons in wide spectral range (1.24–6.20 eV) through absorption coefficient fitting. Significantly, due to the strong localization of electrons and holes induced by the intralayer built-in electric field, the exciton binding energy (E b) value of 3.54 nm-Bi 2 O 2 Se (234 meV at Γ position) is apparently larger than typical multi-layer TMDCs, which offering unprecedented opportunities in applications in optoelectronic devices. Furthermore, E b of two excitons at low energy region (E b 1 , E b 2) red-shift with increasing thickness, while E b of higher-energy excitons (E b 3 , E b 4) blue-shift, owing to the dispersion characteristic of the effect dielectric screening effects. Our results are vital to wide-ranging applications of Bi 2 O 2 Se from fundamental science to optoelectronic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Correlation analysis can be used on large XPS datasets identify relationships in atomic % and binding energy. • A phase model, consisting of the different chemical phases present in the sample, can be used to interpret correlations. • This can be used to judge between different peak models in terms of their consistency with chemistry. X-ray photoelectron spectroscopy (XPS) is a powerful technique for surface analysis, but its application can be hindered by uncertainty in modelling spectra. Often, many spectral models have a similar goodness of fit, and distinguishing between them can be impossible without additional information. A further challenge is found in interpreting spectra from samples consisting of multiple chemical compounds. We show here how correlation analysis can be used to interpret large XPS datasets. Correlations in atomic concentrations and binding energies of core lines can be interpreted within a framework of an underlying chemical model and this can yield additional information compared with analysis of each spectrum individually. We give examples of the usage of this analysis on some simple systems, and discuss the potential and limitations of the technique. [ABSTRACT FROM AUTHOR]

MnO 2 phase of manganese oxide was identified as the final product of a multiple steps reaction in near ambient pressure-X-ray photoemission (NAP-XPS) chamber. At the first stage of the reaction, an intermediate stable manganese hydroxide film was obtained at ∼ 400 °C in presence of p(O 2) and p(H 2 O) and verified by the formation of sizeable hydroxide peak, OH, at binding energy 531.4 (1) eV. The Mn hydroxide film is kept unaltered even when is subsequently exposed to p(O 2)= 2 mbar at ∼ 450 °C, and it is modified into δ -MnO 2 phase at ∼ 480 °C when p(O 2) pressure is suddenly reduced to below 10−9 mbar. Thus, the OH spectral feature becomes the main signature in O 1s core level spectral regions and a Mn 4 + related feature is identified in Mn 2p energy range. The multiple step reaction follows the proposed mechanism for the MnO 2 formation in electrolytic cell and it is the first observation in a controlled way in NAP-XPS chamber. The findings open new roots for the birnessite manganese oxide phase formation and its manipulation. [Display omitted] • Reactivity of Mn 3 O 4 under near ambient pressure of H 2 O and O 2. • MnO 2 thin film formation. • Mn oxidation state modification in near ambient pressure reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microscopic scale friction between soft metals and 2D materials reconstructed by DFT calculations. • The sliding potential energy and friction force of the MoO 3 (0 1 0)/Ag(1 1 1) heterogeneous sliding interface are anisotropic when sliding along different directions. • Pressure-induced charge redistribution between the interface atoms is the essence of the variation of the tribological properties. The atomic-scale tribological properties of the MoO 3 (0 1 0)/Ag(1 1 1) heterogeneous sliding interface were studied by first-principles calculation method. The interface binding energy, sliding potential energy, friction force, charge density difference, partial density of states, Mulliken bond population and HiRshfeld charge were analyzed, and the essence of the friction was revealed. The results show that the sliding potential energy and friction exhibit anisotropy for the pressure-induced MoO 3 (0 1 0)/Ag(1 1 1) heterogeneous sliding interface. The friction force can be described by the change of the sliding potential energy, and the charge redistribution between interface atoms is the intrinsic reason for the change of tribological properties. This work provides atomic and electronic level insights for understanding the tribological characteristics between two-dimensional materials and soft metals. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT calculations and experiments are combined to tunne cation types of LDHs. • CaAl-LDH has highest Cl- adsorption capacity, aligned with lowest binding energy. • CaAl-NO 3 -LDH transforms into Friedel's salt after reacted with Cl- • ZnAl-LDH retains the most Cl- after addition of SO 4 2- with crystallinity improved. • Divalent cations dominate LDHs' interlayer spacing and binding energy in some cases. Layered double hydroxides (LDHs) are new concrete additives that improve Cl- sorption capacity by varying their chemical composition. In this work, first-principles calculations were used to design the chemical compositions of LDHs with various cations. Accordingly, four cation types of LDHs (CaAl, MgAl, MgFe and ZnAl) were selected to be synthesized, their Cl- sorption kinetics were further measured. The objective was to establish a high-throughput screening approach to identifying the most promising cations for enhancing the sorption capacity of LDHs towards Cl-. Results revealed that the absolute value of Cl- binding energy increased as the interplanar spacing of different LDHs decreased from first-principles calculations. Particularly, CaAl exhibited the highest adsorption capacity for Cl- (3.25 mmol/g) from experiments, validating the simulation results that it has the highest absolute value of Cl- binding energy. MgFe-Cl-LDH has the smallest absolute value of Cl- binding energy with the lowest adsorption capacity for Cl- as well as the crystallinity. Moreover, multiple factors influencing the Cl- sorption ability of LDHs, such as chemical composition, crystallinity, microstructures and their synergistic effects, are discussed thoroughly based on the experimental results. This study established a connection between the simulation and experimental approaches in understanding the mechanism of Cl- adsorption. [ABSTRACT FROM AUTHOR]

Schematic depiction of the synchrotron scanning photoelectron microscopy (SPEM) measurement setup and concept of contact hole nano-mapping inspection. [Display omitted] • We report a nanoscale analysis of contact holes featuring diverse sizes. • Shifts in binding energies indicate the electrical states of contact holes. • SPEM assesses individual contact holes at the nanoscale precision. • SPEM discriminates variations of buried insulator thickness. With the rise in demand for high aspect ratio hole etching in semiconductor device fabrication, developing efficient inspection methods to detect etching failures is increasingly vital. Such failures can compromise the reliability of electrical connections of contact holes in highly sophisticated 3D semiconductor geometries. In this study, we present a nanoscale inspection technique employing synchrotron-based scanning photoelectron microscopy (SPEM) to assess the electrical connectivity of contact holes. Samples were systematically prepared with an array of contact holes of varying sizes. To simulate etching failure, a residual silicon oxide layer was deliberately left to induce the binding energy shift in photoelectron peak positions due to electrical charging. By obtaining W 4 f and Si 2 p spectra for the W-filled and W-unfilled structures, respectively, we objectively determined the electrical states of the contact holes. With its focused X-ray beams, SPEM has demonstrated its suitability for investigating the electrical connectivity of individual contact holes at the nanoscale. SPEM possesses the additional capability of non-destructive imaging the thickness of buried insulators inside an individual contact hole. Our results cast potential application of SPEM as a nanoscale inspection methodology for advanced semiconductor manufacturing. [ABSTRACT FROM AUTHOR]

A novel CoRu alloy nanosheet-coupled carbon nitride nanotube (TCN) Schottky junction photocatalyst (CoRu/TCN) was designed for photocatalytic hydrogen evolution reaction. [Display omitted] • A novel CoRu/TCN Schottky junction photocatalyst was designed for photocatalytic HER. • The interfacial electric field enhances the interfacial charge transfer kinetics. • The synergistic effect of Co and Ru optimizes the Ru–H binding energy. • The photocatalytic HER performance of optimum CoRu/TCN is 23 times higher than bare TCN. Developing an efficient and inexpensive Pt-metal-free co-catalyst is of crucial importance but challenging for photocatalytic hydrogen evolution reaction (HER). Herein, a novel CoRu alloy nanosheet-modified g-C 3 N 4 nanotube (TCN) Schottky junction photocatalyst is designed for the first time for photocatalytic HER. The photocatalytic hydrogen evolution rate of the optimized CoRu/TCN photocatalyst is 1601.32 μmol·g−1·h−1, which is 74 and 23 times higher than that of bulk carbon nitride (BCN) and TCN, respectively. Strikingly, its photocatalytic hydrogen production performance is obviously superior to Pt/TCN (1271.32 μmol·g−1·h−1). The experimental and theoretical results confirm that the superior photocatalytic hydrogen evolution activity of CoRu/TCN is ascribed to the formed an interfacial electric field between CoRu alloy and TCN, which improves the interfacial charge transfer kinetics and accelerates charge separation and transfer. Furthermore, the CoRu alloy has an appropriate hydrogen Gibbs free energy (ΔG H*) relative to Pt and Ru metals, uncovering that the synergistic effect of Co and Ru rationally optimizes the Ru–H binding energy. This makes CoRu alloy exhibit superior co-catalytic performance than Pt. This work highlights that the synergistic effect of CoRu alloy markedly strengthens the photocatalytic hydrogen evolution performance and provides new insights for designing efficient Pt alternative hydrogen production co-catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The surface chemical composition of β-Ga 2 O 3 films is discussed in depth. • The component of O 1s with the binding energy around 531.8 eV is attributed to surface lattice O atoms. • The defects inside the β-Ga 2 O 3 films were analyzed by HRTEM. β gallium oxide (β-Ga 2 O 3) is an ultrawide bandgap semiconductor with great potential for solar-blind ultraviolet detection, power devices, and gas sensing. However, the understanding of the surface properties of β-Ga 2 O 3 remains insufficient. Here, epitaxial growth of β-Ga 2 O 3 films was carried by metal–organic chemical vapor deposition (MOCVD) on sapphire substrates. The surface chemical composition, surface layer crystalline properties, and surface morphology of the β-Ga 2 O 3 films were discussed and analyzed in detail. By comparing the atomic ratios of O/Ga, the surface morphology, and the crystalline properties of the films, we attribute the component of O 1s with the binding energy around 531.8 eV to surface lattice O atoms. Moreover, the one-dimensional defects inside the surface layers and the near-interface regions of the films were observed at atomic scale by high resolution transmission electron microscopy (HRTEM). By comparing the lattice fringes of different facets, the geometric phase uniformity, and the distribution of strain, we found that the crystalline quality of the surface layers is much higher than the near-interface regions. [ABSTRACT FROM AUTHOR]

[Display omitted] • • C1s core level spectrum of the graphene/Ir(1 1 1) cannot be properly fitted with a single component. • • The best fit is achieved with 200 components originating from non-equivalent carbon atoms. • • Fit performed with DFT calculated binding energies and C-Ir distance-dependent Lorentzian width. • • Dependence of core-hole lifetime is explained in terms of different density of s and p states. The energy resolution that can be achieved in x-ray photoelectron spectroscopy experiments allows to disentangle the contribution arising from the presence of a large variety of surface atoms in non-equivalent configurations which manifests itself not only with the appearance of different spectral components, but also as unusual lineshape. In the present work, we show that the fit of the C 1s core level spectrum of graphene grown on Ir(1 1 1) realized using 200 peaks based on ab initio calculations, accounting for the non-equivalent C atoms in the 10 × 10 moiré cell, does not improve the fit quality with respect to the use of a single component. On the contrary, the quantitative fit quality can be drastically increased by introducing a dependency of the Lorentzian width on the distance between C and Ir first-layer atoms. This result is associated to the different electronic properties, and in particular to the different density of states of the σ and π bands, of C atoms sitting on TOP (hills) or FCC (valleys) regions of graphene which affect the lifetimes of the core-holes generated during the photoemission process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The pore diameter of hydrothermal carbon was simulated, optimized and experimentally verified according to actual forms of cadmium and lead in the soil. • Modification methods had a direct impact on the binding energy of functional groups to cadmium and lead. • The contents of TCLP-Cd decreased by 86% and TCLP-Pb decreased by 79% after remediation. • Structure-tunable hydrothermal carbon is potent, low energy consumption of carbon material for effective remediation in coal gangue accumulation areas. As industrial mining develops, massive cadmium (Cd) and lead (Pb) have migrated and polluted the soil in large mining areas, which seriously threatens human health and ecology. Here, a bowl-shaped structure-controllable hydrothermal carbon (HC) was prepared with D-ribose as biomass raw material and sodium oleate (SO) and PEO-PPO-PEO (P123) as template agents for passivating Cd and Pb in soil. The binding energies of functional groups and matched pore size between HC and pollutants were simulated by Density Function Theory (DFT) and Materials Studio (MS). The results showed that –COOH-Cd and –OH-Pb have the largest binding energies (0.261 ev and 0.271 ev), with bond lengths of 2.27 Å and 2.21 Å respectively. A pore diameter of 3–6 nm of HC is more suitable for adsorbing Cd and Pb pollutants. Furtherly, acidic D-ribose HC (PDHC) and alkaline D-ribose HC (NDHC) have more oxygen-containing functional groups and a larger specific surface area, the specific surface area of NDHC can reach 178.459 m2·g−1. The OM content of soil was increased by 98 %, 113 % and 120 % after remediation with DHC, PDHC and NDHC, respectively. Comparatively, PDHC is excellent for reducing the TCLP-Cd content by 86 %, and NDHC decrease the TCLP-Pb content by 79 % in the remediated soil. This work offers a specific instructive method to developing high-performance HC for remediating Cd and Pb polluted sites. [ABSTRACT FROM AUTHOR]

The effective synthesis of two-dimensional (2D) heterostructures is essential for their use in electronic devices. In this study, by using atomic layer deposition (ALD), 2D transition metal dichalcogenide (TMD) heterostructures were grown by a halide precursor. This study shows the growth characteristics of the fluoride precursor compared to the chloride precursor used for the synthesis of the TMD on the graphene layer and the other TMD layer. Additionally, a carbonyl precursor was used for comparison with the halide precursor in terms of the thermal stability. From these experiments, the fluoride precursor was adequate for synthesizing on the graphene, however, was inappropriate for the TMD/TMD heterostructure because of its etching characteristic. Meanwhile, the chloride precursor was appropriate for the TMD/TMD heterostructure, even for a low binding energy with the substrate, but was inadequate in forming the TMD/graphene heterostructure, even if the ALD cycle increased. Through our experiments, we show, for the first time, that there exists a suitable halide precursor for a 2D layer for a substrate. Unlabelled Image • Synthesis of two-dimensional MoS 2 synthesized by MoF 6 precursor using atomic layer deposition • MoF 6 is suitable for MoS 2 /graphene heterostructure • Chloride precursor is suitable for transition metal dichalcogenide based heterostructure • Different precursors are suitable depending on the substrate when forming the heterostructure in the atomic layer deposition [ABSTRACT FROM AUTHOR]

In this work, we describe the efficiency of ultra-violet (UV) photodetector performance through RF magnetron sputtered TiO 2 /WO 3 bi-layer thin films. The structural, chemical, morphological and photocurrent response properties of as-grown TiO 2 , WO 3 and bi-layer TiO 2 /WO 3 films were systematically studied. Herein, the merit of enhanced oxygen vacancies in the TiO 2 /WO 3 bi-layer plays a crucial role in photoresponse which is due to the shift of W4f spectrum towards lower binding energy side. Consequently, the addition of WO 3 layer on TiO 2 might be responsible for the superior charge carrier generation when light is illuminated on bi-layer thin film. Besides, linear I-V characteristics of as-resulted samples confirm the ohmic-contact behaviour between the photodetector material and the electrode. The bi-layer of TiO 2 /WO 3 sample generates more electrons and these are might be trapped at Fermi-level of the film surface and it causes for the suppression of the charge carriers recombination rate. As a result, by fine tuning of the bi-layer of TiO 2 /WO 3 structure provides a promising UV photodetector performance than the single-layer of TiO 2 and WO 3. Unlabelled Image • We describe an improved UV photodetector performance by bi-layer of TiO 2 /WO 3. • Crystalline nature is one of the promising factors, especially for bi-layer thin films. • The superior charge carrier generation was achieved through bi-layer samples. • The photocurrent was significantly increased in TiO 2 /WO 3 samples. • The excellent photocurrent properties of the bi-layer allow us to design the various photodetector devices. [ABSTRACT FROM AUTHOR]

In this paper, the effects of the two edges, i.e., S and Mo terminals for zigzag MoS 2 nanoribbons, on Li atom adsorption and migration were studied from first principles. The lattice constants of NRs are width-dependent. The adsorption energy of single or multi-lithium adatoms is stronger when they are bound to the top of Mo atoms and when a Li atom is closer to the edge of a nanoribbon, particularly the S terminal edge. The symmetric two-sided adsorption configuration is more to form for multi-lithium adatoms. In addition, Li atoms initially adsorbed at the S or Mo terminal edge always prefer to diffuse along their corresponding edges. For other ones, they prefer to diffuse towards their nearby S or Mo terminal edge. These results indicate that zigzag MoS 2 nanoribbons can significantly increase the Li binding energy while providing a high mobility path for Li. We hope our theoretical studies will inspire experimental studies on zigzag MoS 2 nanoribbons for use as cathode materials. • Whether single- or multi-lithium adatoms, they are bound to the top of Mo atoms near the edges. • The symmetric two-sided adsorption configuration is more advantageous for multi-lithium adatoms. • Zigzag MoS 2 nanoribbons can provide the high Li mobility path. • The lattice constants of NRs are width dependent. [ABSTRACT FROM AUTHOR]

In this article, Molecular dynamics (MD) simulation were applied to investigate the adsorption behavior and mechanism of neutral polymeric bonding agents (NPBA) in nitrate ester plasticized polyether (NEPE). The simulation results indicate that due to the strong van der Waals (vdW) force interaction, NPBA has the highest binding energy with RDX compared to PEG and nitrate plasticizer. Then, the influences of temperature on the compatibility of nitrate plasticizer and two polymers, NPBA and PEG, were studied. The results show that PEG can dissolve in nitrate plasticizer over a wide range of temperature, while the compatibility of NPBA and nitrate plasticizer decrease with the reducing of temperature. Moreover, the adsorption behavior of the NPBA on RDX surface in nitrate plasticizer was investigated. The results demonstrate that the NPBA chains can penetrate through nitrate plasticizer, adsorb on the RDX surface, and form a compact protection layer, which prevents the bonding interface from nitrate plasticizer damage. Our researches afford a microscopic insight into the mechanism of NPBA, and can be helpful to the NPBA molecular and NEPE formulation design. Unlabelled Image • The adsorption process of NPBA and PEG on RDX surface in nitrate plasticizer were investigated by MD simulations. • RDX could form hydrogens bond and strong vdW interaction with NPBA. • NPBA could form a dense protective film on the surface of RDX, prevent the invasion of nitrate plasticizer. [ABSTRACT FROM AUTHOR]

The oxidation state studies of Mn 1-x Ln x S (Ln = Dy, Tm, Yb; x = 0; 0.01; 0.05) solid solutions was carried out for the first time using X-ray photoelectron and emission spectroscopy. The binding energy of the S(2 p)-, Ln(4 d)-, multiplet splitting analysis of Mn(3 s)-level and the S K α 1 -line energy position allow one to determine atoms oxidation state. The lanthanide atoms were found to be in the trivalent, while the manganese and sulfur atoms were in the divalent state. The near-surface layers contain sulfur atoms in the 0, +4 and +6 oxidation states. The obtained data on the oxidation state were compared with those in lanthanide sulfides Ln 2 S 3 (Ln = Dy, Tm, Yb). The additional 4f -electrons emerged after cationic substitution are assumed to be delocalized in the conduction band and affect physical properties of doped manganese monosulfide. The oxidation state of lanthanide and manganese atoms both on the surface and in the bulk was found to be the same in the compounds studied. The surface layer doesn't contain an additional metal oxidation states (magnetic scattering centers) that significantly affect the colossal magnetoresistance. • Oxidation state study of Mn 1-x Ln x S was carried out using XPS and XES. • The lanthanide atoms in the bulk are +3, the Mn and S atoms are in divalent state. • The S atoms on the samples surface give an significant contributions in the S(2 p)-region. [ABSTRACT FROM AUTHOR]

In recent years, continuous and stable antibacterial ability has received extensive attention in the field of antibacterial composite materials. The researchers expect a kind of antibacterial composites with continuous and stable antibacterial acting and good biocompatibility. Herein we used a unique in-situ modification methods which inspired self-polymerization of dopamine to fix the nano-Ag on the bacterial cellulose (BC). The antibacterial properties of composites were tested in two new methods (antibacterial stability and antibacterial durability). We researched the cause of the antibacterial properties by analyzing the valence state and binding energy of Ag. The chelation between PDA and Ag is considered to the key to stable release of Ag+. The three-dimensional network of BC is also thought to play some role in making Ag+ release stability. Moreover, PDA as a reducing agent, reacting with Tollens reagent to produce nano-Ag nanoparticles, is a good method for reducing the toxicity of nano-Ag and enhancing the biological compatibility of composites. Our results hence illustrate that the BC antimicrobial composites by PDA in-situ reduction nano-Ag has a great potential as an antibacterial dressing with stable antimicrobial properties and biocompatibility. Unlabelled Image • PDA can reduce toxicity of nano-Ag and enhance biocompatibility of composites. • Antibacterial properties are tested in two methods called stability and durability. • The cause of antibacterial properties is researched by XPS and Ag+ release curve. [ABSTRACT FROM AUTHOR]

The interfacial properties of Cs 2 AgBiBr 6 /M 3 C 2 heterostructures were systematical examined by DFT calculations. In addition, experimental synthesis of Cs 2 AgBiBr 6 /Ti 3 C 2 heterostructures successfully confirmed the feasibility of the proposed approach. [Display omitted] • This study delves into the analysis of how early transition metal substitution impacts the interfacial properties of Cs 2 AgBiBr 6 /M 3 C 2. • The AgBiBr 3 /Ti 3 C 2 and AgBiBr 3 /Zr 3 C 2 heterostructures exhibit exceptional stability, remarkable charge transfer, and high light absorption within the visible range. • The successful synthesis of Cs 2 AgBiBr 6 /Ti 3 C 2 serves as compelling evidence for the rationality of its structural design. In this study, we have constructed and characterized Cs 2 AgBiBr 6 /M 3 C 2 (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) heterostructures, utilizing a combination of density functional theory (DFT) and experimental studies. We constructed eighteen different Cs 2 AgBiBr 6 /M 3 C 2 heterojunctions by considering the two different terminal types of Cs 2 AgBiBr 6 as well as the nine different terminal types on the side of various early transition metal carbides. The results indicate that AgBiBr 3 /M 3 C 2 heterostructures possess superior interfacial properties compared to Cs 2 BiBr 3 /M 3 C 2 heterostructures, displaying a smaller interfacial distance, higher binding energy, and better charge transfer ability. Among the AgBiBr 3 /M 3 C 2 heterostructures, AgBiBr 3 /Ti 3 C 2 and AgBiBr 3 /Zr 3 C 2 showed the best binding energy and charge transfer ability. Additionally, all the constructed heterostructures exhibited improved light absorption coefficient, broadened visible light absorption range, and reduced effective mass of the charge carriers. Finally, to validate the experimental synthesis feasibility of the theoretical models, we synthesized Cs 2 AgBiBr 6 /Ti 3 C 2 composite materials, and scanning electron microscopy (SEM) images confirmed the presence of a composite structure consisting of Cs 2 AgBiBr 6 /Ti 3 C 2. These results provide valuable theoretical guidance for developing high-performance Cs 2 AgBiBr 6 /M 3 C 2 heterostructures in optoelectronic perovskite devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphyne exhibits promising potential as nanocarriers for anti-viral drug favipiravir. • A 0.013 e of charge is transferred from the graphyne surface to favipiravir molecule. • The acidic environment has been shown to cause a substantial decrease in the magnitude of binding energy. • The faster release of the favipiravir drug from graphyne surface is indicated by the low recovery time. This study utilized density functional theory (DFT) calculations to explore the potential of pristine graphyne as a drug delivery vehicle for the antiviral drug favipiravir. Favipiravir molecule absorbed on the pristine graphyne surface with the lowest binding energy (−1.485 eV) and can be inferred that chemisorption of favipiravir molecule occurred on pure graphyne surface. Interestingly, a significant reduction in band gap is noted after favipiravir adsorption that enhances the electrical conductivity. From the Bader charge transfer analysis, a transfer of 0.013 e charge has been observed from the graphyne surface to the drug molecule. A significant increase in the binding energy (−0.066 eV) in comparison to the non-acidic condition shows that the interaction between the favipiravir molecule and the pristine graphyne weakens in an acidic environment. Consequently, the graphyne can effectively release the drug molecule to the intended location. Outcome of this study confirmed the ability of pristine graphyne as a favipiravir drug delivery vehicle for the treatment of antiviral diseases. Moreover, the desorption of the drug molecule in the target site occurs very rapidly and demonstrates the potential of the pristine graphyne as a drug delivery vehicle for transporting the favipiravir drug molecule. [ABSTRACT FROM AUTHOR]

[Display omitted] • Study the hydrogen storage properties of primitive and B-doped lithium modified phagraphene by the DFT and GCMC. • B atom doping can effectively improve the binding energy of Li atom. • The mass ratio of H 2 by Li modified B-phagraphene is 6.36 wt% at 298 K and 1 bar. In recent years, various applications of two-dimensional carbon nanomaterial phagraphene, whose protocells contain 5, 6 and 7 carbon rings, have been investigated. In this paper, first-principles and Grand Canonical Monte Carlo (GCMC) simulation methods are used to study the hydrogen storage properties of primitive and B-doped lithium modified phagraphene. The DFT results show that the binding energy of lithium atoms in Li-phagraphene is 2.0 eV. After B doping, the binding energy was significantly increased to 2.8 eV, and the molecular weight ratio of hydrogen was 13.07 wt%. According to the calculation of GCMC, the hydrogen storage weight ratio could reach 6.36 wt% under the environmental conditions of 298 K and 1 bar. The calculated Van't Hoff equation shows that doping B is more conducive to hydrogen desorption at atmospheric pressure. These results indicate that Li-modified B-doped phagraphene is a candidate material for realizing reversible hydrogen storage in near-environmental conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Calculated and simulated the binding energies and electric dipoles of three stacking orders in graphene/h-BN heterobilayer. • Found that the AB stacking structure exhibits the lowest energy. • Discovered that the electric field perpendicular to the 2D plane can control the dipole magnitude of the bilayer system and even change the polarization direction. • Studied the kinetic and thermodynamic stability of the graphene/h-BN heterobilayer under the action of external electric fields using Ab initio molecular dynamics (AIMD). • Proposed potential applications of the graphene/h-BN heterobilayer in the field of information electronics due to its interesting physical properties. The first-principles computer-aided design of atomistic heterostructures can discover the physical properties of new materials and help them widely find applications in frontier scientific fields. Here, we report an investigation on the heterobilayer composed of one sheet of two-dimensional (2D) graphene on the surface of one-layer hexagonal boron nitride (h-BN). We calculate and simulate the binding energies, electric dipoles related to interlayer sliding, and twisting angles of three stacking orders in graphene/hBN heterobilayer. The relative energies of these three heterobilayers are obtained by using first-principles calculations method and the AB stacking structure exhibits the lowest energy. We have also found that the electric field perpendicular to the 2D plane can control the dipole magnitude of the bilayer system, and even change the polarization direction. We studied the kinetic stability of graphene-hBN bilayer heterostructures under the action of external electric fields using Ab initio molecular dynamics (AIMD), as well as the thermodynamic stability. Finally, we propose that the graphene/h-BN heterobilayer might play an important role in the field of information electronics as a 2D material with interesting physical properties. [ABSTRACT FROM AUTHOR]

The structural and electronic properties on Nd 0.6- x Bi x Sr 0.4 MnO 3 nano powders with x = 0, 0.05 and 0.1 are reported. The compounds were prepared using sol-gel combustion method. X-ray diffraction studies confirm that all samples crystallize in orthorhombic structure having Pnma space group. The powders consist of spherical particles that tend to agglomerate, with average grain sizes of about 40–50 nm. XPS measurements reveal a shift toward lower binding energies of Mn 3 s , Mn 2 p , Nd 3 d , and O 1 s core levels with increasing Bi content, which can be explained by the larger 'c' lattice parameter and therefore larger atomic distances. The analysis of the core level XPS spectra proves the existence of both Mn4+ and Mn3+ ions in all samples, as well as the localization of Bi3+ ions in the perovskite lattice. The XPS valence-band is dominated by extensively hybridized Nd 4 f -O 2 p states, with contributions from Mn 3 d -O 2 p bonding and Mn 3 d states. • Nd 0.6- x Bi x Sr 0.4 MnO 3 nano-powders were synthesized via sol-gel combustion method. • TEM images show 20 to 50 nm spherical particles that tend to agglomerate. • XPS spectra prove the existence of both Mn4+ and Mn3+ ions in all samples. • XPS valence-band spectra are due mainly to hybridized Nd 4 f -O 2 p and Mn 3 d states. [ABSTRACT FROM AUTHOR]

Based on spin-polarized DFT calculations, we have studied the interaction mechanism of recently synthesized blue phosphorene (BlueP) monolayers towards selected key volatile organic compounds (VOCs) such as acetone, ethanol and propanal. Our binding energy analysis shows that pristine BlueP weakly binds the VOCs and that this binding does not appreciably change the electronic properties of the monolayer – a prerequisite for any sensing material. However, mono, di, and tri-vacancy defects and Si/S-substitutional doping significantly enhance the binding energies with VOCs. Density of state (DOS) calculations show that upon adsorption of VOCs, mono-vacancy and S-substituted BlueP monolayers undergo a major change in electronic structure, which make them potential candidates for VOCs sensing materials. By contrast, binding of VOCs to di- and tri-vacancy and Si-substitution sites does not alter the electronic structure of BlueP monolayers drastically, therefore, are not qualified for VOCs sensing applications. • Studying blue phosphorene (BlueP) as sensor for volatile organic compounds. • Pristine BlueP cannot bind volatile organic compounds. • Point and substitution defects improve the binding mechanism. • Visible change in electronic properties of BlueP guarantee efficient sensing. [ABSTRACT FROM AUTHOR]

Herein we investigated how Fe-coordinated, N-doped carbon nanotubes (CNT) enhance oxygen reduction reaction (ORR) activity by comparatively studying CNT with different pyridinic and graphitic nitrogen ratios, "Fe-CNT-PA" and "Fe-CNT-Py" in reported experimental results. Density functional theory (DFT) calculations revealed that the catalytic activity of Fe or N-doped CNT sponge for ORR was affected by nature of N dopant (pyridinic N (N P) or graphitic N (N G)) and Fe doping states (adatom or substituent). The N components in the carbon network of CNT changed the catalytic properties of metal-free CNT to that of a semi-metal-like CNT by reducing the band-gap energy. Further incorporation of Fe reduced the band-gap energy to zero, producing metal-like conductor properties. When Fe is coordinated with N components on the CNT structure, coordination of Fe as an adatom than as a substituent causes the coordination sites to exhibit higher spin density distribution and stronger hybridization, enhancing the ORR catalytic properties of CNT. This catalytic activity is more substantial when the Fe adatom is combined with a pyridinic N (N P) site by lowering the adsorption energies of ORR intermediates rather than that of O 2. Based on these results, we investigated the structural and electronic properties of "Fe-CNT-PA" and found that a "Fe-CNT-PA" structure with Fe adatom adjacent to an N P site had zero band-gap energy, higher binding energy, lower working function, and magnetic moment, and thus exhibited more improved ORR activity than "Fe-CNT-Py". Unlabelled Image • Change from metal-free CNT to metal-like CNT by pyridinic N and graphitic N-incorporated CNT. • More enhanced ORR on the Fe adatom site than Fe substituent in the CNT. • More enhanced ORR on Fe adatom-pyridinic N coordination site than Fe adatom-graphitic N coordination site. [ABSTRACT FROM AUTHOR]

Controllable protein adsorption on solids is of great importance in many modern technological applications. The role of the water phase in mediating the protein-surface interactions, however, still remains poorly understood. Herein, we employ free energy calculations to systematically explore the mechanisms of the surface adsorption/bioresistance correlating with the interfacial water layers. The studied peptide shows strong binding affinity with the hydrophobic surface, as illustrated by a monotonic decrease in the free energy profile with no energy barriers. However, the surface bioresistance could be triggered in two distinct ways, by not only an enhancement of the surface-water interactions, but also increased interactions between the water and adsorbates. The enhanced surface-water interactions decrease the tendency of the surface dehydration and the subsequent adsorbate penetration into the surface-bound water layers, thus leading to the surface bioresistance. On the other hand, the enhanced water-adsorbate interactions could promote water stabilization of the adsorbate in the bulk solution, effectively preventing the peptide adsorption. Our results further elucidate that the increase in the peptide size favors its adsorption on the hydrophobic surface, but go against the adsorption on the hydrophilic surface. The mechanisms revealed here may facilitate the design of novel proteins/peptides, materials, and solvents for a controllable adsorption at a solid-water interface. • The effect of the interfacial features on peptide adsorption is reported. • The water phase act as the origin of the surface resistance to peptide adsorption. • Two distinct roles of the water phase in the surface bioresistance are identified. • As the molecule size increases, the effect of water phase becomes more pronounced. [ABSTRACT FROM AUTHOR]

Binding of tyrosine (Tyr) with two finite size graphene sheets of 62 and 186 carbon atoms was investigated using M06-2X/6-31G(d) level. Thorough conformational analysis was done for tyrosine to select few conformers to explore their complexation by considering different orientations on the surface of graphene. The binding energy values are not significantly changed while moving from small to large graphene. Tyrosine exhibits strong π-π interactions that support recent experiments on binding of aromatic amino acids on the surface of graphene and modified graphene. The binding energies of 9.4–9.9 kcal/mol were obtained for different conformers of tyrosine binding with graphene via parallel orientation (having π-π and C(β)-H...π interactions). Owing to multiple interactions including C-H...π, N-H/O-H...π and π-π, the bent prefers over parallel orientation (by 1 kcal/mol) for the high energy conformer of Tyr adsorption on graphene. The binding energies in the aqueous medium are slightly lower than those obtained in the gas phase. HOMO-LUMO energy gaps calculated at the TPSSh/6-31G(d) level suggest that adsorption of tyrosine conformers with different orientations on the surface of graphene does not affect the band gap value of graphene (1.43 and 0.08 eV correspondingly for small and large graphene). Intermolecular orbital interactions support the π-π interactions in bent and parallel orientations of tyrosine with graphene. Unlabelled Image • Tyrosine exhibits strong π-π interactions on the graphene surface. • Different conformers of tyrosine generally prefer parallel orientation on graphene. • Large graphene system is recommended to correctly predict the HOMO-LUMO energy gap. • Intermolecular orbital interactions strongly support the π-π interactions. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT), we theoretically investigated the electronic and structural properties of monolayer and few-layer 2D materials obtained from the exfoliation of zinc-based layered hydroxide salts (LHSs). Four different compounds are investigated: Zn 3 (OH) 4 (NO 3) 2 , Zn 5 (OH) 8 Cl 2.H 2 O, Zn 5 (OH) 8 (NO 3) 2.2H 2 O and NaZn 4 (OH) 6 SO 4 Cl.6H 2 O. We found exfoliation energies in the range of 30 meV/Å̊2 for all cases. Monolayer structures remained semiconducting like the respective bulk compounds, although in some cases, the band gap changes its character from indirect to direct. We also explored the effects of dehydration, which can also change the gap character from indirect to direct in some monolayer structures. Finally, we found that the anion or cation removal from the interlayer region can turn the monolayer systems into metallic, by means of electron and hole doping, respectively. • DFT calculations were performed for the investigation of the exfoliation of four layered hydroxide salts. • The structures of the exfoliated materials were explored. • The exfoliation energies were computed for the four materials. • The electronic structure of the bulk and the exfoliated structures were compared. • The effects of doping and dehydration on the electronic structure were also explored. [ABSTRACT FROM AUTHOR]

We conducted X-ray photoelectron spectroscopy (XPS) and first-principles calculations based on density functional theory (DFT) to confirm the presence of Ga 2 O sub-oxide in high-pressure water vapor annealed AlGaN surface. We note that the Ga 3 d XPS peak broadens and shifts towards higher binding energies, which suggests surface oxide formation. Deconvoluted Ga 3 d XPS profiles between HPWVA-treated and reference samples reveal reasonable inclusion of Ga 2 O peak, suggesting formation of Ga 2 O sub-oxide. To theoretically confirm the presence of Ga 2 O, we calculated the Ga 3 d core-level shift using initial state approximation. We obtained a 0.74 eV shift, in reasonable agreement with that of Ga 2 O. Moreover, based on the calculation of net charge on Ga using DFT, we also obtained a +1 oxidation state for Ga, indicating its existence in Ga 2 O form. By combining theory and experiment, therefore, we have explored the possibility of the formation of Ga 2 O sub-oxide, which may provide new avenues for obtaining highly stable operation in GaN-based devices. • XPS and DFT confirm Ga 2 O's presence in high-pressure water vapor annealed AlGaN/GaN. • Broadening and shifts of Ga 3 d XPS peak suggest sub-oxide formation. • Fitting of deconvoluted XPS profile indicates reasonable inclusion of Ga 2 O peak. • Ga 3 d core level shift by initial state approximation falls within that of Ga 2 O values. • DFT–calculated oxidation state of +1 for Ga confirms its presence in Ga 2 O form. [ABSTRACT FROM AUTHOR]

Abstract Thermally-inducing activation mechanism of titanium dioxide (TiO 2) in air was investigated using X-ray diffraction (XRD) measurement and X-ray photoelectron spectrometry (XPS) under high temperatures. TiO 2 (anatase) crystal expanded toward the c-axis direction as compared with the a-axis direction under heating. These show that the anatase crystal was distorted under high temperature, that is, the lattice vacancy generated in the crystal at high temperatures from the XRD measurement. It was recognized that Ti3+ (binding energy of 457.8 eV) in TiO 2 increased slightly with temperature rise from the XPS. The decreasing of the ratio of O/Ti with heating would indicate that the oxygen vacancy in TiO 2 increased with heating. From these results, the thermal activation of TiO 2 must be induced by the generation of oxygen vacancy and Ti3+ in TiO 2 at high temperatures followed by the formation of trapped electron. The oxidative decomposition of toluene over TiO 2 , as an application to the oxidation of organic compounds, was superior to the only thermal decomposition over SiO 2. Highlights • Thermal activation of TiO 2 is induced by the generation of oxygen vacancy and Ti3+ in TiO 2 at high temperatures followed by the formation of trapped electron. • Oxygen radical must generate from the trapped electron and air. The active radical species decompose gaseous toluene oxidatively. [ABSTRACT FROM AUTHOR]

Abstract The PVP capped Cd and Ag-doped ZnO (Cd:Ag:ZnO: PVP) multifunctional nanocomposites for photocatalytic applications have been synthesized by facile microwave aided precipitation way. The synthesized samples were characterized by XRD, SEM mapping, EDX, HR-TEM, XPS, UV–Vis DR spectroscopy, PL spectroscopy, BET, EIS analysis along with their chief photocatalytic and antibacterial activities. XRD and HRTEM analyses describe the moral crystalline nature. The binding energy and the elements presents were confirmed by XPS analysis. The degradation rate of Cd:Ag:ZnO: PVP nanocomposite was 4.7 times higher than that of undoped ZnO by degrading methylene blue (MB) dye within 120 min under visible-light exposures. Besides, the Cd:Ag:ZnO: PVP nanocomposites have good cycling stability up to five successive cycles of photocatalytic degradation. EIS responses show the improved photocatalytic properties and more charge carrier's ability due to the large surface area (94.51 cm3 g−1). The improved antibacterial activities were projected by Cd:Ag:ZnO: PVP nanocomposites, hence it can be used for environmental remediation application. Graphical abstract Unlabelled Image Highlights • Cd:Ag:ZnO: PVP nanocomposite as photocatalyst has prepared by microwave assisted precipitation method • Ag and Cd with PVP could modify the bandgap of ZnO, enhanced the charge-carrier separation and less recombination rate. • Optimal degradation rate of MB dye reached 99 % at 120 min which was almost 4.7 times of undoped ZnO • Excellent photocatalytic reusability with stability after five successive runs and effective antibacterial activity [ABSTRACT FROM AUTHOR]

Highlights: • Hydrogen enrichment in two dimension Cr 2 O 3 /Fe 2 O 3 (0 0 0 1) interface. • Hydrogen weakens the cleavage strength of Fe-O bond and stability. • Fe and Cr vacancy are better hydrogen trappings compared to O vacancy. • All calculations were carried out using density functional theory. Abstract By means of first-principles calculations based on the density-functional theory, we investigate the vacancy trappings prevent hydrogen damage in two dimension α-Cr 2 O 3 /α-Fe 2 O 3 (0 0 0 1) interface structure. Our calculations show that H atoms prefer to occupy the unoccupied O atoms octahedral interstitial site (O site) in the center of the interface structure without vacancy defect, weakening the cleavage strength of Fe and O atoms and decreasing the work function and stability of interface structure. To prevent hydrogen damage in this interface structure, we model three Fe, Cr and O vacancy defects in this interface structure, respectively. Fe and Cr vacancy defects with lower H binding energy and higher work function, are better hydrogen trappings compared to O vacancy. These results confirm the Fe and Cr vacancy defects are effective hydrogen trappings to prevent hydrogen damage for passive film of steel, which has significant practical implications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • SmNbO 4 (SNO) and SmTaO 4 (STO) precursors were prepared by sol-gel method. • Effect of samarium in Nb5+ and Ta5+ structures was studied using XPS method. • Binding energy differences revealed characterize average Nb O and Ta O bonding. • XPS confirmed Sm3+ and Sm2+ valence states in ratio 21/1 (SNO) and 24/0.3 (STO). Abstract Samarium niobate SmNbO 4 (SNO) and tantalate SmTaO 4 (STO) precursors were prepared by sol-gel method and annealing at 1000 °C. The different polymorphs, orthorhombic and monoclinic SmNbO 4 or tetragonal SmTa 7 O 19 and monoclinic SmTaO 4 were identified. Structural properties of precursors were investigated by the X-ray photoelectron spectroscopy (XPS). Core-level XPS studies of sol-gel SNO and STO were performed for the first time. The binding energy differences Δ(O Nb) = B E (O 1s) – B E (Nb 3d 5/2) and Δ(O Ta) = B E (O 1s) – B E (Ta 4f 7/2) were used as suitable parameter to characterize average Nb O bonding in SNO (323.1 eV) and Ta O bonding in STO (503.9 eV). The Sm 3d 5/2 peak consists of strong features characteristic for Sm3+ (1083.0 eV) with (4f5) electron configuration and Sm2+ (1072 eV) with (4f6) electron configuration. The molar concentration of Sm3+ in SNO and STO was higher (21.0 and 24.7 at.%) than Sm2+ in SNO (1.0 at.%) and STO (0.3 at.%). The XPS demonstrated two valence states of Sm in precursors for application as nanophosphors for lighting and display technologies. [ABSTRACT FROM AUTHOR]

Comprehensive first-principles calculations are performed to investigate the effects of the Silicon clusters (Si-CLs) anchored in nitrogen-doped defective graphene hybrid materials on their potential applications as very promising interface energy storing materials in lithium-ion batteries (LIBs). Three different kinds of defective models, graphitic, pyridinic, and pyrrolic graphene have been introduced in our work. First, the stability of Si-CLs deposited on various N-doped graphene (N-G) sheets has been investigated, and their electronic properties have been explored using first-principles theory. Second, single and multiple lithium (Li) atoms adsorption on Si-CLs anchored in N-G have been carried out to test the Li storage performances of the hybrids. Our results confirm that the N-doped pyridinic graphene hybrid is the most suitable material s for Li adsorption among those three different structural graphene sheets. Due to the symmetric vacancy presence, the binding strength of Si-CLs on N-doped defective graphene (N-DG) is much more powerful than that of graphitic one. Furthermore, the Li uptaking ability of Si/graphene (Si-G) is studied by calculating the binding energy of Li atoms. As a result, that N-G not only can be used as a bumper material restricting Si volume expansion, but can also provide extra intercalation places for Li atoms. [ABSTRACT FROM AUTHOR]

The investigations of interactions between hydrogen and transition metal surfaces are of vital importance to the comprehension of principals involved in many chemical processes. In this work, the influences of coverage on H adsorption and absorption on and in a series of transition metals have been studied. High enough hydrogen coverage is needed to make H absorption much more feasibly. The pre-adsorbed H adatoms can modify H binding energies as well as H absorption energetics and can be felt very deeply in the 2nd-subsurface. As a result, surface penetration of atomic H and further diffusion into the bulk can be facilitated, and in turn the resurfacing process of absorbed H is blocked. [ABSTRACT FROM AUTHOR]

The low cycle stability and low efficiency of lithium-sulfur (Li-S) batteries stemming from the dissolution and diffusion of lithium polysulfides in the electrolyte severely hinder their commercialization. Using first-principles calculations, we demonstrate that the strong Ti-S interaction leads to stable S-terminated Ti 2 C MXene (Ti 2 CS 2 ). Compared with other surface-functionalized Ti 2 C MXenes, such as Ti 2 CO 2 and Ti 2 CF 2 , Ti 2 CS 2 has the highest binding energy to polysulfides and thus highest efficiency to suppress the shuttle phenomenon of polysulfides. In addition, the metallic features of Ti 2 CS 2 facilitate the electrochemical activity during the charge (or discharge) process. The diffusion of Li ions on Ti 2 CS 2 experiences a relatively low energy barrier which is expected to assist the electrochemical process. These results provide a surface-functionalization strategy to design of sulfur host materials for high performance Li-S batteries. [ABSTRACT FROM AUTHOR]

The structural and electronic effects produced by several gold atoms embedded into sulfur vacancies of molybdenum disulfide monolayers are assessed theoretically for the first time. These MoS 2 defects need less formation energies, of about 3 eV per sulfur vacancy, than those found for other commonly studied bidimensional systems. The defects introduce several new states, mostly from the molybdenum d orbitals, in the band gap. The gap is reduced by means of the sulfur vacancies; which are lowered up to 0.570 eV for the tri-sulfur vacancies. Previously, the inert MoS 2 monolayer is activated through sulfur vacancies, which becomes able to trap gold atoms. The gold clusters occupying sulfur sites are energetically favorable, as shown by the estimated binding energies, higher than −2.4 eV per atom. These defects create states in the band gap, which arise from the molybdenum and gold orbitals, gradually reducing the energy up to 0.450 eV. Moreover, the Au atoms receive charges from Mo atoms; being able to transfer it towards other species. That is, the gold atoms may define the catalytic site of the MoS 2 monolayer. In fact, those embedded atoms could be suitable for nucleophilic as well as electrophilic attacks according to Fukui indices. Embedded clusters enhanced the reactivity of the whole material which is suggested to act as a catalyst, due to the properties found on it. [ABSTRACT FROM AUTHOR]

[Display omitted] • The work provides a rapid preparation method for defective HKUST-1 with hierarchical micropores and mesopores and Cu1+/Cu2+ mixed-valence sites. • Defective HKUST-1 exhibited specific loading of silibinin A&B with larger molecules from silymarin within 5 min, and high separation efficiency with 91.2% purity after primary separation. • The site competition mechanism for specific recognition and loading of active monomers into mesopores of defective MOF was elucidated at molecular level. • Silibinin A&B preferentially acted on Cu2+ and Cu1+ clusters with the highest binding energy via hydrogen and coordination bonds, respectively. • The separation approach by defective MOF is easy to operate, and requires no specific equipment. Discovering and separating active monomers from natural products is an efficient way to develop new drugs, but faces the difficulty in complex and time-consuming separation process. Metal-organic frameworks (MOFs) are considered a promising separation strategy due to their molecular recognition properties, but their microporous nature poses challenges for capturing most natural compounds with molecule sizes larger than 20 Å. For the first time, this study proposed a simple and efficient approach to separate active monomeric components with larger diameters from structurally similar natural compounds by defect modulation strategy. In this study, defective HKUST-1 with hierarchical microporous/ mesoporous structures and Cu1+/Cu2+ mixed-valence sites was rapidly synthesized. The defective MOF demonstrated specific loading of silibinin A&B from silymarin containing seven structurally similar flavonoids within 5 min, and high separation capacity with the purity of ∼91.2% after primary separation. FTIR, XPS, and DFT calculation revealed the site competition mechanism for specific recognition and loading, where silibinin A&B preferentially acted on Cu2+ and Cu1+ clusters with the highest binding energy via hydrogen and coordination bonds, respectively. Compared to traditional separation techniques, the separation approach via defective MOF shows multiple advantages including high specificity, high separation efficiency, and easy to operate. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ calibrated assignments to carbon and oxygen species of in situ IR and XPS. • Correlating the O 1 s bonding energies of In 2 O 3 surface with both in situ XPS and DFT. • Reveal the surface structures of important O species on In 2 O 3 for CO 2 hydrogenation. • Formation of O v does not induce new feature to O1s binding energy. • CO 2 exposure induced carbonates formation on In 2 O 3 replaces the original hydroxyl. The In 2 O 3 catalyst has been shown to have a high activity for CO 2 hydrogenation to methanol. For this high pressure process, reliable spectral assignment of surface species formed by interaction with CO 2 , H 2 O, and other major reaction ingredients, is the key step to achieve mechanistic understanding. In this study, in situ IR and XPS are performed to investigate the O1s binding energies of the adsorbates induced by CO 2 and H 2 O treatments along with density functional theory (DFT) simulations to further correlate the calibrated assignments with surface structures. Time resolved IR indicates that carbonates formation induced by CO 2 exposure replaces the original hydroxyl on In 2 O 3 , and XPS further reveals that these two oxygen species have very similar binding energies (532.0 ± 0.2 eV). Computational results using the In 2 O 3 (1 1 0) and (1 1 1) slab models give good agreement with the XPS experiments, further suggesting that the amount of oxygen vacancy concentration does not induce new lattice oxygen O1s binding energy, but resulting in a slight shift to a higher binding energy instead. Our results provide useful structure information for the In 2 O 3 catalyst surface and shed light for further investigations into its kinetic behavior under methanol synthesis condition. [ABSTRACT FROM AUTHOR]

[Display omitted] • H and Cl atoms produced from SiH 2 Cl 2 (DCS) decomposition are strongly bound to an amine-functionalized SiN surface by forming –NH 3 +Cl- complexes. • Ammonium chloride (–NH 3 +Cl-) salt formation inhibits DCS adsorption and decomposition, leading to a decrease in the SiN growth rate. • Atomic-level insights into the effects of by-products and surface functionality are crucial for design and selection of precursors as well as optimization of the SiN PEALD process. Plasma-enhanced atomic layer deposition (PEALD) has been demonstrated to be a promising technique for controlled growth of silicon nitride (SiN x) thin films. Based on first-principles calculations, we present the effects of by-product production on the reaction of dichlorosilane (DCS) as the Si precursor with a hydrogen-terminated N-rich surface created upon ammonia (NH 3) plasma treatment relevant to thin film growth. The presence of amines, especially primary amines (–NH 2), plays a key role in DCS decomposition by generating H and Cl atoms as by-products. Our work clearly demonstrates that the by-products can be strongly bound to the surface by forming stable –NH 3 +Cl- complexes, which may in turn affect the SiN x ALD process. The HCl desorption reaction, i.e., –NH 3 +Cl- → –NH 2 + HCl(g), is predicted to be endothermic by 1.1–1.2 eV, depending on HCl surface coverage. The large HCl binding energy suggests that a high thermal energy would be required for its removal from the surface, as evidenced by results from experimental spectroscopic analysis. We also discuss how the by-product presence inhibits DCS adsorption and decomposition, leading to a decrease in the SiN x growth rate. [ABSTRACT FROM AUTHOR]

First-principles calculations are performed to predicted the physical properties and property-guided potential applications of group IV-V compound MX 2 (M = Si, Ge, Sn; X= N, P, As) and its Janus structure MXY (X ≠ Y). [Display omitted] • 8 out of 18 monolayers from group IV-V compound MX 2 are demonstrated to be thermodynamically, dynamically, and mechanically stable. • The screened 2D materials have suitable band edge positions, excellent solar absorption, moderate exciton binding energies, and fair light conversion rates. • The calculated piezoelectric coefficients d 11 for the MX 2 and MXY monolayers are in the range from 8.0 to 26.9 pm/V. • The property-guided potential applications in water splitting are thoroughly examined. Using first-principles calculations, we predicted the physical properties and property-guided potential applications of group IV-V compound MX 2 (M = Si, Ge, Sn; X = N, P, As) and its Janus structure MXY (X ≠ Y), which are isostructural to the synthesized compound SiP 2. We demonstrated that 8 out of 18 monolayers are stable in thermodynamics, dynamics, and mechanics. Electronic calculations showed that these monolayers are semiconducting with optimal bandgaps ranging from 0.99 to 2.33 eV. The calculated piezoelectric coefficients d 11 for the MX 2 and MXY monolayers are in the range from 8.0 to 26.9 pm/V. Moreover, our results showed that these 2D materials have suitable band edge positions, excellent solar absorption, moderate exciton binding energies, and fair light conversion rates, rendering them potential application in photocatalytic water splitting. Our results may be instructive for the design, synthesis, and applications of group IV-V compounds for the future electronic, optoelectronic devices, and hydrogen producing materials. [ABSTRACT FROM AUTHOR]

[Display omitted] We investigated systematically adsorption behaviors, electronic and gas-sensing properties of SF 6 decomposed gases, i.e., H 2 S, SO 2 , HF, SOF 2 and SO 2 F 2 , on the C 3 N 4 monolayers and heterojunctions via first-principles methods. The pure C 3 N 4 monolayer was predicted to be reusable gas sensors for H 2 S detection with high sensitivity at room temperature in a dry environment. We further found two stable configurations of the C 3 N 4 /graphene heterojunctions, (simply as R-C 3 N 4 /graphene and T-C 3 N 4 /graphene). Their stabilities were confirmed by lattice mismatch, binding energy and MD simulations, and both of them can be distinguished via their different optical properties. Finally, we found that the T-C 3 N 4 /graphene heterojunction has little sensitivity to SF 6 decomposed species, which indicates that the T-C 3 N 4 /graphene heterojunction is unaccommodated for SF 6 decomposed gas sensor, however, the R-C 3 N 4 /graphene heterojunction could be viewed as a promising gas sensor towards H 2 S, SOF 2 , and SO 2 F 2 , whether the humidity exists or not. [ABSTRACT FROM AUTHOR]

The accuracy of chemical-state determination by x-ray photoelectron spectroscopy (XPS) used in contemporary advanced materials research relies on a trustworthy binding energy (BE) referencing method. The C 1s peak corresponding to C C/C H bonds of adventitious carbon (AdC), present on a majority of air-exposed samples, is most commonly employed for this purpose, irrespective of whether samples are electrically conducting or not. Contrary to conventional practice, which takes the BE of C 1s peak of AdC as a constant, we find that the C 1s peak position E B F varies over an alarmingly large range, from 284.08 to 286.74 eV, depending on the substrate, for nearly a hundred predominantly thin-film samples comprising metals, nitrides, carbides, borides, oxides, and oxynitrides. Our consistent measurements also show that, independent of materials system, E B F of the C 1s peak is closely correlated to the sample work function ϕ SA , such that the sum E B F + ϕ SA is constant, indicating that the electronic levels of the AdC layer align to the vacuum level, rather than to the Fermi level as commonly assumed. This phenomenon can be understood given that the AdC layer is not an inherent part of the analyzed sample and that the interaction to the substrate is weak, showing in that a common Fermi level is not established at the interface. Thus, a straightforward complementary measurement of ϕ SA enables using the C 1s peak of AdC for the purpose of BE–scale calibration for samples exhibiting decent electrical conductivity. This new practice resolves problems associated with the conventional method and allows for more reliable bonding assignments. It is thus advisable that both ASTM and ISO XPS referencing guides relying on the use of AdC should be reviewed. [ABSTRACT FROM AUTHOR]

To understand the underlying physics behind the interaction of biomolecules with the nanomaterials to use them practically as bio-nanomaterials is very crucial. A first principles calculation under the frame work of density functional theory is executed to investigate the electronic structures and binding properties of alkaloids (Caffeine and Nicotine) over single walled boron nitride nanotube (BNNT) and boron nitride nanoribbon (BNNR) to determine their suitability towards filtration or sensing of these molecules. We have also used GGA-PBE scheme with the inclusion of Van der Waals (vdW) interaction based on DFT-D2. Increase in the accuracy by incorporating the dispersion correction in the calculation is observed for the long range Van der Waals interaction. Binding energy range of BNNT and BNNR with both alkaloids have been found to be −0.35 to −0.76 eV and −0.45 to −0.91 eV respectively which together with the binding distance shows physisorption binding of these molecules to the both nanostructures. The transfer of charge between the BN nanostructures and the adsorbed molecule has also been analysed by using Lowdin charge analysis. The sensitivity of both nanostructures BNNT and BNNR towards both alkaloids is observed through electronic structure calculations, density of states and quantum conductance . The binding of both alkaloids with BNNR is stronger. The analysis of the calculated properties suggests absence of covalent interaction between the considered species (BNNT/BNNR) and alkaloids. The study may be useful in designing the boron nitride nanostructure based sensing device for alkaloids. [ABSTRACT FROM AUTHOR]

This work reports on theoretical investigation of the temperature and hydrostatic pressure effects on the confined donor impurity in a AlGaAs-GaAs hollow cylindrical core-shell quantum dot. The charges are assumed to be completely confined to the interior of the shell with approximately rigid walls. Within the framework of the effective-mass approximation and by using a variational approach, we have computed the donor binding energies as a function of the shell size in order to study the behavior of the electron-impurity attraction for a very small thickness under the influence of both temperature and hydrostatic pressure. Our results show that the temperature and hydrostatic pressure have a significant influence on the impurity binding energy for large shell quantum dots. It will be shown that the binding energy is more pronounced with increasing pressure and decreasing temperature for any impurity position and quantum dot size. The photoionization cross section is also analyzed by considering only the in-plane incident radiation polarization. Its behavior is investigated as a function of photon energy for different values of pressure and temperature. The opposite effects caused by temperature and hydrostatic pressure reveal a big practical interest and offer an alternative way to tuning of correlated electron-impurity transitions in optoelectronic devices. [ABSTRACT FROM AUTHOR]

We report x -ray photoelectron spectroscopy (XPS) core level binding energies (BE’s) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar + ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2–0.5 eV towards lower BE. These destructive effects of Ar + ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table ( 3d , 4d , and 5d ) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides. [ABSTRACT FROM AUTHOR]

A series of ZnMgO oxide films single doped with arsenic was grown by plasma assisted molecular beam epitaxy method. The concentration of Mg in Zn 1-x Mg x O alloys was evaluated on the basis of X-Ray photoelectron spectroscopy (XPS). Changes of the band gap energy in Zn 1−x Mg x O were evidenced by cathodoluminescence measurements. Analysis of high resolution As 3d XPS spectra revealed three arsenic states with binding energies of ∼41 eV, 44.2 eV and 45.6 eV assigned to: deep acceptor of As O , acceptor As Zn -2V Zn and donor As Zn , respectively. Small concentrations of As O species were detected in all samples. The As contribution due to As Zn -2V Zn centers was found to be intensive, and increased with the concentration of Mg. [ABSTRACT FROM AUTHOR]

The adsorption behaviors and properties of hydrazine (N 2 H 4 ) molecules on pristine and Li-decorated graphene sheets were investigated by means of first-principles based on density functional theory. We systematically analyzed the optimal geometry, average binding energy, charge transfer, charge density difference and density of states of N 2 H 4 molecules adsorbed on pristine and Li-decorated graphene sheets. It is found that the interaction between single N 2 H 4 molecule and pristine graphene is weak physisorption with the low binding energy of −0.026 eV, suggesting that the pristine graphene sheet is insensitive to the presence of N 2 H 4 molecule. However, it is markedly enhanced after lithium decoration with the high binding energy of −1.004 eV, verifying that the Li-decorated graphene sheet is significantly sensitive to detect N 2 H 4 molecule. Meanwhile, the effects of the concentrations of N 2 H 4 molecules on two different substrates were studied detailedly. For pristine graphene substrate, the average binding energy augments apparently with increasing the number of N 2 H 4 molecules, which is mainly attributed to the van der Waals interactions and hydrogen bonds among N 2 H 4 clusters. Li-decorated graphene sheet has still a strong affinity to N 2 H 4 molecules despite the corresponding average binding energy emerges a contrary tendency. Overall, Li-decorated graphene sheet could be considered as a potential gas sensor in field of hydrazine molecules. [ABSTRACT FROM AUTHOR]