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The incorporation of potassium into perovskite solar cells (PSCs) has been empirically validated to mitigate hysteresis phenomena and boost the power conversion efficiency (PCE). However, the doping mechanism of potassium ions in the perovskite film and their effect on photocarrier recombination remains a topic of debate. Here, we grew doped MAPbI3: K single crystals by inverse temperature crystallization using KI as a dopant, and then perovskite thin films were spin-coated with dissolved MAPbI3: K crystals as a precursor. The doped MAPbI3: K perovskite films exhibit better crystal quality with large columnar grains and lower defect density. Employing Hall effect, ultraviolet photoelectron spectroscopy, and Kelvin probe force microscopy measurements, we definitively demonstrate that K-doping transforms the conductivity type of the perovskite film from a marginally N-type to a distinct P-type semiconductor. Furthermore, this doping strategy induces a concurrent downward shift in both the conduction band minimum and valence band maximum. As a result, the PCE of the PSCs increases from 15.15% to an impressive 20.66%, and the J–V curve hysteresis almost disappears. Additionally, theoretical simulations using SCAPS-1D software reveal a profound modification in the device's energy band diagram after K+-doping. Specifically, the energy level offset between the perovskite layer and the electron transport layer diminishes from 0.24 to 0.14 eV, with a result of bigger quasi-Fermi energy level splitting. This, in turn, elevates the open-circuit voltage (Voc) of the doped perovskite solar cell, underscoring the profound impact of potassium doping on enhancing PSC performance. [ABSTRACT FROM AUTHOR]

In order to understand the dispersion interactions between molecules and to provide information about the potential energy surface of geometry evolutions, NbN12− and N2·NbN12− complexes were investigated by using photoelectron spectroscopy and ab initio calculations. The experimental adiabatic detachment energy (ADE) and vertical detachment energy (VDE) of NbN12− were both measured to be 2.129 ± 0.030 eV. The experimental ADE and VDE of N2·NbN12− were measured to be 2.17 ± 0.05 and 2.23 ± 0.05 eV, respectively, which are slightly higher than those of NbN12−. The structures of NbN12−/0 were confirmed to be hexacoordinated octahedrons. The investigation of N2·NbN12− structures shows that it is stable for N2 to bind to the face or vertex site of octahedron NbN12−; the face-side-on structure has the lowest energy. The calculations based on symmetry-adapted perturbation theory suggest that the dispersion term is predominant and leads to the stability of N2·NbN12− complexes. [ABSTRACT FROM AUTHOR]

The valence and core photoelectron spectra of three substituted disulfide systems, α-lipoic acid, trans-4,5-dihydroxy-1,2-dithiane, and di-Boc-cystamine, are presented alongside detailed theoretical analysis based on equation-of-motion coupled-cluster singles doubles for ionization potentials and the nuclear ensemble approach. A comparison of the linear and five- and six-membered ring cyclic structures reveals that the energetic separation of the non-bonding sulfur orbitals can be used to calculate a reliable estimate of the C–S–S–C dihedral angle, even for substituted disulfides, and that the sulfur 2p, oxygen 1s, and valence band photoelectron spectra are a useful site-specific probe of hydrogen bonding. [ABSTRACT FROM AUTHOR]

Using size-selected anion photoelectron spectroscopy and density functional theory, we investigated the structures and properties of fluorinated bimetallic clusters CoAuF1-2− and CuAuF1-2− and their neutrals. Both experimental and theoretical results show that in these cluster anions, Au behaves like a halogen atom. For example, the measured vertical detachment energies (VDEs) of CoAuF− (2.00 ± 0.08 eV) and CuAuF− (3.8 ± 0.1 eV) are close to those of CoF2− (2.12 ± 0.08 eV) and CuF2− (3.58 ± 0.08 eV), respectively. The theoretical results show that the geometries and electronic structures of CoAuF− and CuAuF− are similar to those of CoF2− and CuF2−. The natural population analysis and natural electron configuration analyses further confirm that the electronic properties of Au in MAuF− (M = Co, Cu) mimic those of MF2−. In addition, the electron localization function analyses show that the M-Au chemical bonds are similar to the corresponding M-F chemical bonds, providing evidence for the ionic nature of the interactions. When a second F atom is attached to the CoAuF− and CuAuF− clusters, the VDEs of the resulting CoAuF2− and CuAuF2− are 4.38 ± 0.08 eV and 3.71 ± 0.08 eV, respectively, indicating their superhalogen character as these values are higher than those of halogen anions. The results may be useful for understanding the properties of gold at the nanoscale that play an important role in catalysis and nanotechnology. [ABSTRACT FROM AUTHOR]

The recent discovery of cyano-substituted aromatic and two-ring polycyclic aromatic hydrocarbon molecules in Taurus Molecular Cloud-1 has prompted questions on how the electronic structure and excited-state dynamics of these molecules are linked with their existence and abundance. Here, we report a photodetachment and frequency- and angle-resolved photoelectron spectroscopy study of jet-cooled para-deprotonated benzonitrile (p-[Bzn-H]−). The adiabatic detachment energy was determined as 1.70 ± 0.01 eV, in good agreement with CCSD(T)/aug-cc-pVTZ calculations. The spectra across the first few electron-volts above threshold are dominated by prompt autodetachment processes associated with excitation of at least five short-lived (tens of femtoseconds) temporary anion shaped resonances since excitation cross sections are several orders of magnitude larger than direct photodetachment cross sections. The photoexcitation vibronic profile is dominated by a ≈640 cm−1 ring deformation mode. [Bzn-H]− lacks a valence-localized excited state situated below the detachment threshold and does not exhibit thermionic emission following excitation of the temporary anion resonances. Thus, [Bzn-H]− is unlikely to be stable in many interstellar environments. [ABSTRACT FROM AUTHOR]

Conducting a comprehensive molecular-level evaluation of a photoacid generator (PAG) and its subsequent impact on lithography performance can facilitate the rational design of a promising 193 nm photoresist tailored to specific requirements. In this study, we integrated spectroscopy and computational techniques to meticulously investigate the pivotal factors of three prototypical PAG anions, p-toluenesulfonate (pTS−), 2-(trifluoromethyl)benzene-1-sulfonate (TFMBS−), and triflate (TF−), in the lithography process. Our findings reveal a significant redshift in the absorption spectra caused by specific PAG anions, attributed to their involvement in electronic transition processes, thereby enhancing the transparency of the standard PAG cation, triphenylsulfonium (TPS+), particularly at ∼193 nm. Furthermore, the electronic stability of PAG anions can be enhanced by solvent effects with varying degrees of strength. We observed the lowest vertical detachment energy of 6.6 eV of pTS− in PGMEA solution based on the polarizable continuum model, which prevents anion loss at 193 nm lithography. In addition, our findings indicate gas-phase proton affinity values of 316.4 kcal/mol for pTS−, 308.1 kcal/mol for TFMBS−, and 303.2 kcal/mol for TF−, which suggest the increasing acidity strength, yet even the weakest acid pTS− is still stronger than strong acid HBr. The photolysis of TPS+-based PAG, TPS+·pTS−, generated an excited state leading to homolysis bond cleavage with the lowest reaction energy of 83 kcal/mol. Overall, the PAG anion pTS− displayed moderate acidity, possessed the lowest photolysis reaction energy, and demonstrated an appropriate redshift. These properties collectively render it a promising candidate for an effective acid producer. [ABSTRACT FROM AUTHOR]

Granular metals (GMs), consisting of metal nanoparticles separated by an insulating matrix, frequently serve as a platform for fundamental electron transport studies. However, few technologically mature devices incorporating GMs have been realized, in large part because intrinsic defects (e.g., electron trapping sites and metal/insulator interfacial defects) frequently impede electron transport, particularly in GMs that do not contain noble metals. Here, we demonstrate that such defects can be minimized in molybdenum–silicon nitride (Mo–SiNx) GMs via optimization of the sputter deposition atmosphere. For Mo–SiNx GMs deposited in a mixed Ar/N2 environment, x-ray photoemission spectroscopy shows a 40%–60% reduction of interfacial Mo-silicide defects compared to Mo–SiNx GMs sputtered in a pure Ar environment. Electron transport measurements confirm the reduced defect density; the dc conductivity improved (decreased) by 104–105 and the activation energy for variable-range hopping increased 10×. Since GMs are disordered materials, the GM nanostructure should, theoretically, support a universal power law (UPL) response; in practice, that response is generally overwhelmed by resistive (defective) transport. Here, the defect-minimized Mo–SiNx GMs display a superlinear UPL response, which we quantify as the ratio of the conductivity at 1 MHz to that at dc, Δ σ ω. Remarkably, these GMs display a Δ σ ω up to 107, a three-orders-of-magnitude improved response than previously reported for GMs. By enabling high-performance electric transport with a non-noble metal GM, this work represents an important step toward both new fundamental UPL research and scalable, mature GM device applications. [ABSTRACT FROM AUTHOR]

The ultrafast relaxation dynamics of tetracene following UV excitation to the bright singlet state S6 has been studied with time-resolved photoelectron spectroscopy. With the help of high-level ab initio multireference perturbation theory calculations, we assign photoelectron signals to intermediate dark electronic states S3, S4, and S5 as well as to a low-lying electronic state S2. The energetic structure of these dark states has not been determined experimentally previously. The time-dependent photoelectron yields assigned to the states S6, S5, and S4 have been analyzed and reveal the depopulation of S6 within 60 fs, while S5 and S4 are populated with delays of about 50 and 80 fs. The dynamics of the lower-lying states S3 and S2 seem to agree with a delayed population coinciding with the depopulation of the higher-lying states S4–S6 but could not be elucidated in full detail due to the low signal levels of the corresponding two-photon ionization probe processes. [ABSTRACT FROM AUTHOR]

Alkali metal doping of multi-walled carbon nanotubes is of great interest, both fundamentally to explore the effect of dopants on quasi-one-dimensional electrical systems and for energy applications such as alkali metal storage. We present an investigation with complementary photoemission and Raman spectroscopies, fully carried out in an ultra-high vacuum, to unveil the electronic and vibrational response of a forest of highly aligned multi-walled carbon nanotubes by in situ potassium doping. The charge donation by the alkali adatoms induces a plasmon mode, and the density of states undergoes an energy shift consistent with electron donation and band filling of the multi-walled carbon nanotube band structure. The π-states in the valence band and the Raman peaks unveil an evolution that can be ascribed to charge donation and partially to a tensile strain exerted by the K adatoms on the carbon lattice. All these effects are thermally reversible, fostering these materials as a potential system for electronic charge harvesting. [ABSTRACT FROM AUTHOR]

The outstanding catalytic property of cerium oxide (CeO2) strongly depends on the polaron formation due to the oxygen vacancy ( V ̈ O ) defect and Ce4+ to Ce3+ transformation. Temperature plays an important role in the case of polaron generation in CeO2 and highly influences its electrical transport properties. Therefore, a much needed attention is required for detailed understanding of the effect of temperature on polaron formation and oxygen vacancy migration to get an idea about the improvement in the redox property of ceria. In this work, we have probed the generation of polarons in CeO2 thin-film deposited on a silicon (Si) substrate using the resonance photoemission spectroscopy (RPES) study. The RPES data show an increase in polaron density at the substrate–film interface of the thermally annealed film, indicating the formation of an interfacial Ce2O3 layer, which is, indeed, a phase change from the cubic to hexagonal structure. This leads to a modified electronic band structure, which has an impact on the capacitance–voltage (C–V) characteristics. This result nicely correlates the microscopic property of polarons and the macroscopic transport property of ceria. [ABSTRACT FROM AUTHOR]

In the present study, we have investigated the effect of magnetic Cr doping on the transport properties of a sputtered Bi2Se3 thin film on the SrTiO3 (110) substrate. The high-resolution x-ray diffraction and Raman spectroscopy measurements revealed the growth of rhombohedral Bi2Se3 thin films. Further electronic and compositional analysis was done by x-ray photoemission spectroscopy and Rutherford backscattering spectroscopy, and the x-value was estimated to be 0.18 in the Bi2−xCrxSe3 thin film. The variation in the resistivity with temperature (2–300 K) revealed the metallic nature in undoped Bi2Se3 up to 30 K and upturn resistivity below 30 K. The Cr-doped Bi2Se3 resistivity data show a traditional semiconducting nature up to 25 K and take an abrupt upturn resistivity below 25 K. The resistivity behavior of both samples was explained by adopting a model that consists of the total resistance, a combination of bulk and surface resistance in parallel. The bulk bandgap value determined by this method is obtained to be 256 meV in an undoped Bi2Se3 thin film. Magnetoconductance data of the undoped thin film revealed a weak anti-localization (WAL) effect, while the Cr-doped thin film showed a weak localization (WL) effect at low temperatures (<50 K). At low magnetic field and low temperature, a competing nature of WAL and WL effects was prominent in the Cr-doped film. A drastic increase in the electrical resistance suggests that Cr doping can significantly modify the electrical properties of Bi2Se3 thin films, which could have potential applications in futuristic devices. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are common atmospheric pollutants, and they are also ubiquitous in the interstellar medium. Here, we report the study of a complex O-containing PAH anion, the deprotonated 2-hydroxytriphenylene (2-OtPh–), using high-resolution photoelectron imaging and photodetachment spectroscopy of cryogenically cooled anions. Vibrationally resolved photoelectron spectra yield the electron affinity of the 2-OtPh radical as 2.629(1) eV and several vibrational frequencies for its ground electronic state. Photodetachment spectroscopy reveals bound valence excited electronic states for the 2-OtPh– anion, with unprecedentedly rich vibronic features. Evidence is presented for a low-lying triplet state (T1) and two singlet states (S1 and S2) below the detachment threshold. Single-color resonant two-photon photoelectron spectroscopy uncovers rich photophysics for the 2-OtPh– anion, including vibrational relaxation in S1, internal conversion to the ground state of 2-OtPh–, intersystem crossing from S2 to T1, and a long-lived autodetaching shape resonance about 1.3 eV above the detachment threshold. The rich electronic structure and photophysics afforded by the current study suggest that 2-OtPh– would be an interesting system for pump–probe experiments to unravel the dynamics of the excited states of this complex PAH anion. [ABSTRACT FROM AUTHOR]

The interaction of Ca evaporated in vacuum onto a 2H–NbSe2 surface held at room temperature was studied by photoelectron spectroscopy. Indications of an intercalation reaction were observed initially, but larger Ca depositions resulted in a layer-breaking reaction producing a disordered overlayer of varying compositions. The layer-breaking reaction is likely due to the intercalation compound becoming unstable as the local Ca concentration exceeds the threshold value. Continued Ca depositions eventually resulted in the growth of three-dimensional islands of Ca metal, exposing relatively unaffected NbSe2 layers between the Ca islands. [ABSTRACT FROM AUTHOR]

This study presents a collaborative experimental and theoretical investigation into the structures and electronic properties of niobium-doped germanium clusters. Anion photoelectron spectra for Nb1–2Gen− (n = 3–7) clusters were acquired using 266 nm photon energies, enabling the determination of adiabatic detachment energies and vertical detachment energies. In conjunction with these experimental measurements, density functional theory (DFT) calculations were conducted to validate the experimentally obtained electron detachment energies and elucidate the geometric and electronic structures of each anionic cluster. The agreement between DFT calculations and experimental data establishes a solid foundation for assessing the structural evolution and electronic properties of niobium-doped germanium clusters. It is noted that both neutral and anionic clusters exhibit predominantly similar overall structural characteristics, with the exception of Nb2Ge6− and Nb2Ge6. Furthermore, this investigation emphasizes the exceptional chemical stability of the D3d symmetric chair-shaped structure in Nb2Ge6−, providing insights into its bonding characteristics. [ABSTRACT FROM AUTHOR]

Magnetic nanometric skyrmions are small complex vortex-like topological defects, mainly found in non-centrosymmetric crystals such as MnSi. They have potential applications for future spintronic devices. In this article, the structural, electronic, and magnetic states of the Mn atoms in a polycrystalline MnSi thin film facing a c-sapphire substrate were studied using x-ray diffraction, x-ray photo-emission spectroscopy, resonance photoemission spectroscopy (RPES), and extended x-ray absorption fine structure (EXAFS). The valence band spectra indicate the metallic nature of the film. The RPES study reveals the presence of major itinerant Mn 3d states near EF and also the mixed Mn 3d and Si 3s–3p states from 5.3 to 11.3 eV. The EXAFS spectrum does not show the existence of oxygen vacancies in the system, and the obtained magnetic moment in the non-stoichiometric MnSi thin film is a combination of the partially itinerant and partially localized Mn 3d states. [ABSTRACT FROM AUTHOR]

The present study focuses on the oxygen (O)-ion implantation-induced structural and electronic modifications in the single crystals of strontium-titanate (s-STO) using synchrotron-based x-ray diffraction (XRD), x-ray photoemission spectroscopy (XPS), and resonant x-ray photoemission spectroscopy. The crystallinity of the epitaxially aligned phases of s-STO is confirmed through XRD. This direct evidence of heavy ion implantation is supported by the Monte Carlo-based simulation of stopping and range of ions in matter/transport of ions in matter. XPS at different core levels is performed to detect the exact oxidation state of Ti ions in s-STO. The dominance of Ti3+ over Ti4+ upon oxygen implantation suggests the disorder in the perovskite material, primarily in the form of oxygen vacancies (VO). The confirmation of VO is explicitly shown by the enhancement in the spectral area of the assigned peak in the O 1s XPS. Resonant photoemission spectroscopy measurements were performed by varying photon energy from 32 to 46 eV to understand the nature of the valence band electronic structure of s-STO. The resonance in the different hybridized states of s-STO is confirmed by the spectral features of constant initial state plots. There is a correlation between the defective state of Ti and the oxygen-deficient state. The transformation from SrTiO3 to SrTiO2.5, partially or completely, is essentially required to underline any modification in the electronic properties of s-STO. s-STO is in a mixed state of an ionic conductor and an electronic conductor. This study outlines the creation of VO due to O-ion implantation and investigates the changes in the electronic structures of s-STO. [ABSTRACT FROM AUTHOR]

Element substitution of BaTiO 3 -based compounds has been demonstrated as a powerful way for designing novel electronic materials (such as polar metals and multiferroics). To trigger magnetism into ferroelectric BaTiO 3 , general substituted elements are magnetic transition metals (such as Mn, Fe, and Co). The doping effect of rare-earth elements (such as Dy) in BaTiO 3 -based compounds was barely investigated. Here, we report the coexistence of magnetism and electric polarization in epitaxial Dy 0.5 Ba 0.5 TiO 3 films. The single-crystalline films were synthesized by high-pressure magnetron sputtering. The crystal and electronic structures were characterized by high-resolution x-ray diffraction, x-ray photoemission spectroscopy, and resonant soft x-ray absorption spectroscopy. Room-temperature electric polarization was demonstrated by optical second-harmonic generation. Temperature-dependent magnetic hysteresis loops were measured to reveal the revolution of magnetism on temperature. Surprisingly, it is uncovered that the Curie temperature of electric-polarized Dy 0.5 Ba 0.5 TiO 3 films is around 100 K, far above the critical temperature of non-polarized DyTiO 3 (near 60 K). Our work provides another view to understand the magnetoelectric materials. [ABSTRACT FROM AUTHOR]

Alkali metal dosing has nowadays been extensively used in angle-resolved photoemission spectroscopy (ARPES) for the in situ surface electron doping of materials to provide access to the unoccupied states. This technique also gives rise to nontrivial physical phenomena, such as the appearance of quantum well states and effects due to alkali metal intercalation. Here, we uncovered a previously unobserved type of electronic behavior induced by alkali metal dosing. By employing ARPES to study the evolution of the electronic structure of the Ti2O3 thin film upon rubidium (Rb) dosing, we found that the electron chemical potential of the system remains unchanged throughout the process. Interestingly, a series of electron-like band dispersions first appear with Rb dosing. A further increase in the Rb dosage leads to the eventual disappearance of the electron-like bands and the emergence of a set of hole-like bands. Our finding enriches the phenomenology brought about by alkali metal surface dosing, suggesting a novel functionality of this popular surface doping technique. [ABSTRACT FROM AUTHOR]

Illumination stress (IS) and negative bias under illumination stress (NBIS) cause considerable device instability in thin-film transistors based on amorphous In–Ga–Zn–O (a-IGZO). Models using in-gap states are suggested to explain device instability. Therefore, to provide reliably their density of states (DOS), this study investigated the valence band, conduction band, and in-gap states of an a-IGZO thin film. The DOS of in-gap states was directly determined in a dynamic range of six orders of magnitude through constant final state yield spectroscopy (CFS-YS) using low-energy and low-flux photons. Furthermore, light irradiation irreversibly induced extra in-gap states near the Fermi level and shifted the Fermi level to the vacuum level side, which should be related to the device instability due to IS and NBIS. Hard x-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy using synchrotron radiation observed the large DOS of in-gap states near the Fermi level as in previous works. Here, we reveal that they are not intrinsic electronic states of undamaged a-IGZO, but induced by the intense measurement light of synchrotron radiation. This study demonstrates that CFS-YS is useful for determining the reliable DOS of the in-gap states for samples that are sensitive to light irradiation. The absorption spectrum measured through photothermal deflection spectroscopy is interpreted based on DOS directly determined via photoemission spectroscopies. This indicates that the line shape in the energy region below the region assigned to the Urbach tail in previous works actually roughly reflects the DOS of occupied in-gap states. [ABSTRACT FROM AUTHOR]

MoS2 has generated significant attention due to its unique electronic properties and versatile applications. Being a van der Waals material, MoS2 is expected to exhibit an inert surface due to lack of dangling bond. However, our photoemission study finds MoS2 to be highly sensitive toward residual gases. The position of the valence band maximum (VBM) shifts even in a vacuum of 10−10 Torr. We find this to be due to CO adsorption causing unintentional electron doping. The time evolution of the position of VBM is exponential, and it reaches two different saturation points, depending on whether the sample is exposed to ultraviolet (UV) radiation or not. Our XPS (x-ray photoemission spectroscopy) study shows no time-dependent escape of sulfur, which was in a previous study attributed to a VBM shift. The VBM shift can be reversed by annealing, sputtering, and UV light, which desorb CO gases. The study shows that the MoS2 surface is easily doped, which offers the possibility of using it as a sensor but in many other applications could diminish device performance and needs to be considered. [ABSTRACT FROM AUTHOR]

MoS2 has generated significant attention due to its unique electronic properties and versatile applications. Being a van der Waals material, MoS2 is expected to exhibit an inert surface due to lack of dangling bond. However, our photoemission study finds MoS2 to be highly sensitive toward residual gases. The position of the valence band maximum (VBM) shifts even in a vacuum of 10−10 Torr. We find this to be due to CO adsorption causing unintentional electron doping. The time evolution of the position of VBM is exponential, and it reaches two different saturation points, depending on whether the sample is exposed to ultraviolet (UV) radiation or not. Our XPS (x-ray photoemission spectroscopy) study shows no time-dependent escape of sulfur, which was in a previous study attributed to a VBM shift. The VBM shift can be reversed by annealing, sputtering, and UV light, which desorb CO gases. The study shows that the MoS2 surface is easily doped, which offers the possibility of using it as a sensor but in many other applications could diminish device performance and needs to be considered. [ABSTRACT FROM AUTHOR]

We launched a combined negative ion photoelectron spectroscopy and multiscale theoretical investigation on the geometric and electronic structures of a series of acetonitrile-solvated dodecaborate clusters, i.e., B12H122−·nCH3CN (n = 1–4). The electron binding energies of B12H122−·nCH3CN are observed to increase with cluster size, suggesting their enhanced electronic stability. B3LYP-D3(BJ)/ma-def2-TZVP geometry optimizations indicate each acetonitrile molecule binds to B12H122− via a threefold dihydrogen bond (DHB) B3–H3 ⁝⁝⁝ H3C–CN unit, in which three adjacent nucleophilic H atoms in B12H122− interact with the three methyl hydrogens of acetonitrile. The structural evolution from n = 1 to 4 can be rationalized by the surface charge redistributions through the restrained electrostatic potential analysis. Notably, a super-tetrahedral cluster of B12H122− solvated by four acetonitrile molecules with 12 DHBs is observed. The post-Hartree–Fock domain-based local pair natural orbital- coupled cluster singles, doubles, and perturbative triples [DLPNO-CCSD(T)] calculated vertical detachment energies agree well with the experimental measurements, confirming the identified isomers as the most stable ones. Furthermore, the nature and strength of the intermolecular interactions between B12H122− and CH3CN are revealed by the quantum theory of atoms-in-molecules and the energy decomposition analysis. Ab initio molecular dynamics simulations are conducted at various temperatures to reveal the great kinetic and thermodynamic stabilities of the selected B12H122−·CH3CN cluster. The binding motif in B12H122−·CH3CN is largely retained for the whole halogenated series B12X122−·CH3CN (X = F–I). This study provides a molecular-level understanding of structural evolution for acetonitrile-solvated dodecaborate clusters and a fresh view by examining acetonitrile as a real hydrogen bond (HB) donor to form strong HB interactions. [ABSTRACT FROM AUTHOR]

We present a joint experimental and computational study on the geometric and electronic structures of deprotonated sulfamic acid (SA) clusters [(SA)n–H]− (n = 1, 2) employing negative ion photoelectron spectroscopy and high-level ab initio calculations. The photoelectron spectra provide the vertical/adiabatic detachment energy (VDE/ADE) of the sulfamate anion (SM−) H2N●SO3− at 4.85 ± 0.05 and 4.58 ± 0.08 eV, respectively, and the VDE and ADE of the SM−●SA dimer at 6.41 ± 0.05 and 5.87 ± 0.08 eV, respectively. The significantly increased electron binding energies of the dimer confirm the enhanced electronic stability upon the addition of one SA molecule. The CCSD(T)-predicted VDEs/ADEs agree excellently with the experimental data, confirming the identified structures as the most stable ones. Two types of dimer isomers possessing different hydrogen bonding (HB) motifs are identified, corresponding to SM− binding to a zwitterionic SA (SM−●SAz) and a canonical SA (SM−●SAc), respectively. Two N–H⋯O HBs and one superior O–H⋯O HB are formed in the lowest-lying SM−●SAc, while SM−●SAz has three moderate N–H⋯O HBs, with the former being 4.71 kcal/mol more stable. Further theoretical analyses reveal that the binding strength advantage of SM−●SAc over SM−●SAz arises from its significant contributions of orbital interactions between fragments, illustrating that sulfamate strongly interacts with its parent SA acid and preferably chooses the canonical SA in the subsequent cluster formations. Given the prominent presence of SA, this study provides the first evidence that the canonical dimer model of sulfamic acid should exist as a superior configuration during cluster growth. [ABSTRACT FROM AUTHOR]

The photophysics of thiobases—nucleobases in which one or more oxygen atoms are replaced with sulfur atoms— vary greatly depending on the location of sulfonation. Not only are direct dynamics of a neutral thiobase impacted, but also the dynamics of excess electron accommodation. In this work, time-resolved photoelectron spectroscopy is used to measure binary anionic clusters of iodide and 4-thiouracil, I− · 4TU. We investigate charge transfer dynamics driven by excitation at 3.88 eV, corresponding to the lowest ππ* transition of the thiouracil, and at 4.16 eV, near the cluster vertical detachment energy. The photoexcited state dynamics are probed by photodetachment with 1.55 and 3.14 eV pulses. Excitation at 3.88 eV leads to a signal from a valence-bound ion only, indicating a charge accommodation mechanism that does not involve a dipole-bound anion as an intermediate. Excitation at 4.16 eV rapidly gives rise to dipole-bound and valence-bound ion signals, with a second rise in the valence-bound signal corresponding to the decay of the dipole-bound signal. The dynamics associated with the low energy ππ* excitation of 4-thiouracil provide a clear experimental proof for the importance of localized excitation and electron backfilling in halide–nucleobase clusters. [ABSTRACT FROM AUTHOR]

Bi1−xBaxFeO3 (BBFO, x = 0, 0.03, 0.1) thin films were epitaxially grown on SrRuO3-buffered SrTiO3 (001) substrates by pulsed laser deposition. With increasing Ba content, the BBFO thin films show significantly reduced leakage currents but suppressed ferroelectric polarization. X-ray diffraction reciprocal space mappings and Raman spectra indicate a structural evolution from a rhombohedral-like to tetragonal-like phase in the BBFO thin films. Optical absorption and photoelectron spectroscopy measurements demonstrate a modulation of energy band structures in the BBFO thin films. With A-site Ba acceptor doping, the BBFO thin films exhibit a blue-shift of optical bandgap and an increase in work function. The energy positions of conduction and valence bands of the BBFO thin films have been modulated, and the Fermi level shifts down to the center of the forbidden band, but acceptor-doped BFO thin films still show n-type conduction. The presence of extra oxygen vacancies by acceptor doping is supposed to make contribution to conduction behavior. This study provides a method to manipulate the functional properties and gives insights into the physics of Ba doping in BFO thin films. [ABSTRACT FROM AUTHOR]

Bandpass filters (BPFs) are optical filters with significantly high transmittance in a specific wavelength range and low transmittance on both sides. Infrared BPFs can reduce system losses and overheating caused by other light wavelengths owing to their ability to selectively transmit infrared light of the desired wavelength. This article discusses the potential of using a high refractive index material, β-FeSi2, in BPFs. To the best of our knowledge, no studies have applied β-FeSi2 to infrared BPFs. Simulation results showed that its high refractive index allows the excellent performance of the BPF to be achieved using a multilayer thin film structure with only three layers. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy results showed that the β-FeSi2 thin film exhibited the lowest absorptance of approximately 0 when the correct stoichiometry (Fe:Si = 1:2) was achieved through co-sputtering. Based on these findings, a β-FeSi2/SiO2/β-FeSi2 multilayer thin film was designed to fabricate the BPF. The fabricated BPF exhibited a narrow peak and achieved a peak transmittance exceeding 80%. This suggested that β-FeSi2 is a promising material for fabricating infrared BPFs. Utilizing these filters is expected to yield significant efficiency improvements and reduce losses across various applications, including thermophotovoltaics and infrared heaters. [ABSTRACT FROM AUTHOR]

The semiconducting behavior of two-dimensional (2D) metal nanostructures has recently attracted much interest for their possible applications in optoelectronics and others. In particular, tuning the bandgap of such nanostructures can open up a new avenue for fabricating functional nano-devices. In the present article, we report the synthesis of 2D metallic Zn nanosheets at room temperature using a ball mill, which is capable of producing large-scale materials in a single run. Initially, nanoplates were formed for ball milling the octahedral-shaped Zn nanoparticles for the time of milling of 6 h. Subsequent ball milling for another 6 h leads these nanoplates to nearly uniform nanosheets. The thickness of these 2D nanostructures was found to decrease with an increase in the time of milling. Visible photoluminescence (PL) emissions centered at ∼3, ∼2.9, and ∼2.75 eV were observed from all the Zn particles showing semiconductor behavior. The origin of such semiconductor behavior was explained based on the radiative transition of electrons from the sp band to the upper states of the 3d band. This argument was confirmed through the studies of photoelectron spectroscopy and the first principle calculations employing density functional theory (DFT). Furthermore, excitation-dependent PL studies indicated that the bandgap of the 2D Zn nanostructures decreased with the increase in the ball milling time. Therefore, a redshift in the bandgap was observed with the increase in the ball milling time. Such changes in the bandgap with the thickness of 2D Zn nanostructures were also verified from the studies of DFT. Thus, the present study demonstrated that the bandgap of 2D metallic Zn nanostructures could be effectively tuned by reducing the thickness. [ABSTRACT FROM AUTHOR]

Realizing an oxide thin film with proper stoichiometry is one of the most challenging objects in materials science. Owing to the growth dynamics as well as kinetics, the physical properties of thin films often differ from their bulk counterparts. Here, we report pulsed laser-deposited thin films of LaBO3 (B = Mn, Fe, Co) grown on a SrTiO3 (001) substrate under various thermodynamic conditions. Structural, magnetic, and optical studies have been carried out. The x-ray diffraction study confirms that an appropriate choice of growth thermodynamics may help one to realize epitaxially grown films on the SrTiO3 substrate with out-of-plane lattice parameters 3.976, 3.984, and 3.825 Å for LaMnO3 (LMO), LaFeO3 (LFO), and LaCoO3 (LCO), respectively. A mixed valence state of Mn2+, 3+, 4+ for LMO, a Fe3+ state for LFO, and a mixed state of Co2+, 3+ for LCO have been confirmed by x-ray photoelectron spectroscopy, which is in good agreement with the Ellingham diagram. The optical study showed a bandgap of 1.2, 2.5, and 1.5 eV for LMO, LFO, and LCO, respectively. Ultraviolet photoelectron spectroscopy (UPS) shows a glimpse of the valence band maximum and Fermi level position. UV, UPS, and photoconductive study simultaneously results in a type II band bending, i.e., staggered type bending is observed at these interfaces. Room temperature weak ferromagnetism along with the insulating nature and a sign of photovoltaic application of these thin films fascinate to carry forward rigorous study from fundamental as well as technological points of view. [ABSTRACT FROM AUTHOR]

A gold surface is functionalized by chemisorption of the enantiopure N,N′-bis-[2,2′;5′,2″]tert-thiophene-5-yl methylcyclohexane-1,2-diamine (2T3N), a chiral oligothiophene derivative, via overnight incubation in a 2T3N ethanol solution. The Au|2T3N interface is characterized by x-ray photoelectron circular dichroism and comparing x-ray photoemission spectroscopy and electro-desorption results. Charge transmission at the Au|2T3N| solution interface is characterized by recording the cyclic voltammetry of the Fe(III)/Fe(II) reversible redox couple, finding a charge transfer rate constant, k°, variation from 1 × 10−1 to 3.3 × 10−2 cm s−1, when comparing the bare Au and the Au|2T3N interfaces, respectively. The "anomalous" high value of k° found for the chiral Au|2T3N interface can be rationalized on the basis of the chiral-induced spin selectivity effect, as further proved by magnetic–conductive atomic force microscopy measurements at room temperature. A spin polarization of about 30% is found. [ABSTRACT FROM AUTHOR]

The physicochemical properties of NZFO/f-MWCNTs composites based on 5 wt% of Ni 0.5 Zn 0.5 Fe 2 O 4 (NZFO) nanoparticles and functionalized multi-walled carbon nanotubes (f-MWCNTs) synthesized via ex-situ method are presented. The influence of annealing on the as-received hybrids is discussed. The structural and microstructural analysis confirms the efficiency of the synthesis process. The slight redistribution of cations over tetrahedral and octahedral sites is noted by Raman and X-ray photoemission (XPS) studies. The NZFO crystallite size is almost stable over sample processing, but the presence of single particles, clusters and aggregates on the f-MWCNTs' surface is proven. The XPS spectra comparison reveals the domination of nanotubes as designed. The deconvoluted Fe2 p lines confirm the iron redistribution slightly modified by annealing. The magnetic properties analysis revealed the cluster-glass state of NZFO particles. The core-shell-like structure with a magnetic core and disordered layer is evidenced. The influence of Fe-based carbon matrix residues in all hybrids was detected. [ABSTRACT FROM AUTHOR]

In this investigation, a new micro‐crosslinked anionic polymer resistant to elevated temperature and high salinity, PKDASN, was synthesized using 3‐chloropropyltriethoxysilane (KMB703), N, N‐Dimethylacrylamide (DMAM), 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), N‐vinyl caprolactam (NVCL), and sodium (4‐vinyl phenyl)methanesulfonate (SVM) employing free radical polymerization in a water‐based solution. The structure of PKDASN was analyzed using Fourier‐transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy, while its microstructure was analyzed using scanning electron microscopy. Thermogravimetric analysis showed that the pyrolysis temperature of PKDASN was above 294°C. Adding KMB703 enables the polymer to form a dense and stable spatial network. This intensified polymer network could interact with bentonite via intermolecular force and Coulomb force and form a dual grid structure, which presents impressive stability and control of filtration in saltwater. This is mainly achieved through creating a "silane coupling layer" on the particle surface by KMB703, which facilitates the crosslinking and aggregation of the polymer, thereby reinforcing the polymer's framework. This implies that under high‐temperature conditions of 230°C, 3 wt% PKDASN can improve the filtration effectiveness of drilling fluids and exhibit resistance to 15 wt% NaCl contamination. American Petroleum Institute filtration(FLAPI) and High temperature and high pressure filtration(FLHTHP) values were 4.6 and 23.0 mL, respectively. Therefore, this investigation provides a novel approach to utilizing the designated silane agent for the advancement of filtration loss additives in drilling fluids resistant to elevated temperature and high salinity. [ABSTRACT FROM AUTHOR]

ABSTRACT The corrosion of 2198 aluminum–lithium alloy in a marine atmospheric environment was simulated using a wet–dry alternating experimental setup. Weight‐loss measurement methods, electrochemical impedance spectroscopy (EIS), scanning electron microscopy/energy‐dispersive spectroscopy (SEM/EDS), macroscopic morphology testing, three‐dimensional morphology testing, and X‐ray photoelectron spectroscopy (XPS) were used to study the wet–dry alternating corrosion behaviors and mechanisms of 2198 aluminum–lithium alloys under simulated marine atmospheric environment. The results indicate that corrosion weight loss increases with decreasing wet‐to‐dry ratios, accompanied by an increase in the corrosion rate. Various data suggest that the primary corrosion products are composed of Al2O3, AlO(OH), and AlCl3. The reduction in the wet‐to‐dry ratio leads to the enrichment of Cl⁻ within the corrosion products, extending the contact time between the substrate and the medium, thereby intensifying the hydrolysis of Al³⁺. This exacerbates the dissolution at pitting sites, which in turn erodes and breaks down the corrosion product film, accelerating the overall corrosion process. [ABSTRACT FROM AUTHOR]

Broadening the scope of functionalities that can be covalently bound to single‐walled carbon nanotubes (SWCNTs) is crucial for enhancing the versatility of this promising nanomaterial class in applied settings. Here we report the covalent linkage of triphenylphosphine oxide [Ph3P(O)] to SWCNTs, a hitherto overlooked surface functionality. We detail the synthesis and structural characterization of a new family of phosphine oxide‐functionalized diaryliodonium salts that can facilitate direct Ph3P(O) transfer and afford novel SWCNTs with tunable Ph3P(O) content (SWCNT‐P). The molecularly‐distributed and robust nature of the covalent Ph3P(O) attachment in SWCNT‐P was supported by a combination of characterization methods including Raman, infrared, UV/Vis‐NIR and X‐ray photoelectron spectroscopies coupled with thermogravimetric analysis. Electron microscopy further revealed the effectiveness of the Ph3P(O) moiety for de‐bundling SWCNTs to yield SWCNT‐P with superior dispersibility and processability. Finally, electrochemical studies established that SWCNT‐P is sensitive to the presence of Li+, Na+ and K+ wherein the Gutmann‐Beckett Lewis acidity parameters of the ions were quantitatively transduced by Ph3P(O) to electrochemical responses. This work hence presents a synthetic, structural, spectroscopic and electrochemical foundation for a new phosphorus‐enriched responsive nanomaterial platform featuring the Ph3P(O) functionality. [ABSTRACT FROM AUTHOR]

In this study, a dual‐mode sensing biopolymer membrane employing chitosan (CS), polyvinyl alcohol (PVA), and ammonium molybdate (AM) was developed for optical and electrochemical detection of ethylene. The biopolymer composite was characterized by X‐ray diffraction (XRD), Fourier transform infra‐red (FTIR), and scanning electron microscopy (SEM).The relationship between ethylene concentration and optical/electrochemical response was investigated. XRD analysis showed enhanced ionic conduction, supported by SEM images showing uniform pore distribution within the synthesized membrane, facilitating effective gas interaction with Molybdenum. The increased FTIR peak intensities with higher amount of molybdenum in the membrane indicates enhanced molecular interactions. Applied to a microelectrode chip, the membrane exhibits a measurable electrochemical response with oxidation peak appearing in cyclic voltammogram as Molybdenum ions undergo reduction upon ethylene exposure. Colorimetric measurements, based on CIELAB values, reveals visible color shift with increasing ethylene concentrations, particularly at 10% molybdenum impregnation. Ionic conductivity and total color difference exhibit parallel variation with ethylene concentrations. X‐ray photoelectron spectroscopy confirms molybdenum oxidation state shift from +6 to +5 in the membrane upon ethylene interaction. The inexpensive colorimetric method enables direct color change visualization in practical applications. The resulting dual‐functional biopolymer membrane shows adaptability and versatility by responding to both optical and electrochemical signals. [ABSTRACT FROM AUTHOR]

This study is aimed at the in situ preparation and antibacterial study of silver nanoparticles within the matrix of an eco‐friendly, biocompatible, biodegradable, and bioavailable biopolymer (chitosan) to form Chi–AgNP film via multiple noncovalent interactions between the organic polymer and the nanoparticles. The film is fully characterized by infrared and ultraviolet spectroscopy, scanning electron microscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. The characterization confirms the successful incorporation of silver nanoparticles into the polymeric network. Infrared spectroscopy reveals peaks corresponding to the vibration of functional groups present in chitosan with enhanced intensity and blueshifts caused by the presence of silver nanoparticles. Well‐monodispersed spherical silver nanoparticles with an average size of 10 nm are observed in the Chi–AgNP film. The surface plasmon resonance at 447 nm is consistent with a typical silver plasmon. Furthermore, the antibacterial effects on E. coli and S. aureus were determined and attributed to the release of AgNPs observed by UV absorption. [ABSTRACT FROM AUTHOR]

NASICON electrode materials exhibit a broad spectrum of electrochemical potentials, robust ionic conductivity, and structural and thermal stabilities. Using solid state reaction method, Li2Cu2(MoO4)3 was synthesized, a member of NASICON family of compounds based on molybdenum. Various analytical techniques employed to assess structural and morphological properties of synthesized nanomaterial. X‐ray diffraction (XRD) pattern indicated that generated Li2Cu2(MoO4)3 nanomaterial exhibited orthorhombic crystalline structure, with crystallite size of approximately 48 nm. The nanomaterial morphology was evaluated using field emission scanning electron microscopy (FESEM), showing columnar‐ or fiber‐like morphology composed of some conductivity points. The elemental composition of Li2Cu2(MoO4)3 was analyzed by EDAX analysis, confirming the presence of elements lithium, copper, molybdenum, and oxygen. The optical properties and band gap of Li2Cu2(MoO4)3 were analyzed by ultraviolet visible diffuse reflectance spectroscopy (UVDRS). Elemental composition of surface along with electronic states and oxidation states of component present in the nanomaterial Li2Cu2(MoO4)3 were investigated from X‐ray photoelectron spectroscopy (XPS). Electrochemical evaluation using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopic (EIS) showed a specific capacitance of 250 F g−1 at 3.5 A g−1 with the high retention rate of 95.82% after 3000 cycles, indicating its potential for high performance supercapacitors. [ABSTRACT FROM AUTHOR]

CuCo2O4 nanoparticles were synthesized via facile hydrothermal route using oxalic as a precipitant, thermal decomposition of CuCo2O4 precursor at 400∘C. The structural studies from X-ray diffraction (XRD), Fourier transform infrared spectrometer, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) disclose the predominant spinel crystal phase for copper cobaltite. The optical absorption spectra reveal two band gaps of 3.8eV and 4.4eV in the CuCo2O4 nanoparticles. The cyclic voltammetry (CV) was used to assess the electrochemical characteristics of the resulting product in an organic electrolyte at −1.5–1.5V under ambient conditions. On 22.4nm CuCo2O4 nanoparticles, a greater capacitance of 920F/g at a scan rate of 5mV/s was achieved. [ABSTRACT FROM AUTHOR]

Lead‐free organic–inorganic metal halides (OIMHs) are highly desirable owing to their remarkable properties including low toxicity, structural diversity, high stability, and solution processability. Nevertheless, the development of their single‐component white emissive films remains a formidable challenge for remote white light‐emitting diodes (WLEDs) application. In this work, (C16H36N)2Cu2I4/polyvinylidene fluoride (PVDF) white emissive composite film is successfully fabricated through an in situ solvent evaporation crystallization process at room temperature. The elemental analysis and bonding between (C16H36N)2Cu2I4 and PVDF are demonstrated by X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) measurements. In addition, this composite film exhibits a broadband white emission with two peaks. Notably, the best photoluminescence quantum yields (PLQYs) of the PVDF based composite film reaches an impressive 96.7%. A (C16H36N)2Cu2I4/PVDF based remote UV‐pumped WLEDs with an impressive color rendering index of 95.5 is realized. Finally, the in situ fabrication method is expanded to fabricate (C16H36N)2Cu2I4/polyacrylonitrile (PAN) composite films, and we further realized their single component remote WLEDs. [ABSTRACT FROM AUTHOR]

A highly efficient, solid, and easily maneuverable adsorbent and photocatalyst, Li‐incorporated titanate nanotubes that manifest adsorption efficiency of 98.1% and photocatalytic efficiency of 99.6% in 60 min and 97.8% and 98.5%, respectively, in a shorter duration of 20 min, is synthesized by a facile two‐stage electrochemical technique. The modified nanotubes exhibit good cyclic stability of 93.7% photodegradation of malachite green dye after three continuous cycles. The adsorption data show the highest correlation for second‐order pseudo kinetics and Freundlich isotherm, suggesting multilayer chemisorption with an adsorption capacity of kF ≈ 219.51 mg1–1/nL1/ng−1. Fourier transform infrared spectroscopy (FTIR) analysis of the adsorbent before and after the adsorption corroborates the findings. X‐Ray photoelectron spectroscopy reveals the formation of a larger number of oxygen vacancies (Ti3+/Ti2+) that facilitate more carrier release for the production of reactive oxygen species during photocatalysis. X‐Ray diffraction and transmission electron microscopy analysis confirm a secondary rutile phase formation on Li doping that promotes heterogeneous multilayer adsorption. Field‐emission spectroscopic studies reveal a change in the morphology of the doped tubes with porous aggregate formation on the surface. The structural, morphological, and compositional change brought about by Li incorporation facilitates the use of titania nanotubes as an efficient adsorbent cum photocatalyst in the removal of malachite green dye. [ABSTRACT FROM AUTHOR]

This article presents the first experiments on filling single‐walled carbon nanotubes (SWCNTs) with the phosphorus sulfides P4S3 and P4S10 using the ampoule method. Transmission electron microscopy examination reveals the encapsulation of phosphorus and sulfur species inside the cavities of SWCNTs without the formation of any regular structures. X‐ray photoelectron spectroscopy observes different oxidation states of P and S atoms, depending on the P/S ratio in the initial mixture used to fill the nanotubes. The Raman signals associated with the encapsulated species are low in intensity, and the vibrational modes are shifted and broadened as compared to those in crystalline P4S3 and P4S10. The proposed models for the arrangement of sulfur and phosphorus inside SWCNTs suggest the formation of 1D amorphous glassy phosphorus sulfides with stoichiometric ratios close to those of elemental phosphorus and sulfur in the initial mixtures. [ABSTRACT FROM AUTHOR]

Highlights To improve the thermal conductivity and mechanical properties of graphene‐acrylonitrile butadiene‐styrene plastic (ABS) composite, sub‐phosphite‐based ionic liquid (IL) was synthesized, and its structure was characterized by FTIR, NMR, and mass spectrometry. IL was as a modifier, and graphite powder (G powder) was modified by the ball milling method to obtain functional graphene thermal conductive filler (G‐IL). The structure and morphology of G‐IL were characterized by FTIR, X‐ray photoelectron spectroscopy (XPS), XRD, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results of the Molau test showed that the presence of IL improved the interfacial interaction of G‐IL and ABS, enhanced the dispersion of G‐IL in the ABS matrix, made G‐IL contact with each other, and it was easier to establish a thermal conduction network and promote phonon transfer. The thermal conductivity of 9 wt% G‐IL/ABS composite was 0.392 W·m−1·k−1, which was 96% and 14% higher than that of pure ABS and G/ABS composite, respectively. The tensile strength and bending modulus of 9 wt% G‐IL/ABS composite were 44.89 and 2124.37 MPa, which were 13% and 11% higher than those of pure ABS, respectively. The impact strength of 9 wt% G‐IL/ABS composite was 34.17 kJ/m2. It was 18% and 7% higher than that of pure ABS and 9 wt% G‐IL/ABS, respectively. Phosphorus imidazole ionic liquids were prepared. Graphene was modified by ionic liquids through non‐covalent. Enhanced mechanical properties and thermal conductivity of G‐IL/ABS composites. [ABSTRACT FROM AUTHOR]

This research aims to develop novel economical and thermally‐stable polymer nanocomposites to seal geothermal wells by dispersing surface‐modified graphite into an inexpensive raw polymer. Using a mixture of nitric acid and sulfuric acid, a nano‐scale graphite filler, namely small‐size lamellar graphite (SFG15), was surface‐modified, which introduced considerable oxygen and carboxylic (COOH) groups to graphite surfaces, as verified by X‐ray photoelectron spectroscopy (XPS) analysis. Polymer nanocomposites were fabricated by dispersing different concentrations of modified graphite SFG15, including 1.5, 3, 6, and 9 wt%, into the ethylene propylene diene monomer (EPDM) matrix. First, characterization techniques, including wide‐angle X‐ray scattering (WAXS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), were employed to examine modified graphite dispersion in the nanocomposites. Then, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were used to quantitatively study the key mechanical and thermal properties of the nanocomposites. It was found that introducing modified SFG15 to EPDM enhances its resistance to deformation at high temperatures significantly. Notably, 9 wt% of modified SFG15 showed superior performances in improving the storage modulus of EPDM by 191.17%, enhancing loss modulus by as high as 136.08%, and decreasing tan δ by 18.93%. After introducing modified graphite, the energy needed for melting EPDM was increased markedly, which was accompanied by improvement in its heat capacity. Compared with pure EPDM, the onset temperature of degradation for developed nanocomposites could be increased by over 30°C, and the temperature of 50% degradation was raised by up to 20°C. Possessing the improved mechanical and thermal performances, the nanocomposites developed could be a primary choice for materials used to seal geothermal wells. Highlights: A technique is developed to reinforce low‐cost polymers for high‐temperature use.Reinforcement of EPDM with high concentrations of modified graphite is investigated.Modified graphite increases the high‐temperature storage modulus of EPDM by 191.17%.Degradation temperatures of EPDM are enhanced by modified graphite considerably.Low‐cost polymer composites are essential seals for application in deep geothermal wells. [ABSTRACT FROM AUTHOR]

In most charge density wave (CDW) systems of different material classes, ranging from traditional correlated systems in low‐dimension to recent topological systems with Kagome lattice, superconductivity emerges when the system is driven toward the quantum critical point (QCP) of CDW via external parameters of doping and pressure. Despite this rather universal trend, the essential hinge between CDW and superconductivity has not been established yet. Here, the evidence of coupling between electron and CDW fluctuation is reported, based on a temperature‐ and intercalation‐dependent kink in the angle‐resolved photoemission spectra of 2H‐PdxTaSe2. Kinks are observed only when the system is in the CDW phase, regardless of whether a long‐ or short‐range order is established. Notably, the coupling strength is enhanced upon long‐range CDW suppression, albeit the coupling energy scale is reduced. Interestingly, the estimation of the superconducting critical temperature by incorporating the observed coupling characteristics into McMillan's equation yields results closely resembling the known values of the superconducting dome. The results thus highlight a compelling possibility that this new coupling mediates Cooper pairs, which provides new insights into the competing relationship not only for CDW but also for other competing orders. [ABSTRACT FROM AUTHOR]

ABSTRACT A considerable number of different tools and operating materials are used in classical optics manufacturing. Moreover, further parameters such as environmental and process conditions contribute to material removal and surface smoothing in the course of production. A large potential variety of the final surface state of optics can thus be expected. Against this background, nominally identical fused silica optics surfaces purchased from different suppliers were investigated in the present work via x‐ray photoelectron spectroscopy, laser‐induced breakdown spectroscopy, infrared spectroscopy, ellipsometry, and atomic force microscopy. It is shown that the surfaces under consideration feature quite different types and degrees of contamination that can be attributed to the particularly used water and polishing agent. Moreover, slight differences in index of refraction and surface roughness were detected. The presented data thus confirm the expectation that the surface state of an optical component might depend on its origin. The findings are intended to sensitize users regarding such a potential impact, for example, when switching to other suppliers for bought‐in parts and outsourced precision optics items. [ABSTRACT FROM AUTHOR]

The poor morphology, and susceptibility to oxidation of tin‐based perovskite quantum dots (TQDs) have posed significant challenges, limiting their application potential. This study presents a straightforward method for synthesizing high‐quality CsSnI3‐based perovskite quantum dots (TQDs) by incorporating a mixed Cs source of Cs2CO3 and CsI. The addition of CsI increased the I:Sn ratio while maintaining Sn:Cs, resulting in TQDs with smaller size and improved uniformity. X‐ray photoelectron spectroscopy (XPS), and Nuclear magnetic resonance (NMR) analyses confirmed enhanced crystallinity, photoluminescence intensity, and antioxidation ability of CsI‐TQDs. Remarkably, these TQDs exhibit exceptional stability, enduring over 1 h in air and more than 24 h before complete oxidation, surpassing the previously reported longest lifetime in air for TQDs with conventional oleic acid (OA) and oleylamine (OAm) ligands. Furthermore, these TQD films retain robustness after ligand exchange with methyl acetate (MeOAc) and formamidinium iodide (FAI), representing the first successful short‐ligand exchange of TQDs and enabling further electronic device applications. These findings suggest that CsI in the Cs source plays a crucial role in facilitating the formation of surface complexes, regulating TQD growth and suppressing iodine vacancies. [ABSTRACT FROM AUTHOR]

Understanding charge transport properties of large‐area single‐layer 2D materials is crucial for the future development of novel optoelectronic devices. In this work, the synthesis and electrical characterization of large‐area single‐layers of Cu3BHT 2D conjugated coordination polymers are reported. The Cu3BHT are synthesized on the water surface by the Langmuir‐Blodgett method and then transferred to SiO2/Si substrates with pre‐patterned electrical contacts. Electrical measurements revealed ohmic responses across areas up to ≈1 cm2, with a mean resistance of approximately 53 ± 3 kΩ at a probe separation of 50 µm. Cooling and heating cycles show hysteresis in the electrical response, suggesting different current pathways are formed as the samples underwent structural‐chemical changes during temperature sweeps. This hysteresis vanished after several cycles and the conductivity shows a stable exponential behavior as a function of temperature, suggesting that a temperature‐dependent tunneling process is governing the conduction mechanism in the analyzed polycrystalline single‐layer Cu3BHT samples. These results, together with density functional theory calculations and valence band X‐ray photoelectron spectroscopy data suggest that the single‐layer samples exhibit a semiconducting rather than a metallic behavior. [ABSTRACT FROM AUTHOR]

In this work, we reported a facile one-pot strategy to construct conjugated vinylene-extended viologen-based ionic radical polyacetylenes (denoted as VIRPs) for visible light-promoted photocatalytic carbon dioxide (CO2) cycloaddition under ambient conditions. As expected, the ionic polymer VIRP-1 was directly prepared in situ by the quaternization-induced spontaneous polymerization (QISP) reaction between 1,2-bis(4-pyridyl)ethylene (BPE) and propargyl bromide (PGB) in CH3CN at 100 °C for 24 h without any catalysts and initiators. To our delight, the radical character of the ionic radical polymer VIRP-2 could be significantly enhanced by using K2CO3 as an alkaline reductant in the QISP reaction process, similar to the synthesis of VIRP-1, which was confirmed by electron paramagnetic resonance (EPR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the use of K2CO3 not only achieved the in situ one-electron reduction of vinylene-extended viologen cations to stable viologen cationic radicals, but also could remove a large proportion of Br− anions and afford non-halogen anions CO32− within VIRP-2 by anion exchange during the synthetic process. Both ionic radical polyacetylenes VIRP-1 and VIRP-2 exhibit strong and broad visible light-harvesting ability; however, VIRP-2 with much stronger radical intensity possesses better photoinduced charge separation and migration ability. Therefore, the ionic radical polymer VIRP-2 was regarded as a highly efficient and green metal-free heterogeneous photocatalyst in the visible-light-promoted catalytic CO2 conversion with various epoxides into cyclic carbonates at room temperature and atmospheric pressure without using any cocatalysts and solvents. This work affords a new direction to construct task-specific ionic radical polymers towards photocatalytic CO2 cycloaddition under ambient conditions. [ABSTRACT FROM AUTHOR]

Acetabular cup liners made of ultra‐high molecular weight polyethylene (UHMWPE), in hip implants fail mostly due to wear debris generation and poor wear resistance. Consequently, strengthening UHMWPE becomes essential. The current work exhibits how the addition of 5 vol% carbon nanotubes (CNT) and functionalized carbon nanotubes (fCNT) in UHMWPE (denoted as U) affects the mechanical properties (hardness, elastic modulus) and tribological properties (wear resistance) of biocomposites. To form a composite, powders were mixed using a planetary centrifugal mixer followed by freeze‐drying to disperse‐CNTs, followed by its compression molding at 220°C for 1 h at 10 MPa. With the addition of CNT and fCNT, ≥95% densification was obtained for all samples resulting an increase in hardness and elastic modulus from 74.96 MPa to 168.11 MPa (124%) and 1.65 GPa to 2.96 GPa (79%), respectively, which led to the reduction in wear rate from 12.5 × 10−5 mm3/Nm (U) to 2.5 × 10−5 mm3/Nm (UfCNT). The amount of apatite formation enhanced from U (58.2%) to UfCNT (65.1%) is confirmed via X‐ray diffraction and X‐ray photoelectron spectroscopy. Cell proliferation studies have validated the cytocompatible efficacy of U‐CNT composites with osteoblast‐like MG‐63 cells, making UfCNT as potential material for acetabular cup liners. [ABSTRACT FROM AUTHOR]

This Letter presents the fabrication and characterization of a 2D SnS memristor, proposing its integrate and fire (I&F) model as a potential hardware implementation of neuronal somatic behavior. The memristor comprises a thin layer of tin (II) sulfide (SnS) sandwiched between copper (Cu) electrodes on a silicon (Si) substrate. This structure exhibits an impressive R off : R o n ratio of 103 at a read voltage V r d of 0.25 V with exceptionally low switching V s w and set V set voltages of 0.3 and 0.35 V, respectively, with ∼ 3 order variation between the maximum R max and R min resistances offered during single voltage sweep cycle. We have explained the memristive behavior using the dual ionic conduction mechanism in the SnS active layer. We extracted the real-time band diagram of SnS using ultraviolet photoelectron spectroscopy, explaining the low V s w observed. We propose that the emulation of the I&F artificial neuron model exhibited by the fabricated device could serve as a promising application in the field of artificial neuron spiking. [ABSTRACT FROM AUTHOR]

We present a study of Ge segregation at the surface of highly germanium-doped gallium oxide (2.5 × 1020 cm−3 nominal doping level) grown by molecular beam epitaxy. We probed the dopant concentration as a function of depth by hard x-ray photoelectron spectroscopy and standard laboratory photoemission spectroscopy. We notably found that there is germanium segregation within the top 2 nm where its concentration is 3 times the nominal doping level. This increased dopant concentration leads to a threefold enhancement of surface conductivity. The results suggest a reliable method for delta doping for power electronics applications. [ABSTRACT FROM AUTHOR]