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Rutile nickel fluoride NiF2 has a theoretically high pseudocapacitance performance in alkaline aqueous solutions, while the actual pseudocapacitance performance of an actual NiF2 electrode material is relatively low. Obviously, the actual NiF2 electrode material's chemical activity of Ni2+ ions, crystal structure of NiF2, electron conductivity, and the amount of NiF2 that contacts with OH− definitely affect the completeness and speed of the pseudocapacitance process or reaction and further the pseudocapacitance performance. Lots of researches devote to improve these structural factors through various strategies, such as synthesizing NiF2 with large specific surface areas or excess F amount, introducing a heterogeneous metal atom (Co) to construct bimetallic fluoride NiCoF2, and introducing another heterogeneous metal atoms (Mn, Fe, Cu, Zn) to construct trimetallic fluorides, so as to benefit for the pseudocapacitance process and enhance the pseudocapacitance performance. The research status of these novel NiF2 materials, including synthetic methods, pseudocapacitance parameter test, structure characterization results representing the above mentioned structural factors, and pseudocapacitance performance, is summarized and clarified in this review. A perspective is given. This review enriches the understanding of anion storage materials. [ABSTRACT FROM AUTHOR]

Long-range (>10 μm) transport of electrons along networks of Geobacter sulfurreducens protein filaments, known as microbial nanowires, has been invoked to explain a wide range of globally important redox phenomena. These nanowires were previously thought to be type IV pili composed of PilA protein. Here, we report a 3.7 Å resolution cryoelectron microscopy structure, which surprisingly reveals that, rather than PilA, G. sulfurreducens nanowires are assembled by micrometer-long polymerization of the hexaheme cytochrome OmcS, with hemes packed within ∼3.5-6 Å of each other. The inter-subunit interfaces show unique structural elements such as inter-subunit parallel-stacked hemes and axial coordination of heme by histidines from neighboring subunits. Wild-type OmcS filaments show 100-fold greater conductivity than other filaments from a ΔomcS strain, highlighting the importance of OmcS to conductivity in these nanowires. This structure explains the remarkable capacity of soil bacteria to transport electrons to remote electron acceptors for respiration and energy sharing.

The understanding and applications of electron‐conducting π‐conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n‐doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n‐doped backbone. Here, the n‐type conducting NDI polymer with enhanced stability of its n‐doped states for prospective "in‐water" applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping‐induced "collapse" of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n‐doped states in water and the high electron conductivity of polymers. [ABSTRACT FROM AUTHOR]

Efficient electrochemical Li + adsorption holds significant promise for lithium extraction, while the mismatched rate between Li + diffusion and electron transport within the electrode material impedes the electrochemical activity and restricts the adsorption efficiency. To address this challenge, herein, we rationally design and integrate the ion and electron dual-conducting poly(vinyl alcohol)-polyaniline (PVA-PANI) copolymer (CP) within the H 1.6 Mn 1.6 O 4 (HMO) electrode matrix to facilitate Li + diffusion and electron transport. The Li + diffusion coefficient ( D Li+ ) increased from 3.03 × 10 -10 to 5.92 × 10 -10 cm 2 /s, while the charge transfer resistance ( R ct ) decreased from 53.73 to 29.57 ohm. Consequently, the HMO@CP electrode exhibits superior adsorption kinetics and a state-of-the-art high adsorption capacity of up to 49.48 mg/g. Comprehensive mechanistic studies reveal that the negatively charged hydroxyl groups (-OH) in PVA accelerate Li + diffusion and that the conjugated structure and redox-active quinoid sites in PANI offer denser electron distribution and promote electron transport. This synergistic effect in CP significantly enhanced Li + diffusion and electron transport, leading to electrochemical activity and adsorption efficiency. Our work highlights the critical role of simultaneously regulating the ion diffusion and electron transport dual pathways for optimizing Li + adsorption performance and inspires development of the next generation electrochemical adsorption electrodes.

Abstract The understanding and applications of electron‐conducting π‐conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n‐doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n‐doped backbone. Here, the n‐type conducting NDI polymer with enhanced stability of its n‐doped states for prospective “in‐water” applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping‐induced “collapse” of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n‐doped states in water and the high electron conductivity of polymers.

TiNb 2 O 7 (TNO) has emerged as a highly potential power-type anodes for extremely fast-charging batteries. Nevertheless, the inherent electron conductivity and crystalline stability of TNO, limiting its actual capacity. Herein, a TNO anode doped by highly oxidized state ions is designed for regulating unit cell volume expansion, oxygen vacancies generation and charge mobility through induced Nb-O bond distortion. The Ce 0.01 -TNO electrode shows a high discharge capacity of 181 mAh·g−1 at 20 C after 1000 cycles. Meanwhile, the density functional theory simulations demonstrate that decreased ion-diffusion barrier and increased electronic conductivity are obtained by narrowing the bandgap and introducing impurity bands induced by Ce doping. This work provides an effective strategy to enhance the electrochemical performance of TiNb 2 O 7 , making a guideline to construct fast-charging batteries with a prolonged cycle lifespan. [Display omitted] • Highly oxidized state ions doped is designed for regulating unit cell volume through induced Nb-O bond distortion. • The DFT simulations demonstrate that ion-diffusion barrier and electronic conductivity are modulated by impurity bands. • The Ce 0.01 -TNO possesses an extremely high capacity, a remarkable high-rate performance and a ultar-long cycle lifespan. [ABSTRACT FROM AUTHOR]

Abstract Analytical expressions for impedance of proton and electron transport in the cathode catalyst layer of a PEM fuel cell operating in H2/N2 regime are derived. In the high–frequency range, the dependence of imaginary part of impedance on 1/ω is a straight line with the slope depending on the cathode catalyst layer (CCL) proton and electron conductivity. The characteristic frequencies of proton fp and electron fe transport associated with the double layer charging are close to each other (denoted below as fpe). The frequency fpe in the cathodes of various type may differ by three orders of magnitude. DRT spectrum of CCL impedance in H2/N2 regime shows two peaks located at the frequencies fpe and fe∗. The second frequency fe∗ of electron transport in the CCL is about four times higher than fpe. Analytical results can be used for simultaneous measurement of proton and electron conductivity of PEMFC cathodes using electrochemical impedance spectroscopy.

Spinel oxides with tunable chemical compositions have emerged as versatile electrocatalysts, however their performance is greatly limited by small surface area and low electron conductivity. Here, ultrathin high-entropy Fe-based spinel oxides nanosheets are rationally designed (i.e., (Co 0.2 Ni 0.2 Zn 0.2 Mg 0.2 Cu 0.2 )Fe 2 O 4 ; denotes A 5 Fe 2 O 4 ) in thickness of ≈4.3 nm with large surface area and highly exposed active sites via a modified sol-gel method. Theoretic and experimental results confirm that the bandgap of A 5 Fe 2 O 4 nanosheets is significantly smaller than that of ordinary Fe-based spinel oxides, realizing the transformation of binary spinel oxide from semiconductors to metalloids. As a result, such A 5 Fe 2 O 4 nanosheets manifest excellent performance for the nitrate reduction reaction (NO 3 - RR) to ammonia (NH 3 ), with a NH 3 yield rate of ≈2.1 mmol h -1 cm -2 at -0.5 V versus Reversible hydrogen electrode, outperforming other spinel-based electrocatalysts. Systematic mechanism investigations reveal that the NO 3 - RR is mainly occurred on Fe sites, and introducing high-entropy compositions in tetrahedral sites regulates the adsorption strength of N and O-related intermediates on Fe for boosting the NO 3 - RR. The above findings offer a high-entropy platform to regulate the bandgap and enhance the electrocatalytic performance of spinel oxides., (© 2024 Wiley‐VCH GmbH.)

Impedance spectra of a PEM fuel cell with three Fe-N-C cathodes have been measured under the H2/N2 testing regime. The spectra have been fitted using a recently developed physics-based impedance model, which takes into account finite proton (σp) and electron (σe) conductivity of the oxygen-free cathode catalyst layer. Fitting allowed to extract numerical data for σp, σe, the double layer capacitance, and the inductance of cables used for measuring impedance spectra. The values of σp and σe are close to what previously found for standard Pt/C electrodes, which is found for the first time using PGM-free catalysts. The method enables simultaneous measurement of reference proton and electron conductivity of PEMFC cathode.

Two stable operating mode, which were called "jet" and "bell" mode, were observed for Hall thrusters. These modes are distinguished from each other by the shape of the plasma plume and the anode efficiency. This paper presents the results of the measurements of the high-frequency floating potential oscillations using a Langmuir probe and of the relative erosion rate of boron nitride ceramic (BN) insulators using passive optical diagnostics in the "jet" and "bell" modes. The studies were carried out for the Hall thruster with the diameter of the middle line of 77 mm and power up to 2.5 kW. [ABSTRACT FROM AUTHOR]

Electron conductivity and dielectric permittivity are essential parameters that determine the external characteristics of laboratory and space plasmas in terms of electromagnetic (EM) wave propagation. In most problems, $\sigma $ and $\varepsilon $ are calculated using the elementary theory under the assumption that the electron distribution function (EDF) is under equilibrium (Maxwellian). But, in real plasma, the EDF is, as a rule, non-Maxwellian. Therefore, the form of EDF can significantly affect the characteristics of various processes involving electrons. In this article, the calculations of the correction coefficients for conductivity and permittivity in argon were performed in a wide frequency range for typical two-temperature EDFs, with which almost any EDF in the laboratory and ionospheric plasma can be approximated. The results show that the form of EDF has a significant effect on the conductivity and the permittivity in plasma. Most substantial differences are observed under conditions when the frequency of the EM wave is less than the transport electron–gas collision frequency of electrons. [ABSTRACT FROM AUTHOR]

We investigate an influence of the crystal structure imperfections on the electronic properties and dielectric functions of the In0.5Tl0.5I semiconductor in the frame of the density functional theory calculations. The tensor of electron effective mass m ij ∗ for the InI, In0.5Tl0.5I and TlI crystals has been calculated for the valence and conduction bands at different K-points of the Brillouin zone. The dielectric functions ε(hν) of the imperfect crystals based on In0.5Tl0.5I solid state solution with iodine vacancy and a thallium interstitial atom were calculated taking into consideration the inter-band and intra-band electron transitions. The studies of the imperfect crystals reveal increased low-frequency and stationary electron conductivity with anisotropy resulted from the anisotropy of the electron effective mass tensor. Our findings explain the origin of crucial changes in the band structure by formation of the donor half-occupied levels close to the unoccupied conduction bands due to the crystal structure defects, i.e., iodine vacancy or a thallium interstitial atom. It has been shown that in the case of real crystals, in particular metal-halides, the proper consideration of defects in quantum-chemical calculations results in a better matching with experimental data and, opposite to the perfect structure calculations, gives opportunities to explain the observed phenomena. [ABSTRACT FROM AUTHOR]

Organic cathodes have the advantages of abundant resources, high theoretical specific capacity, and mild synthesis conditions, but suffer from low density, poor electronic conductivity, and high solubility in liquid electrolytes. Herein, we develop a charge-transfer complex by combining 2,5-dihydroxyterephthalic acid (Li 4 C 8 H 2 O 6) and tetracyanoquinodimethane (TCNQ) at room temperature in 1,3-Dioxolane (DOL) solvent, for application in all-solid-state battery to overcome the above problems. Li 4 C 8 H 2 O 6 /TCNQ act as the electron donor/acceptor and combine to form an enhanced electron cloud through π-π interaction to facilitate electron transport. The electron conductivity of charge transfer complex Li 4 C 8 H 2 O 6 -TCNQ is enhanced to 7 × 10−5 S/cm, which is three orders of magnitude higher than the two pristine materials and much higher than most conventional organic cathodes. The Li 4 C 8 H 2 O 6 -TCNQ electrode exhibits a discharge specific capacity of 172 mAh/g at 0.5 C, which is approximately 2.5 times higher than that of Li 4 C 8 H 2 O 6 and higher than its capacity in a liquid cell, and is stable for 100 cycles at 2 C. This result demonstrates that enhancing electron cloud through π-π interaction in charge transfer complexes is an effective way to realize the practical application of organic cathodes in sulfide all-solid-state batteries. [Display omitted] • A charge transfer complex Li 4 C 8 H 2 O 6 -TCNQ was developed for application in all-solid-state batteries. • An enhanced electron cloud is formed by binding through π-π interactions to facilitate electron transport. • The electronic conductivity (7 x 10-5 S/cm) of Li 4 C 8 H 2 O 6 -TCNQ was improved by three orders of magnitude. • Li 4 C 8 H 2 O 6 -TCNQ electrodes showed a 2.5-fold increase in discharge specific capacity to 172 mAh/g at 0.5 C. [ABSTRACT FROM AUTHOR]

Among graphene-like family, phosphorene is a typical semiconducting layered material, which can also be a superconductor in low temperature. Applying pressure or tension on phosphorene lattice results in changing the hopping terms, which change the energy bands of the material. In this research we use the tight-binding Hamiltonian, including relevant hopping terms, to calculate energy bands of normal and under tension phosphorene. Our results show that the energy gap decreases by decreasing / from 3 to 2, and finally the gap disappears.

Olivine-structure LiFePO4 is considered as promising cathode materials for lithium-ion batteries. However, the material always sustains poor electron conductivity, severely hindering its further commercial application. In this work, zinc oxide and carbon co-modified LiFePO4 nanomaterials (LFP/C-ZnO) were prepared by an inorganic-based hydrothermal route, which vastly boosts its performance. The sample of LFP/C-xZnO (x = 3 wt%) exhibited well-dispersed spherical particles and remarkable cycling stability (initial discharge capacities of 138.7 mAh/g at 0.1 C, maintained 94.8% of the initial capacity after 50 cycles at 0.1 C). In addition, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) disclose the reduced charge transfer resistance from 296 to 102 Ω. These suggest that zinc oxide and carbon modification could effectively minimize charge transfer resistance, improve contact area, and buffer the diffusion barrier, including electron conductivity and the electrochemical property. Our study provides a simple and efficient strategy to design and optimize promising olivine-structural cathodes for lithium-ion batteries.

Methods are considered for improving the quality of babbit sliding bearings by applying individual elements to their surface with electrospark alloying of soft antifriction metals. Numerical values are determined for the adhesion force between metals during formation of an antifriction layer using traditional (Fe-Sn) and suggested technology (Fe-Cu and Fe-Cu-Sn). The expediency of using an intermediate copper layer for improving sliding bearing running in is confirmed by calculation. [ABSTRACT FROM AUTHOR]

The Fe-Ni-O system designed for producing bimetal-containing composite anodes of solid oxide fuel cells (SOFCs) was studied. The solubility of nickel in the structure of spinel (Fe,Ni)3O4 ± δ at atmospheric oxygen pressure is ~1/3. Moderate reduction at 1023 K and p(O2) ≈ 10-20 atm leads to partial decomposition of spinels, forming an electron-conducting phase (Fe,Ni)1-yO and submicron bimetallic Fe-Ni particles on the oxide surface, which have potentially high catalytic activity. The electron conductivity has a thermally activated character and increases substantially during the reduction. In the anode conditions of SOFCs, the electric conductivity reaches 30-100 S/cm, while the thermal expansion coefficients are ~12 × 10-6 K-1, which ensures compatibility with solid electrolytes. At the same time, significant volume changes during the redox cycling (up to ~1% on the linear scale) necessitate the introduction of additional components such as yttria-stabilized zirconia (YSZ). The polarization resistance of the model composite anode of reduced Fe2NiO4 ± δ and YSZ deposited on the YSZ solid electrolyte membrane was ~1.8 Ohm cm2 at 923 K in a 4% H2-Ar-H2O atmosphere. [ABSTRACT FROM AUTHOR]

A series of carbon aerogels (C-AGs) were prepared by the pyrolysis of resorcinol-formaldehyde aerogels at 700−1100 °C as potential supercapacitor electrodes, and their texture and electrochemical properties were determined. The specific surface area of all C-AGs was in the range of 700−760 m2/g, their electron conductivity increased linearly from 0.4 to 4.46 S/cm with an increase of the pyrolysis temperature. The specific capacitance of electrode material based on C-AGs reached 100 F/g in sulfuric acid and could be realized at a 2 A/g charge-discharge current, which makes it possible to use carbon aerogels as electrode materials.

The electron conductivity of an extended metal atom chain (EMAC) that consisted of penta-nickel(II) ions bridged by oligo-α-pyridylamino ligands was examined by density functional theory (DFT) and elastic scattering Green’s functions (ESGF) calculations. The calculated results revealed that an intramolecular ferromagnetic (FM) coupling state showed a higher conductivity in comparison with an anti-ferromagnetic (AFM) coupling state. The present results suggest the potential of the complex as a molecular switch as well as a molecular wire.

Computational investigation based on the density functional theory (DFT) and Green’s function methods reveals that electron conductivity of one-dimensional (1-D) tri-nickel(II) complex significantly change depending on their magnetic coupling states and structures. A ferromagnetic (FM) state shows a high conductivity (∼89 times) in comparison with an anti-ferromagnetic (AFM) state. From the analysis of the molecular orbitals of DFT calculations, we found that the anti-bonding orbitals between axial isothiocyanate (NCS) ligands and Au electrodes are widely delocalized in the FM state, the feature of which is the origin of the higher conductivity. The present results contribute to paving the way to realizing a novel molecular switch based on open-shell 1-D metal complexes. [ABSTRACT FROM AUTHOR]

Samarium molybdates Sm 6-x MoO 12-δ (x = 0, 0.5) and samarium tungstate Sm 6 WO 12 – potential mixed electron-proton conductors have been studied by X-ray diffraction, Raman spectroscopy, SEM and impedance spectroscopy (in ambient air and in dry and wet air). Solid solutions differing in structure have been obtained in the Sm 2 O 3 -MoO 3 system at 1600 °C. The samarium molybdate Sm 6 MoO 12 has the fluorite structure ( Fm¯3m ). The less samarium rich solid solution Sm 5.5 MoO 11.25 crystallizes in a rhombohedral ( R 3 ¯ ) structure. The morphotropic transformation is due to the change in the chemical composition of the solid solution with decreasing Sm 3 + concentration. The total conductivity of the cubic fluorite phase Sm 6 MoO 12 at 750 °C in air (1.48 × 10 − 3 S/cm, E a = 1.22 eV) is an order of magnitude higher than that of rhombohedral Sm 5.5 MoO 11.25 (2.34 × 10 − 4 S/cm, E a = 1.11 eV). At low temperatures (T < 500 °C), the Arrhenius plot of total conductivity for Sm 6 MoO 12 and Sm 5.5 MoO 11.25 in air deviates from linearity, suggesting that there is a proton contribution to its conductivity at these temperatures, like in the case of the Sm 5.4 Zr 0.6 MoO 12.3 zirconium-doped molybdate. Below ~ 500 °C, Sm 6 MoO 12 fluorite and fluorite-like Sm 6 WO 12 have identical Arrhenius plots of conductivity in ambient air. The region of dominant proton conductivity is wider for Sm 6 WO 12 than Sm 6 MoO 12 , reaching temperatures as high as 750 °С for the former. The absolute values of total conductivity obtained for samarium tungstate and molybdate at 400 °С in wet air are virtually identical and close to 3 × 10 − 6 S/cm, which suggests the conductivity of both compounds is dominated by protons at low temperatures and the proton transport numbers are similar. [ABSTRACT FROM AUTHOR]

Doping of TiO 2 by metal elements for the scaffold layer of the perovskite solar cells has been proved to be one of the effective methods to improve the power conversion efficiency. In the present work, we report the impact of doping of TiO 2 nanoparticles with different amounts of tungsten (W) on the photovoltaic properties of hole transport material free perovskite solar cells (PSCs) that employ carbon counter electrode. Light doping with W (less than 1000 ppm) improves the power conversion efficiencies (PCEs) of solar cells by promoting the electron conductivity in the TiO 2 layer which facilitates electron transfer and collection. With the incorporation of W, average efficiency of PSCs is increased from 9.1% for the un-doped samples to 10.53% for the 1000 ppm W-doped samples, mainly originates from the increase of short circuit current density and fill factor. Our champion cell exhibits an impressive PCE of 12.06% when using the 1000 ppm W-doped TiO 2 films. [ABSTRACT FROM AUTHOR]

The in situ formation of a heterostructure delivers superior electrochemical properties as compared to the mechanical mixing, which shows great promise for developing new electrolytes for solid oxide fuel cells (SOFCs). Herein, in an SOFC constructed by the Ba 5 Nb 4 O 15 electrolyte and Ni 0.8 Co 0.15 Al 0.05 LiO 2-δ anode, an in situ formation of Ba 3 CoNb 2 O 9 /Ba 5 Nb 4 O 15 heterostructure is designed by Co-ion diffusion from the anode to the electrolyte during cell operation, resulting in improved ion conductivity and fuel cell performance. An abnormal phenomenon is observed that the SOFC based on the Ba 3 CoNb 2 O 9 /Ba 5 Nb 4 O 15 electrolyte delivered a peak power density of 703 mW/cm 2 at 510 °C, which is higher than that at 550 °C. Characterization in terms of X-ray photoelectron spectroscopy and X-ray diffraction verifies that the operating temperature affected the Co doping concentrations, leading to different conducting behaviors of the heterostructure. Furthermore, it is found that the heterojunction of Ba 3 CoNb 2 O 9 and Ba 5 Nb 4 O 15 can restrict the electron migration to avoid current leakage of the cell and simultaneously enhance the proton conductivity. These findings manifest the developed in situ Ba 3 CoNb 2 O 9 /Ba 5 Nb 4 O 15 heterostructure as a promising electrolyte for SOFCs.

Soft-material PEDOT is used to network hard Co 3 O 4 nanowires for constructing both ion- and electron-conductive hierarchical porous structure Co 3 O 4 /PEDOT to greatly boost the capacitor energy density than sum of that of plain Co 3 O 4 nanowires and PEDOT film. Specifically, the networked hierarchical porous structure of Co 3 O 4 /PEDOT is synthesized and tailored through hydrothermal method and post-electrochemical polymerization method for the PEDOT coating onto Co 3 O 4 nanowires. Typically, Co 3 O 4 /PEDOT supercapacitor gets a highest areal capacitance of 160 mF cm −2 at a current density of 0.2 mA cm −2 , which is about 2.2 times larger than the sum of that of plain Co 3 O 4 NWs (0.92 mF cm −2 ) and PEDOT film (69.88 mF cm −2 ). Besides, if only PEDOT as active mass is counted, Co 3 O 4 /PEDOT cell can achieve a highest capacitance of 567.21 F g −1 , this is the highest capacitance value obtained by PEDOT-based supercapacitors. Furthermore, this soft-hard network porous structure also achieves a high cycling stability of 93% capacitance retention after the 20,000th cycle. This work demonstrates a new approach to constructing both ion and electron conductive hierarchical porous structure to significantly boost energy density of a supercapacitor. [ABSTRACT FROM AUTHOR]

The structure, stability and electron conductivity of LiVPO 4 F covered by MoS 2 were investigated by a first-principles method based on density functional theory. Calculations show that the low-index LiVPO 4 F (010) surface exposing Li and O atoms is the lowest energy surface. The formation of a new surface-state near the Fermi level reduces the band gap of the LiVPO 4 F surface compared to that of the bulk. For clean LiVPO 4 F surfaces, the quantum state near the Fermi level is dominated by the V-3 d orbital. In addition, PDOS of V atoms shows significant differences in different atomic layers. MoS 2 coating dramatically increases the stability of the LiVPO 4 F surface by forming strong covalent bonds with this surface. Additionally, it also enhances the electronic conductivity by reducing the band gap and generating new electronic states at the Fermi level. These theoretical results are consistent with experimental data. [ABSTRACT FROM AUTHOR]

Novel mesoporous carbon materials (MCMs) with excellent electron conductivity and high surface area are successfully synthesized from waste litchi shells. The as-prepared MCMs possess a narrow pore size distribution (0.5–2.0 nm) and exhibit similar electron conductivities to conductive carbon black (Super P, Timcal). Because of the unique properties of MCMs, they are used as host matrixes to encapsulate sulfur for lithium-sulfur cathodes. The obtained MCMs-sulfur (MCMs-S) composite cathodes deliver a high initial specific capacity of 1667 mAh g −1 . Moreover, 300 °C treated MCMs-S composite cathode shows a more stable discharge capacity than the untreated MCMs-S composite cathode, it remains 612 mAh g −1 after 200 cycles at a high current density of 0.5 C. [ABSTRACT FROM AUTHOR]

The carboranylpyrrole polymers are functional materials with superior thermal resistance and conducting performances. The carboranylpyrrole structures and Laplacian bond order (LBO) of carborane moiety, as well as the thermal resistance and conducting properties of carboranylpyrrole dimers or polymers, were investigated theoretically. The B NMR chemical shifts of 3-(2-methyl- o-carboranyl)alkyl-1H-pyrrole monomers (CP-1 to CP-5) were calculated and analyzed. The average LBO values of some characteristic chemical bonds in the carborane cages of CP-1 to CP-5 molecules were calculated. It is found that the average LBO values of carborane moieties change slightly with the increase in alkyl chain length. The temperature resulting in about 15-20 % weight loss for CP-1, CP-3, CP-4 and CP-5 polymers is predicted to be more than 700 °C. Apart from the C-C bonds in carborane moieties of 3-(2-R- o-carboranyl)propyl-1H-pyrrole (R = CHOH, CHOCH, CN, COCl, Ph) substituents, the LBO values of other bonds in these cages change slightly relative to that in the molecule of 3-(2-methyl- o-carboranyl)propyl-1H-pyrrole (CP-3). The C-C bond LBO values in the carborane cages of these substituents with electron-donating groups (R = CHOH, CHOCH) are bigger than that in CP-3, while those values in those substituents with electron-withdrawing groups (R = CN, COCl, Ph) are smaller than that in CP-3. The polymerization activity calculated for CP-1 to CP-5 monomers increases with the increase in alkyl chain length. The calculated orbital energy gap (∆ E ) of CP-1 to CP-5 dimers decreases with the increase in alkyl chain length, and accordingly, the electronic conductivity has the potential to increase. In addition, the calculated band gaps of CP-1 to CP-5 dimers cell models also decrease with the increase in alkyl chain length. [ABSTRACT FROM AUTHOR]

A new formulation of the Kubo–Greenwood conductivity for average atom models is given. The new formulation improves upon previous treatments by explicitly including the ionic-structure factor. Calculations based on this new expression lead to much improved agreement with ab initio results for DC conductivity of warm dense hydrogen and beryllium, and for thermal conductivity of hydrogen. We also give and test a slightly modified Ziman–Evans formula for the resistivity that includes a non-free electron density of states, thus removing an ambiguity in the original Ziman–Evans formula. Again, results based on this expression are in good agreement with ab initio simulations for warm dense beryllium and hydrogen. However, for both these expressions, calculations of the electrical conductivity of warm dense aluminum lead to poor agreement at low temperatures compared to ab initio simulations. [ABSTRACT FROM AUTHOR]

The Ziman formulation of electrical conductivity is tested in warm and hot dense matter using the pseudo-atom molecular dynamics method. Several implementation options that have been widely used in the literature are systematically tested through a comparison to the accurate, but expensive Kohn–Sham density functional theory molecular dynamics (KS-DFT-MD) calculations. The comparison is made for several elements and mixtures and for a wide range of temperatures and densities, and reveals a preferred method that generally gives very good agreement with the KS-DFT-MD results, but at a fraction of the computational cost. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis and electrochemical properties of mesoporous titanium oxysulfides prepared through the chemical treatment of pristine mesoporous titanium oxide under various synthesis conditions. The materials were doped with sulfur by using hexamethyldisilathiane (HMDST), a strategy that was developed to improve the conductivity of the material, whilst also retaining the porosity and thermal stability. Varying amounts of HMDST and different synthesis temperatures were tested to optimize the surface area and electrochemical performance. Lower temperatures generally yielded materials with superior properties and, even though the conductivity was improved by using higher loading levels of HMDST, it also led to a drop in initial capacity at the highest synthesis temperature of 200 °C (137-41 mAh g−1). The best performing material was, thus, synthesized by using the highest level of HMDST (3.5 mL) at lower heating temperatures (100-150 °C). This set of conditions maximizes the combination of surface area, initial capacity, conductivity, and capacity retention, the latter of which was notably superior to that of the pristine material (81 vs. 35 %), emphasizing the overall success of this doping strategy in improving the electrochemical properties of these otherwise insulating materials. [ABSTRACT FROM AUTHOR]

The design and synthesis of new solid oxide materials are important areas in both fundamental and applied chemistry. In the present work, we consider weakly studied Ba 2 SnO 4 layered materials for high-temperature applications. The Ba 2–x La x SnO 4+δ (x = 0.05 and 0.1) samples were prepared according to the conventional solid-state synthesis method followed by sintering at 1150–1200 °C. Although a single-phase state was achieved for all the studied compositions, the decomposition of the layered phases into individual oxides (BaO, SnO 2 /SnO and La 2 O 3) following their long-term storage even under ambient conditions can be explained in terms of their interactions with gas components (H 2 O and CO 2). Nevertheless, the chemical stability of Ba 2–x La x SnO 4+δ was slightly improved by La-doping. The electrical characterisation indicated that Ba 2 SnO 4 at 700–900 °C is an n- and p-type conductor with negligible oxygen ionic conductivity. Ba 2 SnO 4 thus represents a relevant research object for fundamental and applied sciences when solving issues with its unsatisfactory chemical stability. • Single-phase Ba 2–x La x SnO 4+δ materials were obtained by solid-state synthesis method. • Ba 2–x La x SnO 4+δ decompose when storing under ambient conditions during a few weeks. • Electrical transport of the as-prepared Ba 2 SnO 4 was studied for the first time. • Ba 2 SnO 4 exhibits pronounced n-type and p-type transport under Red and Ox conditions. • Ionic conductivity of Ba 2 SnO 4 is estimated to be below 10–5 S cm–1 at 900 °C. [ABSTRACT FROM AUTHOR]

A core-shell structured lithium iron phosphate (LFP) with LFP as the core and LiCo x Fe 1−x PO 4 as the shell was prepared using the solvothermal method. The doped Co broadened the diffusion channel of Li+ in the [010] direction. Combined with the interface migration model, this core-shell structure was found to enhance the diffusion of Li+. The doped Co facilitated the formation of CoP, thereby improving the electronic conductivity of LFP. In addition, Co on the surface inhibited the corrosion of electrolytes during the cycle and protected the olivine structure of LFP. This core-shell structure cathode material possesses good interface stability and cycle stability during the cycle process. Electrochemical tests found the Co-doped core-shell structure to improve conductivity and exhibit excellent cycle performance and rate performance and it maintained 165.1mAh g−1 300 cycles at 0.1 C. • A core-shell structured LiFePO 4 (LFP) with LFP as the core and LiCo x Fe 1-x PO 4 as the shell was prepared. • It is proved that Co element not only exists on the surface of LFP particles, but also changes in gradient with depth. • Combined with the interface migration model, this core-shell structure was found to enhance the diffusion of Li+. • Co on the surface inhibited the corrosion of electrolytes during the cycle and protected the olivine structure of LFP • A capacity of 165.1mAh g-1 after 300 cycles at 0.1 C. [ABSTRACT FROM AUTHOR]

Peculiarities of the tunneling conduction of electrons in systems of quantum wells and barriers are studied numerically on the basis of the laws of quantum mechanics. [ABSTRACT FROM AUTHOR]

In this paper, the anisotropic magnetoresistance (AMR) and electron conductivity of electron gas in presence of the Rashba and Dresselhaus spin-orbit coupling are investigated. Boltzmann equation is solved exactly for low temperature, including electron scattering. Calculations have been performed within the coherent potential approximation. Results of the transport study demonstrate that the AMR enhances as the Rashba strength increases. It is also observed that the AMR depends critically on spin-orbit coupling strength, wave vector and Dresselhaus strength. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the synthesis and characterization of high surface area mesoporous Ti and Ta oxides with polypyrrole nanowires in the pores. The incorporation of polymer was used to improve the electron conductivity into the channels inside these high surface area (400–1000 m2 g−1) materials in order to exploit surface redox sites for possible pseudocapacitive Li storage. Synthesis was achieved using catalyst‐free UV‐initiated polymerization of vapor‐loaded pyrrole monomer. The best materials showed improved conductivity for both the Ti and Ta oxides as well as improved Li capacity (190 mA h g−1) relative to the pristine material (128 mA h g−1) and superior capacity retention (49 % as compared to 22 %) for the Ti composites. The retention in surface area was also 87 % compared to 49 % reported previously for analogous materials synthesized by catalyst‐initiated methods, which only yielded Li capacities of 170 mA h g−1, further highlighting the superiority of this new photochemical approach. [ABSTRACT FROM AUTHOR]

Zr-doped rare-earth molybdates (Nd 5.4 Zr 0.6 MoO 12.3 , Sm 5.4 Zr 0.6 MoO 12.3 , Dy 5.4 Zr 0.6 MoO 12.3 and La 5.8 Zr 0.2 MoO 12.1 ) demonstrate appreciable mixed electron–proton conductivity in the low and intermediate temperature range under wet oxidizing and mild reducing conditions. Proton contribution to their total conductivity decreases as the lanthanide cation radius decreases. Among the samples studied, La 5.8 Zr 0.2 MoO 12.1 showed the highest total conductivity of about 2.5 × 10 − 5 S/cm at 500 °C in wet air. Its impedance spectra did not provide any evidence of the grain boundary contribution, which seems to be an inherent feature of lanthanum molybdates. Exposure of Nd 5.4 Zr 0.6 MoO 12.3 to wet argon was found to increase its total conductivity by almost one order of magnitude relative to the values obtained in dry argon. Although all the rare-earth molybdates studied in this work became essentially electronic conductors in Ar–5% H 2 atmosphere, La 5.8 Zr 0.2 MoO 12.1 demonstrated much lower propensity to reduction than the rest of the samples. [ABSTRACT FROM AUTHOR]

The design of cathodic catalysts layer (CCL) consisted of Platinum Group Metal-free (PGM-free) electrocatalysts was done by catalyst coated membrane approach. Three different Fe-Mn-N-C compounds were synthesized with Fe:Mn ratio of 1:1, 2:1 and 2:1 with modified heat treatment profile. The catalysts were characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, pore and particle size distribution, zeta potential and transmission electron microscopy. Electrocatalysts were integrated into membrane electrode assembly and evaluated by electrochemical methods. Electrochemical impedance spectroscopy in combination with modeling were used for estimation of proton conductivity of CCL and its oxygen diffusivity. It was found that all CCLs possess extremely high proton conductivity, which was demonstrated for the first time for these types of PGM-free catalysts. The observed ORR mechanism was predominantly 4e- due to peroxide/radicals scavenging effect of Mn. [Display omitted] • Bi-metallic Fe-Mn-N-C PGM-free catalysts were synthesized. • Highly performed, industrial quality MEAs were fabricated. • Detailed electrochemical fuel cell evaluation was combined with EIS modeling. • The proton conductivity in catalyst layer was improved 5 times vs literature data. [ABSTRACT FROM AUTHOR]

Graphite-silicon (GS) composite electrodes have been actively studied due to the practical aspects as anodes for lithium ion batteries. Unfortunately, the amount of loaded Si in the GS composite electrode is required to be limited to avoid catastrophic issues arising from the volume change of Si anodes. To keep pace with the research trend and enhance the energy density of lithium ion batteries, it is inevitable to increase the density of GS composite electrodes in the cell. However, the permeability of organic electrolyte is typically deteriorated as the electrode gets denser. In addition, some relevant issues associated with the cell resistance and electrode utilization seriously aggravate the cell performance. In this study, a capillary-inspired conductive agent (CCA) is employed as an electron/ion dual-conductive agent to address the above-mentioned challenges of high-density GS composite electrodes. Unlike conventional carbon blacks, the CCA is capable of providing an efficient conductive pathway for electrons and improving the electrolyte impregnation property due to the hydrophilic nature of polyanion polymer. Even when a trace amount of CCA (around 2 wt %) is introduced in the electrode composition, high-density GS composite electrodes show significant improvements in capacity retention (85% after 150 cycles) and Coulombic efficiency (99.9%). • A capillary-inspired conductive agent was first designed by polyanion and CNT. • The CNT backbone affords continuous conductive network within the Si-based anode. • The polyanion layer on CNTs effectively improves the electrolyte permeability. • The designed conductive agent provides conduction pathways for electrons and ions. • Excellent electrochemical performances of Si-based anodes were achieved. [ABSTRACT FROM AUTHOR]