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Strategies for changing the conductivity of Li 2 CO 3 is introduced into the fabrication of Li-CO 2 battery. Benefitting from the favorable hierarchical architecture constructed (CPM-MnO 2), facile charge transfer occurs between catalytic surface and Li 2 CO 3 by –OH⋯O hydrogen bonds improves the metallicity of Li 2 CO 3 , facilitating the formation/decomposition of Li 2 CO 3 and bestowing an ultra-long-term stability of 1087 cycles (4348 h). Taking into account its simplicity, scalable character and outstanding performance, this hierarchical composite electrode paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [Display omitted] • Excellent hierarchical structure of MXene and MnO 2 on carbon paper was fabricated. • Enriched charge transfer occurred on MXene and the MnO 2 by OH⋯O hydrogen bonding. • The prepared batteries showed an ultra-long cycle lifetime and low overpotential. • The optimized electronic structure can improve the metallicity of Li 2 CO 3. • The accelerated decomposition of discharge products promoted CRR and CER kinetics. Lithium-CO 2 batteries are recognized as an essential strategy for efficient carbon sequestration and energy storage to achieve carbon neutrality. Their cycle-ability and polarization voltage, however, are hindered by high decomposition voltage (≈4.3–4.5 V) of insulating Li 2 CO 3. Herein, we report a significant advance toward the rational design of self-supporting and ultra-long cycle lifetime cathode for Li-CO 2 batteries, dependence on a favorable hierarchical architecture and rich charge transfer constructed by homogeneously distributed MnO 2 nanoplates rooted in the MXene surface supported by carbon paper. Detailedly, it exhibits impressive ultra-long-term stability of 1087 cycles (4348 h) with a low polarization gap (≈ 0.47 V) at a high current of 200 μA cm−2, which is outperformed by all the liquid electrolyte-based Li-CO2 batteries reported previously. Electronic structure analysis reveals that facile charge transfer occurs between catalytic surface and Li 2 CO 3 , springing from the –OH functional group (in MXene) to MnO 2 by –OH⋯O hydrogen bonds, which acts as charge transfer channels, improving the metallicity of Li 2 CO 3 and facilitating its decomposition and extending battery cyclability. This work paves an effective trajectory for the future development of highly efficient cathodes for durable metal-CO 2 batteries. [ABSTRACT FROM AUTHOR]

In this paper the electronic structure of the valence states in CuInSe 2 , CuGaSe 2 and CuIn 0.5 Ga 0.5 Se 2 is considered in details in a wide energy range up to 20 eV from the Fermi level. Examining the electronic structure within the LDA + U method we focus on the deep, occupied 4d indium and 3d gallium electronic states. The calculated electronic structure is compared with high-resolution experimental photoemission (PE) spectra measured for high structural quality single crystals of these compounds at a photon energy of 600 eV. The comparison helped us to understand the nature of the observed spectral features associated with electronic states near the Fermi level. The calculated energies of the Ga-3d and In-4d states exhibited a good agreement with the experimentally determined spectral positions of these states in the PE spectra. The significance of these states for the application in quantum optics is discussed. • The electronic structure of Cu(In,Ga)Se 2 is studied within LDA + U method. • The calculations are found to be in a good agreement with the photoemission spectra. • We explore the effect of spin-orbit coupling of the deep 4d In and 3d Ga states. • We discuss the influence of deep states on applications in quantum optics. [ABSTRACT FROM AUTHOR]

Vacancy engineering has repeatedly proven to be a powerful strategy for manipulating material properties. The important influence of selenium vacancies (V Se) on the physicochemical properties of rhenium diselenide (ReSe 2), exciting applications can be opened in areas such as catalysis and photoelectric devices. However, the effects of V Se on electronic structure, carrier lifetime, and electrochemical activity of ReSe 2 have remained inadequately explored and poorly elucidated. Herein, hydrothermal controlled growth of ReSe 2 with vacancy (V Se -ReSe 2) is used by different synthesis strategies, revealing its growth mechanism. An ethanol-assisted hydrothermal method based on carbon paper was used to adjust the V Se concentration by changing the time parameters. Mediated excitonic effects in the transient absorption (TA) spectroscopy and photoluminescence response of ReSe 2 regulated by V Se were characterized. The defect level (DL) leads V Se -ReSe 2 to produce a unique defect emission peak, and the V Se -mediated exciton dynamics problem was discussed. Moreover, the TA result of V Se -ReSe 2 shows that high V Se concentration prolongs carrier lifetime and causes high carrier separation efficiency and electron utilization. The electrocatalytic hydrogen evolution reaction of ReSe 2 catalyst revealed the ability of V Se concentration to regulate the electrochemical activity, which provides ideas for vacancy management catalyst performance. The presence of DL and the reduction of band gap are indicated by density functional theory, which confirms the regulatory effect of V Se concentration on the electronic structure of ReSe 2. This work proffers an optimal solution strategy for hydrothermal preparation of ReSe 2 , which demonstrates the feasibility of regulating electrochemical activity by vacancy engineering, and the excellent performance of V Se -ReSe 2 makes it show great potential in many fields such as water cracking and physical devices. [Display omitted] • A regulation strategy for the successful construction of V Se rich ReSe 2 nanoflowers was developed. • DFT investigated the reduction of the band gap and orbital contribution of ReSe 2 regulated by V Se. • Mediated excitonic effects in the TA and PL response of ReSe 2 regulated by V Se were analyzed. • The effectively regulate the HER activity of V Se -ReSe 2 were analyzed. Vacancy engineering is powerful for manipulating material properties. Selenium vacancies (V Se) exert significantly impact on the physicochemical properties of rhenium diselenide (ReSe 2), triggering applications in catalysis and photoelectric devices. However, the effects on electronic structure, carrier lifetime, and electrochemical activity are inadequately explored and poorly elucidated. Herein, hydrothermal-controlled growth of ReSe 2 with V Se is synthesized by different strategies. The ethanol-assisted hydrothermal method can adjust V Se concentration of ReSe 2 on carbon paper by time parameters. Mediated excitonic effects were characterized in the transient absorption spectroscopy and photoluminescence of V Se -regulated ReSe 2. The defect level produces unique defect emission peak, and the V Se -mediated exciton dynamics problem was discussed. The transient absorption result shows that high V Se concentration can optimize carrier lifetime, carrier separation efficiency, and electron utilization. The electrocatalytic hydrogen evolution reaction of ReSe 2 catalyst revealed the electrochemical activity regulation by V Se concentration, which provides ideas for enhancing catalyst performance. Density functional theory result confirms the role of selenium vacancies in the regulation of the electronic structure of ReSe 2. This work proffers an optimal solution strategy for hydrothermal preparation of ReSe 2 , and demonstrates the feasibility of regulating electrochemical activity by vacancy engineering. The excellent performance is beneficial for water cracking and physical devices. [ABSTRACT FROM AUTHOR]

The introduction of the entropy effect has paved the way for a new realm of research in high entropy oxide ceramics (HEOCs). Through ongoing exploration, numerous HEOCs with exceptional properties have been discovered. This review provides a comprehensive summary of the research progress on the entropy effect in HEOCs, covering aspects such as structure, preparation methods, properties, and applications. [Display omitted] In 2004, Yeh and Cantor introduced high-entropy alloys (HEAs), which maximize configurational entropy by utilizing nearly equal elemental molar ratios. These HEAs are valuable for exploring the central regions of phase diagrams. Building on this concept, Rost et al. proposed entropy-stabilized oxides in 2015, revealing that high-entropy oxides (HEOs) exhibit structural stability driven by entropy. This article provides a comprehensive overview of HEOs, with a specific focus on high-entropy oxide ceramics (HEOCs). The paper explores the origins of the high-entropy concept and the fundamental effects of high-entropy materials. It examines entropy from its basic definition and investigates microscopic atomic distribution, crystal-level distortions, and electronic structures. Additionally, the article introduces theoretical prediction methods applied to high-entropy materials. Furthermore, this review systematically summarizes HEOCs, encompassing three key aspects: crystal structure, preparation methods, and performance applications. Finally, the review concludes by proposing future research directions based on the current progress in HEOCs. [ABSTRACT FROM AUTHOR]

• N-doped CoSe 2 on carbon paper is prepared by hydrothermal and plasma nitridation. • N- possesses numerous active sites and beneficial electronic structures. • N- needs 106 mV and 237 mV to drive 10 mA cm−2 towards HER and OER. • Only 1.57 V is required to arrive at 10 mA cm−2 for overall water splitting. N-doped CoSe 2 porous nanomesh arrays grown on carbon paper (N-CoSe 2 @CP) have been prepared through hydrothermal method followed by a facile plasma nitridation strategy. The obtained N-CoSe 2 @CP electrodes combine advantages of abundant electrochemical active sites and beneficial electronic structures induced by porous structure and N doping, respectively, thus exhibiting low overpotentials towards HER and OER in alkaline medium. Moreover, it can also be employed as an excellent bifunctional electrocatalyst for overall water splitting. [Display omitted] CoSe 2 has been as one of promising electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) due to its earth-abundant resource, and tunable electronic structure. However, enhancing electrocatalytic activity of CoSe 2 to meet the large-scale practical applications is desirable. Herein, we report a facile plasma nitridation strategy to generate N-doped CoSe 2 nanomesh arrays on commercial carbon paper (N-CoSe 2 @CP). The obtained N-CoSe 2 @CP electrodes combined advantages of abundant electrochemical active sites and beneficial electronic structures, thus exhibiting a low overpotential of 106 mV and 237 mV to drive 10 mA cm−2 towards HER and OER in alkaline medium, respectively. Moreover, it can be employed as bifunctional electrocatalyst for overall water splitting, where a small potential of 1.57 V was required to reach 10 mA cm−2, and long-term stability was also realized. This work develops a promising strategy to explore highly-efficient nanocatalysts towards new energy conversion. [ABSTRACT FROM AUTHOR]

The design of nanostructures and the adjustment of components are very important to improve the performance of hydrogen evolution electrocatalysts. In this paper, Ni, W and Mo trimetallic catalysts are studied from the aspects of morphology, structure and electronic transfer, and a better combination of hydrogen reaction efficiency is obtained. The W/Mo co-doped nickel sulfide electrocatalyst was synthesized on Ni foam by one-step hydrothermal method. As anticipated, the individual incorporation of either tungsten (W) or molybdenum (Mo) into the electrocatalyst did not yield satisfactory enhancements in hydrogen evolution reaction (HER) performance. However, when both W and Mo were co-doped onto the electrocatalyst, a significant improvement in catalyst material performance was observed. Hence, the coexistence of W and Mo is the key to improve HER electrocatalytic activity. In 1 M KOH solution, the W/Mo-Ni 3 S 2 /NF electrocatalyst exhibited exceptional HER activity with an overpotential of only 136 mV at a current density of 10 mA·cm−2 and demonstrated excellent cycle stability exceeding 20 hours. In this paper, the strategy of bimental co-doping composite is adopted to adjust the structure of nickel sulfide, which provides reference value for the design of reasonable and efficient HER electrocatalyst. • Due to the combined action of tungsten and molybdenum elements, the electrocatalyst forms a unique nanowire structure. • The combined action of bimetallic elements results in an electrode material with superhydrophilic and aerophobic properties. • The nanowire structure provides greater roughness to the surface of the electrode material, increasing the exposed active sites, thereby improving the overall performance of the electrocatalyst and maintaining better stability in long-term testing. [ABSTRACT FROM AUTHOR]

In recent years, spinel ferrites with chemical formula MFe 2 O 4 , have attracted much attention due to their impressive photocatalytic and electrocatalytic performances, which are significantly influenced by their spinel structures. However, it is still a big challenge to distinguish or predict spinel structures for spinel ferrites. As an attempt to address this issue, this paper presents a first-principles study of the thermodynamics and electronic structures for six spinel ferrites with different spinel structures. The configurational free energy of these spinel ferrites at different inversion degrees is calculated to determine the equilibrium inversion degree for each spinel, which successfully predicts the spinel structure type of these spinel ferrites. The partial density of states is obtained for six spinel ferrites assuming they are normal or inverse spinels. The electronic states close to the Fermi energy of each spinel ferrite are carefully examined, showing that normal spinels have weak interactions between M and Fe states, while strong interactions exist in mixed or inverse spinels. Our results offer an insightful understanding of different spinel structures, and provide a reliable approach to determine the spinel structure of spinel ferrites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ppb-level, ratiometric detection of pyrophosphate: Signal amplification. • Pyrophosphate induced demetallation which led to disassembly of probe molecule. • Electronic influence of spacer unit: rigid vs flexible spacer. • Detection in diluted blood serum samples and inside living cells. • On-location rapid detection using low-cost, reusable paper strips. In the present work, we have designed and synthesized two dimeric fluorescein derivatives with flexible salen (1) or a rigid salophen (2) linker unit. The Fe(III) complexes of these compounds ([ 1.Fe]+ and [ 2.Fe]+) showed changes in solution color specifically upon addition of inorganic pyrophosphate (PPi) at pH 7.0 in PBS buffer. Along this, we also observe appearance of green fluorescence (turn-on) in the prescence of PPi. The mechanistic studies suggested PPi-induced demetallation process, which led to disassembly for molecular structure in the aqueous medium and release of highly fluorescent fluorescein aldehyde. The disassembly process was found to be dependent on electronic structure, rigidity of the linker unit, temperature, and local pH etc. The selectivity as well as sensitivity of [ 1.Fe]+ towards PPi was also found to be superior than that observed with [ 2.Fe]+. Since each disassembly process released two signalling unit (fluorescein), we could observe a huge increment in FL intensity even with small quantity of PPi (<10 µM). Finally, the sensory system was utilized for detection of PPi in diluted blood serum samples and inside living mammalian cells (HeLa, cervical cancer cells). Chemically-modified paper strips have been developed for the detection of PPi in water samples at outside laboratory conditions. [ABSTRACT FROM AUTHOR]

In this paper, the crystal structure and electronic structure of Ti 4 O 7 were calculated based on density functional theory, and Magnéli phase Ti 4 O 7 bulks were successfully prepared by spark plasma sintering (SPS). Results indicated that the contribution of Ti 3 d to Fermi level increased due to the lack of oxygen atom in lattice, and the energy band gap of Ti 4 O 7 was reduced compared with that of TiO 2. By calculating the relationship between the densification rate and effective stress in the process of SPS, it can be known that the densification mechanism of Ti 4 O 7 powders was controlled by diffusion. Based on this, under the conditions of sintering temperature of 1000 °C, holding time of 10 min and sintering pressure of 30 MPa, Ti 4 O 7 bulks with the optimal electrical conductivity (961.5 S cm−1) could be obtained, which was more than 30% higher than the graphite material reported in literature. The results reveals that Ti 4 O 7 will be one of the most promising electrode materials in the electrochemical field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inducing lattice distortion in NiFe-LDH nanosheets by Ce-doping towards accelerating electrocatalytic oxygen evolution reaction. • The optimal NiFeCe-LDH@CP only requires 267 mV to deliver 100 mA cm−2, which is 41 mV lower than pure NiFe-LDH@CP. • NiFeCe-LDH@CP have retained their structural property after 70 h stability. • DFT calculations reveal that lattice distortion could optimize the electronic structure of the Ni element in active sites and lower the energy barrier, thus accelerating the OER. Nickel-iron layered double hydroxide (NiFe-LDH) is a promising active electrocatalyst for oxygen evolution reaction (OER). However, the development of NiFe-LDH is limited by poor electrical conductivity and inferior cycling stability. Herein, we present a structural perturbation and distinct distorted lattice strategy via Ce doping in NiFe-LDH on carbon paper (CP) (NiFeCe-LDH@CP) to boost its OER performance. Lattice distortion results in a large accessible surface area and induces more O vac , accelerating the OER by modifying the intrinsic electronic structure and optimizing the adsorption energy of intermediates. As a result, the optimized NiFeCe-LDH@CP possesses excellent stability over 70 h and can deliver the current density of 100 mA/cm2 with the overpotentials of only 267 mV, which is 41 mV lower than pure NiFe-LDH@CP. Theoretical calculations indicate that the introduction of lattice distortion into NiFe-LDH could optimize the electronic structure of the Ni element in active sites and lower the energy barrier, thus leading to a significant increase in OER activity. This work figures out the effect of lattice distortion strategy on the improvement of OER performance, which opens new perspectives on the development of defect-rich OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Herein, using first-principles density functional theory (DFT) calculations, we have investigated the effects of Bi substitution on the structural, electronic, and magnetic properties of barium hexaferrite (BaFe 12-x Bi x O 19 , x = 0; 0.5; 1.5 and 2). As a result of the calculation, it was determined that the most stable structure exists if the spin of the Fe atom on the 2a, 2b, and 12k positions of the barium hexaferrite compound is taken in the upward direction. The calculated lattice constant c a = 3.9 and magnetic moment (4.24 μ B) of iron ions are in reasonable agreement with other experimental works. Moreover, the presence of bismuth reduces the electronic band gap. Energy gain and magnetic anisotropy energy calculations for FIM, FM, and NM states were performed for the most stable states. It has been established that the most stable structural state is characteristic of х = 0.5. It has been calculated that substitution by the large Bi3+ ion dramatically changed the electronic structure and sharply reduced the band gap. This paper is the first step towards establishing the nature of the distribution of ions in M-type hexaferrites under conditions of substitution by ions with a large ionic radius. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structure of paritaprevir in protic and aprotic solvents was investigated. • The weak noncovalent interactions within different conformations in liquid environments were analyzed. • The antitumor potential of paritaprevir was elucidated through molecular docking. Macrocyclic molecules have emerged as significant contenders in drug development and supramolecular chemistry. Paritaprevir is a 15-membered macrocycle approved for the treatment of chronic Hepatitis C virus infection. The structural flexibility inherent in paritaprevir enables the presentation of diverse conformational features in solutions, thereby influencing its binding pattern with proteins. In this paper, we investigated the structural characteristics of paritaprevir in protic solvents (methanol and trifluoroethanol) as well as an aprotic solvent (acetonitrile) by using experimental electronic circular dichroism spectra combined with density functional theory calculations. Our study reveals that paritaprevir can adopt different molecular conformations due to its flexible carbon chain and the solvent environment. Conformer B is particularly stable in polar solvents because of the planar hydrophobic interactions between the phenanthridine and methylpyrazine groups. Density functional theory calculations-assisted structural analyses further disclosed the weak noncovalent interactions within the stable conformations of paritaprevir. Molecular docking of paritaprevir on different cancer proteins showed that the macrocycle was highly selective against lymphoma, endometrial carcinoma, colorectal cancer, and breast cancer. This suggests that paritaprevir could potentially serve as a promising lead compound for drug design targeting these specific types of cancers. The comparison between the low energy conformation and pharmacophore conformation (docking conformation) indicates that conformer B is the primary pharmacophore conformation of paritaprevir, providing important macrocyclic structural characteristics for future macrocyclic drug development. [ABSTRACT FROM AUTHOR]

Theoretical studies on CdS/BiOI heterojunctions are lacking; therefore, this paper studies their electronic structure and optical properties through density functional theory calculations. First-principles calculations were made to investigate the effect of introducing oxygen vacancy defects on the photocatalytic efficiency of CdS/BiOI. The band gap of CdS/BiOI was effectively narrowed compared to that of its constituent materials, resulting in a redshift of the absorption edge. Based on the obtained work functions, the difference in Fermi energy levels caused a spontaneous flow of electrons, resulting in band bending and the establishment of a local electric field. The electric field promoted the separation of electron–hole pairs. At the same time, the addition of oxygen vacancies created impurity levels, allowing light absorption to extend to the infrared region, further promoting carrier separation. Our study reveals the origin of the enhanced efficiency of CdS/BiOI heterostructures and also predicts the photocatalytic activity of CdS/BiOI heterojunctions after introducing oxygen vacancies. These results may facilitate the design of such structures with enhanced photocatalytic properties. • The electronic structure and optical properties of CdS/BiOI heterojunction are studied by using density functional theory, and the effect of introducing oxygen vacancy defects into the structure is predicted theoretically. • According to the band structure, density of state, 3D/2D charge density difference and work function calculated by the first principle, the electron transfer from BiOI to CdS can be analyzed, and the trend is enhanced after the introduction of oxygen vacancy defect. • The calculation of optical properties shows that the formation of heterojunction and the introduction of oxygen vacancy defects promote the enhancement of optical absorption intensity. • This paper supplements the theoretical calculation of vacancy in CdS/BiOI heterojunction. And defects are introduced into the heterostructure to enhance the catalytic performance of such materials. [ABSTRACT FROM AUTHOR]

When preparing SiC/Mg composites, alloy elements play key roles in the nucleation and interfacial wetting. In this paper, effects of Al, Zn and Zr additions on the Mg/SiC interfacial bonding properties were investigated comprehensively via method of first-principle calculations. Mg(0001)/SiC(0001) interfaces with different terminations and stacking sequences were built and C Ⅱ-T C Ⅱ top interface has the largest work of adhesion (W ad). Zn dopants can not improve the W ad for both C-T and Si-T interfaces. Al atom can only strengthen the C-T interface. Zr addition can greatly improve the W ad for both C-T and Si-T interfaces. W ad of C-T interfaces can reach up to 11.55 J/m2 and 12.55 J/m2 after doping 1 monolayer (ML) of Al and Zr atoms. Larger W ad can lead to lower contact angles of Mg on SiC surfaces, which can improve wetting and nucleation in SiC/Mg composites. Analysis of electronic structure shows that Al-C and Zr-C bonds have more covalent composition than the Mg-C bond, which is responsible for the improvement of interfacial bonding strength. Experimental results in references were also analyzed, which are in well agreement with our calculation results. [ABSTRACT FROM AUTHOR]

Regulating the dual active sites is crucial for enhancing the carrier-directed migration efficiency and shortening mass transfer distance of intermediates, particularly in photocatalytic overall water splitting. In this paper, we adopt in situ hydrothermal coupled gas phase chemical reduction methods to synthesize janus cobalt cocatalysts on g-C 3 N 4. Experimental measurement and density functional theory calculations show that the janus cobalt cocatalysts fine-tunes the local electronic structure of g-C 3 N 4 , which can greatly reduce energy barriers and shorten mass transfer distance of intermediates for reactions. And while the built-in electric field of CoP and CoO also further efficiently facilitates rapid directional separation of interface carriers of the cocatalysts. This study elucidates atom-level mechanisms underlying overall water splitting and offers valuable insights for rational design of high-performance catalysts for overall water splitting. As a result, the CoP/CoO@g-C 3 N 4 samples exhibit a remarkable enhancement in overall water splitting activity (133.2 μmol g−1 h−1 H 2 and 67.2 μmol g−1 h−1 O 2), surpassing that of the CoP@g-C 3 N 4 and CoO@g-C 3 N 4 samples by 1.4 and 3.8 times, respectively. [Display omitted] • The Janus cobalt structure vastly shorten mass transfer distance of intermediates. • The inherent electric field to further enhance the carriers directional separation. • Theoretical calculations demonstrated the reaction path of overall water splitting process. • CoP/CoO@g-C 3 N 4 photocatalysts exhibit remarkable performance in the overall water splitting process. [ABSTRACT FROM AUTHOR]

MOFs (metal-organic frameworks) are stable materials with both organic and inorganic pores, and possess high surface area fascinating structures. Owing to the unique octahedral of aluminum center and strong Al–O bonds, Al-based MOFs show excellent thermal stability. In this paper, MIL-96(Al) is proved to be effective at dispersing Pt particles evenly and sparsely as it is employed as catalyst support. MIL-96(Al) is synthesized via a water based route and different contents of Pt particles are directly deposited on the surface of MIL-96 in one step by hydrothermal method to prepare Pt X MIL-96 (x represents Pt content) catalysts. The catalyst are sprayed evenly on carbon paper, with Pt content of 0.03%, 0.11%, 0.27% and 0.41%, respectively, and are applied in a gas diffusion reactor with snakelike flow field for low temperature H 2 -SCR. For Pt 5 MIL-96/CP, the NO removal efficiency can reach up to 100% at 60 °C. Electron transfer between Pt and MIL-96 is observed via X-ray photoelectron spectron (XPS). It reveals that the deposited Pt is in metallic state. Meanwhile, the electronic structure of MIL-96 is kept intact in the process of Pt depositing. The excellent performance of Pt 5 MIL-96/CP catalyst strongly suggests its potential application. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Pt-O bond between Pt and TiO 2 enhances interfacial stability of Pt/TiO 2 /Ti. • Optimized interfacial electronic structure promotes an appropriate H adsorption. • The perfect encapsulation of TiO 2 prevents hydrogenation breakage of Ti substrate. • Pt/TiO 2 /Ti performs high and stable HER activity (η 10 = 23 mV, 180 mA cm−2 for 25 h). • Constructed acidic electrolyzer presents efficient water splitting performance. The development of efficient and stable integrated electrodes is crucial for the advancement of electrolyzer. Herein, the ultra-low platinum (12.7 μg Pt cm−2) anchored TiO 2 nano-polyhedrons protective titanium fibers paper (Pt/TiO 2 /Ti) is synthesized as an integrated electrode for gas diffusion, current collector and catalytic hydrogen production. The Pt/TiO 2 /Ti electrode exhibits remarkable activity (23 mV at 10 mA cm−2) and durability (180 mA cm−2 for 25 h) for hydrogen evolution reaction in acidic electrolyte, which is attributed to the enhanced interface via Pt-O bond between Pt and TiO 2. Specifically, the optimizing electronic structure of Pt anchoring on the TiO 2 enhances hydrogen adsorption energy to improve the intrinsic activity of HER. In addition, the relatively negative adsorption energy (E ads) of Pt atom on TiO 2 significantly contributes to the structural stability of the Pt/TiO 2 /Ti electrode. Moreover, the complete encapsulation of titanium fibers by TiO 2 layer enhances the structural stability of Pt/TiO 2 /Ti by preventing hydrogenation-induced breakage of the titanium substrate. The constructed electrolyzer of (−) Pt/TiO 2 /Ti || IrO 2 /TiO 2 /Ti (+) presents efficient water splitting performance (1.464 V at 10 mA cm−2) and long-term durability (∼100% retention for 30 h) in acidic electrolyte. This work highlights the importance of integrated electrodes and the feasibility of acidic electrolyzer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Molar diamagnetic susceptibility values for some amino acids are reported for the first time. • The results obtained are evaluated in terms of electronic structure principles. • Molar diamagnetic susceptibility can be used in the introducing new chemical hardness, polarizability and entropy scales. One of the main aims of the theoretical chemists is to introduce new and useful approaches for the estimation of chemical reactivity descriptors of Conceptual Density Functional Theory (CDFT) like absolute hardness, polarizability and magnetizability. In addition to providing results close to experimental results, the methods developed for this purpose must also be easily applicable to many molecular systems and easy to learn. "Property Prediction from Structural Differences" method proposed by one of the authors of this article is based on the idea that various properties of molecules can be easily calculated by taking the sum of the functional group contributions in the structure of the molecule. The most important thing in the applying of the method is the reliable determination of functional group contributions. In the present paper, using "Property Prediction from Structural Differences" method, we predicted the molar diamagnetic susceptibilities of amino acids with reasonably good accuracy. The computed values are in good agreement with experimental data and the results of previously introduced theoretical models. The reason why amino acids were especially preferred in the study is the lack of the molar diamagnetic susceptibility data of some amino acids in the literature. Additionally, to test whether a molar diamagnetic susceptibility based scale can be proposed for the calculation of any CDFT based reactivity descriptor, DFT computations were also performed for amino acid molecules. The relationships between parameters were evaluated in terms of the electronic structure rules like Maximum Hardness, Minimum Polarizability, Minimum Magnetizability and Minimum Electrophilicity Principles. [ABSTRACT FROM AUTHOR]

Metal fluorides are ionic compounds with intriguing properties and a wide range of industrial and technological applications. In this paper, we present the results of an extensive first-principles study of the electronic band structure of nineteen mono-, di-, and tri-fluorides. Four approaches are employed in this study: LDA, pseudopotential and all-electron modified Becke–Johnson (mBJLDA@PP and mBJLDA@AE) potentials, and Yukawa Screened Hybrid Functional (YS-PBE0). The mBJLDA and YS-PBE0 band gaps are in good overall agreement with the available G 0 W 0 results and experimental data, which ensures the reliability of the provided predictions for systems where accurate band gaps are lacking. The LDA and YS-PBE0 upper valence band (UVB) widths are very close to each other, and these results are, in general, slightly smaller than the G 0 W 0 results and experimental data. It is shown that the band gap and UVB width vary with F F distance, and distinct trends are identified. The LDA density of states of the UVB for the alkali and alkaline-earth fluorides are analyzed and compared to the available XPS and XES spectra. It is found that the LDA approach provides accurate results for peak intensities as well as satellite peak positions relative to the main peak. A strong correlation is demonstrated between the adopted crystal structures of the considered fluorides and their bond ionicity. • Four approaches are used to study the electronic structure of 19 metal-fluorides. • For several of the fluorides considered, reliable predictions have been made. • Band gaps and upper valence band widths are found to exhibit clear trends. • The bonding mechanisms of fluorides are discussed in detail. • A correlation is established between bond ionicity and crystal structure. [ABSTRACT FROM AUTHOR]

• The geometric, electronic and elastic properties of Fe 3 SnC are calculated in detail for the first time. • The results show that Fe 3 SnC is a magnetic metal. • The large elastic modulus indicates that Fe 3 SnC is a potential cermet. In this paper, the structural, electronic, and elastic properties of Fe 3 SnC were calculated based on local density approximation (LDA) and generalized gradient approximation (GGA) in density functional theory (DFT). Compared with GGA, LDA underestimates lattice constants and overestimates binding energy and elastic constants. The calculated lattice constants are 3.76 Å (LDA) and 3.83 Å (GGA), respectively, and the latter is closer to the experimental values. With U correction in GGA and LDA, the magnetic properties of the system are shown in the band structure. The GGA calculation results are more accurate, and the calculated magnetic moment of Fe 3 SnC is 5.74μ B. The band structure indicates that Fe 3 SnC is a metallic compound. The elastic constants show that Fe 3 SnC has a large elastic constant and bulk modulus, in which the C 11 calculated by GGA is as high as 463.81GPa, and the Young's modulus is as high as 350.72GPa. This indicates that Fe 3 SnC is a potential cermet due to a strong deformation resistance. At the same time, with the minimum thermal conductivity of 1.65 W/mK calculated by the Cahill model. [ABSTRACT FROM AUTHOR]

• A self-standing, non-noble metal and 3D-networked ultrathin nanosheet array (Cu-CoP NAs/CP) is fabricated. • The optimized Cu-CoP NAs/CP exhibits excellent HER and OER activities in neutral media. • DFT investigation corroborated that Cu doping effectively tailor the electronic structures of CoP. • This electrolyzer can be powered by a single AA battery for neutral-pH water splitting. We report here, an effective strategy to optimize the electronic structure of CoP using copper doping, for greatly enhancing the intrinsic activity and conductivity of CoP in neutral-pH water splitting. As a result, the as-synthesized 3D self-supported Cu-doped CoP nanosheet arrays on carbon paper (Cu-CoP NAs/CP) exhibits admirable electrocatalytic performance toward both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with overpotentials of 81 and 411 mV at 10 mA cm−2 in 1.0 M PBS (Phosphate Buffer Solution) , respectively. Moreover, a neutral electrolyzer, using Cu-CoP NAs/CP as both the anode and cathode, achieves a low cell voltage of 1.72 V at 10 mA cm−2, superior to that of the typical Pt/C||IrO 2 couple (1.81 V) and of most of the state-of-the-art bifunctional electrocatalysts. Impressively, the electrolyzer can be driven by a single AA battery (∼1.5 V), indicating its practicality in neutral water or seawater splitting. Experimental and density functional theory (DFT) calculations results reveal that the incorporation of Cu into CoP can effectively improve the conductivity and optimize the electronic structure to facilitate the H* adsorption and desorption and the formation of O* intermediates (generated CoOOH active species), thus yielding superior HER and OER catalytic activities. This study opens up a promising way to rationally design highly efficient and low-cost electrocatalysts for electrocatalysis applications. [ABSTRACT FROM AUTHOR]

Unusual secondary relaxations were revealed in metallic glasses (MGs) recently. In this paper, we explore the structural origins of secondary relaxations in La-based MGs alloyed with different species of elements. With the combination of synchrotron X-ray diffraction and ab initio molecular dynamics simulations, solute-atom-centered clusters with a string-like type of medium-range order are found in the MGs, the formation of which leaves dispersed low-electron-density regions. It is found the activation energy of fast secondary relaxation increases with the reduction of low-electron-density regions, while slow secondary relaxation relates to the distance of La in next nearest La-La atomic pairs and the size of the string-like solute-atom-centered clusters. The phenomena are interpreted within the framework of the generalized Maxell model and free volume model. Our results demonstrate fast secondary relaxation as the activation of a small concentration of liquid-like regions with extremely low viscosities preceding slow secondary relaxation, and provide evidence for the correlation of secondary relaxations with short- to medium-range electronic and atomic structure in MGs. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Free-form texts from electronic medical records are often used to build predictive models for medical and healthcare processes. In different medical centers, treatment of patients and other healthcare processes can occur in different ways according to the hospital's internal protocols, which affects the structure of electronic medical records and the style of free-form texts. The paper aim is to compare two medical corpora in content to understand whether trained models of the first corpora apply to the second corpora. The approach contains topic modeling, topic segmentation, topic cross-segmentation and specific metric Topic Segmentation Collation to compare cross-segmentation results. Also, the results of the word-level analysis for both corpora are provided. We conclude each of the corpora needs different word-level processing and has a specific set of descriptions, which limits the use of predictive models for some diseases. [ABSTRACT FROM AUTHOR]

In this paper, K-doped ZnO nanocrystalline powders were prepared by the sol-gel method at 500 °C. The effects of potassium (K) doping on the particle size, phase composition, and light absorption properties of zinc oxide nanocrystals were investigated by X-ray diffraction, transmission electron microscopy and ultraviolet–visible spectroscopy. The main crystalline phase of the powders before and after K doping is wurtzite ZnO. With the increased K doping amount, the purple and blue luminescent peaks are enhanced. The band gap of the sample obtained from the light absorption spectra initially increased with the K doping amount, then decreased, and increased again with the K doping amount, which is consistent with the theoretical calculation results. The calculated energy band and density of states results show that when the K doping amount is small, the band gap is reduced because the K doping forms the impurity level and the conduction band moves downward. This decrease is due to the two impurity levels generated at the bottom of the valence band. [ABSTRACT FROM AUTHOR]

Alkaline zinc-based batteries have become a current research hotspot due to their high energy density and safety, but their low cycle stability and rate performance limit their commercial applications. Herein, vertically ordered NiCo 2 S x nanoneedle arrays are prepared using different sulfidation concentrations based on the anion exchange reaction. The highly uniform nanoneedle arrays provide fast ion transport paths and abundant active sites, and the prepared NiCo 2 S x @Ni foam (NiCo 2 S x @NF) electrode has the excellent capacity (121.9 mAh g−1), stable cycle performance (91.1 % of capacity retention after 500 cycles), also achieves a maximum energy density of 636.3 Wh kg−1 and a maximum power density of 40.9 kW kg−1. This paper provides a more precise and accurate idea for preparing cathode materials for durable alkaline Ni–Zn batteries. • Vertically ordered NiCo 2 S x nanoneedle arrays prepared based on anion exchange reaction. • Nanoneedle arrays provide fast ion transport pathways and abundant active sites. • NiCo 2 S x //Zn battery exhibits excellent stability with 91.1 % retention after 500 cycles. [ABSTRACT FROM AUTHOR]

As a consequence of its high atomic number density, diamond can incorporate a relatively limited range of impurities as distributed point-defects, chiefly N, B and H. A few other species can be grown-in, and other impurity species incorporated via implantation and annealing. For applications including electronic, electrical and quantum devices, the presence of states deep within the wide band-gap is of importance, and the list of potential colour centres available for exploitation continues to grow. Although B can be grown into diamond at high concentration, study of other group-13 elements is rather limited. In this paper we present the results of modelling of Al, Ga and In. We find all species readily form complexes with vacancies, and exhibit electronic structures that parallel those of the Si V complex. We report electronic structures, electrical levels, optical transitions and hyperfine interactions of the colour centres, as well as reflect upon the thermodynamics of the complexes. We suggest that co-implanting group-13 elements with nitrogen would give rise to the defect charge states with potential for quantum applications. [Display omitted] • Group-13 impurities, Al, Ga and In, form viable colour centres in diamond for quantum-based technology when co-doped with N • Colour centres may either involve a vacancy or a complex with both a vacancy and nitrogen • Predictions of observables of substitutional Al, Ga and In, their complexes with vacancies and nitrogen are reported • Implanted impurities are not expected to be observed as interstitials after annealing [ABSTRACT FROM AUTHOR]

Phosphorene's desired bandgap, high carrier mobility and weak spin–orbit coupling qualify it as an exceptional semiconductor spin channel material. These traits underscore the importance of examining phosphorene's electronic structure and that of half-metal heterojunctions (HJs) in innovating spintronic device design. This paper methodically investigates the electronic structure and Schottky barrier (SB) of a van der Waals HJ, comprising phosphorene and the half-metal Co 3 Sn 3 S 2 , subjected to biaxial mechanical strain via a first-principles method. The investigation unveils that phosphorene, as an n-type semiconductor, possesses substantial spin polarization. Remarkably, phosphorene undergoes three states – metallic, half-metallic, and semiconducting – subject to varying strain ratios (E). Furthermore, we discern that phosphorene's spin polarization, peaking at 100% for − 2 % < E < 1 % , is tunable with strain. The SB heights (SBHs) also exhibit a consistent escalation with strain: for − 5 % ≤ E < 1 % , the electron SBH is 0 eV, which increments from 0.017 eV to 0.021 eV for 1 % ≤ E ≤ 3 %. Intriguingly, the spin-down band alignment of the HJ transitions from type-II to type-I at E = 3%. Our Bader charge analysis validates that the n-doping of phosphorene is primarily due to electron acceptance from Co 3 Sn 3 S 2. The orbital hybridizations between phosphorene and Co 3 Sn 3 S 2 leads to complete spin polarization of phosphorene. Collectively, these observations confirm phosphorene's capability to attain n-type doping with 100% spin polarization. Moreover, our findings suggest the possibility to modulate both the bandgap of phosphorene and the SBHs of the HJ with strain. This highlights the potential of the phosphorene/Co 3 Sn 3 S 2 HJ in advancing the field of low-dimensional, flexible spintronics. [Display omitted] • Within the range of − 2 % < E < 1 % , phosphorene achieved 100% spin polarization. This indicates that the electron spins were aligned in a specific direction. • The SB heights of the HJ were found to be strain-dependent. The electron SB height was 0 eV for − 5 % ≤ E < 1 % , and it increased from 0.017 eV to 0.021 eV for 1 % ≤ E ≤ 3 %. • The spin-down band alignment of the HJ was identified as type-II for − 5 % ≤ E < 3 %. However, it changed to type-I at E = 3 %. [ABSTRACT FROM AUTHOR]

The simultaneous introduction of oxygen and cyano defects not only induced the distortion of the heptazine structure thus effectively activated the n → π* electron transition, but also can achieve the qualitative changes of broad-spectrum photocatalytic H 2 O 2 production from "0″ to "1" (λ ≥ 700 nm) of CNNO. [Display omitted] • CNNO with broad-spectrum absorption was synthesized. • CNNO effectively activated the n → π* electron transition. • The modulating of electronic structure is critical to activate O 2 molecules. The development of photocatalysts that effectively utilize broad-spectrum light, which occupies a primary percentage of the solar spectrum, remains a great challenge. In this paper, we propose a salt-assisted method mediated by sodium oxalate template to achieve both oxygen doping and formation cyano group defects in carbon nitride materials (CNNO). The simultaneous introduction of oxygen and cyano defects not only induced the distortion of the heptazine structure thus effectively activated the n → π* electron transition, but also can achieve the qualitative changes of broad-spectrum photocatalytic H 2 O 2 production from "0″ to "1" (λ ≥ 700 nm) of CNNO, which has rarely been reported in single photocatalysts. DFT calculations show that the electronic structure of CNNO is rearranged to favor O 2 adsorption as well as the formation of the key intermediate OOH*. The present work achieves the co-optimization of electronic structure and light absorption of CN through the synergistic effect of oxygen doping and the construction of cyano defects, which provides a new strategy for the design and synthesis of CN materials that effectively utilize sunlight. [ABSTRACT FROM AUTHOR]

The figure of merit of n-type monolayer BiSbS 3 increases with the increase of temperature, and does not show a downward trend in the temperature range studied in this paper. The maximum figure of merit of p-type monolayer BiSbS 3 is 0.78025, which is obtained at a temperature of 1100 K and carrier concentration of 1 × 1020 cm−3. The optimal figure of merit, which is procured from n-type monolayer BiSbS 3 within the range of carrier concentration interval considered in this paper, is about 1.27742 at 1500 K and 5 × 1019 cm−3, which is larger than the maximum figure of merit of p-type monolayer BiSbS 3. The optimal figure of merit of monolayer BiSbS 3 studied in this paper is higher than that of Bi 2 O 2 Se (ZT = 0.53 at 800 K) [87] , Bi 2 O 2 Te (ZT = 0.62 at 800 K) [87] , SnS (ZT = 1.0 at 750 K) and PdTe 2 (ZT = 0.91 at 700 K). [Display omitted] The electronic structure and thermoelectric properties of bulk to monolayer BiSbS 3 are studied by density functional theory and semi-classical Boltzmann transport equation. Meanwhile, it is clear that bulk and monolayer BiSbS 3 are semiconductors with indirect band gaps by using the TB-mBJ scheme, respectively. Further, it can be known that the phonon spectrum of thin film BiSbS 3 has no negative frequency, and it can be inferred further that thin film BiSbS 3 is stable. Monolayer BiSbS 3 studied in this paper has extremely low lattice thermal conductivity at room temperature, which is lower than that of single quintuple layer Bi 2 Te 3 , bulk Sb 2 Te 3 , single-QL Bi 2 Se 3 and Bi 2 Te 3 S at room temperature. The maximum figure of merit of p-type monolayer BiSbS 3 is obtained at a temperature of 1100 K and carrier concentration of 1 × 1020 cm−3. The optimal figure of merit, which is procured from n-type monolayer BiSbS 3 within the range of carrier concentration interval considered in this paper, is obtained at 1500 K and 5 × 1019 cm−3. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy (XPS) studies reveal that the doping of Ag into Cu nanosheets leads to the modified electronic structures of Cu atoms. Thanks to the modified electronic structures and abundant active sites, the Ag-Cu NS /CP exhibits highly electrocatalytic activity for NRR with an NH 3 yield rate of 61.5 µg h−1 mg-1 cat. with a Faradaic efficiency of 20.9% at −0.4 V versus reversible hydrogen electrode under ambient conditions. [Display omitted] • Ag-doped Cu nanosheets grown on carbon paper were synthesized by an electrochemical deposition method. • The doping of Ag leads to the formation of electron-deficient Cu atoms. • Electron-deficient Cu atoms can suppress hydrogen evolution reaction and enhance N 2 adsorption. • Ag-Cu NS /CP gives an ammonia yield rate of 61.5 µg h−1 mg−1 with a Faradaic efficiency of 20.9% for NRR. Electrochemical nitrogen reduction reaction (NRR) at ambient conditions is a highly attractive route for ammonia (NH 3) synthesis. However, the NRR suffers from low NH 3 yield and Faradaic efficiency (FE) due to the lack of effective electrocatalyst. Here Ag-doped Cu nanosheets grown on carbon paper (Ag-Cu NS /CP) have been synthesized and utilized as efficient electrocatalysts for NRR. The doping of Ag leads to the formation of electron-deficient Cu atoms in Ag-Cu NS /CP, which can suppress hydrogen evolution reaction and enhance N 2 adsorption in neutral media, leading to enhanced NRR activity. In 0.1 M Na 2 SO 4 electrolyte, the Ag-Cu NS /CP catalyst exhibits a high FE of 20.9% with a NH 3 yield rate of 61.5 µg h−1 mg-1 cat. at −0.4 V versus the reversible hydrogen electrode. This study offers a simple but effective approach to design highly active and selective NRR electrocatalysts for NH 3 synthesis. [ABSTRACT FROM AUTHOR]

Stable and high-efficiency narrow-band green phosphor is a key component for wide color gamut liquid crystal display (LCD) backlights. In this paper, narrow-band green-emitting Sr 3-3x Si 13 Al 3 O 2 N 21 :3xEu2+ (0.001 ≤ x ≤ 0.09) (Sr-Sialon:Eu2+) phosphor with a full-width at half maximum of 66 nm has been successfully synthesized by using the solid-state reaction method. All the samples are the pure phase with Sr 3 Si 13 Al 3 O 2 N 21 -type structure. Their emission band maximum can be tuned from 495 to 523 nm by increasing Eu2+ content. The compound with x = 0.03 possesses the highest luminescence intensity with the peak position around 510 nm. Luminescent thermal stability gets better with Eu2+ concentration decreasing. The integrated intensity of the sample with x = 0.01 at 425 K remains about 80% of the intensity at room temperature. The host referred binding energy (HRBE) and vacuum referred binding energy (VRBE) schemes are constructed to further explain its luminescent thermal quenching mechanism. White light-emitting-diode (w -LED) device using optimized Sr 2.91 Si 13 Al 3 O 2 N 21 :0.09Eu2+ phosphor demonstrates its potential application for LCD backlights. • The emission peaks of Sr 3-3x Si 13 Al 3 O 2 N 21 :3xEu2+ can be tuned from 495 to 523 nm by increasing Eu2+ content. • Luminescent thermal stability gets better with Eu2+ concentration decreasing. • HRBE and VRBE schemes for Sr-Sialon:Eu2+ phosphor are constructed. [ABSTRACT FROM AUTHOR]

Developing new optoelectronic devices based on two-dimensional materials is an important research topic at present. In these developments, to construct GaAs/Graphene hetero-structure is becoming research hotspot, which can significantly improve the performance of GaAs-based optoelectronic devices. For the application of optoelectronic devices, the interfacial properties and effects are the key factors. However, these issues are not yet fully explored and understood so far, especially the atom diffusion from GaAs substrate to Graphene active layer. In the present work, the electronic structures and atom transportation of GaAs/Graphene hetero-structures were systematically investigated by First-principle calculations. The Ga or As atom, which diffuses from GaAs substrate to Graphene active layer, can open the zero-band-gap of Graphene. Furthermore, Ga atoms adsorbed onto Graphene is the most obvious to realize the purpose of opening the zero-band-gap of Graphene. Moreover, owing to the existence of interfacial built-in electric field, the electrons can efficiently transfer from GaAs substrate to Graphene active layer. This may be the underlying physical mechanism, by which to improve the optoelectronic performance of GaAs-based devices. The findings in this paper can explain the experimental phenomena reported in some literatures, and are helpful for the development of novel GaAs-based optoelectronic devices in the future. Image 1 • Built-in field is favorable for the separation of electron-hole pairs. • Ga/As atom can diffuse from GaAs surface to Graphene. • Diffused Ga/As atom can open the zero-bandgap of Graphene. • Doping effects of Ga are more obvious than those of As for Graphene. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report the effect of carbon encapsulation on the magnetic behavior of magnetite (Fe 3 O 4) nanoparticles obtained through chemical coprecipitation. Using starch, Fe 3 O 4 /carbon core–shell nanoparticles were produced through a hydrothermal method. Magnetic studies revealed that both the Fe 3 O 4 and Fe 3 O 4 /carbon core–shell nanoparticles were nearly superparamagnetic at room temperature; more importantly, carbon encapsulation significantly enhanced the room-temperature ferrimagnetism. Transmitting optical magnetic circular dichroism analysis indicated the existence of interfacial charge transfer in the Fe 3 O 4 /carbon heterosystem. The ferrimagnetic enhancement was attributed to the charge transfer to polarized states of the A- site in Fe 3 O 4 , which is equivalent to chemical reduction of the A- site irons of Fe 3 O 4. We concluded that Fe 3 O 4 /carbon core–shell nanoparticles formed a heterosystem so that the amorphous carbon passivated the magnetic semiconducting Fe 3 O 4 nanoparticles, to which the sp 2 electron was transferred. Highlights • Room-temperature ferrimagnetic enhancement was observed for carbon-encapsulated magnetite NPs. • Process temperature and the amount of starch precursor used in coprecipitation process was found to be crucial. • VSM and OMCD measurement have revealed interfacial charger transfer engendered the magnetic enhancement. • Chemical reduction of the A-site irons of Fe 3 O 4 caused by carbon-encapsulation was attributed to the observed magnetic enhancement. [ABSTRACT FROM AUTHOR]

Electronic structures that determine the energetics of interatomic bond breaking and reforming are the key parameters to predict and control the mechanical behavior, especially for transition metals/alloys with orientation-dependent bonding characteristics. First-principles calculations are ideal tools to provide accurate information for these electronic features. In this paper, the electronic structure factors that affect the strength and ductility of transition metals and alloys are reviewed from two different aspects. First, the electronic effects on the mechanical properties of perfect crystals, such as elastic modulus and ideal strength behavior, are reviewed. Second, the real deformation behaviors depend on the evolution of deformation defects, such as dislocations and deformation twinning. The recent processes on the studies of electronic structures that affect the stability and mobility of these defects in transition metals and alloys are also summarized. These electronic factors enhance our understanding of fundamental mechanisms of the mechanical properties; they can also be used as key parameters for the design of advanced alloys based computational materials science and machine learning techniques. [ABSTRACT FROM AUTHOR]

Abstract This paper demonstrates that a highly thermal stable and tunable-luminescence phosphors Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ with efficient energy transfer, which is prepared by the high-temperature solid-state reaction. First-principles method is performed to analyze the electronic structures, band structure, density of states and formation energy of Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+. For high luminescence output, Y 3- x Al 2 Ga 3 O 12 : x Tb3+ and Y 3- y Al 2 Ga 3 O 12 : y Eu3+ with high concentration quenching (x = 0.5 and y = 0.7) are achieved. The effect of energy transfer from Tb3+ to Eu3+on emission color tuning and luminescence thermal stability is studied. The energy transfer efficiency from Tb3+ to Eu3+ reaches as high as 74.2% and emission color can be tuned from green, yellow and red by adjusting the ratio of Tb3+/Eu3+. What's more, Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ phosphor exhibits a good thermal stability, of which emission intensity still keeps 60% at 150 °C. Highlights • The color-tunable emission is obtained by adjusting the ratio of Eu3+ and Tb3+. • The energy transfer mechanism of Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ is discussed in detail. • Y 3 Al 2 Ga 3 O 12 : Tb3+, Eu3+ phosphor show high thermal stabilities. [ABSTRACT FROM AUTHOR]

Abstract The binding configurations of the nitrogen have a great influence on the performance of the doped graphene-based lithium ion batteries anode, while the mechanism of lithium storage is still unclear. In this paper, the binding configuration of the nitrogen is controlled in doped graphene by introducing little sulfur atoms to produce more proportion of graphite nitrogen, which have an excellent cyclic performance with delivering 589 mAh g−1 at 5 A g−1 after 1000 cycles in the lithium ion batteries anode. What's more, the kinetics is improving with higher lithium ion diffusion coefficient and a smaller impedance of charge-transfer compared to the samples which do not regulated the binding configurations of the nitrogen. The characteristic electronic structure of graphite nitrogen is considered to reveal the lithium storage mechanism. Consequently, this work can provide a new insight for regulating binding configurations of nitrogen to improving lithium storage kinetics of the doping graphene electrodes. Graphical abstract Image 1 Highlights • The binding configurations of nitrogen are controlled by a facile method. • The kinetics mechanism of lithium storage for graphite nitrogen is revealed. • The material affords a high capacity of 589 mAh g−1 after 1000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

Abstract Similar atom substitution is an effective strategy to develop (La Ce) Al-(Ni Co) bulk metallic glasses (BMGs) with high glass forming ability (GFA). But the effect of similar element substitution on GFA has not been clarified. In this paper, the effect of similar atom substitution (Co and Ce) on the GFA of La 62 Al 14 Ni 24 ternary alloy has been studied based on the concept of Fermi sphere - Brillouin zone interaction. The effect of Co atom substitution is primarily on the electron hybridization between Al atoms and Ni (Co) atoms, affecting the diameter of the Fermi sphere (2 K F), and that of Ce atom substitution is mainly a change in the diameter of the pseudo-Brillouin zone (K P). And their effects on the Fermi level and Brillouin zone size are monitored using spectroscopy experiments. The | δ | = | K P -2 K F | criterion was used to evaluate this similar atom substitution effect, which guides us to predict the influence trend of similar atom substitution (Co and Ce) on the GFA in the La Al Ni ternary alloy system and was confirmed by the experimental results. Highlights • Similar atom substitution effect on the glass forming ability was revealed. • Column substitution affects the diameter of the Fermi sphere. • Row substitution affects the diameter of the pseudo-Brillouin zone. • The evaluation criterion of similar atom substitution for GFA has been proposed. [ABSTRACT FROM AUTHOR]

Abstract We present a single-crystal study of ThOs 2 Al 10 and UOs 2 Al 10 , crystallizing in the YbFe 2 Al 10 -type orthorhombic structure. We have performed for the first time the refinement of their cage-type crystal structure and also first-principles calculations of their electronic structures. Moreover, we carried out the magnetic, thermal and transport measurements on a single-crystalline sample of UOs 2 Al 10. Based on the local character of the 5 f 2−electron configuration of the U4+ ion in UOs 2 Al 10 , the effective crystal field (CF) potential in the intermediate coupling form was estimated using the CF level scheme, composed only of singlets. The obtained scheme satisfactorily reproduces both the magnetic susceptibility (measured along the three main crystallographic directions) and the Schottky-type anomaly of the specific heat. Both these data underline the ionic character of the central atom in its cage. The latter was estimated using the specific heat data of ThOs 2 Al 10 as a phonon reference. In addition, the strong anisotropic behavior of the Seebeck coefficient measured along the two principal directions, namely a and b axes, and the low-temperature pronounced maximum along the latter axis have been approximately explained by the CF effect. As the calculations pointed out, the latter also dominates in the S-shaped temperature dependencies of the electrical resistivity, measured using the current flowing along the three main axes. Simultaneously, the magnetoresistivity reveals a strong metallic character of UOs 2 Al 10 and an anisotropic electronic structure reflected in the anisotropic Fermi surface that certainly originate from a c - f hybridization effect in an orthorhombic unit cell. All these give rise to the typical metallic character in a similar way as it was previously found for Fe- and Ru-bearing analogs. Moreover, the coexistence of ionic and metallic characters of all these three cage-type compounds comes from the dual behavior of the U 5 f electrons. In turn, the presence of low-frequency anharmonic Einstein modes reflects the regular rattling of the U4+ ion located in the [ T 4 Al 16 ] cage. This rattling is, however, less apparent for UOs 2 Al 10 than for the Fe- and Ru-based counterparts, reported in our previous papers. Highlights • Electronic, magnetic, thermal and transport properties of single-crystalline UOs 2 Al 10. • Low-frequency Einstein vibrations – rattling of the U atom observed in UOs 2 Al 10. • Crystal field models of magnetic susceptibility, electrical resistivity and specific heat. • Dual nature of U 5 f electrons (both localized and itinerant) revealed in UOs 2 Al 10. [ABSTRACT FROM AUTHOR]

Abstract Nanotubes are easy to collapse due to van der Waals interactions and the low bending stiffness of their walls. The collapse may significantly alter the mechanical, thermal, and electronic properties of nanotubes, which can lead to many exciting applications of nanotubes in nanoelectronics and nanocomposites. In this paper, a theoretical model based on finite deformation beam theory is established to analyze the collapsing of single- and multi-wall nanotubes. Using this model, the critical diameters and the profile of collapsed nanotubes are predicted, which agree well with those obtained by molecular dynamics simulations. Furthermore, a simple scaling law of the critical collapse conditions of carbon nanotubes is built as a function of geometrical parameters, which can determine whether the carbon nanotube collapse. This scaling law can be easily extended to determine the collapsing state of other nanotube systems with different bending stiffness and binding energy. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional is employed to explore the structural, electronic, and optical properties of M 2 Si 5 N 8 :Eu2+ phosphors (M = Mg, Ca, Sr, Ba) on the ground–state and excited–state levels. From the detailed study of electronic structures of pure M 2 Si 5 N 8 , the top of the valence band is predominantly of N p character and the calculated band gaps are consistent with the reported experimental values. By Eu doping, the occupied 4f band is located directly in the band gap and results in the optical transition of the 4f–5d character. In order to confirm the location of the Eu 5d band below the conduction band, the excited–state calculation was executed. Using the position of the lowest excited–state 5d band below the conduction band, the calculated 4f–5d energy gaps agrees well with the experimental data. The excited–state calculation confirms that the Eu2+ d–f emission will be predominant in these phosphors. Furthermore, in order to understand and explain the excitation and emission observations, the energy level scheme was constructed from the calculated electronic structures. The findings in this article could well suggest a new Mg 2 Si 5 N 8 :Eu2+ phosphor with a stable Eu2+ d–f emission and can also be applied to select another rare-earth dopant. Graphical abstract Image 1 Highlights • First principles calculations of M 2 Si 5 N 8 :Eu2+ phosphors (M = Mg, Ca, Sr, Ba) are performed. • The structural, electronic, and optical properties are investigated. • The energy level scheme is constructed from the calculated electronic structures. • New Mg 2 Si 5 N 8 :Eu2+ phosphor with a stable Eu2+ d–f emission is predicted. [ABSTRACT FROM AUTHOR]

Abstract Salicylhydroxamic acid (SHA) is a typical chelate collector. This study elucidated the effect of steric hindrance on SHA adsorption on the MgTi 2 O 5 surface using density functional theory. The geometry optimisation and electronic structures of SHA ion and the MgTi 2 O 5 (110) surface were calculated. Subsequently, six adsorption configurations of SHA ion on the MgTi 2 O 5 (110) surface were calculated and compared by analysing geometric configuration, bond length, adsorption energy, density of states (DOS), and Mulliken population. The results show that both the oxygen molecules of C ╱ ╲ = O and N ╱ ╲ O − in SHA ion can coordinate to the metal ion. Steric hindrance affects the formation of a five-membered ring structure. The four adsorption configurations of the newly established structure can effectively avoid steric hindrance, and stable chelate rings are formed. The adsorption energies of the four new configurations range from −300 kJ/mol to −400 kJ/mol, and the bond lengths are about 2 Å. DOS and Mulliken population results indicate that O atoms bond to Ti and Mg atoms. Traditional chelate collector adsorption theory ignores the presence of steric hindrance. At the same time, the species distribution of SHA solution, zeta potential and flotation have also been studied in this paper, and there is a consistency between the calculation and experiment results. This study provides insights into the adsorption mechanism of a chelate collector on a mineral surface. Highlights • Steric hindrance affects the formation of a five-membered ring structure. • The limitation of the traditional chelate collector adsorption theory was discussed. • New adsorption configurations of SHA ion on the MgTi 2 O 5 (110) surface were established. • Experiments were conducted to validate adsorption mechanism of DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes how to build models of PbTiO3 crystal in the material studio and how to do CASTEP calculation. This article focuses on discussing the best CASTEP calculation and pseudopotential, and analyzing the structure and properties of PbTiO3, namely the band structure and density of states (DOS). The calculated results are in good agreement with the experimental ones. The purpose of this paper is to prove the feasibility and accuracy of calculation. [Copyright &y& Elsevier]

Abstract: This paper demonstrates that the Clausius–Mosotti equation cannot be used for Si2N2O since the Lorenz approximation is invalid therein. Therefore a modified definition for the Lorenz electric field is suggested which can be derived from the optical dielectric constant calculated using the plane-wave pseudopotential method. In addition, other parameters of Si2N2O such as the energy band gap, density of states, elastic and optical properties are also given in this paper. Based on the new expression for local electric field, the modified Clausius–Mosotti equation is suggested, and then the dielectric constant of Si2N2O is discussed by using the additivity rule. It is found that the result of the phenomenological analysis of the dielectric constant is basically consistent with the experimental data and the first principles results, which explain the experimental observation that the dielectric constant of Si2N2O is enhanced with the increase of Li content. Also, the modified Clausius–Mosotti equation and the additivity rule are suggested to be used in predicting the dielectric behaviors of the new and complex compounds. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Structural, magnetic and optical properties of Mg-doped CeO 2 (1 1 1) surface were investigated. • The doped CeO 2 (1 1 1) surface systems exhibit different bonding character. • The doped surface and subsurface systems result in local and scattered spin atmosphere. • The incorporation of Mg can lead to the red shift of absorption edge. Abstract The electronic structure, magnetic and optical properties of Mg-doped CeO 2 (1 1 1) surface have been investigated by first-principles calculations. In this paper, the doping case is actively favorable to process under O-rich conditions than under Ce-rich conditions. The distortion of doping systems of Mg replacing Ce of surface is larger than that of subsurface. The covalent character is getting weaker and the ionic character is gradually obvious for Mg O bond from surface to subsurface doping. The results show that the existence of defect states with O 2 p orbital character makes spin splitting, causing the local and scattered magnetic moments for surface and subsurface doping of Ce, respectively. And the 9 and 12 atomic layers doping systems exhibit magnetic ground states with different magnetic moments. In particular, the calculated Curie temperature (about 434, 483, 1200 K) is higher than room temperature (RT), therefore, the theoretical results showed that Mg-doped CeO 2 (1 1 1) thin films would can be obtained stable room temperature ferromagnetism (RTFM), which is beneficial to practical application. In addition, the optical properties show that all doped systems are capable of enhancing effective absorption of visible and near-infrared light. [ABSTRACT FROM AUTHOR]

Abstract: The ground state properties of W–C binary compounds (h-WC, c-WC, α-W2C, β-W2C, γ-W2C, ɛ-W2C) are studied in this paper by using first-principles calculations. Formation enthalpy and cohesive energy for each phase are calculated. The calculated elastic constants satisfy the Born–Huang''s stability criterion, indicating all studied compounds are mechanically stable. All W–C compounds studied in this paper exhibit larger bulk modulus values than many other binary types of carbide such as Fe3C, Cr7C3, Cr3C, and TiC. Using a theoretical method based on the works of Šimůnek, the hardness of the crystal is estimated. The electronic structures of these compounds are calculated and discussed. Stoner''s polarization theory for itinerant magnetism is applied to explain the observed paramagnetic behavior of the compounds. Moreover, the heat capacity is also calculated for each compound based on the knowledge of the elasticity and Debye temperature. [Copyright &y& Elsevier]

Abstract: X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) methods were employed in the present paper to investigate the electronic structure of face-centred cubic (fcc) molybdenum dioxide, fcc-MoO2. For the mentioned compound, the XES O Kα and Mo Lβ2,15 bands reflecting the valence O p- and Mo s,d-like states, respectively, were derived and compared on a common energy scale with the XPS valence-band spectrum. For comparison, the similar experimental studies of the electronic structure were made for a usual orthorhombic form of molybdenum trioxide, MoO3. Band-structure calculations of fcc-MoO2 were made using the full potential linearized augmented plane wave (FP-LAPW) method. A rather good agreement of the experimental XES and XPS results and the theoretical FP-LAPW data for the electronic properties of fcc-MoO2 has been achieved in the present paper. A new near-Fermi sub-band was detected on both the XES Mo Lβ2,15 band and the XPS valence-band spectrum when going from orthorhombic MoO3 to fcc-MoO2. The FP-LAPW calculation reveals that the main contributors into the aforementioned sub-band of fcc-MoO2 are the Mo 4d(eg) states. Further, the FP-LAPW data indicate that the O 2p and Mo 4d(t2g) states contribute into both the central part and the bottom of the valence band of fcc-MoO2, while the Mo 4d(eg) states contribute almost exclusively into the bottom of the valence band of the oxide. A significant portion of density of states (mainly Mo 4d(eg) states) detected by the FP-LAPW calculation at the Fermi energy of fcc-MoO2 indicates that the oxide is rather unstable. [Copyright &y& Elsevier]

The non-linear threshold-type current-voltage behavior that characterizes selector devices for three-dimensional (3D) crossbar-type nonvolatile memory devices relies upon a phenomenon known as Ovonic threshold switching (OTS). Because current practical OTS materials are based on toxic elements, such as Se and As, Te-based OTS materials are expected to offer a more environmentally friendly option. However, the electronic structure that determines the OTS behavior of Te-based OTS materials is not well understood. In this paper, the electronic structure of amorphous Si 0.29 Te 0.71 , has been explored using hard X-ray photoelectron spectroscopy (HAXPES) in conjunction with density functional theory (DFT) calculations. The HAXPES results show that the Si 0.29 Te 0.71 amorphous network of the simulated amorphous structure is based upon Te-Te, Te-Si, and Si-Si bonding. DFT calculations revealed that Si3p and Te5p states contribute to bonding, whereas occupied non-bonding Te5p states form the top of the valence state. A projected local density of states analysis shows that the Si site forms conduction-tail states, whereas the Te site forms both conduction- and valence-tail states. Furthermore, Te-Te dimers contribute significantly to the midgap states that characterize the OTS behavior. Finally, the valence-tail state extension within the mobility gap of Si 0.29 Te 0.71 was experimentally demonstrated. [Display omitted] [ABSTRACT FROM AUTHOR]

The main goal of this paper is to investigate the structural and electronic properties of small tin-oxide clusters, Sn x O y (x = 2–6), before and after methane (CH 4 ) physisorption. To this end, we employ the dispersion-corrected density functional theory (DFT-D2). At first, we demonstrate the relative binding stability of Sn x O y clusters with a fixed number of tin atoms via analysis of their binding energy per atom and second-order energy differences. Our results show that the highest relative stability occurs at y = 2, y = 3, y = 4, y = 6 and y = 8 for Sn 2 O y , Sn 3 O y , Sn 4 O y , Sn 5 O y and Sn 6 O y clusters, respectively. Furthermore, with the cluster size increasing, the ring-shape to cube-like structural crossover is occurred. The higher average coordination and total number of bonds in cube-like clusters make their interatomic bonds weaker and longer. On the other hand, the cube-like clusters, in comparison with ring-shape ones, possess higher chemical potential and lower chemical hardness that lead to their more chemical reactivity. We then proceed to study the CH 4 adsorption properties of the resulted most stable clusters. The lowest-energy structures of CH 4 -adsorbed clusters have been found by comparing the adsorption energy of different configurations. It is found that Van der Waals interactions lead to exothermic physisorption of CH 4 on each tin-oxide cluster with the adsorption energy ranging from −101 to −191 meV. In addition, upon CH 4 adsorption on Sn x O y clusters, the energy gap is decreased which shows an enhancement in the conductivity of the clusters. As a result, the CH 4 physisorption ability of these small studied tin-oxide clusters provides their application feasibility as the low-temperature CH 4 gas sensors. [ABSTRACT FROM AUTHOR]

Phenanthrocarbazole (PC)-based organic dye-sensitized solar cells (DSSCs) have been recently reported in experiments with an impressive high power conversion efficiency of over 12%. In this paper we report a computational study of the electronic structures, optical parameters and electron injection properties of a series of five PC dyes and the dye-TiO 2 interfaces. Density functional theory (DFT) and time-dependent DFT (TDDFT) approaches were employed. We show that the incorporation of additional building blocks (indoline, carbazole, triphenylamine, or coumarin) to the PC donor moiety leads to obvious influence on the electronic structures and properties, compared to unitary electron donor PC dye. The binary electron-donor PC based dyes demonstrate better electronic properties and spectroscopic parameters. The calculated injection time of electrons from the excited state of dye to the conduction band of TiO 2 is ideal for DSSC applications. The newly designed coumarin-PC and indoline-PC dyes show desirable energetic, electronic, and spectroscopic parameters for DSSCs. Our results are useful for a better understanding on the design rule of PC based organic dyes for future DSSCs. [ABSTRACT FROM AUTHOR]