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The regulation of electronic structure is intricately linked to the intrinsic activity of oxygen reduction. Herein, a strategy for electronic structure modulation induced by bimetallic push–pull electronic effects in dual‐atom catalysts (Fe,Ni/N‐C@NG) is developed. Experiments and theoretical analysis reveal that Fe sites exhibit favorable bonding behaviors (Fe–O: dxz‐p, dyz‐p, and dz2‐p) and spin configurations, which can enable rapid desorption of *OH and thus enhance the intrinsic activity of oxygen reduction. In situ monitoring techniques and Gibbs free energy diagram further demonstrate that the adjacent Ni could serve as second active center to participate in oxygen reduction. The Fe,Ni/N‐C@NG exhibits enhanced oxygen reduction reaction activity and excellent stability. Meanwhile, the assembled Zn–air battery maintains stability for over 300 h with a small voltage gap. This study provides multiple insights into the orbital scale laws of oxygen reduction. [ABSTRACT FROM AUTHOR]

Two-dimensional materials have a larger specific surface area and more active sites and are widely used in the design of hydrogen storage media. In this article, the hydrogen-storage properties of Li-decorated g-C 6 N 7 monolayer are investigated by the density functional theory. It is found that the g-C 6 N 7 monolayer possesses the thermodynamic and dynamic stability and the Li-decorated g-C 6 N 7 monolayer is also thermodynamically stable under 500 K. The calculation of the electronic structure reveals that covalent bonds are formed between C and N atoms and there are not only orbital interactions but also ionic bonds between Li atoms and the g-C 6 N 7 sheet. The hydrogen storage performance for the Li-doped g-C 6 N 7 sheet indicates that the storage capacity of hydrogen reaches 11.94 wt%, and the average adsorption energy of H 2 molecule is −0.145 ∼ −0.196 eV, which is attributed to electrostatic attraction, weak orbital interactions and van der Waals interaction. The value of the adsorption energy of H 2 molecule and the capacity of hydrogen storage reveal that the g-C 6 N 7 monolayer modified by Li atoms can be used as a reversible and promising hydrogen storage medium. [Display omitted] • The Li-doped C 6 N 7 is thermodynamically and kinetically stable due to the strong chemical bond. • The average adsorption energy is −0.145 ∼ −0.196 eV and the storage density reaches to 11.94 wt%. • The adsorption mechanism is attibuted to electrostatic, weak orbital and van der Waals interaction. • The Li decorated g-C 6 N 7 monolayer is a potential reversible hydrogen-storage material. [ABSTRACT FROM AUTHOR]

First‐principles simulations of electronic properties of hybrid inorganic/organic interfaces are challenging, as common density functional theory (DFT) approximations target specific material classes like bulk semiconductors or gas‐phase molecules. Taking as a prototypical example anthracene (ANT) physisorbed on monolayer MoS2, the ability of different ab initio schemes to describe the electronic structure using semilocal and hybrid DFT is assessed. For the latter, an unconstrained three‐parameter range‐separation scheme is used. Comparisons against results from the many‐body perturbation theory indicate that properly parametrized hybrid functionals can approximate with reasonable accuracy the quasiparticle properties of both ANT and MoS2 taken by themselves. However, this is not the case for the hybrid interface, where neither functional can predict the correct‐level alignment nor provide a particularly good starting point for G0W0 calculations. It is shown that nonempirically parametrized electrostatic models can accomplish the same task at negligible computational costs. Such schemes can include substrates of hybrid interfaces in good agreement with experimental data. The results indicate that currently, fully atomistic, many‐body simulations of weakly interacting hybrid systems are not worth the required computational resources. In contrast, ab initio‐parametrized effective models mimicking the environment offer a scalable alternative without compromising accuracy and predictivity. [ABSTRACT FROM AUTHOR]

First-principles DFT calculations by utilizing FP-LAPW under GGA+PBE method are performed to investigate the structural, electronic and optical characteristics of bromide perovskites MGeBr3 (M = Rb, Cs, Fr). It is found that the cubic structure (Pm-3m) and optimized lattice constants are in good agreement with the previous data. Our GGA+PBE results reveal that MGeBr3 show nonmagnetic semiconductor behavior with direct bandgap (Eg = 0.925 eV (M = Rb), 0.898 eV (M = Cs), 0.952 eV (M = Fr)) along the L–L symmetry direction. Formation energy, octahedral ration and tolerance factor for MGeBr3 have also been calculated. The 2-D charge densities confirm that the chemical bonds (Ge2+–Br-) and (M+–Br-) follow the covalent and ionic bonding types. Moreover, we have calculated and discussed the optical parameters, dielectric constants, absorption, conductivity and refractivity. The calculated electronic and optical properties show the narrow band-gap, high absorption and semiconductor nature making these inorganic materials suitable for optoelectronics applications. [ABSTRACT FROM AUTHOR]

Zn–Cd alloys are important industrial materials which have attracted much attentions in recent years. But, few reports on Zn–Cd clusters are currently available. An interesting structural feature in previous studies is that Zn and Cd atoms do not mix in binary Zn–Cd clusters. However, the analysis based on the empirical potential function can only give very limited structure information about them. Here, geometric structures of (Zn–Cd)n (n = 1–9) clusters are globally searched by the unbiasedly genetic algorithm with DFT methods. We found that the ground state structures of Zn–Cd clusters are singlet states and prefer compact characteristics, where the Cd atoms prefer to be located on the surfaces of the structures, thus coating Zn atoms that are for the kernel growths. The Eb and Δ2E results show that the (Zn–Cd)2 and (Zn–Cd)5 clusters have higher stability than that of their neighbors. The molecular dynamics simulations verify that they still have excellent thermal stability at 700 K. The molecular orbitals and DOS reveal that the 8/20 valence electrons of the (Zn–Cd)2 and (Zn–Cd)5 clusters fill the superatomic shells resulting in electronic configurations of 1S21P6/1S21P61D102S2, respectively. Moreover, we considered different adsorption structures of (Zn–Cd)2 with one CO molecule, and only the four stable isomers are finally obtained. It is found that the CO in the form of molecule is adsorbed on the cluster, resulting in the unbroken C–O bond. [ABSTRACT FROM AUTHOR]

Ni–Cu under-bump metallisation (UBM) can reduce stress and improve wetting ability in technology for electronic packaging technology advances with three-dimensional integrated circuit (3D IC) devices. The bond between the Sn-based solder and Ni–Cu UBM is affected by the formation of intermetallic compounds (IMCs), specifically Ni3Sn4 and (Ni,Cu)3Sn4. This paper investigates the mechanical properties of IMCs, which are critical in assessing the longevity of solder joints. First-principles calculations were carried out to investigate the phase stability, mechanical properties and electronic structures of Ni3Sn4, Ni2.5Cu0.5Sn4, Ni2.0Cu1.0Sn4, and Ni1.5Cu1.5Sn4 IMCs. The calculated formation enthalpies show that the doping of Cu atoms leads to a decrease in the stability of the phases and a reduction in the mechanical properties of the Ni3Sn4 crystal structure. As the concentration of Cu atoms in the Ni3Sn4 cells increases, the bulk modulus values of (Ni,Cu)3Sn4 formed with different compositions decrease from 107.78 GPa to 87.84 GPa, the shear modulus decreases from 56.64 GPa to 45.08 GPa, and the elastic modulus decreases from 144.59 GPa to 115.48 GPa, indicating that the doping of Cu atoms into the Ni3Sn4 cells may adversely affect their mechanical properties and increase the possibility of microcracking at the interface during actual service. The anisotropy of (Ni,Cu)3Sn4 is more significant than that of Ni3Sn4, with Ni2.0Cu1.0Sn4 showing the highest anisotropy. After evaluating the electronic structures, the metallic properties of Ni3Sn4 and the Ni2.5Cu0.5Sn4, Ni2.0Cu1.0Sn4, and Ni1.5Cu1.5Sn4 phases are revealed by electronic structure analysis. The total density of states (TDOS) for (Ni,Cu)3Sn4 structures is mainly influenced by Ni-d and Cu-d states. The addition of Cu atoms can increase the brittleness of Ni3Sn4. In addition, the region where d and p hybridisation occurs gradually increases with increasing Cu content. The electronic properties suggest that the binding energy between Ni and Sn atoms weakens with the addition of Cu atoms, resulting in a decrease in the elastic modulus. This research can serve as a valuable reference and theoretical guide for future applications of these materials. [ABSTRACT FROM AUTHOR]

The numerical atomic orbital (NAO) basis sets offer a computationally efficient option for electronic structure calculations, as they require fewer basis functions compared with other types of basis sets. Moreover, their strict localization allows for easy combination with current linear scaling methods, enabling efficient calculation of large physical systems. In recent years, NAO bases have become increasingly popular in modern electronic structure codes. This article provides a review of the ab initio electronic structure calculations using NAO bases. We begin by introducing basic formalisms of the NAO‐based electronic structure method, including NAO base set generation, self‐consistent calculations, force, and stress calculations. We will then discuss some recent advances in the methods based on the NAO bases, such as real‐time dependent density functional theory (rt‐TDDFT), efficient implementation of hybrid functionals, and other advanced electronic structure methods. Finally, we introduce the ab initio tight‐binding model, which can be generated directly after the self‐consistent calculations. The model allows for efficient calculation of electronic structures, and the associated topological, and optical properties of the systems. This article is categorized under:Electronic Structure Theory > Ab Initio Electronic Structure MethodsElectronic Structure Theory > Density Functional TheoryStructure and Mechanism > Computational Materials Science [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Energy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment is presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Energy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment is presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given. [ABSTRACT FROM AUTHOR]

We have used first-principles density-functional theory calculations to determine the structural, electronic and optical properties of four known ZnO phases (B1, F m 3 ¯ m ), (B2, P m 3 ¯ m ), (B3, F 4 ¯ 3 m ), (B4, P 6 3 m c ) and three predicted phases of ZnO modification (GeP, I4mm), (5–5, P 6 3 / m m c ), (NiAs, P 6 3 / m m c ). The difference of data calculated by LDA and LDA + U has been compared. In addition, the calculated ground state energies and structural parameters of these phases are in consistent with the reported theoretical and experimental results. We have discussed the band structures, densities of states and chemical bonding of the seven types. Further, we have compared the calculated values of the dielectric function of the B4 phase with the experimental values. In addition, the optical constants of the seven types of ZnO have been calculated by LDA + U and LDA, respectively, the results obtained by the two methods are compared and analyzed. [ABSTRACT FROM AUTHOR]

Based on the first principle method of density functional theory, this paper studies the stabilities, electronic structures, and optical properties of Sc, C single doped and co-doped MgS systems. The results show that compared with the intrinsic MgS system, the binding energy of the doped system is still negative, indicating that the doped systems are in a stable state. Among them, the binding energy of Sc-C co-doped MgS system is the smallest, indicating that Sc-C co-doped system is the most stable. After doping, the band gap width of the system decreases, indicating that the energy of electron transition from valence band to conduction band decreases. In addition, the doping system has an obvious red shift in the low-energy region, indicating that Sc and C doping can effectively broaden the response range of the system to visible light. Among them, Sc-C-MgS system produces impurity levels near the Fermi level, and the band gap width is small. The absorption coefficient is the best in the visible light range. It can be inferred that Sc-C co-doping can be used as an effective means to improve the photocatalytic activity of MgS system. [ABSTRACT FROM AUTHOR]

Green hydrogen production through the electrocatalytic hydrogen evolution reaction (HER) is a promising solution for transition from fossil fuels to renewable energy. To enable the use of a variety of electrolytes with different pH values, HER catalysts with pH universality are highly desirable but their performance remains mediocre. Herein, a pH‐universal HER catalyst composed of ruthenium nanoparticles decorated on amorphous Ni‐doped MoO3 (a–Ni–MoO3) nanowire support is reported, that is, Ru/a–Ni–MoO3, which achieves enhanced performance as compared to the commercial Ru/C catalyst. Electron transfer from Ru to a–Ni–MoO3 is identified by spectroscopic techniques, which results in a modified electronic structure of the Ru active sites with a reduced electron density of 4d states near the Fermi level. Density functional theory calculations further reveal that the modulated electronic structure weakens the interactions between the Ru active sites and the reaction intermediates, which facilitates the HER reaction steps including H intermediate desorption and water dissociation. Experimental and theoretical findings provide insight into enhancing pH‐universal HER performance through modulation of electrocatalyst electronic structure. [ABSTRACT FROM AUTHOR]

There are works have reported the crystal structures and mechanical properties of ferrite cement (C4AF) at the atomic scale with deviation owing to the omission of the Coulomb interaction effect (Ueff) between 3d electrons of Fe in C4AF. In this work, the DFT+U method was used to evaluate its effect on their electronic structures and mechanical properties of C4AF with two different phases I2mb (C4AF‐I) and Pnma (C4AF‐P). The FeO bonds of the two phases are all weaker and display Ueff due to the presence of Fe ions. The mechanical properties of C4AF calculated using DFT+U method significantly differ from those obtained without considering Ueff, in which the former shows lower inferior mechanical properties than the latter. This work presents a comparative study the effect of Coulomb interaction to the internal electronic structures and mechanical properties, which will pave the way for designing high hydration reaction cement and high toughness materials. [ABSTRACT FROM AUTHOR]

The effect of uniaxial strain on the electronic structure of intrinsic and N-doped 4H-SiC is investigated by first principles method based on density functional theory. The results show that the strain can effectively regulate the band gap of the intrinsic and N-doped 4H-SiC, and the band gap decreases monotonically under tensile strain. Under compressive strain, the band gap firstly increases and then decreases. When the compressive strain is -1%, the band gap reaches the maximum value. By analyzing the density of states that the valence band maximum of the intrinsic and N-doped 4H-SiC are mainly from the electrons of Si 3p and C 2p states, and the conduction band minimum are mainly from the electrons of Si 3p states. The C 2p states and Si 3p states affect the valence band maximum and conduction band minimum, leading to the change of band gap in the strain structure. Mulliken Population and differential charge density analysis show that the charge transfer from the atom of Si to C and N decreases with the increase of lattice constants, and the covalence between Si-C atom and Si-N atom are weakened. [ABSTRACT FROM AUTHOR]

As for spintronic applications, all information is encoded in the spin degree of freedom, so the key issues are the high spin-polarization, large half-metallic (HM) bandgap, large magnetic moment and higher Curie temperature than room temperature. In this paper, we studied halogen based CsYZ2 (Y = V or Cr; Z = F, Cl, Br or I) full-Heusler alloys. Our study reveals that CsVF2, CsVCl2, CsVI2 and CsCrI2 alloys are all HM ferromagnets while remaining alloys exhibits magnetic semiconductor behavior. The electronic structures indicate that these alloys open very large bandgaps in the spin-down channel. Following the Slater-Pauling rule Mt=Zt-16, these alloys exhibit very large total magnetic moments Mt of 4.00 μBf.u. when Y = V and 5.00 μBf.u. when Y = Cr. The high Curie temperatures indicate these alloys are appropriate for spintronic applications at room temperature. Furthermore, the absorption coefficient α(ω) of the CsVF2 alloy is better from other alloys in the visible region. The maximum ZT = 0.7 is obtained for CsCrBr2 and is an ideal candidate for thermoelectric (TE) applications.

To explore carbide superconductors with higher transition temperature, two novel carbon structures of cage‐network are designed and their superconductivity is studied by doping metals. MC6 and MC10 are respectively identified as C24 and C32 cage‐network structures. This study finds that both carbon structures drive strong electron–phonon interaction and can exhibit superconductivity above liquid nitrogen temperature. Importantly, the superconducting transition temperatures above 100 K are predicted to be achieved in C24‐cage‐network systems doped by Na, Mg, Al, In, and Tl at ambient pressure, which is far higher than those in graphite, fullerene, and other carbides. Meanwhile, the superconductivity of cage‐network carbides is also found to be sensitive to the electronegativity and concentration of dopant M. The result indicates that the higher transition temperatures can be obtained by optimizing the carbon‐cage‐network structures and the doping conditions. The study suggests that the carbon‐cage‐network structure is a direction to explore high‐temperature superconducting carbides. [ABSTRACT FROM AUTHOR]

A series of neutral and anionic platinum(II) complexes bearing Janus-type N-Heterocyclic carbenes (NHC) with different extents of π conjugation were constructed theoretically by bridging two cyclometallated platinum(II) centers using diNHC linkers. The diNHCs bind to Pt(II) in either in monodentate (neutral complex I, II) or bidentate (anionic complex III−V) fashion. Structures of all complexes were first optimized. Single point and TD-DFT calculations have been carried out using the gas-phased optimized geometries to gain insight into their electronic structures, possible electronic transitions, and to probe the influence of diNHC ligand design on the photo-responsiveness of the complexes. The response of complexes I−III is limited to UV light; however, complexes IV and V, which contain cyclometallated diNHCs, exhibit absorption bands in the visible region. Additionally, the emissive triplet excited state and the metal-center triplet excited states (3MC) were also investigated. Interestingly, the results suggest that the internal conversion triplet excited state to 3MC in I and III, which induces significant coordination geometry distortion, is energetically favorable for complexes I and III suggesting potentially photo-enhanced reactivities of these two complexes. [ABSTRACT FROM AUTHOR]

Wide bandgap and large birefringence, as well as strong second harmonic effect, are important but often mutually restraint prerequisites for deep‐ultraviolet (DUV) nonlinear optical (NLO) crystals, a type of photoelectronic materials that play an indispensable role in the DUV laser generation. For the long term, the search for new DUV NLO crystals has focused on the alkali‐metal inorganic acid salts where the variations of anionic groups are considered. Herein, another design strategy is reported, in which the alkali‐metal cations are substituted by the asymmetrical non‐π‐conjugated cations to harmonize the above mutual restrictions. Accordingly, LiN2H5SO4 (LNHSO) crystal is obtained by the substitution of [N2H5]+ for alkali‐metal ions in LiMSO4 (M = Na, K, and Rb). Compared with LiMSO4 (M = Na, K, and Rb), LNHSO exhibits a moderate phase‐matching second‐harmonic generation response (0.6 × KH2PO4), increased birefringence (two to three times that of other sulfates), and the widest bandgap (7.69 eV) among all the reported NLO sulfates. The structural analysis and theoretical calculation reveal that the structural anisotropy, arrangement, and packing configuration of the novel NLO‐active [N2H5]+ cation in LNHSO effectively promotes the optical properties and enlarges the bandgap. This work provides an innovative perspective for the rational design and synthesis of DUV NLO materials with excellent performance. [ABSTRACT FROM AUTHOR]

In this work, the structural, electronic, elastic, optical, and magnetic properties for the B1, B2, and B3 phases of Sr0.875Mn0.125O with relaxed structure (RS) and unrelaxed structure (URS) are investigated. The investigations are accomplished by the adoption of first‐principle methods established on spin‐polarized density functional theory, based on the full‐potential linearized augmented plane wave method as implemented in the WIEN2k code, where the electronic exchange‐correlation potential is studied by the Perdew–Burke–Ernzerhof generalized gradient approximation (GGA‐PBEsol) and the revised TB‐mBJ rapprochement. The negative formation energy and elastic constant that are acquired indicate the thermodynamical and mechanical stability of all these structures. The ternary Sr0.875Mn0.125O alloys for all structures show half‐metallic ferromagnetic behavior with a spin polarization of 100 % at the Fermi level, except the B2 phase without unrelaxed structure (URS). The total magnetic moments are 5 µB for all compounds and the interaction is ferromagnetic between Mn─Sr and Mn─O sites. Optical properties such as refractive index and the optical reflectivity for these alloys are computed and discussed. These materials are half‐metallic ferromagnets, and they can be desirable applicants for spintronics implementations and ultraviolet spectra. [ABSTRACT FROM AUTHOR]

Flower‐like spherical micrometer‐sized particles of FeS2 and NiS2 are synthesized using the solvothermal method. The microstructure, phase composition, saturation magnetization and optical characteristics of the synthesized FeS2 and NiS2 are described, and the atomic structure, electronic structure, and optical characteristics of the materials are calculated systematically founded upon the first principles of density functional theory. This work shows that the magnetic saturation intensity of FeS2 and NiS2 is respectively 0.36 and 0.02 emu g−1. The FeS2 and NiS2 bandgaps are separately 0.81 and 2.07 eV, calculated by Tauc's relation. Through the comparison of optical properties, the maximum absorption coefficient of FeS2 and NiS2 is separately 3.26 × 105 and 3.3 × 105 cm−1, and the two crystals' absorption coefficient accordingly drops to 0 at 23.8 and 25.8 eV, indicating that the maximum absorption value and energy absorption range of NiS2 are higher than those of FeS2. The reflectivity above 60% ranges from 15.3 to 20.6 eV and 15.2 to 21.5 eV for FeS2 and NiS2, respectively, which indicates that the reflectivity of NiS2 is stronger than that of FeS2. [ABSTRACT FROM AUTHOR]

Context: Schiff base-containing metal complexes have been the subject of extensive research. In this work, a coordination polymer-derived complex called [Cu(L)] that is solution-stable (L = 2-(2-hydroxybenzylidene-amino)phenol) has been explored theoretically with five different pyridyl-based ligands using DFT/TDDFT in order to understand the structural–functional and electronic transitions of these five complexes. Frontier molecular orbital (FMO) analysis was carried out to assess the reactivity behavior of all five complexes. For the purpose of studying the charge energy distribution over complexes, electrostatic potential maps were also drawn. Furthermore, in order to identify any stabilizing interactions that may be present in the given complexes, an NBO analysis was studied. To learn more about any potential correlations between the properties of these five complexes, a comparative analysis was explored. Our calculations demonstrate that complex 3 having pyridine-4-carboxamide as a ligand has a lower energy gap and a higher negative electrostatic potential which may indicate its higher reactivity and this may be due to the electron withdrawing group (carboxamide). TDDFT results show that the highest light harvesting efficiency (LHE) of all the studied complexes is found in the range of 440–448 nm. Complexes 1, 2, and 4 show the higher light harvesting efficiency as compared to complexes 3 and 5. Our findings are in good accordance with the available experimental data. Methods: All DFT computations were performed using the Gaussian16 with unrestricted B3LYP-D2 functional with the basis sets 6-31G(d,p) for O, N, C, and H while LanL2DZ for Cu. The polarized continuum model (PCM) was used for the solvation. The software GaussView6.1 was utilized for the modeling of initial geometries and the plotting of MEP maps. The NBO6.0 program which is incorporated in Gaussian16 was utilized to investigate the bonding nature and stabilization energies of the complexes. The ORCA program was used to simulate the absorption spectra. [ABSTRACT FROM AUTHOR]

Dual‐atom site catalysts (DACs) have emerged as a new frontier in the heterogeneous catalysis field for electrochemical energy conversion systems. In this review, the superiority of DACs over single‐atom site catalysts is fully discussed. The origin of synergistic effects such as optimized d‐band structure, tailored spin state, and tuned charge transfer are pointed out. The merits in geometric and electronic structure render the active moiety versatile binding behavior toward adsorbed intermediate and beneficial synergistic effects to break the scaling relationships. The approaches to engineer the active moiety of DACs through modulating the central atoms, tuning the coordination environment, and engineering the metal‐support interaction are summarized. Finally, the current challenges and future research perspectives of DACs for efficient electrocatalysis are outlined. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of oxygen into hydrogen peroxide in an acidic medium offers an energy‐efficient and green H2O2 synthesis as an alternative to the energy‐intensive anthraquinone process. Unfortunately, high overpotential, low production rates, and fierce competition from traditional four‐electron reduction limit it. In this study, a metalloenzyme‐like active structure is mimicked in carbon‐based single‐atom electrocatalysts for oxygen reduction to H2O2. Using a carbonization strategy, the primary electronic structure of the metal center with nitrogen and oxygen coordination is modulated, followed by epoxy oxygen functionalities close to the metal active sites. In an acidic medium, CoNOC active structures proceed with greater than 98% H2O2 selectivity (2e−/2H+) rather than CoNC active sites that are selective to H2O (4e−/4H+). Among all MNOC (M = Fe, Co, Mn, and Ni) single‐atom electrocatalysts, the CoNOC is the most selective (> 98%) for H2O2 production, with a mass activity of 10 A g−1 at 0.60 V vs. RHE. X‐ray absorption spectroscopy is used to identify the formation of unsymmetrical MNOC active structures. Experimental results are also compared to density functional theory calculations, which revealed that the structure‐activity relationship of the epoxy‐surrounded CoNOC active structure reaches optimum (ΔG*OOH) binding energies for high selectivity. [ABSTRACT FROM AUTHOR]

First‐principles calculations based on density functional theory (DFT) are used to investigate the phase transition characteristics, electronic structures, and optical properties of pure and Co‐doped VO2 (M1 and R phase). Studies show that the metal‐to‐insulator phase transition temperature of VO2 is significantly reduced after Co doping, which is correlated to the decrease of bandgap value. Besides, the decrease of the energy required for electron transition of M1‐phase Co‐doped VO2 corresponds to the imaginary part of the dielectric peak moving to the low‐energy region. For both the M1‐ and R‐phase VO2, the visible light transmissivity of the Co‐doped VO2 is increased than that of pure VO2, which is beneficial to the application of VO2 film as visible windows. In addition, the absorptivity and reflectivity of Co‐doped R‐phase VO2 in the infrared light range are larger than those of M1‐phase VO2, indicating that the Co‐doped VO2 can block more infrared light at higher temperature to fulfill the purpose of lowering temperature. Overall, these results give new insights for the application of Co‐doped VO2 as a photoenergy material to regulate the room temperature. [ABSTRACT FROM AUTHOR]

Ultrasensitive gas sensors have been fabricated depending on novel 2D materials. The adsorption behavior of diatomic molecules (H2, HF, N2, CO, O2, and NO) on the 2D‐SnP3 monolayer is investigated by utilizing first‐principle calculations for seeking the applications of sensing and detecting gases. H2 molecule displays weak adsorption effects on the SnP3 monolayer, while N2, CO, HF, and O2 show a moderate adsorption effect. NO molecule tends to chemisorb, resulting in a significant change transition for the electrical conductivity of the SnP3 monolayer. The calculation results of adsorption energies, charge transfers, and work function indicate that the SnP3 monolayer can be a promising candidate as a room‐temperature NO gas sensing 2D material due to its high selectivity, conspicuous sensitivity, and short recovery time. This study can guide the feasibility of using SnP3 monolayer as a NO gas sensor in further experimental applications. [ABSTRACT FROM AUTHOR]

In the past decades, remarkable progress has been achieved in the exploration of electrocatalysts with high activity, long durability, and low cost. Among these, defective graphene (DG)‐based catalysts are considered as one of the most potential substitutes for precious metal‐based electrocatalysts. DG‐based catalysts contain abundant active centers with different configurations resulting from their extraordinary high‐structural tunability. Herein, an overview on recent advancements in developing four kinds of DG‐based catalysts is presented: 1) heteroatoms‐doped graphene; 2) intrinsic DG (vacancy and topological defect); 3) nonmetal atoms or/and metal species‐modified intrinsic DG (heterogeneous species and intrinsic defects co‐tuned DG); and 4) DG‐based van der Waals‐type multilayered heterostructures. In particular, the synergistic effects between various defects are discussed, and the origin of catalytic activity is reviewed. Meanwhile, the established defect‐derived catalytic mechanism is summarized, which is beneficial for the rational design and fabrication of high‐performance electrocatalysts for practical energy‐related applications. Finally, challenges and future research directions on defect engineering in noble metal‐free materials for electrocatalysis are proposed. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of molecular hydrogens (H2) on boron nitride (BN) frameworks was investigated using the density functional theory (DFT) technique. The results of optimized geometric structures revealed that molecular hydrogens were favourably adsorbed on top of nitrogen atoms in the BN monolayers. In addition, the optimized equilibrium geometries were utilized to calculate the electronic structures, including binding energies, energies of the highest and lowest occupied molecular orbitals (HOMO and LUMO), molecular electrostatic potentials (MEPs), and Mulliken atomic charges (MACs). The binding energy values were calculated to be approximately 0.01 eV per molecular hydrogen based on the results. As the number of molecular hydrogens increased in the BN framework, a slight increase was observed in the binding energy value per hydrogen molecule. Furthermore, the HOMO-LUMO gaps were determined with the corresponding energy values of about 6 eV. Regarding the Frontier molecular orbitals (FMOs) diagrams, the electron densities for the HOMOs of the studied systems were primarily focused on the N-edges. Conversely, for the LUMO, the electron density distribution was localized in the B-edges of titled systems. In the context of hydrogen adsorption on BN nanosheets, the MEP maps indicated that hydrogen atoms at the N-edges of the studied systems exhibited the most positive electrostatic potentials in this research. In contrast, surfaces with negative electrostatic potential surfaces were situated in the region close to B-edges. The computed results are consistent with the corresponding Mulliken atomic charge distributions. From the analyses of the Mulliken scheme, all nitrogen atoms displayed negative charge values, and positive charges were found on the boron atoms. The DFT results obtained in this report may serve as the foundation for developing hydrogen storage materials.. [ABSTRACT FROM AUTHOR]

First‐principles calculations based on density functional theory (DFT) are used to investigate the phase transition characteristics, electronic structures, and optical properties of pure and Co‐doped VO2 (M1 and R phase). Studies show that the metal‐to‐insulator phase transition temperature of VO2 is significantly reduced after Co doping, which is correlated to the decrease of bandgap value. Besides, the decrease of the energy required for electron transition of M1‐phase Co‐doped VO2 corresponds to the imaginary part of the dielectric peak moving to the low‐energy region. For both the M1‐ and R‐phase VO2, the visible light transmissivity of the Co‐doped VO2 is increased than that of pure VO2, which is beneficial to the application of VO2 film as visible windows. In addition, the absorptivity and reflectivity of Co‐doped R‐phase VO2 in the infrared light range are larger than those of M1‐phase VO2, indicating that the Co‐doped VO2 can block more infrared light at higher temperature to fulfill the purpose of lowering temperature. Overall, these results give new insights for the application of Co‐doped VO2 as a photoenergy material to regulate the room temperature. [ABSTRACT FROM AUTHOR]

Organic semiconductors with distinct molecular properties and large carrier mobilities are constantly developed in attempt to produce highly‐efficient electronic materials. Recently, designer molecules with unique structural modifications have been expressly developed to suppress molecular motions in the solid state that arise from low‐energy phonon modes, which uniquely limit carrier mobilities through electron–phonon coupling. However, such low‐frequency vibrational dynamics often involve complex molecular dynamics, making comprehension of the underlying electronic origins of electron–phonon coupling difficult. In this study, first a mode‐resolved picture of electron–phonon coupling in a series of materials that are specifically designed to suppress detrimental vibrational effects, is generated. From this foundation, a method is developed based on the crystalline orbital Hamiltonian population (COHP) analyses to resolve the origins—down to the single atomic‐orbital scale—of surprisingly large electron–phonon coupling constants of particular vibrations, explicitly detailing the manner in which the intermolecular wavefunction overlap is perturbed. Overall, this approach provides a comprehensive explanation into the unexpected effects of less‐commonly studied molecular vibrations, revealing new aspects of molecular design that should be considered for creating improved organic semiconducting materials. [ABSTRACT FROM AUTHOR]

Dopamine (DA) is a crucial molecule for the central nervous system, and the ability to detect it in samples containing molecules such as Ascorbic Acid (AA) and Uric Acid (UA) could facilitate early diagnosis of related disorders. In this work, the interaction of DA, UA, and AA with InBi and Graphene (GR) monolayers under charging was investigated using Density Functional Theory (DFT) calculations with van der Waals (vdW) correction and nonequilibrium Green's function method for the first time. According to our calculations, the most influential factor in the interaction was observed to arise from the π – π and π –O interaction between molecules and surfaces. It has been concluded that InBi is a better adsorbent than GR for DA, AA, and UA, where the adsorption energies from the highest to lowest were found as UA > AA > DA. Furthermore, the charge transfers between molecules and surfaces were investigated, and it was demonstrated that the molecules on GR act as charge acceptors. In contrast, for InBi–molecule systems, electronic drift from molecules to the InBi surface was observed. The Partial Density of States (P-DOS) plots were examined, and the results were discussed in detail. The consequences of adding/removing charges to/from the systems were also examined, and it was shown that removing Q = 2 e/cell from the GR–molecule systems effectively detected DA molecules from the others. Charging also broke the topological state of InBi, leading to semiconductor to metal, except for the Q = − 2 e/cell case. Finally, the changes in transmittance due to adsorption were simulated, and our results show that InBi is a possible candidate for DA sequencing biosensor applications compared to GR. The findings of this work provide a theoretical framework for the development and creation of highly precise biodevices and biosensors. [ABSTRACT FROM AUTHOR]

Transition metal‐nitrogen‐carbon (M‐N‐C) catalysts with CoN4 centers have attracted great attention as a potential alternative to precious metal catalysts for bifunctional oxygen electrocatalysis. However, the asymmetric charge environment of the active site of MN4 obtained by conventional pyrolysis strategy makes the unbalanced adsorption of oxygen molecules, which restricts the activities of both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, a series of well‐defined quasi‐phthalocyanine conjugated 2D covalent organic polymer (COPBTC‐M) is developed with MN4+4 active sites through a pyrolysis‐free strategy. Compared to CoN4 site, the additional subcentral N4 atoms in MN4+4 site in COPBTC‐Co catalyst balance the charge environment and form a symmetric charge distribution, which changes the antibonding orbital of the active metal and regulate the oxygen species adsorption, thus improving the activity of the bifunctional oxygen electrocatalysis. In Silico screening demonstrates that cobalt has the best ORR and OER activity for COPBTC‐M with MN4+4 sites, which can be attributed to the fewer anti‐bonding orbital below the Fermi level, which weakens the oxygen species adsorption. Both theoretical and experimental results verify that the COPBTC‐Co possesses unique CoN4+4 active sites and the harmonious coordinating environment can lead to superior bifunctional oxygen catalytic activity with a high bifunctional oxygen catalytic activity (ΔE [Ej10 – E1/2] = 0.76 V), which is comparable with the benchmark Pt/C‐IrO2 pairs. Accordingly, the as‐assembled Zn–air battery exhibits a maximum power density of 157.7 mW cm −2 with stable operation for >100 cycles under an electric density of 10 mA cm −2. This study provides a characteristic understanding of the intrinsic active species toward MNx centers and could inspire new avenues for designation of advanced bifunctional electrocatalysts that catalyze ORR and OER processes simultaneously. [ABSTRACT FROM AUTHOR]

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Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) has been widely employed to characterize transition metal complexes. However, because of the high degree of complexity of transition metal EPR spectra, how to extract the underlying electronic-structure information inevitably poses a major challenge to beginners, in particular for systems with S>12. In fact, the physical principles of transition metal EPR have long been well-established and since 1970s a series of dedicated voluminous monographs have been published already. Not surprisingly, they are not appropriate stating points for novices to grasp a panorama of the profound theory prior to scrutinizing in-depth references. The present review aims to fill this gap to provide a perspective of transition metal EPR and unveil some peculiar subtleties thereof on the basis of our recent work.

A plasma approach is reported to synthesize carbon cloth supported carbon fiber and oxygen defect‐rich NiCoO/NiCoN hetero‐nanowire co‐integrated hybrid catalyst (P‐NCO/NCN‐CF@CC), which includes the advanced features of carbon integration, cation doping, defect/vacancy introduction, and heterostructuring. The P‐NCO/NCN shows a fascinating structure with the periphery composed of NCO and the interior co‐composed of NCO and NCN. Its formation mainly depends on the high reactivity of energetic species of NH, Ha, and Hb formed during the plasma discharge. The P‐NCO/NCN‐CF@CC exhibits the oxygen reduction reaction (ORR) activity comparable to the Pt/C and the oxygen evolution reaction (OER) activity higher than RuO2. When used in the all‐solid‐state zinc‐air batteries, it gives a high maximum power density of 109.8 mW cm−2 with no performance drop observed for >300 cycles. The DFT calculations indicate that the NCO/NCN heterostructuring and oxygen defects in NCO play the important roles in the high ORR/OER activities of the catalyst. They can modulate the electronic structure of the catalyst, lowering the energy barriers of rate determining steps. [ABSTRACT FROM AUTHOR]

Transition-metal-doped clusters have long been attracting great attention due to their unique geometries and interesting physical and/or chemical properties. In this paper, the geometries of the lowest- and lower-energy CoKn (n = 2–12) clusters have been screened out using particle swarm optimization and first principles relaxation. The results show that except for CoK2 the other CoKn (n = 3–12) clusters are all three-dimensional structures, and CoK7 is the transition structure from which the lowest energy structures are cobalt atom-centered cage-like structures. The stability, the electronic structures, and the magnetic properties of CoKn clusters (n = 2–12) clusters are further investigated using the first principles method. The results show that the medium-sized clusters whose geometries are cage-like structures are more stable than smaller-sized clusters. The electronic configuration of CoKn clusters could be described as 1S1P1D according to the spherical jellium model. The main components of petal-shaped D molecular orbitals are Co-d and K-s states or Co-d and Co-s states, and the main components of sphere-like S molecular orbitals or spindle-like P molecular orbitals are K-s states or Co-s states. Co atoms give the main contribution to the total magnetic moments, and K atoms can either enhance or attenuate the total magnetic moments. CoKn (n = 5–8) clusters have relatively large magnetic moments, which has a relation to the strong Co-K bond and the large amount of charge transfer. CoK4 could be a magnetic superatom with a large magnetic moment of 5 μB. [ABSTRACT FROM AUTHOR]

Understanding the nature of charge‐trapping defects in amorphous chalcogenide alloy‐based phase‐change memory materials is important for tailoring the development of multilevel memory devices with increased data storage density. Herein, hybrid density‐functional theory simulations have been employed to investigate electron‐ and hole‐trapping processes in melt‐quenched glassy models of four different Ge‐Sb‐Te compositions, namely, GeTe, Sb2Te3, GeTe4, and Ge2Sb2Te5. The calculations demonstrate that extra electrons and holes are spontaneously trapped, creating charge‐trapping centers in the bandgap of the amorphous materials. Over‐ and undercoordinated atoms, tetrahedral and "see‐saw" octahedral‐like geometries, fourfold rings, homopolar bonds, near‐linear triatomic configurations, and chain‐like motifs comprise the range of the defective atomic environments that have been identified in the structural patterns of the charge‐trapping sites inside the glassy networks. The results illustrate that charge trapping corresponds to an intrinsic property of the glassy Ge‐Sb‐Te systems, show the impact of electron and hole localization on the atomic bonding of these materials, and they may have important implications related to the operation of phase‐change electronic‐memory devices. [ABSTRACT FROM AUTHOR]

Density functional theory was employed to investigate the electronic structures of atomic bilayer materials that form between graphene (g‐C) or graphitic silicon carbide (also known as siligraphene: g‐SiC and g‐SiC2) and graphitic zinc oxide (g‐ZnO). The results indicate that g‐C/g‐ZnO bilayers have semimetallic properties with an energy band gap of zero like in graphene. For a g‐SiC/g‐ZnO bilayer, an ensemble of three sp2‐hybridized carbon atoms periodically separated by three silicon atoms on g‐ZnO has indirect and direct band gaps of 3.32 and 3.78 eV, respectively, which is suitable for use in light‐emitting diode applications. For a g‐SiC2/g‐ZnO bilayer, an ensemble of four sp2‐hybridized carbon atoms periodically separated by two silicon atoms on g‐ZnO has a direct band gap of 1.15 eV, which approaches the optimal value of the band gap (Eopt ≃ 1.3 eV) for solar cell applications. The results show that increasing Si content in siligraphene can help to open the band gap of graphene and enhance the band gap of graphitic silicon carbide. The band gaps of siligraphene/g‐ZnO bilayers depend on a smaller band gap from the monolayer component. Therefore, adjusting the Si content in siligraphene permits tuning of the band gap, and constructing a bilayer in the presence of a g‐ZnO monolayer can slightly decrease the band gap. These results could lead to a new design of heterostructures with tunable band gaps for various applications. [ABSTRACT FROM AUTHOR]

Density functional theory is applied to account the ligand effect on modification in the redox potential of coordination of three NN bidentate ligands (bpy/phen) to the metal ion (Fe2+/3+/Co2+/3+). Also, the role of the ligand framework for the stabilization of [M(bpy/phen)3]2+/3+ species is discussed in detail. In this work, we have found that the M2+ ions are more stabilized with the bpy ligands while the M3+ ions are more stable with the phen ligands. The electronic structure and geometrical study disclosed the electronic configurations of the metal ions in both the possible spin states of a species. Furthermore, the HOMO–LUMO analysis demonstrates that the M3+ ion coordinated species have more energy gap as compared to the M2+ ion coordinated species. Among all the species, HOMO–LUMO energy gap has been found highest (4.62 eV) in the [Fe(bpy)3]3+ whereas lowest (3.28 eV) in the [Co(phen)3]2+ species. Additionally, we have also found that the bpy coordinated species have relatively higher redox potential value as compared to phen ligated species. Here we have noticed a close relationship between the redox potential and the optimized structural parameters of the studied species. Also, all the computed structural parameters of the studied species are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Van der Waals materials and their interfaces play critical roles in defining electrical contacts for nanoelectronics and developing vehicles for mechanoelectrical energy conversion. In this work, we propose a vertical strain engineering approach by enforcing pressure across the heterostructures. First-principles calculations show that the in-plane band structures of 2D materials such as graphene, h-BN, and MoS2 as well as the electronic coupling at their contacts can be significantly modified. For the graphene/h-BN contact, a band gap in graphene is opened, while at the graphene/MoS2 interface, the band gap of MoS2 and the Schottky barrier height at contact diminish. Changes and transitions in the nature of contacts are attributed to localized orbital coupling and analyzed through the redistribution of charge densities, the crystal orbital Hamilton population, and electron localization, which yield consistent measures. These findings offer key insights into the understanding of interfacial interaction between 2D materials as well as the efficiency of electronic transport and energy conversion processes. [ABSTRACT FROM AUTHOR]

Unusual thermoelectric (TE) transport in n‐type In4Se3 has been reported in the context of first‐principles electronic structure calculation and Boltzmann transport theory. The density of states (DOS) shows certain peaks due to a nontopological Mexican hat and parabolic capping around the edges of Kane bands. The effect of such hard shifts of bands shows anomalously high Seebeck coefficient (S = 550 μV K−1 at ≈1017 cm−3) at room temperature due to very slow decreasing S(SDFT∝n−1/7.84)$\left(\right. S_{\text{DFT}} \propto n^{- 1 / 7.84} \left.\right)$ and rapidly increasing DOS effective mass (m*DOS∝n1/1.90)$\left(\right. m^{\star} _{\text{DOS}} \propto n^{1 / 1.90} \left.\right)$ with carrier concentration compared to that obtained from Kane and parabolic band model. The best TE performance is predicated in Kane transport region (≈1018 cm−3) over the wide range of temperature, 300–700 K. The calculated values of relaxation time (≈10−14 s at 660 K), electrical conductivity, power factor and figure of merit in iodine‐doped sample and those obtained from the rigid band model of pure sample show excellent agreement with the reported experimental results. [ABSTRACT FROM AUTHOR]

Group IIIA elements are electron deficient, and the transition metal doped clusters can be used to build cluster-based materials. This paper study the global lowest energy structures of In8FeNan (n = 0, 2, 4, 6, 8) by using evolutionary algorithm combined with spin polarized density functional theories. The electronic structures show that the Na atoms donate electrons to the In8Fe core and combine on the peripheries of the clusters through electrostatic interactions. Analyses on density of states and molecular orbitals reveal that the 5s orbitals of In atoms do not mix with other atomic orbitals and form superatomic orbitals with lower energies. The 3d orbitals of Fe atom interact strongly with the superatomic orbitals formed by In 5p. Different interaction patterns compete and it makes the lowest electronic ground states be singlet or triplet. In the triplet states of In8FeNan, the α orbitals have three or four 3d orbitals localized on the Fe atom. For the singlet states, there exists no pure 3d atomic orbitals and the upper valence states show obvious features of bonding or antibonding interactions between atomic Fe 3d and superatomic orbitals composed of In 5p. The strong orbital interactions enhance significantly the stabilities of the clusters. [ABSTRACT FROM AUTHOR]

CH3NH3PbI3 perovskite solar cells using metal phthalocyanines (MPcs) with decaphenylcyclopentasilane (DPPS) are fabricated and characterized. The effect of addition of MPcs on the photovoltaic properties is investigated by changing the central element of the MPc and depositing MPc and DPPS successively on the perovskite layer. When silicon phthalocyanine is used to the cell, the microstructure of the perovskite film improves, which results in improvement of the open‐circuit voltage, fill factor, and photoconversion efficiency. For cells with only MPcs as the hole‐transport layer, the conversion efficiency increases by passivation with the phthalocyanine and crystal growth at room temperature. [ABSTRACT FROM AUTHOR]

Metal-superoxo species are supposed to be a key intermediate in metalloenzyme to carry out catalytical reactions. Some biomimetic metal-superoxo species have been synthesized and characterized such as chromium/iron/nickel-superoxo species. Density functional theory (DFT) studies on metal with + 3 oxidation state superoxo species are already reported whereas less exploration encountered with + 2. Inspired from here, we have modeled metal(II)-superoxo having 14-TMC (1,4,8,11-tetramethyl-1,4,8,11- tetraazacyclotetradecane) ligand with V, Cr, Mn, Fe, Co, and Ni. Here, we have performed DFT calculations using B3LYP-D2 functional for the possible spins of all the six species and predicted the ground state. We have also computed the frontier molecular orbitals and elaborated isodensity over the molecules. Electrostatic potential maps are also drawn for studying the charge energy distribution over the species. Our calculations also reveal that a significant spin density and charge on the distal oxygen may activate the C-H/O–H bond of organic substrates. [ABSTRACT FROM AUTHOR]

The dimensions of nanoribbons have a significant impact on their material properties. In the fields of optoelectronics and spintronics, one-dimensional nanoribbons exhibit distinct advantages due to their low-dimensional and quantum restrictions. Novel structures can be formed by combining silicon and carbon at different stoichiometric ratios. Using density functional theory, we thoroughly explored the electronic structure properties of two kinds of silicon–carbon nanoribbons (penta-SiC2 and g-SiC3 nanoribbons) with different widths and edge conditions. Our study reveals that the electronic properties of penta-SiC2 and g-SiC3 nanoribbons are closely related to their width and orientation. Specifically, one type of penta-SiC2 nanoribbons exhibits antiferromagnetic semiconductor characteristics, two types of penta-SiC2 nanoribbons have moderate band gaps, and the band gap of armchair g-SiC3 nanoribbons oscillates in three dimensions with the width of the nanoribbon. Notably, zigzag g-SiC3 nanoribbons exhibit excellent conductivity, high theoretical capacity (1421 mA h g−1), moderate open circuit voltage (0.27 V), and low diffusion barriers (0.09 eV), making them a promising candidate for high storage capacity electrode material in lithium-ion batteries. Our analysis provides a theoretical basis for exploring the potential of these nanoribbons in electronic and optoelectronic devices as well as high-performance batteries. [ABSTRACT FROM AUTHOR]

Context: In this study, we predict the stability, elastic, electronic and optical properties of double perovskite (DP) Cs2CuIrF6. The detailed investigation of electronic structure and optical properties to find the suitability of DP Cs2CuIrF6 for device applications. From the structural optimization results, the stability of DP (Cs2CuIrF6) is in cubic order and belongs to the Fm-3 m space group (#225) with a nonmagnetic (NM) state. Additionally, the elastic results show that this DP is mechanically stable in a cubic and ductile manner. Further, we explain in detail the semiconducting nature of the proposed DP with the help of electronic structure and density of states (DOS). The electronic band gap of DP Cs2CuIrF6 is 0.72 eV (LV-XC). The optical part discussion, like the dielectric function ε, reflectivity R, refractive index n, absorption coefficient α and optical conductivity σ up to 13.00 eV. The studied compound is explored as a potential candidate for optoelectronic applications. Methods: The density functional theory (DFT) within generalized gradient approximation (GGA) scheme of Perdew, Burke and Ernzerhof (PBE) as implemented in Wien2k computational code is utilized to achieve stable structure, elastic, electronic and optical properties of this material. The dynamic stability of this material was studied using the finite displacement method implemented in the CASTEP computational code. The elastic results have been computed by the IRelast package implemented in the Wien2k computational code. [ABSTRACT FROM AUTHOR]

The catalytic performance of carbon nanotubes has still been hindered by the intrinsic and limited in‐plane electrocatalytic active sites, with a focus on improving their catalytic activity by covalent modifications, which require the relatively high energy input to dissociate the in‐plane atoms and create the active sites. Herein, an effective route is developed to modulate the in‐plane defective density and electronic structure of multi‐walled carbon nanotubes (MWCNTs) by ultra‐small‐sized g‐C3N4 quantum dots (CNQDs) with abundant nitrogen species via π–π stacking. The non‐covalent bonded CNQDs on MWCNTs endow them with abundant catalytic active sites on the basal plane, still inheriting the intrinsic and fast electron‐transfer characteristics of MWCNTs. The optimized CNQDs/MWCNTs‐4 heterogeneous catalyst exhibits an optimal photoelectric conversion efficiency of up to 8.30% in probing reaction for triiodide reduction, outperforming the Pt reference (7.86%). The thermodynamic calculations further reveal that the CNQDs integrated on MWCNTs are capable of reducing the reaction energy barrier (ΔG) of the rate‐determining step from I2 to I− and adsorption state I*. The present study provides an efficient and non‐covalent strategy to construct excellent carbon‐based catalysts with abundant active sites, which is also enlightening for the preparation and application of other carbon‐based catalysts. [ABSTRACT FROM AUTHOR]

The chemical and electronic structure of the interface between a sputter‐deposited Zn(O,S) buffer layer and an industrial Cu(In,Ga)(S,Se)2 (CIGSSe) absorber for thin‐film solar cells is investigated with X‐ray and UV photoelectron spectroscopy, inverse photoemission spectroscopy, and X‐ray emission spectroscopy. We find a CIGSSe absorber surface band gap of 1.61 (±0.14) eV, which is significantly increased as compared to the minimal value derived with bulk‐sensitive methods (≈1.1 eV). We find no indication for diffusion of absorber elements into the buffer layer. Surface‐ and bulk‐sensitive measurements of the buffer layer suggest the presence of S‐Zn and S‐O bonds in the Zn(O,S) layer. We find that the naturally existing downward band bending toward the CIGSSe absorber surface is increased by the formation of the interface, likely enhancing carrier separation under illumination. We also derive a flat conduction band alignment, in line with the reported high conversion efficiencies of corresponding large‐area solar cells. [ABSTRACT FROM AUTHOR]