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[Display omitted] Engineering platinum-free catalysts for hydrogen evolution reaction (HER) with high activity and stability is essential for electrochemical hydrogen production. In this paper, we report the synthesis of cobalt-doped AlNi 3 /NiO (Co-AlNi 3 /NiO) electrode with three-dimensional nanoporous structure via chemical dealloying method. Density functional theory (DFT) calculations reveal that Co-AlNi 3 /NiO can accelerate water adsorption / dissociation and optimize adsorption–desorption energies of H* intermediates, thus improving the intrinsic HER activity. Both the introduction of Co and Al can efficiently ameliorate the electronic density around Ni sites of NiO and AlNi 3 , which can effectively reduce the energy barrier towards Volmer–Heyrovsky reaction and thus synergistically promote the hydrogen evolution. Benefiting from the large electrochemical active surface area, high electrical conductivity and electronic effect, the nanoporous Co-AlNi 3 /NiO catalyst exhibits remarkable HER activity with an overpotential of 73 mV at a current density of 10 mA cm−2 in alkaline condition, outperforming most of the reported non-precious metal catalysts. The nanoporous Co-AlNi 3 /NiO catalyst can operate continuously over 1000 h at high current densities with a robust stability. This work provides a new vision for the development of low-cost and efficient electrocatalysts for energy conversion applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1D MWO 4 (M = Mn, Co, Cd) nanomaterials were synthesized by electrospinning method. • CoWO 4 nanotubes exhibited superior efficiency in degrading BPA under UV–Vis–NIR light. • The wide-spectrum responses mechanism for MWO 4 (M = Mn, Co, Cd) were explained by DFT. Broadening the absorption region to near-infrared (NIR) light is critical for the photocatalysis due to the larger proportion and stronger penetration of NIR light in solar energy. In the present paper, one-dimensional (1D) MWO 4 (M = Mn, Co, and Cd) materials synthesized by electrospinning technique, were studied by combining the density functional theory (DFT) with experiment results, which possessed the enhanced light absorption capability within the range of 200–2000 nm. It was proved that in the ultraviolet–visible (UV–Vis) region, the absorption bands of CoWO 4 and MnWO 4 samples were attributed to the metal-to-metal charge transfer mechanism, while the absorption of CdWO 4 sample may be referable to the ligand-to-metal charge transfer mechanism. In the near-infrared (NIR) region, the absorption of CoWO 4 and MnWO 4 primarily originated from the d-d orbital transitions of Mn2+ and Co2+. The photocatalytic experimental results showed that the degradation rates for bisphenol A (BPA) over CoWO 4 , MnWO 4 , and CdWO 4 photocatalysts under UV–Vis/NIR light irradiation for 140 min/12 h were 78.8 %/75.9 %, 23.8 %/21.3 %, 12.8 %/8.7 %, respectively. This research offers the novel insights into the precise construction of tungstate catalytic systems and contributes to the advancement of UV–Vis–NIR full spectrum photocatalytic technology, and lays a foundation for a cleaner and more environmental-friendly future. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co 2 N C with diatomic pair sites was successfully prepared. • Co 2 N C exhibited much faster degradation kinetic rate than Co 1 N C. • More ROS were generated by the catalysis of Co 2 N C. • DFT calculation further revealed the enhanced activity of Co 2 sites. A novel strategy for better catalytic performance in terms of precisely tuning the metal atom number of active centers is gradually getting attention. In this paper, the Co atom pair sites on N -doped porous carbon was engineered. The binuclear Co 2 site structure was identified by aberration-corrected scanning transmission electron microscopy and X-ray absorption spectroscopy. As expected, the Co 2 N C display an outstanding Fenton-like catalysis activity in tetracycline degradation with turnover frequency exceeding 0.91 min−1 that is approximately 4 times higher than the conventional CoN 4 site. The EPR tests indicated that the ROS strength stimulated by the binuclear site was much stronger than that of single site. Theoretical density functional theory calculations reveal that the optimized adsorption configuration is the O1 of peroxymonosulfate (PMS) interacting with two Co atoms, leading to stronger interaction effect and electron transfer for PMS comparing to single atom sites. [ABSTRACT FROM AUTHOR]

This work vividly demonstrates the rational design of VSe 2-x O x -SS cathode as an effective strategy to achieve fast and highly aqueous zinc ion storage. [Display omitted] • A simple and fast surface oxygen implantation strategy was designed to adjust the electronic structure of VSe 2 and form a surface protective film. • The VSe 2-x O x -SS-30 electrode showed higher specific capacity, better rate performance and more satisfactory cycling stability. • The zinc (de)intercalation and transformation reactions mechanism was revealed by some ex-situ/in-situ techniques. Interfacial chemical modification is an effective strategy to adjust the strong Coulombic ion-lattice interactions with high valence cations experienced by electrode materials, facilitating the reaction kinetic. In this paper, a simple and fast surface oxygen implantation strategy was designed to adjust the electronic structure of stainless steel (SS) supported vanadium diselenide (VSe 2) nanosheets and form a surface protective film, which effectively accelerates the reaction kinetics of Zn2+ and extends the cycle life of the battery. It is demonstrated that the conductivity, pseudocapacitance and specific capacity can be tuned by selectively introducing oxygen species to the surface, which provides an important reference for the design of electrodes with controlled surface chemistry. Density functional theory (DFT) calculations also confirm that the electronic structure can be adjusted by surface oxygen injection strategy, which not only improves the conductivity, but also adjusts the adsorption energy, thus providing favorable conditions for zinc ion storage. Benefiting from the selenium vacancies and pores generated by the removal of part of selenium, and the oxide film formed on the surfaces, the VSe 2-x O x -SS-30 electrode showed higher specific capacity (188.4 mAh/g at 0.5 A g−1 after 50 cycles), better rate performance (107.1 mAh/g at 4 A g−1) and more satisfactory cycling stability (83.1 mAh/g at 5 A g−1 after 1800 cycles) than VSe 2 -SS electrode. Importantly, the flexible quasi-solid-state VSe 2-x O x -SS-30//Zn battery also exhibits high specific capacity and excellent environmental adaptability. Furthermore, the zinc (de)intercalation and transformation reactions mechanism was revealed by some ex-situ/in-situ techniques. [ABSTRACT FROM AUTHOR]

As a high-active metal-free electrocatalyst for NH 3 production via NO reduction reaction, honeycomb carbon nanofiber achieves an NH 3 yield of 22.35 μmol h−1 cm−2 with a high Faradaic efficiency of 88.33%. [Display omitted] Electrocatalytic NO reduction is a promising technology for ambient NO removal with simultaneous production of highly value-added NH 3. Herein, we report that honeycomb carbon nanofiber coated on carbon paper acts as an efficient metal-free catalyst for ambient electroreduction of NO to NH 3. In 0.2 M Na 2 SO 4 solution, such catalyst achieves an NH 3 yield of 22.35 μmol h−1 cm−2 with a high Faradaic efficiency of up to 88.33%. Impressively, it also shows excellent stability for 10-h continuous electrolysis. Theoretical calculations reveal that the most active center of functional groups is –OH group for NO reduction with a low energy barrier (ΔG of 0.29 eV) for the potential-determining step (*NO + H → *HNO). [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption energies of CO 2 on the surface oxygen vacancies of different crystalline In 2 O 3 were calculated using DFT. • The effect of the spatial distributions of two active components on the CO 2 hydrogenation to aromatics was studied. • The acidity of catalyst under different spatial distributions was studied through NH 3 -TPD. In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO 2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as "the closer, the better". However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In 2 O 3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO 2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO 2 by oxygen vacancy on c-In 2 O 3 (1 1 1) and h-In 2 O 3 (1 0 4) planes, it was found that O v1 on c-In 2 O 3 (1 1 1) and O v4 on h-In 2 O 3 (1 0 4) had the strongest adsorption energy for CO 2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO 2 conversion and aromatic selectivity are decreased. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new MgFe 2 O 4 /Bi 2 WO 6 composite photocatalyst was successfully prepared by wet ball milling process. • Through DFT calculations and a series of characterizations, it was confirmed that the MgFe 2 O 4 /Bi 2 WO 6 composite material conforms to the Z-scheme electron transfer mechanism. • The degradation rate of TCH by 25%-MgFe 2 O 4 /Bi 2 WO 6 composite photocatalytic material is as high as 95.82%. • · OH and · O 2 – are the main active substances in this photocatalytic reaction. • The composite has high stability in repeated experiments. In this study, a new Z-scheme MgFe 2 O 4 /Bi 2 WO 6 heterojunction was successfully prepared by hydrothermal and wet ball milling process. The results of the study showed that after 90 min of visible light exposure, the photocatalytic degradation of tetracycline hydrochloride (TCH) by 25%-MgFe 2 O 4 /Bi 2 WO 6 heterojunction was as high as 95.82%, and the highest photocatalytic rate (0.0281 min−1) was 4.61 and 3.43 times higher than that of pure Bi 2 WO 6 (0.0061 min−1) and MgFe 2 O 4 (0.0082 min−1), respectively. Furthermore, spin-polarized density functional theory (DFT) calculations were performed to provide additional evidence of the presence of a Z-scheme charge transfer mechanism between MgFe 2 O 4 and Bi 2 WO 6. We investigated the effects of initial TCH concentration, pH, coexisting ions and different water sources on the efficiency of photocatalytic degradation of TCH in composite samples. The recovery experiments demonstrated that the MgFe 2 O 4 /Bi 2 WO 6 composites had good stability and repeatability. A series of experimental results showed that 25%-MgFe 2 O 4 /Bi 2 WO 6 had a larger specific surface area, better ultraviolet and visible absorbance, superior charge transfer and higher efficiency of photogenerated electron-hole pair separation. This paper provides new ideas for the design and preparation of new Z-scheme heterojunctions and has great prospects for practical applications in the field of wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Understanding the dynamic evolution of catalysts under reaction condition is critical to rational design of catalysts and control of catalytic properties, yet presents great challenges to both experimental and computational techniques. • Here we report an original study that aims to advance the fundemental understanding of the dynamic change of an supported Cu catalyst and the corresponding catalytic property during electrochemical reduction of CO 2 to ethanol by a comprehensive structural and mechanistic study. • This study integrates in-situ X-ray absorption near edge structure (XANES) spectroscopy with ab initio XANES simulations to identify the structural changes of the catalyst, combined with systematic density functional theory (DFT) caclulations of reaction mechanism on various catalytic sites. • The evolution of single-atom Cu to Cu nanoparticles under electrochemical condition has been identified, and Cu partcile size effect on activity and product selectivity is demonstrated. This work also demonstrates an effective strategy on studying the dynamic evolution of catalysts. Direct electrochemical conversion of CO 2 to ethanol (CH 3 CH 2 OH) offers a promising strategy to lower CO 2 emission while storing energy from renewable electricity. Our recent study reported a carbon-supported atomically dispersed Cu catalyst that achieved the highest reported selectivity for CH 3 CH 2 OH formation (91%) at a relatively low potential (-0.6 V), however, the active site structure that is responsible for such high activity and selectivity has yet to be understood. In this paper, we demonstrate a computational investigation combining X-ray absorption near edge structure (XANES) simulations and a mechanistic study via density functional theory (DFT) to understand the catalyst structures of this Cu catalyst during electrocatalysis and the corresponding reaction mechanisms of the key products. An integrated computational and experimental XANES analysis depicted the dynamic evolution of the catalytic site during electrocatalysis. The as-prepared, atomically dispersed Cu catalyst aggregates and forms metallic clusters/nanoparticles under electrochemical condition, which then break down to smaller oxidized clusters after electrocatalysis. The formed Cu clusters/nanoparticles showed distinct catalytic activity and selectivity as a function of particle size based on the mechanistic investigation using DFT, which is consistent with experimental observations for catalyst samples with different Cu loadings. This comprehensive study which combines experimental and computational XANES investigation, mechanistic study via DFT calculations, and experimental performance of the catalysts, provides unprecedented dynamic and mechanistic insights into the supported atomically dispersed metal catalysts for CO 2 reduction. Such strategy and details gained can further guide discovery of novel catalyst materials for CO 2 electrochemical reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Zn-In-O catalyst exhibits FE HCOO− (94.25 %) at −1.16 V RHE. • Rich interface effects improve the catalytic performance of Zn-In-O. • In 2 O 3 active center of Zn-In-O is protected from reducing by sacrificing ZnO phase. Electrochemical CO 2 reduction reaction (eCO 2 RR) is considered an efficient approach to produce value-added chemicals and fuels. In this paper, a series of MOF-derived composite catalysts with coexisting In 2 O 3 and ZnO are fabricated using a simple process for eCO 2 RR to produce formate. The Zn-In-O/800 catalyst achieves a formate Faradaic efficiency (FE HCOO−) of 94.25 % at −1.16 V vs. RHE, which can maintain over 89 % after 30 h in a stability test. The electrochemical evidence and density functional theory analysis show that the strong interface effect between In 2 O 3 and ZnO can enhance the CO 2 adsorption and activation, and promote the conversion of CO 2 to formate. In addition, the ZnO phase can protect In 2 O 3 , as the main active site, from being reduced to a certain extent for a long time under negative potential, which ensures the high stability of the composite catalyst. [ABSTRACT FROM AUTHOR]

Environmental monitoring of mercury (Hg2+) ions has become increasingly important as a result of their detrimental effects on biological organisms at all levels. To recognize toxic metal ions, utmost effort has been devoted to developing new materials that are highly selective, ultra-sensitive, and provide rapid response. In this context, a new chemosensor, 2-imino [N - (N-amido phenyl)]-6-methoxy-3-carbethoxy quinoline (L), has been synthesized by combining 2-formyl-6-methoxy-3-carbethoxy quinoline and benzhydrazide and it has been extensively characterized by NMR, FTIR, ESI-Mass and SCXRD analysis. Probe L has excellent specificity and sensitivity toward Hg2+ ions in semi-aqueous solutions, with a detection limit of 0.185 μM, regardless of the presence of other interfering cations. Chromogenic behavior was demonstrated by the L when it changed the color of the solution from colorless to light yellow, a change that can be observed visually. The probe L forms a 1:1 stochiometric complex with an estimated association constant (K a) of 6.74 × 104 M−1. The 1H NMR change and density functional theory calculations were analyzed to improve our understanding of the sensing mechanism. Also, an inexpensive and simple paper-based test kit has been developed for the on-site detection of mercury ions in water samples. • Quinoline Schiff base probe (L) was designed and synthesized as a colorimetry sensor for Hg2+ ions. • Probe L showed highly selective towards Hg2+ ions with a LOD of 0.185 μM. • Probe L forms a 1:1 stochiometric complex with a binding constant of 6.74 × 104 M−1. • The paper-based test kit has been developed for detecting mercury ions. [ABSTRACT FROM AUTHOR]

Atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters (Ni 6 NCs) supported on g-C 3 N 4 nanosheets were constructed to enhance the photocatalytic hydrogen evolution performances. [Display omitted] Much effort has been devoted to improving the photocatalytic capacity of graphitic carbon nitride (g-C 3 N 4). In this paper, we reported the successful synthesis of a hybrid photocatalyst with superb photocatalytic hydrogen production activity through decorating atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters on g-C 3 N 4 nanosheets (labeled as Ni 6 /g-C 3 N 4) at room temperature. Zeta potential experiments demonstrated that the electrostatic interaction between Ni 6 and g-C 3 N 4 led to the formation of Ni 6 /g-C 3 N 4. The photocatalytic measurements revealed that the 5 %-Ni 6 /g-C 3 N 4 prepared with the original mass ratio of m(Ni 6)/m(g-C 3 N 4) = 1/20 exhibited the strongest hydrogen production activity. In the system with triethanolamine (TEOA) as the sacrifice agent, the visible-light hydrogen production rate reached up to 5.87 mmol h−1 g−1, approximately 290 times higher than that of pure g-C 3 N 4 (0.02 mmol h−1 g−1). Density functional theory (DFT) calculations testified that the above significant enhancement of photocatalytic hydrogen evolution of the hybrid photocatalyst arose from the photogenerated electrons transfer from Ni 6 to g-C 3 N 4. [ABSTRACT FROM AUTHOR]

We propose an unconditionally energy-stable, orthonormality-preserving, component-wise splitting iterative scheme for the Kohn-Sham gradient flow based model in the electronic structure calculation. We first study the scheme discretized in time but still continuous in space. The component-wise splitting iterative scheme changes one wave function at a time, similar to the Gauss-Seidel iteration for solving a linear equation system. At the time step n , the orthogonality of the wave function being updated to other wave functions is preserved by projecting the gradient of the Kohn-Sham energy onto the subspace orthogonal to all other wave functions known at the current time, while the normalization of this wave function is preserved by projecting the gradient of the Kohn-Sham energy onto the subspace orthogonal to this wave function at t n + 1 / 2. The unconditional energy stability is nontrivial, and it comes from a subtle treatment of the two-electron integral as well as a consistent treatment of the two projections. Rigorous mathematical derivations are presented to show our proposed scheme indeed satisfies the desired properties. We then study the fully-discretized scheme, where the space is further approximated by a conforming finite element subspace. For the fully-discretized scheme, not only the preservation of orthogonality and normalization (together we called orthonormalization) can be quickly shown using the same idea as for the semi-discretized scheme, but also the highlight property of the scheme, i.e., the unconditional energy stability can be rigorously proven. The scheme allows us to use large time step sizes and deal with small systems involving only a single wave function during each iteration step. Several numerical experiments are performed to verify the theoretical analysis, where the number of iterations is indeed greatly reduced as compared to similar examples solved by the Kohn-Sham gradient flow based model in the literature. • This paper proposes a novel and efficient numerical scheme for the Kohn-Sham gradient flow based model. • The scheme is an unconditionally energy-stable, orthonormality-preserving, component-wise splitting iterative scheme. • The scheme does not modify the original energy, allows large time step sizes, and solves small systems at each time step. • The rigorous proof is presented in the paper. • Several numerical examples are illustrated to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

S -nitrosothiols (RSNOs) are an important group of nitric oxide (NO)-donating compounds with low toxicity and wide biomedical applications. In this paper, we, for the first time, demonstrate that the concentration of buffer remarkably affects the stability of RSNOs including naturally occurring S -nitrosoglutathione (GSNO) and synthetic S -nitroso- N -acetylpenicillamine (SNAP). For a solution with a high concentration of GSNO (e.g., 50 mM) and an initial near-neutral pH, the optimal buffer concentration is close to the GSNO concentration under our experimental conditions. A lower buffer concentration does not have adequate buffer capacity to resist the pH drop caused by GSNO decomposition. The decreased solution pH further accelerates GSNO decomposition because GSNO is most stable at near-neutral pH according to our density functional theory (DFT) calculations. A higher-than-optimal buffer concentration also reduces the GSNO stability because buffer ingredients including phosphate, Tris base, and HEPES consume NO/N 2 O 3. In contrast to GSNO, the highest SNAP stability is obtained when the starting solution at a neutral pH does not contain buffer species, and the stability decreases as the buffer concentration increases. This is because SNAP is more stable at mildly acidic pH and the SNAP decomposition-induced pH drop stabilizes the donor. When the RSNO concentration is low (e.g., 1 mM), the buffer concentration also matters because any excess buffer accelerates the donor decomposition. Since the effect of buffer concentration was previously overlooked and suboptimal buffer concentrations were often used, this paper will aid in the formulation of RSNO solutions to obtain the maximum stability for prolonged storage and sustained NO release. • S -nitrosothiol decomposition generates nitrous acid that tends to reduce the solution pH under aerobic conditions • Adequate buffer capacity inhibits the pH drop of a S -nitrosothiol solution and affects the decomposition rate of S -nitrosothiol • Excess buffer accelerates S -nitrosothiol decomposition via its reaction with N 2 O 3 • Density-functional theory calculations confirmed the pH dependence of the S -nitrosoglutathione stability [ABSTRACT FROM AUTHOR]

Multiple active-sites of Fe-N 4 , pyridinic N C and pore defect co-exist in the as-prepared single-atom Fe N C catalyst, which synergistically promote a high-efficiency oxygen reduction electrocatalysis by a combination of experimental results and DFT calculations. [Display omitted] • High N -content melamine foam as the self-sacrificed template can produce pyridinic N C active-site. • Spatial location confinement through π-π interaction between phthalocyanine-based macrocycles can make for dense Fe-N 4 active-site. • Zn-evaporation can create pore defect active-site which will meanwhile anchor pyridinic N C and Fe-N 4 active-sites. • The experimental results and DFT calculations suggest that multiple active-sites of Fe-N 4 , pyridinic N C and pore defect can synergistically promote a high-efficiency ORR electrocatalysis. Revealing the types of and interplays among multiple active-sites in iron-nitrogen-carbon (Fe N C) materials is of great significance for developing high-performance, Fe-based non-precious metal catalysts for oxygen reduction reaction (ORR). In this paper, a single-atom Fe N C catalyst is prepared through high-temperature pyrolyzing of melamine foam (MF), iron phthalocyanine (FePc), phthalocyanine (Pc), and zinc (Zn)-salts composite. The catalyst is found to contain a variety of active-sites, including carbon atom next to pyridinic-N (pyridinic N C), Fe-N 4 and pore defect. It is shown that MF with high N -content is responsible for the formation of the main pyridinic N C sites and in the meantime acts as the self-sacrificed template for framework of the catalyst. The presence of Pc can facilitate the formation of the predominant Fe-N 4 sites, since the interplay between Pc and FePc results in a confinement of Fe-N 4. Zn-salts serve as the pore-forming additives to create sufficient pore defects which can also anchor pyridinic N C and Fe-N 4 structures. The results of density functional theory (DFT) calculations suggest that the multiple active-sites function synergistically to enable high-efficiency ORR electrocatalysis. The optimal Fe N C catalyst shows superior ORR activity with a half-wave potential of ∼0.88 V (vs. RHE), as well as high methanol tolerance and electrochemical stability compared to the commercial carbon-supported platinum (Pt/C) catalyst. [ABSTRACT FROM AUTHOR]

A carbon superstructure material (PTA-700) was synthesized by a simple self-assembly method and one-step carbonization, and showed remarkable high energy and long cycle life stability in lithium/sodium ion half battery. [Display omitted] Due to abundant resources and low prices, biomass-derived carbons as anodes for lithium ion batteries (LIBs) and sodium ion batteries (SIBs) have been widely reported. However, it is still a challenge to design a biomass-derived carbon material that has immunity to environmental influences, stable chemical composition and controllable morphology. In this paper, tannic acid (TA) as a precursor is first reported to synthesize rod structures with abundant mesopores and defects (PTA-700). These features can provide more active sites and space for lithium and sodium ions storage, which is conducive to lithium and sodium ions transfer. Excellent electrochemical performance is observed in LIBs (535 mAh/g after 100 cycles at 0.1 A/g) and SIBs (114.0 mAh/g after 3000 cycles at 1 A/g). Kinetics analysis and density functional theory (DFT) calculations were carried out to further analyze the superior lithium and sodium ions storage performance of PTA-700. More importantly, PTA-700 solves many problems faced by traditional biomass-derived carbons in commercialization. Our work suggests an effective way to develop high-performance biomass-derived carbon anode materials for LIBs and SIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous few-layer bimetallic co-doped g-C 3 N 4 is prepared via a facile bottom-up method. • The bimetallic synergetic regulating effect on the electronic structure can be produced in Co/Ni-g-C 3 N 4. • The superior performance results from the improved charge separation efficiency and visible light harvestability. • This work provides meritorious guidance for new bimetallic co-doped g-C 3 N 4 photocatalysts. The low specific surface area and low charge transfer efficiency of conventional graphite carbon nitride (g-C 3 N 4) are the main obstacles to its application in photocatalytic CO 2 reduction. In this paper, graphite carbon nitride was protonated by phosphoric acid (H 3 PO 4), and a new few-layer porous carbon nitride was prepared by intercalation polymerization with doping bimetal in the cavity of g-C 3 N 4. Under visible light irradiation, the CO formation rate of Co/Ni co-doped g-C 3 N 4 can reach 13.55 μmol g−1 h−1, which was 3.9 times higher than that of g-C 3 N 4 (3.49 μmol g−1 h−1). The density functional theory (DFT) calculations showed that the addition of Co and Ni in the cavity of g-C 3 N 4 can induce bimetallic synergistic regulation of the electronic structure, thus improving the separation efficiency of charges and visible light capture ability of g-C 3 N 4. Our work has great reference value for designing and synthesizing novel bimetallic co-doped g-C 3 N 4 photocatalytic materials. [ABSTRACT FROM AUTHOR]

The bimetallic phosphide nano-interfaces are constructed only by electrochemical high-voltage activation, so as to increase the electrode capacity of about 150 % (compared to the original NiCoP electrode). The 3D cathode has an ultra-high capacity of 544.9 mAh g−1 and excellent rate performance (still about 69.5 % at 30 A g−1). The assembled NCPOH//Zn battery has excellent reversibility and long life (maintained 97 % of initial capacity after 2000 cycles) and achieves a remarkable energy density of 933.5 Wh kg−1. [Display omitted] Aqueous zinc ion batteries (AZIBs) have broad prospects in many fields because of their high theoretical capacity, high hydrogen overpotential, low equilibrium potential, low cost and high safety. However, the surface chemical reactivity of cathode is usually limited by the utilization of active materials, resulting in insensitive edge position and unsatisfactory capacity. In this paper, a simple and convenient strategy is reported, in which the bimetallic phosphide nano-interfaces are constructed only by electrochemical high-voltage activation, so as to increase the electrode capacity of about 150 % (compared to the original NiCoP electrode). Under the combined action of water and oxygen, a coating of NiCo-OH nanosheet is formed on the NiCoP nano-wall, and the surfaces are rich in low-priced mixed state with remarkable reactivity and structural stability, which is theoretically confirmed by density functional theory (DFT). As a result, the 3D cathode has an ultra-high capacity of 544.9 mAh g−1 and excellent rate performance (still about 69.5 % at 30 A g−1). The assembled NCPOH//Zn battery has excellent reversibility and long life (maintained 97 % of initial capacity after 2000 cycles) and achieves a remarkable energy density of 933.5 Wh kg−1. Our work explores the relationship between interface corrosion mechanism and corrosion surface activity, which is a powerful strategy to build metal phosphides with high surface electrochemical activity as advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Mechanism of H 2 O 2 production over P-doped carbon nitride was firstly revealed based on the melon crystal structure of carbon nitride. [Display omitted] Melon-based carbon nitride (CN) is a semiconductor photocatalyst with a conduction band position suitable for photocatalytic H 2 O 2 production. However, the thermodynamic inability to adsorb O 2 molecules greatly limits its photocatalytic efficiency for H 2 O 2 production. In this paper, P-doped CN with good performance for H 2 O 2 production was synthesized by a simple one-step calcination method. The experimental results show that when the doping amount of P is about 9.0 wt% of CN, the yield of H 2 O 2 can reach 12990 μM/h/g, which is about 6.6 times as that of pure CN. The mechanism of H 2 O 2 production over P-CN was firstly revealed by using the density functional theory calculations based on the melon crystal structure of carbon nitride. The results show that P-doping is easier to the strong thermodynamic adsorption of O 2 on CN, which is more beneficial to the formation of intermediate products. Further experimental results show that the substitution of C in CN by P-doping suppresses the electron and hole recombination, and therefore promoting the photocatalytic performance of P-doped CN. [ABSTRACT FROM AUTHOR]

Sovolthermally synthesized Co-MOFs exhibits high activity and stability for water oxidation. [Display omitted] The development of efficient and robust non-precious electrocatalysts for water oxidation at a mild condition is extremely desirable for industrial water splitting. Herein we developed a facile solvothermal strategy to synthesize cobalt metal organic frameworks (Co-MOFs) with sheet-like structure, which showed highly promising performance for electrocatalytic oxygen evolution. The best Co-MOF sample afforded an ultra-high oxygen evolution current density of 63.4 mA cm−2 at 1.75 V in 1 M KOH with a catalyst loading of only 0.21 mg cm−2. Notably, its electrochemical performance remained unchanged after 10,000 cyclic voltammograms indicating very promising long-term stability. Detailed study of the mechanism of the oxygen evolution by density functional theory (DFT) indicated that the strong π-conjugation formed between the central cobalt ion and adjacent aromatic rings favored the high electrocatalytic performance. The solvothermally synthesized MOFs proposed in this paper are expected to inspire the rational design of high-performance electrocatalysts for water oxidation with atomic and molecular level structural control and the exploration of structure-performance relationships to understand the electrocatalytic origin. [ABSTRACT FROM AUTHOR]

Carbon dots (CDots) with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared. The as-prepared CDots with a size of 3.5 nm possess excellent biocompatibility, good photostability, strong solid-state luminescence, and remarkable resistance to organic solvent, allowing their applications in biological imaging in vitro and in vivo and as the color conversion layer for white light-emitting diodes. [Display omitted] Carbon dots (CDots), a class of environmentally friendly carbon-based luminescent nanomaterial, have been applied in a wide variety of fields, including bioimaging and light-emitting diodes (LEDs). Prior to these applications, however, CDots usually require modifications because some of its limitations (e.g. , the aggregation-induced luminescence quenching) make it difficult to apply in solid state. In order to realize CDots-based multiple applications simultaneously, this paper examines how CDots with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared by microwave-assisted heating salicylic acid and thiourea. Based on control testing and the analysis of density functional theory calculations, S element from thiourea is doped into CDots and proves to be critical in governing the photoluminescence (PL) emission color. Featured with excellent biocompatibility and photostability, the dispersed CDots with photoluminescence quantum yields (32%) are able to function as a biological imaging reagent in vitro and in vivo without any side effect. Furthermore, the aggregated CDots also exhibit high photoluminescence quantum yields (26%) and remarkable resistance to organic solvent. These advantages will ensure that S-doped CDots can be applied as a color conversion layer so that white LEDs with different Commission International de L'Eclariage coordinates and tunable color temperature can be fabricated. [ABSTRACT FROM AUTHOR]

Hypochlorite/hypochlorous acid (ClO - /HClO) is one of many species of reactive oxygen species (ROS) that play a vital part in a variety of biological processes. The reliable, effective and rapid detection of ClO - ions is particularly significant for us humans. In this paper, an excellent novel "turn-on" response probe (ENMN) for detecting hypochlorite in different fruits, vegetables and water samples was designed and practically prepared based on diaminomaleonitrile (DAMN). The recognizing researches of ENMN presented a "turn–on" fluorescent response from colorless to blue, and it was found to be highly selective towards various metal ions, anions and reactive oxygen species (ROS). The probe ENMN is facile to synthesize, and showed fast for ClO - (within 5 s) and remarkable stability at a wide pH range (6.0–10.0). The response of ENMN to hypochlorite led to a maximum absorption shift from 385 nm to 320 nm. After treatment with ClO - the probe displayed distinct alterations in absorbance and emission bands with an approximately 434-fold enhancement in fluorescence. A nice linear response range of 0–200.0 μM with the detection limit of 0.169 μM could be fulfilled. NMR, HRMS, IR, and density functional theory (DFT) research findings forcefully sustained the sensing mechanisms which was the C N bond in the probe being oxidated into the C O bond by ClO-. Importantly, the probe ENMN has been not only successfully applied to detect ClO - in buffalo milk (98.3–103.3%), water samples (99.1–109.8%), but also was employed for vegetables and fruits with satisfactory results. Based on its quick response rate, the newly developed probe can be used to real time monitor ClO- in actual water environments and foods. [Display omitted] • The probe ENMN exhibits very rapid response time (within 5 s) to ClO- and has high selectivity and sensitivity toClO-. • The probe ENMN has been successfully applied to detect ClO- in water samples, buffalo milk, vegetables and fruits. • The synthesis of the novel fluorescence enhancement probe ENMN for ClO- was very easy. [ABSTRACT FROM AUTHOR]

This paper studies DFT models for homogeneous 2D materials in 3D space, under a constant perpendicular magnetic field. We show how to reduce the three-dimensional energy functional to a one-dimensional one, similarly as in our previous work. This is done by minimizing over states invariant under magnetic translations and that commute with the Landau operator. In the reduced model, the Pauli principle no longer appears. It is replaced by a penalization term in the energy. [ABSTRACT FROM AUTHOR]

Lead(II)–benzohydroxamic acid (Pb–BHA) complex collectors perform well with respect to scheelite flotation, and, due to their structure, they are widely used for industrial purposes. This paper examines the controversial issue of whether "O, O" five-membered ring or "N, O" four-membered ring complexes are formed when BHA coordinates with Pb ions, with their structure being comprehensively studied from the aspect of colloid and interface science. The configurations of Pb–BHA complexes are examined in a solution and on a mineral surface with experimental and computational methods. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) revealed that the five-membered ring is the dominant form of Pb–BHA complexes in a solution, whereas four-membered ring complexes are the stronger electron acceptor of the two. Moreover, XPS and time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that the four-membered ring complexes are stable with respect to being adsorbed on the scheelite surface. Therefore, although the four-membered ring is not as stable as the five-membered ring in a solution, it offers advantages with respect to adsorption on an electron-rich mineral surface during short-flotation processes. [ABSTRACT FROM AUTHOR]

The energy level diagram for electronic transfer vs. Vacuum level; (B and C) The photocatalytic mechanism over EY-sensitized UiO-66/WP. The abundant transition metal phosphides co-catalysts on the earth can satisfy the sustainable and clean solar H 2 production through photocatalytic water splitting, which is promising to replace the rare precious metals, such as Pt, Au, Pd, Ru and so on. In this paper, we use the temperature-programmed solid phase method to prepare WP nanoparticles. Based on the Density Functional Theory (DFT) calculations, we demonstrate that the WP nanoparticles possess outstanding electrical conductivity and excellent capability to transport electrons. WP nanoparticles are loaded onto the surface of UiO-66 via the ultrasound-assisted impregnation method to induce a highly efficient visible-light photocatalytic H 2 production activity of 384 µmol in 5 h, which is 10.67 times than that of pure UiO-66. The catalytic performance is attributed to the excellent metallic conductivity and the favourable Fermi level position of WP nanoparticles. Further studies of PL, TRPL and Mott-Schottky curves, we can not only know that the modification of WP nanoparticles do improve the electron transfer ability, but also that the matched work functions between the EY and UiO-66 provides a feasible thermodynamic path for the transmission of electrons. Our work demonstrates that the earth-abundant transition metal phosphides material have the potential to construct cheaper and high catalytic performance photocatalysts. [ABSTRACT FROM AUTHOR]

Regulation mechanism of typical substances including OH−, CN−, SCN−, S2−, NH 3 on the distribution of heavy metals was investigated in coking wastewater treatment plant with our self-designed Anaerobic-Oxic-Hydrolytic-Oxic (A-O 1 -H-O 2) system through engineering data exposure and computational density functional theory (DFT) verification. The results showed that coking sludge had superior enrichment ability for heavy metals, especially for the sludge from the A and H tanks. The enrichment ratio of the 8 heavy metals including Cd, Pb, Ni, Zn, Cu, Hg, Cr and As in coking waste sludge was found to be 6232 (comparing to these in the influent wastewater of A-O 1 -H-O 2 system). The distribution of 8 heavy metals was closely related to their chemical (precipitation and/or complexation) and biochemical reaction potential with OH−, CN−, SCN−, S2−, NH 3 in the A-O 1 -H-O 2 system. The regulation mechanism of these precipitation and/or complexation agents on heavy metals was confirmed by DFT calculation. The stable energy of complexes formed between typical compounds and common heavy metal ions follow the order: OH: Cu2+>Pb2+>Zn2+>Cd2+>Hg2+>Ni2+; S2−: Pb2+>Cu2+>Zn2+>Cd2+>Hg2+>Ni2+; CN−: Zn2+>Cu2+>Cd2+>Hg2+>Pb2+>Ni2+; SCN−: Zn2+>Cd2+>Pb2+>Hg2+>Cu2+>Ni2+; NH 3 : Cu2+>Zn2+>Cd2+>Pb2+>Hg2+>Ni2+, providing reference for the judgement of which metal ions were preferentially combined with the typical compounds in coking wastewater. The results of this paper indicated that the enrichment of heavy metal ions in coking wastewater can be achieved by process design combined with the control of operating conditions (dissolved oxygen, hydraulic retention time, sludge retention time and pH), basing on the nature of heavy metal ions. Finally, the separation and differential management of heavy metals can be achieved. Image 1 • Regulation of OH-, S2-, CN-, SCN- and NH 3 on the distribution of heavy metals in A-O 1 -H-O 2 system was investigated. • Heavy metals in coking wastewater can be enriched by process design combined with operating conditions control. • The interaction of heavy metals and typical compounds in coking wastewater were calculated by DFT. [ABSTRACT FROM AUTHOR]

• Ultrafine Pt succeeded photocatalytic overall water splitting without back-reaction. • Pt clusters less than 100 atoms remained oxidized on SrTiO 3. • The oxidized Pt is insensitive to CO poisoning for water splitting. The metal cluster size in supported metal catalysts impacts the oxidation state of the metal atoms, coordination capability, and finally the catalytic activity—especially when the number of atoms becomes countable. The correlation between metal oxidation state and its catalytic consequences for ultrafine Pt was studied for photocatalytic overall water splitting using a Pt/SrTiO 3 (photo)catalyst. A distinctive change in catalytic behavior and oxidation state was observed below 100 Pt-atom clusters at ∼2 nm. Combining density functional theory (DFT) and experimental characterizations including X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the smaller Pt clusters obtained by the surface organometallic route (under 100 Pt atoms) were predominantly oxidized and selectively performed photocatalytic water splitting selectively without activation of the water-forming back-reaction from H 2 and O 2. When the Pt clusters obtained by classical impregnation were larger than 2 nm, they remained metallic (Pt0) and were active for both water splitting and the competing thermal water formation back reaction. In addition, Pt0 clusters are poisoned in the presence of CO, whereas highly dispersed ultra-fine oxidized Pt clusters are insensitive to CO. This paper presents evidence of ultrafine PtO x (below approximately 2 nm clusters) that are insensitive to coordination of various gas identities (H 2 , O 2 , CO), resulting in efficient and selective photocatalytic overall water splitting. [ABSTRACT FROM AUTHOR]

This paper establishes new connections between many-body quantum systems, One-body Reduced Density Matrices Functional Theory (1RDMFT) and Optimal Transport (OT), by interpreting the problem of computing the ground-state energy of a finite-dimensional composite quantum system at positive temperature as a non-commutative entropy regularized Optimal Transport problem. We develop a new approach to fully characterize the dual-primal solutions in such non-commutative setting. The mathematical formalism is particularly relevant in quantum chemistry: numerical realizations of the many-electron ground-state energy can be computed via a non-commutative version of Sinkhorn algorithm. Our approach allows to prove convergence and robustness of this algorithm, which, to our best knowledge, were unknown even in the two marginal case. Our methods are based on a priori estimates in the dual problem, which we believe to be of independent interest. Finally, the above results are extended in 1RDMFT setting, where bosonic or fermionic symmetry conditions are enforced on the problem. [ABSTRACT FROM AUTHOR]

This paper presents results for four types of morphology-controlled two-dimensional cobalt based tetrakis (4-carboxyphenyl) porphyrin metal-organic frameworks (2D Co-TCPP MOFs) with different catalytic properties for nitrite, and an electrochemical sensor was fabricated by the Co-TCPP MOF with superior catalytic properties. The sensor exhibited a high sensitivity of 311.3 μg/g, an extra low detection limit (LOD) of 0.03 μM, and a wide linear range of 0.1–375 μM, which was applied successfully for nitrite detection in water, milk and sausage. Moreover, density functional theory (DFT) calculations were used to establish the sensing method, the adsorption structures of nitrite on the surface of Co-TCPP MOF were built and the electrocatalytic mechanism was confirmed. The results explained why the sensor fabricated by a single Co-TCPP MOF exhibited equal or better performance than reported sensors fabricated by composite materials based on a combination of theory and experiment. This work reported a universal electrochemical sensing method for nitrite detection in food based on a single morphology-controlled 2D TCPP MOF, which provided a new and valuable strategy for establishing an efficient food safety determination method guided by theoretical calculations. • An ultrasensitive and rapid method for nitrite detection in food is reported. • For the first time, DFT calculation is used for establishment of sensing method. • The method is established based on single morphology controlled 2D Co-TCPP MOFs. • The nitrite sensor exhibits high sensitivity, extra low LOD and wide linear range. • The work provides a new strategy for establishment of food analytical method. [ABSTRACT FROM AUTHOR]

The performance of the nanoelectronics devices is highly dependent on morphology of the defects and quality of low-dimensional materials. This paper reports magnetic and electronic properties of MoS 2 monolayer with two kinds of antisite defects, which were obtained based on density functional theory. One Mo atom substituting one S atom (MoS) and the opposite condition (SMo) are focused. For MoS system, we find that the interactions between impurity Mo atom and its surrounding atoms are weak due to the metal character of Mo atom, leading to the appearance of dangling bonds. Thus, we obtained total magnetic moment of 2 μ B in MoS system. On the contrary, the covalent bonds are formed between impurity S atom and its neighbors, leading to the nonmagnetic ground state of SMo system. The adsorption of six nonmetal elements H, B, C, N, O, F on defective MoS 2 monolayer is also investigated. The total magnetic moment of 1μ B can always be obtained when the adatoms H, B, N, F are used no matter which substrate is functionalized. The adsorption of C atom does not influence the magnetic behavior of the substrate. The nonmagnetic ground states of O-MoS and O-SMo systems are obtained. Image 1 • Electronic and magnetic properties of MoS 2 monolayer with two kinds of antisite defects are investigated. • The antisite defect with one Mo atom substituting one S atom can induce magnetic moment of 2 μ B in MoS 2 monolayer. • The interactions between impurity atoms and its neighbors are different for these two kinds of antisite defects. • The adsorption of H, B, C, N, O, F on defective MoS 2 monolayer induces the interesting magnetic behavior. [ABSTRACT FROM AUTHOR]

In this paper, we present a detailed theoretical study of structural, electronic and optical properties of two-dimensional (2D) Al x B 1-x N monolayer compounds for 0 ≤ x ≤ 1. All possible arrangement of atoms have been determined for five concentration (x = 0, 0.25, 0.50, 0.75 and 1). Stabilities of all configurations are demonstrated by cohesive energies. In addition, we have investigated the composition dependence of the lattice constants a (x) and b (x), and band gaps Eg(x). The results show that the incorporation of aluminum (Al) atoms increases the lattice parameters in both zigzag and armchair direction. The cohesive energies and band gap values decreases with increasing (Al) composition. Cohesive energy and band gap bowing are more significant then bowing lattices. Monolayer of Al 0.50 B 0.50 N exhibits a direct band gap at Γ point with energy value of about 3.3 eV. Calculation of optical properties suggests potential characteristics for UV applications. • Possible arrangement of atoms in two-dimensional (2D) Al x B 1-x N monolayer compounds have been determined for five concentration (x = 0, 0.25, 0.50, 0.75 and 1). • Stabilities of all configurations are demonstrated by cohesive energies. • Band gap transition of Al x B 1-x N monolayer from indirect (0 ≤ x < 0.50) to direct (x = 0.50) and again to indirect (0.50 > x ≥ 1). • Calculated lattice bowing parameters are found to be small compared to the obtained cohesive and band gap bowings. • UV light-emitting diodes and detectors. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have attracted much attention as anode materials for lithium ion batteries. However, most of the 2D materials are semiconductors with limited electron transportation. In this paper, the electronic properties of Cu 2 Si monolayer and adsorption and diffusion of Li/Na on Cu 2 Si monolayer were investigated by the density functional theory. The Cu 2 Si monolayer shows metallic characteristics. The adsorption energies are around −2.5 eV, which is stronger than those of Li/Na absorbed on other 2D materials. In addition, the diffusion energy barriers are 0.15 and 0.11 eV for Li and Na diffuses on Cu 2 Si monolayer, respectively, indicating that Cu 2 Si monolayer can be fast charged/discharged. These results indicate that Cu 2 Si monolayer can be a promising anode material for lithium and sodium ion batteries. Density functional theory calculations show that the Cu 2 Si monolayer is metallic material, lithium and sodium show strong adsorption on the Cu 2 Si monolayer, but with small diffusion energy barrier. Thus, Cu 2 Si monolayer can be used as a promising anode material for lithium and sodium ion batteries. Image 1 • Adsorption and diffusion of Li/Na on Cu 2 Si monolayer were investigated. • Li and Na show strong adsorption on the Cu 2 Si monolayer. • The diffusion barriers are relative small for Li and Na on Cu 2 Si monolayer. • Cu 2 Si monolayer can be used as anode materials of LIBs and SIBs. [ABSTRACT FROM AUTHOR]

Abstract The Bohr–Jessen limit theorem is a probabilistic limit theorem on the value-distribution of the Riemann zeta-function in the critical strip. Moreover their limit measure can be written as an integral involving a certain density function. The existence of the limit measure is now known for a quite general class of zeta-functions, but the integral expression has been proved only for some special cases (such as Dedekind zeta-functions). In this paper we give an alternative proof of the existence of the limit measure for a general setting, and then prove the integral expression, with an explicitly constructed density function, for the case of automorphic L -functions attached to primitive forms with respect to congruence subgroups Γ 0 (N). [ABSTRACT FROM AUTHOR]

Abstract In this paper, optical properties of silicene and germanene under compressive homogeneous strain are investigated within the density function theory. Results show that the optical-field response are strongly depend on the amount of applied strain. As the strain increases, the amount of optical absorption increases. In fact, by applying the compressive strain in the silicene and germanene, the band gap at the Dirac points decreases where ultimately reaches zero. Depending on the amount of strain, absorption peak shows red and blue shifts by increasing the strain. This can be realized by considering the change of the band gap energy and transition rates by the strain. In both of these graphene-like structures, the light absorption along zigzag direction is greater than that of the armchair direction. Highlights • Strain induced red and blue shifts of the silicene and gemanene photon absorption. • DFT based optical calculations in strained graphene-like materials. • Realization of the different absorption frequency ranges based on their response to strain. [ABSTRACT FROM AUTHOR]

Abstract In this paper, four types of compounds are considered: ideal wurtzite (B N), N vacancies in B N (B N − V N), A l doped ideal B N (A l : B N) and A l doped B N with N vacancies(A l : B N − V N). The structural, electronic and magnetic properties are calculated by using the density functional theory (DFT) based on the generalized gradient approximation implemented in Quantum-Espresso code. Our results show that the nitrogen vacancies and the aliminium impurities are responsible of the magnetic properties in these compounds. We have also found that aluminium impurities have a remarkable effect on the optical band gap. Our results are in good agreement with experimental and other theoretical studies. We can conclude from this study, that this material can be used as diluted magnetic semiconductors. Highlights • The DFT method has been used to study the Al doped (w−BN). • The lattice parameters increase with the incorporation of Al in the BN supercell. • The Al impurities decrease the value of the band gap. • Al and N vacancy induce magnetic properties. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we study the difference in electronic and optical properties of bulk and monolayer zirconium sulfide by applying the APW + lo method in the framework of density functional theory. All calculation is performed at the energy level of visual light and higher ranging from 0 eV to 15 eV. Our results demonstrates that except for the underestimated band gap like other GGA calculation, the remain properties like dielectric function, the reflectivity, absorption and loss energy are close to experiment. The valence band is constructed by mainly sulfur s / p -states and the lower portion of zirconium s / p / d -states. The conduction band is mostly donated by zirconium d -state. In contrast with bulk structure, the valence band maximum in monolayer has the triple peak at Γ point, making its monolayer be more sensitive to light absorption. The dielectric function has the highest peak at about 1.5–2.5 eV with remarkable anisotropy, beyond this level to the ultraviolet region the anisotropy decreases and almost disappears at energy larger than 10 eV. The absorption is at 106 x 10 4 cm -1 for energy range 5–10 eV, while the reflectivity is at its highest value of 30 %–50 % in the energy range from 0 to 8 eV. The energy loss of monolayer is higher than those of bulk. For optical and electronic properties, the monolayer show sharper peaks and their clear separation indicate the progressive application of monolayer zirconium sulfide. Highlight • Monolayer ZrS 2 has new interband transitions at energy levels of 4-7 eV and 7-10 eV. • For energy ranging from -14 eV to 6 eV, the dielectric constants, energy loss, and reflectance are close to experimental values. • ZrS 2 is highly anisotropic to the parallel and perpendicular components of electric field at energy lower than 10 eV. • The energy loss L (ω) in monolayer is higher than in bulk. • Our results give an explanation on perspective optical properties of monolayer ZrS 2 , which can be helpful for further design and application of this material. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The GIPAW method yields reliable chemical shifts for Li diamagnetic solids. • Induced current effects of nearest neighbour heavy atoms on Li are significant. • Access to Li dynamics in disordered materials by atomistic simulation and experiment. • Li CSA computations ideally complement NMR experiments in Li ion battery research. Abstract For studying electrode and electrolyte materials for lithium ion batteries, solid-state (SS) nuclear magnetic resonance (NMR) of lithium moves into focus of current research. Theoretical simulations of magnetic resonance parameters facilitate the analysis and interpretation of experimental Li SS–NMR spectra and provide unique insight into physical and chemical processes that are determining the spectral profile. In the present paper, the accuracy and reliability of the theoretical simulation methods of Li chemical shielding values is benchmarked by establishing a reference scale for Li SS–NMR of diamagnetic compounds. The impact of geometry, ionic mobility and relativity are discussed. Eventually, the simulation methods are applied to the more complex lithium titanate spinel (Li 4 Ti 5 O 12 , LTO), which is a widely discussed battery anode material. Simulation of the Li SS–NMR spectrum shows that the commonly adopted approach of assigning the resonances to individual crystallographic sites is not unambiguous. [ABSTRACT FROM AUTHOR]

The paper presents experimental and DFT simulated data on temperature dependence of heat capacity for C 60 - l -arginine derivative. Smoothed C p , m ∘ T values in the temperature range from T  → 0 K to 320 K are presented along with the values of standard thermodynamic functions: S m ° , [ H m ∘ T - H m ∘ 0 ] and [ Φ m ∘ T - Φ m ∘ 0 ]. In addition, the molar third law entropy and the molar formation entropy of the C 60 - l -arginine derivative in crystalline state at T  = 298.15 K are calculated. The data on complex thermal analysis reveal that the C 60 - l -arginine derivative is stable up to 340 K. Further increasing of temperature leads to destruction of l -arginine groups and oxidation of fullerene core. [ABSTRACT FROM AUTHOR]

This paper deals with improvements of the Trudinger–Moser inequality related to the operator Q V ( u ) : = − Δ n u + V ( x ) | u | n − 2 u , where n ≥ 2 and the potential V : R n → R belongs to a class of nonnegative and continuous functions. Precisely, under suitable assumptions on V we consider the subspace E : = { u ∈ W 1 , n ( R n ) : ∫ R n V ( x ) | u | n d x < ∞ } endowed with the norm ‖ u ‖ : = [ ∫ R n ( | ∇ u | n + V ( x ) | u | n ) d x ] 1 / n and we prove that if ( u k ) is a sequence in E such that ‖ u k ‖ = 1 , u k ⇀ u ≢ 0 in E and 0 < p < p n ( u ) : = β n ( 1 − ‖ u ‖ n ) − 1 / ( n − 1 ) , then ( ⁎ ) sup k ⁡ ∫ R n Ψ ( p | u k | n / ( n − 1 ) ) d x < ∞ , where Ψ ( t ) : = e t − ∑ i = 0 n − 2 t i i ! , β n : = n ω n − 1 1 / ( n − 1 ) and ω n − 1 is the measure of the unit sphere in R n . Furthermore, p n ( u ) is sharp in the sense that there exists a sequence ( u k ) ⊂ E satisfying ‖ u k ‖ = 1 and u k ⇀ u ≢ 0 in E such that the supremum (⁎) is infinite for p ≥ p n ( u ) . As an application of the previous result we prove the following sharp form of the Trudinger–Moser inequality for the subspace E . Considering ℓ ( α ) : = sup { u ∈ E : ‖ u ‖ = 1 } ⁡ ∫ R n Ψ ∘ ν α ( u ) d x , where ν α ( u ) : = β n ( 1 + α ‖ u ‖ n n ) 1 / ( n − 1 ) | u | n / ( n − 1 ) , assuming some conditions of symmetry on V it is established (1) for 0 ≤ α < λ 1 ( V ) we have ℓ ( α ) < ∞ , (2) for α ≥ λ 1 ( V ) , ℓ ( α ) = ∞ and (3) moreover, we prove that for 0 ≤ α < λ 1 ( V ) , an extremal function for ℓ ( α ) exists. Here λ 1 ( V ) denotes the first eigenvalue of Q V ( u ) . [ABSTRACT FROM AUTHOR]

Abstract In this paper, we systematically investigate the adsorption properties, atomic structures, electronic, and thermodynamic properties of tungsten, nitrogen, and oxygen atoms on the Ti-terminated TiB 2 (0001) surface without and with vacancies of titanium and boron atoms using the density functional theory (DFT). Local atomic structures of the surfaces R/TiB 2 (0001) (R = W, N, O) of adsorption models and their thermodynamic and electronic properties are studied by DFT. The bond lengths and the adsorption energy for different reconstructions of the atomic surface of the R/TiB 2 (0001) systems are established. The role of the degree of coverage of W, N and O atoms on the electronic structure and mechanisms of their adsorption on the surface (0001) of titanium diboride is investigated. We also consider the mechanisms of possible nucleation of tungsten on the surface of TiB 2 (0001). Effective charges on the tungsten atom (N and O) and nearest-neighbor atoms in the studied reconstructions are estimated. Our calculations show that the charges are transferred from the titanium atom to the W, N, and O atoms, which are due to the reconstruction of the local atomic and electronic structures and correlates with the electronegativity of the nearest-neighbor atoms. Highlights • Adsorption, electronic and thermodynamic properties of W, N, O atoms on TiB 2 (0001) surfaces with vacancies were investigated. • Reconstructions of the TiB 2 surfaces with different adsorbate coverage are examined. • Charges are transferred from the Ti atom to the adsorbate and B atoms due to the reconstruction. • Chemisorption mechanisms in the N/TiB 2-y (0001) system are 1.5 times more intense than in the O/TiB 2-y (0001) system. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive finite element method is proposed for solving Kohn–Sham equation with the multilevel correction technique. In the method, the Kohn–Sham equation is solved on a fixed and appropriately coarse mesh with the finite element method in which the finite element space is kept improving by solving the derived boundary value problems on a series of adaptively and successively refined meshes. A main feature of the method is that solving large scale Kohn–Sham system is avoided effectively, and solving the derived boundary value problems can be handled efficiently by classical methods such as the multigrid method. Hence, the significant acceleration can be obtained on solving Kohn–Sham equation with the proposed multilevel correction technique. The performance of the method is examined by a variety of numerical experiments. [ABSTRACT FROM AUTHOR]

In this paper, based on a tight-binding (TB) model, first we present the calculations of eigenvalues as band structure and then present the eigenvectors as probability amplitude for finding electron in atomic orbitals for monolayer MoS 2 in the first Brillouin zone. In these calculations we are considering hopping processes between the nearest-neighbor Mo-S, the next nearest-neighbor in-plan Mo-Mo, and the next nearest-neighbor in-plan and out-of-plan S-S atoms in a three-atom based unit cell of two-dimensional rhombic MoS 2 . The hopping integrals have been solved in terms of Slater-Koster and crystal field parameters. These parameters are calculated by comparing TB model with the density function theory (DFT) in the high-symmetry k-points ( i.e. the K- and Γ-points). In our TB model all the 4d Mo orbitals and the 3p S orbitals are considered and detailed analysis of the orbital character of each energy level at the main high–symmetry points of the Brillouin zone is described. In comparison with DFT calculations, our results of TB model show a very good agreement for bands near the Fermi level. However for other bands which are far from the Fermi level, some discrepancies between our TB model and DFT calculations are observed. Upon the accuracy of Slater-Koster and crystal field parameters, on the contrary of DFT, our model provide enough accuracy to calculate all allowed transitions between energy bands that are very crucial for investigating the linear and nonlinear optical properties of monolayer MoS 2 . [ABSTRACT FROM AUTHOR]

In this paper, the carbon-doped boron nitride nanoplate (C-BNNP) was prepared by pyrolyzing the precursor under N 2 and served as an excellent adsorbent for removal of Rhodamine B (RhB). The structure and composition of C-BNNP were characterized and its adsorption behavior for RhB was investigated. Compared with boron nitride nanoplate (BNNP) which was synthesized under NH 3 , C-BNNP displayed an enhancement of the adsorption capacity for RhB (833 mg/g). The adsorption activity was comprehensibly studied by kinetics, isotherm and thermodynamics. The adsorption kinetics followed pseudo-second-order model. The equilibrium adsorption data agreed well with the Langmuir isotherm. And the thermodynamics indicated that the adsorption process was a spontaneous, exothermic and physisorption process. In addition, the density functional theory was proposed that doping carbon in the BNNP decreased the chemical hardness of the adsorbent and enhanced the adsorption capacity of C-BNNP for RhB. [ABSTRACT FROM AUTHOR]

In this paper, the electronic properties of graphene/monolayer antimonene (G/m-Sb) heterostructure have been studied using the density functional theory (DFT). The effects of out-of-plane strain (interlayer coupling) and electric field on the electronic properties and Schottky contact of the G/m-Sb heterostructure are also investigated. The results show that graphene is bound to m-Sb layer by a weak van-der-Waals interaction with the interlayer distance of 3.50 Å and the binding energy per carbon atom of −39.62 meV. We find that the n -type Schottky contact is formed at the G/m-Sb heterostructure with the Schottky barrier height (SBH) of 0.60 eV. By varying the interlayer distance between graphene and the m-Sb layer we can change the n -type and p -type SBH at the G/m-Sb heterostructure. Especially, we find the transformation from n -type to p -type Schottky contact with decreasing the interlayer distance. Furthermore, the SBH and the Schottky contact could be controlled by applying the perpendicular electric field. With the positive electric field, electrons can easily transfer from m-Sb to graphene layer, leading to the transition from n -type to p -type Schottky contact. [ABSTRACT FROM AUTHOR]

In this paper, we use surface barrier electroreflectance technique to probe the optical transitions in hematite (α-Fe 2 O 3 ) thin film. An electric field was induced normal to the surface of α-Fe 2 O 3 thin film in an Ag/α-Fe 2 O 3 /Ag based capacitor type structure and the corresponding electroreflectance analysis was performed. Based on the electroreflectance analysis, we observed the fundamental as well as two high order critical points associated with α-Fe 2 O 3 . Standard critical point model was used to find the exact energy locations and the broadening parameters associated with these critical points. The existence of the fundamental critical point was further confirmed by the spectrophotometric analysis. The quantitative analysis based on the electro-optic energy confirmed that the obtained electroreflectance spectrum was within the low field regime, and the obtained critical points above the fundamental transition were attributed to the high order transitions of electrons from the valence band to the deep in the conduction band. [ABSTRACT FROM AUTHOR]

In this paper we present the results of a high–resolution single crystal X–ray diffraction experiment of a triphenylantimony diacrylate (Ph 3 Sb(O 2 CCH=CH 2 ) 2 ( 1 )) and a subsequent charge density study based on a topological analysis according to quantum theory of atoms in molecules (QTAIM) together with density functional theory (DFT) calculation of isolated molecule. The QTAIM was used to investigate nature of the chemical bonds and molecular graph of Ph 3 Sb(O 2 CCH=CH 2 ) 2 complex. The molecular graph shows that only in one acrylate group there is an evidence of bonding between antimony and carbonyl oxygen atom in terms of the presence of a bond path. Thus the molecular graph for this class of compounds does not provide a definitive picture of the chemical bonding and should be complemented with other descriptors, such as and а source function (SF), noncovalent interaction (NCI) index and delocalization index (DI). Moreover the realization of π…π interactions between double bonds of acrylate groups in adjacent molecules allowed us to carry out a thermopolimerization reaction in crystals of Ph 3 Sb(O 2 CCH=CH 2 ) 2 complex and to determine a probable structure of polymer by solid state CP/MAS 13 C NMR. [ABSTRACT FROM AUTHOR]

This paper investigated the geometric structural and electronic properties of infinite chiral single- and doubel-walled silicon nanotubes (SWSiNTs and DWSiNTs) using density functional theory (DFT). With the periodic boundary conditions (PBC), the structures of infinite chiral silicon nanotubes (SiNTs) were obtained and their electronic properties were discussed in detail. The stability of the chiral SWSiNTs was enhanced with the increase of the diameter. For the chiral DWSiNTs, with the increase of the wall spacing, the stability of chiral DWSiNTs (n,n/2)@(2n,n) was gradually enhanced but the chiral DWSiNTs (2n,n)@(3n,3n/2) was reduced; and with the increase of the diameter, the stability of chiral DWSiNTs was gradually enhanced. And the chiral SWSiNTs (n,m) showed semiconductor properties when the chiral indexs were not multiple of 3; otherwise, they exhibited metal characteristics. The electronic properties of SWSiNTs (4,2) and (6,3) were abnormal due to the curvature effect. For chiral DWSiNTs, the orderliness of band gaps was the same as SWSiNTs. In other words, when the chiral indexs for two tubes were both multiple of 3, they show metal characteristics. When the chiral indexs of just one tube were not multiple of 3, they exhibited semiconductors properties, except for (4,2)@(8,4) which showed metal characteristics due to the curvature effect. [ABSTRACT FROM AUTHOR]

In this paper, the structural, electronic, and magnetic properties of Ga, Ge, P and Sb doped monolayer arsenene have been systematically investigated by first-principles calculations based on density functional theory. The properties of monolayer arsenene can be effectively tuned by substitutional doping. Especially, the dopant Ga could lead to an indirect-to-direct bandgap transition and doping a Ge atom could exhibit dilute magnetic semiconductor property. In addition, the second Ge atom slightly prefers to occupy the next nearest-neighbor site of As atom to form the complex substituted defect (Ge As - As - Ge As ) in As 30 Ge 2 system and is found to be anti-ferromagnetic coupling. The diverse electronic and magnetic properties highlight the potential applications of monolayer arsenene in electronics, optoelectronics and spintronics. [ABSTRACT FROM AUTHOR]

In this paper, germanium nanowires (GeNWs) with different cross-sectional areas are considered as the channel of a cylindrical surrounding gate field effect transistors (CSG-FETs) and the electronic properties of them are calculated through the density functional method and Slater-Koster (SK) tight binding model. The corresponding transistor parameters are obtained using Non-equilibrium Green’s function (NEGF) combined by SK model. We find that SK model predicts the well-nigh same bandgap value compared to meta-GGA-DFT approximation, while GGA-DFT underestimates the value of the bandgap. CSG-GeNW-FETs Transistor figure of merit shows a supreme I on /I off ratio which is equal to 10 12 for one of the considered structures with a circular cross-section. The obtained sub-threshold swing (SS) values for the FETs illustrate an increment trend when the supercell size of the germanium nanowire increases whereas the transconductance and ON-current of the FETs decrease when the GeNW supercell size scales down due to the declining of the density of states and electron transmission spectrum. [ABSTRACT FROM AUTHOR]

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn–Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann–Feynman forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Since the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the Hellmann–Feynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H 2 and liquid Al–Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical properties of Na and Pt decorated arrays of 2D graphyne sheet is investigated. The proposed structures are consisted of Na and Pt decorated graphyne sheet (CC), analogous system of Boron nitride sheet (BN-yne), and graphyne-like BN sheet (CC-BN-yne). The properties such as In-plane stiffness and Bulk module are studied using Energy-Strain correlation. The calculations were carried out based on Density functional theory (DFT) using the generalized gradient approximation (GGA) framework. The results offered very competitive values of stiffness and Bulk module for Pt decorated CC and BN-yne. However, the Pt decorated CC-BN-yne structure demonstrated around 80% of stiffness and 77% of Bulk module, compared to those of pure structure. Na decorated system showed the same trend for all three mentioned structures. [ABSTRACT FROM AUTHOR]