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The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction (HOR). Here, we show the Pt-Ni alloy nanoparticles (PtNi2) have an enhanced HOR activity compared with single component Pt catalyst. While, the interface electron-transfer kinetics of PtNi2 catalyst exhibits a very wide electron-transfer speed distribution. When combined with carbon dots (CDs), the interface charge transfer of PtNi2-CDs composite is optimized, and then the PtNi2-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20% commercial Pt/C. In this system, CDs also contribute to trapping H+ and H2O generated during HOR, tuning hydrogen binding energy (HBE), and regulating interface electron transfer. This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.

The development of highly efficient electrocatalysts toward hydrogen oxidation reaction (HOR) under alkaline media is essential for the commercialization of alkaline exchange membrane fuel cells (AEMFCs). However, the HOR kinetics in alkaline is two to three orders of magnitude slower than that in acid. More critically, fundamental understanding of the sluggish kinetics derived from the pH effect is still debatable. In this review, the recent development of understanding HOR mechanism and rational design of advanced HOR electrocatalysts are summarized. First, recent advances in the theories focusing on fundamental understandings of HOR under alkaline electrolyte are comprehensively discussed. Then, from the aspect of intermediates binding energy, optimizing hydrogen binding energy (HBE) and increasing hydroxyl binding energy (OHBE), the strategies for designing efficient alkaline HOR catalysts are summarized. At last, perspectives for the future research on alkaline HOR are pointed out.

A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10606) demonstrated that the interaction between H2 and MXene (Sc2C and Ti2C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc2C and Ti2C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc2C and Ti2C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti2C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti2C, Sc2C and their oxygen-functional counterparts, the binding energy of H2 on Sc2CO2 surface is the closest to the ideal range of 0.16–0.42 eV/H2 at ambient conditions, and thus the Sc2C with oxygen group is expected to be more suitable as hydrogen storage materials.

Hydrogen permeation experiments were performed in quenched and tempered (Q&T) low alloy steels with varying Ni contents exposed to 1 bar H2 at 30, 50 and 70 °C. From the analysis of build-up and decay transients, it is concluded that the permeation coefficient, the apparent diffusion coefficient ( D a p p ) and the concentration of hydrogen in interstitial sites on the charging surface ( C 0 ) decreases as the Ni concentration increases from 0 to 5 wt.%. The total concentration of hydrogen on the charging surface ( C 0 , r ), which includes interstitial and reversibly trapped hydrogen, is about an order of magnitude larger than C 0 . The hydrogen binding energy ( E b ) and trap density ( N r ) were calculated from the D a p p vs. temperature dependence, under the hypothesis of low trap occupancy. C 0 , r , E b and N r do not show a clear correlation with Ni content, indicating that trapping is controlled by a microstructural feature other than Ni atoms in solid solution.

Single-atom catalysts (SACs) have been considered as a potential candidate for fuel cell application due to the fact that they exhibited good oxygen reduction reaction (ORR) activity. In this study, the ORR catalytic activities of Co-N4 /C, Co-N3 S/C, Co-N2 S2 /C, Co-NS3/C, and Co-S4/C catalysts are studied using density functional theory (DFT) calculations based on BEEF-vdW functional. The reduction of *OH into H2O is found to be the potential determining step of ORR on Co-N4/C catalysts. This implies that the activity of the Co-N4/C system could be improved by weakening the binding energy of the *OH intermediate. The DFT results revealed that the adsorption energy of the *OH intermediate bound on Co-N3S/C, Co-N2S2/C, Co-NS3/C, and Co-S4/C is weaker than that of the Co-N4/C catalyst. The results show that the overpotentials of Co-N4/C, Co-N3S/C, Co-N2S2/C, Co-NS3/C, and Co-S4/C catalysts are 0.57, 0.37, 0.46, 0.40, and 0.42 V, respectively. Thus, the Co-N3S/C catalyst revealed the lower overpotential pathway. Slightly less amount of charges are transferred from Co atom in Co-N3S/C to ORR intermediates as compared to Co-N4/C and the d-band center of Co atom changes from -0.71 eV (Co- N4/C) to -0.91 eV (Co-N3S/C). This can explain the weaker adsorption energy of *OH on Co-N3S/C catalyst. Therefore, Co-N3S/C is a promising non-precious single-atom catalyst for an efficient ORR activity in acidic solution in fuel cells. Keywords: Oxygen reduction reaction, Single-atom catalysts, adsorption energy, catalytic activity, Density functional theory.

In this work, we performed molecular dynamics (MD) simulations on the interactions between a basal edge dislocation and point defects including vacancies and self-interstitial atoms in magnesium. Simulation results suggest that both self-interstitial atoms and vacancies have a blocking effect on dislocation motion, but the blocking effect of vacancies is much weaker than that of self-interstitial atoms. During interactions, self-interstitial atoms are absorbed and move with dislocation, and the edge dislocation climbs after absorbing self-interstitial atoms. In contrast, vacancies cannot be absorbed. To explain these observations, the binding energy and migration energy are calculated. The binding energy of both vacancies and self-interstitial atoms increases as they approach the dislocation core, seemingly indicating that they can be absorbed. However, the migration barrier of a vacancy is found to be about two orders in magnitude higher than that of a self-interstitial atom. Therefore, only self-interstitial atoms are absorbed, while vacancies cannot.

Promoting charge separation is still the main challenge in the rational design of photocatalysts for visible light photocatalytic reduction of CO2. Based on the unique advantages of the Eu3+ single atom and the Type-II heterojunction in the field of photocatalytic reduction, a Eu3+ single atom doped CdS/InVO4 Type-II heterojunction was successfully constructed through the combination of hydrothermal and in situ synthesis. The prepared CdS/InVO4:Eu3+ single atom composite material has excellent photocatalytic CO2 reduction activity under visible light. The XPS test results show that the In 3d, O 1s, V 2p, and Eu 3d peaks of 10-CdS/IVO:Eu3+ move slightly towards a low energy direction, while, the positions of Cd 3d and S 2p peaks are both shifted to the direction of high binding energies, which indicated that the electrons can be transferred from CdS to IVO with the help of Eu3+. The CO yield of CdS/InVO4:Eu3+ was 11.02 μmol g−1 h−1, which was almost 2.4 times that of pure InVO4 and 1.9 times that of pure CdS, and the yield of CH4 of CdS/InVO4:Eu3+ reached 8.24 μmol g−1 h−1, which was 5.3 times and 10.6 times that of InVO4 and CdS, respectively. Both the theoretical and experimental results show that the single atom Eu3+ can not only modify InVO4 and activate CO2 molecules, but can also promote charge separation between the interface and improve the photocatalytic performance. It is expected that the research results of this paper can provide a novel idea for the rational design of rare earth monatomic catalysts.

In the present study, copper (II) complex of 4, 4′-di-tert-butyl-2,2′-bipyridine [Cu (C18H24N2) (NO3)2], 1 is investigated through its synthesis and characterization using elemental analysis technique, infra-red spectroscopy, and single-crystal analysis. The compound 1 crystallizes in orthorhombic space group P212121. The copper atom in the mononuclear complex is hexa coordinated through two nitrogen and four oxygen atoms from bipyridine ligand and nitrate ligands. The thermal analysis depicts the stability of the entitled compound up to 170 °C, and the decomposition takes place in different steps between 170 and 1000 °C. Furthermore, quantum chemical techniques are used to study optoelectronic, nonlinear optical, and therapeutic bioactivity. The values of isotropic and anisotropic linear polarizabilities of compound 1 are calculated as 41.65 × 10−24 and 23.02 × 10−24 esu, respectively. Likewise, the static hyperpolarizability is calculated as 47.92 × 10−36 esu using M06 functional compared with para-nitroaniline (p-NA) and found several times larger than p-NA. Furthermore, the antiviral potential of compound 1 is studied using molecular docking technique where intermolecular interactions are checked between the entitled compound and two crucial proteins of SARS-CoV-2 (COVID-19). Our investigation indicated that compound 1 interacts more vigorously to spike protein than main protease (MPro) due to its better binding energy of −9.60 kcal/mol compared with −9.10 kcal/mol of MPro. Our current study anticipated that the above-entitled coordination complexes could be potential candidates for optoelectronic properties and their biological activity.

Whereas pnicogen atoms like P and As have been shown repeatedly to act as electron acceptors in pnicogen bonds, the same is not true of the more electronegative first-row N atom. Quantum calculations assess whether N can serve in this capacity in such bonds and under what conditions. There is a positive π-hole belt that surrounds the central N atom in the linear arrangement of NNNF, NNN-CN, and NNO, which can engage a NH3 base to form a pnicogen bond with binding energy between 3 and 5 kcal/mol. Within the context of a planar arrangement, the π-hole above the N in NO2OF, N(CN)3, and CF3NO2 is also capable of forming a pnicogen bond, the strongest of which amounts to 11 kcal/mol with NMe3 as base. In their pyramidal geometry, NF3 and N(NO2)3 engage with a base through the σ-hole on the central N, with variable binding energies between 2 and 9 kcal/mol. AIM and NBO provide somewhat different interpretations of the secondary interactions that occur in some of these complexes.

The sluggish oxygen reaction kinetics concomitant with the high overpotentials and parasitic reactions from cathodes and solvents is the major challenge in aprotic lithium-oxygen (Li-O2 ) batteries. Herein, PtIr multipods with a low Lewis acidity of the Pt atoms are reported as an advanced cathode for improving overpotentials and stabilities. DFT calculations disclose that electrons have a strong disposition to transfer from Ir to Pt, since Pt has a higher electronegativity than Ir, resulting in a lower Lewis acidity of the Pt atoms than that on the pure Pt surface. The low Lewis acidity of Pt atoms on the PtIr surface entails a high electron density and a down-shifting of the d-band center, thereby weakening the binding energy towards intermediates (LiO2 ), which is the key in achieving low oxygen-reduction-reaction (ORR) and oxygen-evolution-reaction (OER) overpotentials. The Li-O2 cell based on PtIr electrodes exhibits a very low overall discharge/charge overpotential (0.44 V) and an excellent cycle life (180 cycles), outperforming the bulk of reported noble-metal-based cathodes.

Developing efficient platinum (Pt)-based electrocatalysts is enormously significant for fuel cells. Herein, we report an integrated electrocatalyst of ultralow-Pt alloy encapsulated into nitrogen-doped nanocarbon architecture for efficient oxygen reduction reaction. This hybrid Pt-based catalyst achieves a mass activity of 3.46 A mgpt−1 at the potential of 0.9 V vs. RHE with a negligible stability decay after 10,000 cycles. More importantly, this half-cell activity can be expressed at full cell level with a high Pt utilization of 10.22 W mgPt−1cathode and remarkable durability after 30,000 cycles in single-cell. Experimental and theoretical investigations reveal that a highly strained Pt structure with an optimal Pt-O binding energy is induced by the incorporation of Co/Ni into Pt lattice, which would account for the improved reaction kinetics. The synergistic catalysis due to nitrogen-doped nanocarbon architecture and active Pt component is responsible for the enhanced catalytic activity. Meanwhile, the strong metal-support interaction and optimized hydrophilic properties of nanocarbon matrix facilitate efficient mass transport and water management. This work may provide significant insights in designing the low-Pt integrated electrocatalysts for fuel cells and beyond.

Using first-principles calculations, we report on the structural and electronic properties of bilayer hexagonal boron nitride (h-BN), incorporating hydrogen (H2) molecules inside the cavity for potential H2-storage applications. Decrease in binding energies and desorption temperatures with an accompanying increase in the weight percentage (upto 4%) by increasing the H2 molecular concentration hints at the potential applicability of this study. Moreover, we highlight the role of different density functionals in understanding the decreasing energy gaps and effective carrier masses and the underlying phenomenon for molecular adsorption. Furthermore, energy barriers involving H2 diffusion across minimum-energy sites are also discussed. Our findings provide significant insights into the potential of using bilayer h-BN in hydrogen-based energy-storage applications.

This work reports the reversible hydrogen storage capacities of Li and Na decorated C20 fullerene using dispersion corrected density functional theory calculation. The alkali metal (AM) atoms are found to bind on the C–C bridge position of C20 through non-covalent closed-shell interaction. Their thermodynamic stabilities are verified through HOMO-LUMO gaps and different reactivity descriptors. Each Li and Na atoms decorated on C20 adsorb maximum up to five H2 molecules through Niu-Rao-Jena interaction. The adsorption energy decreases with successive addition of H2 molecules with average binding energy lying in the range of 0.12 eV–0.13 eV. The systems can have a maximum gravimetric density of 13.08 wt% and 10.82 wt% for C20Li4–20H2 and C20Na4–20H2 respectively. ADMP molecular dynamic simulations illustrate the reversibility of adsorbed hydrogen molecules at higher temperature (≧ 300 K). The calculated thermodynamic useable hydrogen capacity shows the room temperature H2 desorption condition of AM decorated C20. Consistent with criteria set by the US-DOE, C20Li4 and C20Na4 can be used as promising hydrogen storage materials.

X-ray photoelectron spectroscopy (XPS) is among the most utilized analytical methods for nitrogen-doped carbon materials. Clarifying the assignments of nitrogen-doped carbon materials with different degrees of carbonization, which relates to conjugated systems, is essential to correlate structures with the performance of various applications, but such precise assignments were challenging. In this work, precise analyses were conducted to overcome the difficulty to assign the peaks of carbon materials with different degrees of carbonization, different edges, and various nitrogen-containing functional groups in graphene nanoribbons (GNRs), such as nitrile, pyridinic, primary with/without charges, secondary with/without charge, tertiary without charges (graphitic nitrogen), and quaternary nitrogen. Electrons donated from hydrogen and Madelung potentials showed a higher correlation to the peak shift of C1s and N1s XPS spectra than Mulliken charges on nitrogen. Zigzag edges showed a greater influence on the peak shift of tertiary amine (graphitic nitrogen) than armchair edges on XPS spectra. Besides, as the degree of carbonization is increased from aromatic compound-like structures to GNRs, the peak positions of C–N in C1s and N1s XPS spectra shifted to higher binding energies. This research proved that XPS could be applied to the precise structural analyses of nitrogen-containing carbon materials.

Carbonaceous materials are the most promising candidates as the anode for sodium-ion batteries (SIBs), however, they still suffer from low electric conductivity and sluggish sodium ion (Na+) reaction kinetics. Appropriate composition modulation using heteroatoms doping and structure optimization is highly desired. A basic empirical understanding of the structure-capacity relationship is also urgent in tackling the above problems. Herein, multi-functional nitrogen (N) doped carbon micro-rods with enlarged interlayer spacing are synthesized and investigated as the anode in SIBs, showing an ultra-stable capacity of 161.5 mAh g−1 at 2 A g−1 for over 5000 cycles. Experimental investigations and first-principle calculations indicate that the enlarged interlayer spacing can facilitate Na+ intercalation and N doping can guarantee the high electric conductivity and favorable electrochemical active sites. Additionally, pyridinic N is theoretically proved to be more effective to enhance Na+ adsorption than pyrrolic N due to the lower adsorption energy and stronger binding energy with Na+. Full SIBs show a high capacity and cyclability, making the biomass-derived carbon micro-rods to be a promising anode for practical SIBs applications.

We investigated the CO2 adsorption and electrochemical conversion behavior of triazole-based C3 N5 nanorods as a single matrix for consecutive CO2 capture and conversion. The pore size, basicity, and binding energy were tailored to identify critical factors for consecutive CO2 capture and conversion over carbon nitrides. Temperature-programmed desorption (TPD) analysis of CO2 demonstrates that triazole-based C3 N5 shows higher basicity and stronger CO2 binding energy than g-C3 N4 . Triazole-based C3 N5 nanorods with 6.1 nm mesopore channels exhibit better CO2 adsorption than nanorods with 3.5 and 5.4 nm mesopore channels. C3 N5 nanorods with wider mesopore channels are effective in increasing the current density as an electrocatalyst during the CO2 reduction reaction. Triazole-based C3 N5 nanorods with tailored pore sizes exhibit CO2 adsorption abilities of 5.6-9.1 mmol/g at 0 °C and 30 bar. Their Faraday efficiencies for reducing CO2 to CO are 14-38% at a potential of -0.8 V vs. RHE.

The large zero-point motion and rapid atomic exchange in quantum solids like helium make defects extremely mobile. Previous shear modulus measurements have shown that mobile dislocations can soften the shear modulus of high purity hcp $$^4$$ He by as much as 90%, and that isotopic impurities ( $$^3$$ He atoms) pin dislocations and restore the intrinsic shear modulus at low temperatures. In this paper, we report shear modulus and dissipation measurements on solid $$^3$$ He in its body-centred cubic (bcc) phase. The lighter mass makes $$^3$$ He an even more quantum solid, with much higher exchange frequencies, but its spin and different crystal structure can change the nature of dislocations and their behavior. Our measurements show that the shear modulus of bcc $$^3$$ He had many similarities to that of hcp $$^4$$ He, including a thermally activated transition from a stiff state to a soft state as $$^4$$ He impurities unbind from dislocations when the temperature increases. The impurity binding energies are smaller than those in hcp $$^4$$ He and depend more strongly on pressure than a simple elastic binding model would suggest. In contrast to hcp $$^4$$ He, the shear modulus of bcc $$^3$$ He continues to decrease at temperatures up to 1 K, accompanied by a second dissipation peak with a larger activation energy. This behavior suggests that dislocation motion may be limited by intersections in tangled network in bcc $$^3$$ He but can overcome these barriers at high temperatures by thermal activation.

Silicon-based clusters have attracted particular attention because they are regard as building blocks for developing silicon-based nanomaterials. However, pure silicon clusters have low chemical stability owing to their dangling bonds. Doping with lanthanide atoms is a good way to form closed-shell of M@Sin clusters and alter their electronic and magnetic properties. Here, we systematically study the lanthanide element Pr doped neutral and anionic silicon clusters by using density functional theory. Extensive searches for ground-state structures of Sin+1λ and PrSinλ (n = 1–9, λ = 0, − 1) clusters were carried out based on the comparison between experimental photoelectron spectroscopy and simulated spectra. Furthermore, the calculated AEA values of our obtained structures show good agreement with the experimental values. Based on averaged binding energies, fragmentation energies and HOMO–LUMO gaps, their relative stabilities were analyzed. Furthermore, the patterns of HOMOs for the most stable isomers were investigated to gain insight into the nature of bonding. The results show that some σ-type and few π-type bonds are formed among Si and Pr atoms. To achieve a insight into localization of charge and charge-transfer information, the Mulliken population are analyzed and discussed.

NiFe-layered double hydroxides (NiFe-LDH) are among the most active catalysts developed to date for the oxygen evolution reaction (OER) in alkaline media, though their long-term OER stability remains unsatisfactory. Herein, we reveal that the stability degradation of NiFe-LDH catalysts during alkaline OER results from a decreased number of active sites and undesirable phase segregation to form NiOOH and FeOOH, with metal dissolution underpinning both of these deactivation mechanisms. Further, we demonstrate that the introduction of cation-vacancies in the basal plane of NiFe LDH is an effective approach for achieving both high catalyst activity and stability during OER. The strengthened binding energy between the metals and oxygen in the LDH sheets, together with reduced lattice distortions, both realized by the rational introduction of cation vacancies, drastically mitigate metal dissolution from NiFe-LDH under high oxidation potentials, resulting in the improved long-term OER stability. In addition, the cation vacancies (especially M3+ vacancies) accelerate the evolution of surface γ-(NiFe)OOH phases, thereby boosting the OER activity. The present study highlights that tailoring atomic cation-vacancies is an important strategy for the development of active and stable OER electrocatalysts.

Abstract Metal–organic frameworks (MOFs) have received significant attention thanks to their promising features in the storage and separation of guest molecules. MOFs without open metal sites are emerging as they are often less susceptible to poisoning compared to those with open metal sites. However, a complete understanding of the binding and gas separation mechanisms in such materials is still missing. In this work, we perform a comparative study of two classes of vanadium-based MOFs without open metal sites: MFM-300-V$$^\text{(III)}$$ (III) and MFM-300-V$$^\text{(IV)}$$ (IV) , as well as MIL-47-V$$^\text{(III)}$$ (III) and MIL-47-V$$^\text{(IV)}$$ (IV) . We employ first-principles van der Waals density functional theory to find the optimal binding conformations and binding energies of a series of small hydrocarbons within the pores of the aforementioned MOFs. Our study provides insight into the host–guest interactions in such MOFs without open metal sites, especially the role played by the bridging hydroxyl group ($$\mu _2$$ μ 2 –OH). We conclude that the bridging –OH group acts as a pseudo open metal site in these MOFs. Graphic abstract

Zinc oxide (ZnO) is used for various purposes because of its special physico-chemical properties, including large band gap, high binding energy of exciton, nontoxicity, high chemical and thermal stability, large piezoelectric constants, and wurtzite crystal structure with various and widespread applications in electronics, optoelectronics, biochemical sensing, biomedical, and energy-saving systems. This review mainly aimed to present the recent improvement in ZnO-based composite materials with utilization in energy storage systems with a specific focus on lithium-ion batteries, dye-sensitized solar cells, and supercapacitors. The first part of this paper looks at the structure and properties of ZnO and then describes some of the most common synthesizing methods of ZnO composites, including electrochemical, chemical, solvo/hydrothermal, and physical deposition methods. Finally, the recent advancement of ZnO-based composite materials applied in energy storage systems was discussed.

The hydrogen trap sites and corresponding hydrogen binding energies in an Al–Cu–Mg alloy with the different microstructures were investigated to unravel the environmental hydrogen embrittlement (HE) behavior of the alloy. The results showed that hydrogen can reside at interstitial lattices, dislocations, S′-phase, and vacancies. In the aged specimen with the highest hydrogen content, it was firstly reported that hydrogen resided at S′-phase particles with relatively high binding energy, which is a determinant factor on HE resistance of the alloy. In the cold-rolled specimen, high content of hydrogen trapped at dislocations with a reversible nature leads to intergranular hydrogen-assisted cracking. In the solution-treated specimen, hydrogen migration to the surface due to low trap density results in low hydrogen content and prevents the GBs from reaching critical hydrogen concentration. The obtained results clearly reveal that trap site density, and the nature of trap sites can determine environmental HE susceptibility of the alloy.

Researching of high performance and low-cost oxygen reduction reaction (ORR) electrocatalysts is one of the core issues for the rapid development of energy conversion and storage devices. Herein, a N and S dual-doped three-dimensional (3D) interconnected mesoporous carbon catalyst (CNS) was constructed via a facile hydrothermal-pyrolysis strategy. Benefiting from the 3D interconnected mesoporous architecture, CNS was endowed with a fast oxygen mass transfer rate together with plentiful of accessible active centers on the surface. Its ORR half-wave potential (E1/2， 0.87 V) surpasses commercial Pt/C catalyst 50 mV in alkaline media. Its E1/2 negatively shifts only 2 mV after 8000 cycles in half-cell tests. More importantly, the zinc-air battery with CNS as cathode catalyst delivers an excellent high peak power density of 144 mW cm−2. DFT calculation results show that when N and S are co-doped, the spin density of adjacent carbon atoms can be changed, thereby increasing the CNS's binding energy to oxygen and conductivity. The excellent comprehensive performance of CNS undoubtedly discloses its potential practical application in the energy conversation and storage area.

Density functional theory calculations are used to determine the suitability of carbon nitrides as potential cathode materials for aluminium ion batteries (AIB). Our calculations reveal that, compared to graphene, carbon nitrides with only pyridinic and pyrrolic nitrogen result in a decline in performance whereas carbon nitrides with only graphitic nitrogen show significantly improved performance. Two different two-dimensional carbon nitrides with graphitic nitrogen only, honeycomb structured graphene-like C11N and C4N which features defects, are tested and compared with graphene as potential cathode materials. It is found that the AlCl4 binds more strongly to carbon nitrides (−3.47 eV to −3.58 eV) than to graphene (−2.21 eV). This higher binding energy significantly reduces AlCl4 agglomeration, suggesting a higher storage capacity of C11N (184 mAh g−1) than graphene (155 mAh g−1) and lower emission of chlorine. The AlCl4 can move on the surface of C4N/C11N without significant energy barrier which will facilitate fast charging. Finally it can be concluded that carbon nitrides with graphitic nitrogen and graphene-like honeycomb structures are more suitable for the AIBs and a small percentage of graphitic nitrogen doping could significantly improve the storage capacity of the AIB with fast charging, lower anion agglomeration rate and low chlorine emission.

Anatase TiO2 was synthesized on Hollow glass spheres (HGS) by a sol–gel method in this work. TiO2/HGS composite (70% HGS + 30% TiO2) could be suspended in water to facilitate light absorption, and the particles were readily separated from water since they floated on water surface after treatment. The oxidation state of titanium (Ti4+) in TiO2/HGS composite was as same as that in pure TiO2, while the binding energies of Ti2p1/2 and Ti2p3/2 orbitals of TiO2/HGS had a slight 0.3 eV shift to high energy end. Nano-sized TiO2 crystals were tightly adhered on HGS surface, while the thickness of TiO2 film might be several hundred nanometers. The electron–hole pairs formed in TiO2 had a little longer lifetime than the electron–hole pairs formed in TiO2/HGS, proven by the photoluminescence intensity of emitted photons. Red 2G azo dye was used to study the degradation activity. The photocatalytic activity of TiO2/HGS composite was comparable to the activity of pure TiO2 particles. 81% of the initial Red 2G molecules (Red 2G solution 50 mL, 40 mg/L) were decomposed on TiO2/HGS composite in 170 min.

Hydrothermal deposition is emerging as a highly potential route for antimony-based solar cells, in which the Sb2(S,Se)3 is typically in situ grown on a common toxic CdS buffer layer. The narrow band gap of CdS causes a considerable absorption in the short-wavelength region and then lowers the current density of the device. Herein, TiO2 is first evaluated as an alternative Cd-free buffer layer for hydrothermally derived Sb2S3 solar cells. But it suffers from a severely inhomogeneous Sb2S3 coverage, which is effectively eliminated by inserting a Zn(O,S) layer. The surface atom of sulfur in Zn(O,S) uniquely provides a chemical bridge to enable the quasi-epitaxial deposition of Sb2S3 thin film, confirming by both morphology and binding energy analysis using DFT. Then the results of the first-principles calculations also show that Zn(O,S)/Sb2S3 has a more stable structure than TiO2/Sb2S3. The resultant perfect Zn(O,S)/Sb2S3 junction, with a suitable band alignment and excellent interface contact, delivers a remarkably enhanced JSC and VOC for Sb2S3 solar cells. The device efficiency with the TiO2/Zn(O,S) buffer layer boosts from 0.54% to 3.70% compared with the counterpart of TiO2, which has a champion efficiency of Cd-free Sb2S3 solar cells with a structure of ITO/TiO2/Zn(O,S)/Sb2S3/Carbon/Ag by in situ hydrothermal deposition. This work provides a guideline for the hydrothermal deposition of antimony-based films upon a nontoxic buffer layer.

Superelectrophilic monoanions [B12 (BO)11 ]- and [B12 (OBO)11 ]- , generated from stable dianions [B12 (BO)12 ]2- and [B12 (OBO)12 ]2- , show great potential for binding with noble gases (Ngs). The binding energies, quantum theory of atoms in molecules (QTAIM), natural population analysis (NPA), energy decomposition analysis (EDA), and electron localization function (ELF) were carried out to understand the B-Ng bond in [B12 (BO)11 Ng]- and [B12 (OBO)11 Ng]- . The calculated results reveal that heavier noble gases (Ar, Kr, and Xe) bind covalently with both [B12 (BO)11 ]- and [B12 (OBO)11 ]- with large binding energies, making them potentially feasible to be synthesized. Only [B12 (OBO)11 ]- could form a covalent bond with helium or neon but the small binding energy of [B12 (OBO)11 He]- may pose a challenge for its experimental detection.

La2O3 catalyzed oxidative coupling of methane (OCM) is a promising process that converts methane directly to valuable C2 (ethylene and ethane) products. Our online MS transient study results indicate that pristine surface without carbonate species demonstrates a higher selectivity to C2 products, and a lower light-off temperature as well. Further study is focused on carbonate-free La2O3 catalyst surface for identification of active oxygen species associated with such products behavior. XPS reveals unique oxygen species with O 1 s binding energy of 531.5 eV correlated with OCM catalytic activity and carbonates removal. However, indicated thermal stability of this species is much higher than the surface peroxide or superoxide structures proposed by earlier computation models. Motivated by experimental results, DFT calculations reveal a new more stable peroxide structure, formed at the subsurface hexa-coordinate lattice oxygen sites, with energy 2.18 eV lower than the previous models. The new model of subsurface peroxide provides a perspective for understanding of methyl radicals formation and C2 products selectivity in OCM over La2O3 catalyst.

The oxidation state of 99Tc adsorbed on the surface of AG-3 (I) and KAU (II) activated carbon from an aqueous potassium pertechnetate (KTcO4) solution has been studied by X-ray photoelectron spectroscopy at binding energies Eb in the range from zero to 1250 eV. The measured Eb(Tc 3d5/2) in sample I is 260.0, 258.2, and 258.3 eV, indicating the presence of three states: Tc7+, Tc5+, and Tc3+. The Tc 3d electron spectrum of the surface of sample II shows only two spin doublets, corresponding to two oxidation states of technetium, Tc3+ and Tc5+, in the ratio 23 : 77.

Understanding how lithium interacts with complex biosystems is crucial for uncovering the roles of this alkali metal in biology and designing extraction techniques for battery production and environmental remediation. In this light, fundamental information about Li+ binding to nucleic acids is required. Herein, a new database of Li+-nucleic acid interactions is presented that contains CCSD(T)/CBS benchmark energies for all nucleobase and phosphate binding locations. Furthermore, the performance of 54 DFT functionals in combination with three triple-zeta (TZ) basis sets (6-311+G(3df,2p), aug-cc-pVTZ, and def2-TZVPP) is tested. The results identify a range of functionals across different families (B2-PLYP, PBE-QIDH, ωB97, ωB97X-D, MN15, B3PW91, B97-2, TPSS, BP86-D3(BJ), and PBE) that can accurately describe coordinated Li+-nucleic acid interactions, with the average mean percent error (AMPE) across binding positions and basis sets being below 2%. Nevertheless, only three functionals tested (B2-PLYP, PBE-QIDH, and ωB97X-D) preserve this accuracy for metal cation-π interactions, suggesting that caution is warranted when choosing a functional to describe a diverse range of Li+-nucleic acid complexes. Removal of counterpoise corrections has very little impact on the reliability of most functionals, while the effect of empirical dispersion corrections varies depending on the functional choice and interaction type. While increasing the basis set to quadruple-zeta quality had little impact on the AMPE, the accuracy of double-zeta basis sets varies with family. Importantly, DFT methods reproduce the CCSD(T)/CBS trend in the preferred binding position for a given nucleic acid component and the global trend across components (phosphate ≫ G > C ≫ A ∼ T = U), as well as the geometries of the metal-nucleic acid complexes. The overall top performing functional is PBE-QIDH, which results in deviations from CCSD(T)/CBS values as small as ∼0.1 kcal/mol for nucleobase contacts and ∼1 kcal/mol for phosphate interactions. The most accurate DFT methods identified in the present work are recommended for future investigations of lithium interactions in larger nucleic acid systems to provide insights into the biological roles of this metal and the design of novel biosensing strategies.

Combining multi-scale calculations with machine learning, we investigate how the ligand functionalization affects the hydrogen storage profile of Metal Organic Frameworks. The binding energy of hydrogen with 58 strategically selected functionalized benzenes was calculated with accurate ab-initio methods. Our results show that many functional groups (e.g. -OPO3H2, –OCONH2) increase the interaction strength up to 15–25% compared to benzene while –OSO3H holds the most promise with an enhancement up to 80%. Grand Canonical Monte-Carlo calculations with interatomic potentials derived from the ab-initio calculations, verify the trend obtained from the meticulous screening. In addition, a proof of principle Machine Learning analysis is performed on the ab-initio results showing a good prediction of the H2 binding energies even with a limited amount of data. The results from our bottom-up approach lead us to conclude that this functionalization strategy can be applied to various porous materials in order to enhance their hydrogen storage performance.

The cytotoxic activity of ligands (O,O′-dialkyl esters of S,S-ethylenediamine-N,N'-di-(3,3′-1H-indol-3yl)propionic acid dihydrochloride (alkyl = ethyl, propyl, butyl, pentyl) and corresponding palladium(II) complexes were determined against human and murine colorectal cancer cells (HCT116 and CT26) and compared to the activities of cisplatin. All tested compounds showed a dose-dependent cytotoxic activity toward used cell lines. According to IC50 values for cytotoxic activities of tested compounds, complex of Pd(II) ion with O,O′-diethyl ester of S,S-ethylenediamine-N,N'-di-(3,3′-1H-indol-3yl) propionic acid dihydrochloride showed significantly, six times higher cytotoxic activity against HC116 cell line, than cisplatin. The interactions of the complexes with calf thymus DNA were analyzed by absorption and emission spectral studies (ethidium bromide displacement studies). The high values of DNA-binding constants (Kb) indicate the good binding affinity for all investigated complexes toward DNA. During the examination of competitive reactions with ethidium bromide, the results showed that complexes can replace ethidium bromide bound DNA and interact with DNA. The molecular docking simulations were applied for better understanding of inhibitory activity of palladium(II) complexes. The obtained values of free binding energies and constants of inhibition also show that the complex of Pd(II) ion with O,O′-diethyl ester of S,S-ethylenediamine-N,N'-di-(3,3′-1H-indol-3yl)propionic acid dihydrochloride has the best inhibitory effect on DNA molecules.

Density functional theory calculations were applied to investigate LiF decoration of B12N12 cage in terms of the structures and stabilities. Then, the resulted LiF-decorated B12N12 cages were explored to find their capability as hydrogen storage. The DFT results showed that decoration of BN cages is independent of the previously decorated BN bonds. LiF decoration of BN bonds leads to charge redistribution so that charges of the atoms nearest to the decorated bonds change and charges of the other ones remain rather unchanged. Hydrogen prefers to bind to the B atoms that are nearest to the decorated Li. It was revealed that H atoms bind more strongly to B atoms of LiF-decorated B12N12 cages in comparison to pristine B12N12 cage. Two types of hydrogen bonding were formed in B12N12Li4F4 and B12N12Li6F6, binding of hydrogens in a quasi-molecular form to the decorated Li atoms, and also binding of hydrogen in atomic to B atoms. Calculated binding energies showed that binding of hydrogen to the models is an intermediate between physical and chemical adsorption, indicating that the LiF-decorated B12N12 cages are suitable as hydrogen storage materials.

Electrocatalytic hydrogen evolution reaction (HER) holds promise in the renewable clean energy scheme. Crystalline Au and Ag are, however, poor in catalyzing HER, and the ligands on colloidal nanoparticles are generally another disadvantage. Herein, we report a thiolate (SR)-protected Au36Ag2(SR)18 nanocluster with low coverage of ligands and a core composed of three icosahedral (Ih) units for catalyzing HER efficiently. This trimeric structure, together with the monomeric Ih Au25(SR)18- and dimeric Ih Au38(SR)24, constitutes a unique series, providing an opportunity for revealing the correlation between the catalytic properties and the catalyst's structure. The Au36Ag2(SR)18 surprisingly exhibits high catalytic activity at lower overpotentials for HER due to its low ligand-to-metal ratio, low-coordinated Au atoms and unfilled superatomic orbitals. The current density of Au36Ag2(SR)18 at -0.3 V vs RHE is 3.8 and 5.1 times that of Au25(SR)18- and Au38(SR)24, respectively. Density functional theory (DFT) calculations reveal lower hydrogen binding energy and higher electron affinity of Au36Ag2(SR)18 for an energetically feasible HER pathway. Our findings provide a new strategy for constructing highly active catalysts from inert metals by pursuing atomically precise nanoclusters and controlling their geometrical and electronic structures.

Dual-site models were constructed to represent manganese nitride (Mn4N)-supported Ni3 and Fe3 clusters for NH3 synthesis. Density functional theory calculations produced an energy barrier of approximately 0.55 eV for N-N bond activation at the interfacial nitrogen vacancy sites (Nv); also, the hydrogenation and removal of interfacial N is promoted by earth-abundant Ni and Fe metals. Steady-state microkinetic modeling revealed that the turnover frequencies of NH3 production follow an order of Fe3@Mn4N ≈ Ni3@Mn4N > Mn4N > Fe ≫ Ni. Moreover, we present clear evidence that, before NH3 formation, NH migrates from Nv onto the metallic sites. Using N binding energy (BEN) and the transition-state energy of N2 activation (ETS) as descriptors, we concluded that the beneficial effects owing to interfacial Nv sites are the most pronounced when BEN is either too strong or too weak while ETS is high; otherwise, excessive Nv sites may hinder catalyst performance.

Elucidating chemical interactions between catalyst surfaces and adsorbates is crucial for understanding surface chemical reactivity. Herein, interactions between O atoms and Pt surfaces and nanoparticles are described as a linear combination of the properties of pristine surfaces and isolated nanoparticles. The energetics of O chemisorption onto Pt surfaces were described using only two descriptors related to surface geometrical features. The relatively high coefficient of determination and low mean absolute error between the density functional theory-calculated and predicted O binding energies indicate good accuracy of the model. For Pt nanoparticles, O binding is described by the geometrical features and electronic properties of isolated nanoparticles. Using a linear combination of five descriptors and accounting for nanoparticle size effects and adsorption site types, the O binding energy was estimated with a higher accuracy than with conventional single-descriptor models. Finally, these five descriptors were used in a general model that decomposes O binding energetics on Pt surfaces and nanoparticles. Good correlation was achieved between the calculated and predicted O binding energies, and model validation confirmed its accuracy. This is the first model that considers the nanoparticle size effect and all possible adsorption sites on Pt nanoparticles and surfaces.

The building of safe and high energy-density lithium batteries is strongly dependent on the electrochemical performance of working electrolytes, in which ion–solvent interactions play a vital role. Herein, the ion–solvent chemistry is developed from mono-solvent to multi-solvent complexes to probe the solvation structure and the redox stability of practical electrolytes. The decrease in energies of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of solvents in lithium-ion solvation shells becomes less significant as the number of coordinated solvents increases, but both the HOMO and LUMO energies of the coordinated solvents remain lower than those of free solvents. A positive and approximately linear relationship was found between the decrease in the HOMO/LUMO energy and the average binding energy between Li+ and the coordinated solvents. A binary-solvent complex model further highlight the significant importance of the electrolyte solvation environment in regulating electrolyte stability, and it is essential to consider electrolyte stability from the perspective of ion–solvent complexes. These fresh insights into the energy chemistry of multi-solvent complexes provide critical references for electrolyte design and cell optimization.

Co(II), Ni(II) and Cu(II) decxycholate complexes are interesting due to their biologically active and deliberate interest in the research due to their coordination properties. The microanalytical ‘elemental analysis’, molar conductivity, (infrared and Raman) spectroscopy, thermal analyses (TGA/DSC), UV-vis spectra, and ESR for copper(II) decxycholate complex investigations were performed in the structural assignments of Co(II), Ni(II) and Cu(II) decxycholate complexes. Reaction of the sodium deoxycholate ligand (C24H39O4Na) with three transition metal ions form the complexes of formulae, [M(C24H39O4)2(H2O)2]. xH2O where M = Co(II), Ni(II) and Cu(II) where x = 2 for Cu(II) and x = 4 in case of M = Co(II) or Ni(II) metal ions. The FTIR spectra of the complexes show that decxycholate molecule is present as bidentate ligand. Molecular docking utilizing to additionally examine the interaction of COVID-19 (6LU7) with different complexes of deoxycholic acid with Co(II), Ni(II) and Cu(II). Furthermore, in the case of Co(II) deoxycholate complex, the probe is surrounded by amino residues Met235, Pro241, Glu240, Pro108, Gln110, Phe294, and Ile152. The probe molecule of Ni(II) deoxycholate complex is sited close to amino acids Tyr126, Tyr239, Leu287, Leu272, and Lys137. For, Cu(II) deoxycholate complex, the residues of amino acids comprise of Pro132, Pro108, Gln110, Gly109, Ile200, Asn203, Val202, His246, Pro293 and Tyr154. The binding energy was determined from the docking reads for Co(II)–6LU7, Ni(II)–6LU7 and Cu(II)–6LU7 deoxycholate compounds were found to be −446.99, −500.52, −398.13 kcal mol−1 individually.

In this work we have carried out extensive Density Functional Theory (DFT) and ab-initio Molecular Dynamics (AIMD) simulations to study the structural and electronic properties, thermal stability, and the adsorption/desorption processes of hydrogen H2 molecules on Lithium (Li) functionalized one-dimensional boron phosphide nanotubes (BPNTs), for possible use as materials of H2-storage media. Our results show that Li atoms can be adsorbed on the hollow sites of (7,7)-BPNT with binding energy ranging from 1.69 eV, for one Li, to 1.65 eV/Li for 14 Li atoms adsorbed on (7,7)-BPNT. These large energies of Li prevent the formation of clusters on the nanotube sidewall. The investigation of the electronic behavior showed that (7.7)-BPNT semiconductor turns metallic upon the Li-adsorption. Furthermore, the average binding energy of H2-molecules adsorbed on nLi@BPNT(mH2) systems (with n = 1, 2, 4, 6, 8, 14 and m = 1, 2, 3, 4, with m the number of H2 for each Li) lies within a range of 0.13–0.20 eV/H2 which is compatible to the required range for adsorption/desorption of H2-molecules at room conditions. A H2-storage gravimetric capacity up to 4.63% was found for 14Li@BPNT(4H2) system. In addition, AIMD simulation strongly indicates that given adequate monitoring of the temperature, the charge/release process of H2-molecules can be controlled. Our findings suggest that Li-functionalized (7,7) boron phosphide nanotubes can provide a valuable underlying material for H2-storage technologies and therefore must certainly be the subject of further experimental exploration.

The development of efficient photoelectrodes via defect engineering of wide-band gap metal oxides has been the prime focus for many years. Specifically, the effect of carbon defects in wide-band gap metal oxides on their performance in photoelectrochemical (PEC) applications raised numerous controversies and still elusive. Herein, the effect of various carbon defects in m-ZrO2 was investigated using the density functional theory to probe the thermodynamic, electronic, and optical properties of the defective structures against pristine m-ZrO2. The defect formation energies revealed that elevating the temperature promotes and facilitates the formation of carbon defects. Moreover, the binding energies confirmed the stability of all studied complex carbon defects. Furthermore, the band edge positions against the redox potentials of water species revealed that all the studied defective structures can serve as photoanodes for water splitting. Additionally, CO3c (carbon atom substituted O3c site) was the only defective structure that exhibited slight straddling of the redox potentials of water. Importantly, all investigated defective structures enhanced light absorption with different optical activities. It is worth mentioning that our results showed exceptional reduction in the bandgap energy compared to those reported experimentally for ZrO2-based materials. Finally, CO3cVO3c (carbon atom substituted O3c associated with O3c vacancy) defective m-ZrO2 enjoyed lowest sub-bandgap (1.9 eV), low defect formation energy, low exciton binding energy, high mobility of charge carriers, fast charge transfer, and low recombination rate. Concurrently, its optical properties were exceptional in terms of high absorption, low reflectivity and improved static dielectric constant. Hence, the study recommends CO3cVO3c defective m-ZrO2 as the leading candidate to serve as a photoanode for PEC applications.

The chlorine (Cl2) drying technology using ionic liquids (ILs) as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level. The hygroscopic IL [EMIM][CH3SO3] was screened as a suitable absorbent from 238 potential IL candidates consisting of 14 cations and 17 anions, by calculating the Cl2 and H2O solubility and separation selectivity of Cl2 to H2O in different ILs based on the COSMO-RS model. The microscopic atomic and molecular insights into the separation mechanisms were deeply revealed by using COSMO-RS model analyses (i.e., σ-profiles, σ-potentials, excess enthalpies, entropies, and Gibbs free energies) and quantum chemistry calculation (binding energies and weak interaction analyses). The Cl2 solubility in pure IL and H2O + IL systems were predicted by the COSMO-RS model, and the results agree with the microscopic mechanism identification. Moreover, the strict equilibrium stage model employed with the COSMO-RS model parameters was built to perform the process simulation, and continuous Cl2 drying with ILs was conceptually designed and optimized at industrial scale. It was confirmed that [EMIM][CH3SO3] is a very promising absorbent leading to a less IL amount, a much lower energy consumption than the other IL [EMIM][BF4], which has a very bright industrialization potential used for Cl2 drying technology.

Efficient storage of hydrogen is one serious impediment in using H2 as an alternate clean fuel, at a larger scale, in the context of alarming levels of global warming and fast depleting fossil fuel resources. Metal nitrides such as Li2N4, Na2N4 and K2N4 using density functional theory with PBE1PBE and B3LYP functional and 6-31G (d,p), 6–31 ++ G (d,p) and 6–311 ++ G (d,p) as basis sets. This has revealed that doping of alkali metal atoms on the nitride systems increases their hydrogen adsorption ability, due to the electron transfer that occurs from the metal atom to the nitrogen surface. The charged surface created around the metal atom is found to enhance the hydrogen adsorption capacity of the complex from 9 to 16.79wt% with an average binding energy from 0.06 to 0.30 eV/H2. Various conceptual reactivity descriptors, bond parameters, Gibbs free energy change (ΔG) and energy gap values support the idea that the stability of the complex increases on hydrogen uptake. Efficient storage of hydrogen is one serious impediment in using H2 as an alternate clean fuel, at large scale, in the context of alarming levels of global warming and fast depleting fossil fuel resources. Herein, we report theoretical studies on some novel metal nitrides in order to probe its hydrogen storage potential. M2N4 systems (where M = Li, Na, K) can store hydrogen around 5–12 H2 molecules with an gravimetric density of 9–16.79 wt% and an average binding energy in the range of 0.06–0.30 eV/H2. It was found that among all the three metal nitrides Li2N4 is found to possess highest binding energy and energy gap, whereas K2N4 adsorbs maximum number of H2 molecules.

A thermoneutral binding energy has been considered to yield maximum catalytic activity for decades. However, recent theoretical studies have challenged this criteria, because thermoneutrality only ...

In a quest to mitigate the undesirable shuttling effect that hampers the performance of Li-S batteries, we adopted first-principles calculations to study the anchoring mechanism of lithium polysulfides on antimonene phases, i.e., alpha-Sb and beta-Sb. The anchoring mechanisms of LiPSs on alpha-Sb and beta-Sb were studied through calculations of binding energy, charge transfer, and vertical binding distances from the monolayer to LiPSs. The results indicated that pristine alpha-Sb and beta-Sb showed significant physisorption/chemisorption interactions toward LiPSs due to the considerable E-b, values (0.71-1.68 and 0.96-2.07 eV, respectively). Meanwhile, with single Sb vacancy, the binding strength was enhanced (0.83-2.91 eV) for the beta-Sb monolayer. Furthermore, we substituted the Sb atom with the Sn/Te atom and found stronger E-b (1.32 5.69 and 0.45-4.81 eV). All these bindings of LiPSs were much stronger than their interactions with those of electrolytes (DME/DOL) (E-b values: 0.20-1.16 and 0.17-1.07 eV). Also, we investigated the redistribution of electrons and the influence of electronic states near the Fermi level in DOS for LiPSs on alpha-Sb and beta-Sb. Our findings suggest that pristine and defected beta-Sb monolayers could be an excellent anchoring material for Li-S batteries.

Chemical state analysis in X-ray photoelectron spectroscopy (XPS) relies on assigning well-defined binding energy values to core level electrons originating from atoms in particular bonding configurations. Here, we present direct evidence for the violation of this paradigm. It is shown that the C 1s peak due to C-C/C-H bonded atoms from adventitious carbon (AdC) layers accumulating on Al and Au foils splits into two distinctly different contributions, as a result of vacuum level alignment at the AdC/foil interface. The phenomenon is observed while simultaneously recording the spectrum from two metal foils in electric contact with each other. This finding exposes fundamental problems with the reliability of reported XPS data as C 1s peak of AdC is routinely used for binding energy scale referencing. The use of adventitious carbon in XPS should thus be discontinued as it leads to nonsense results. Consequently, ISO and ASTM charge referencing guides need to be rewritten. Funding Agencies|Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [KAW2016.0358]; Swedish Research Council VR Grant [2018-03957]; Swedish Energy AgencySwedish Energy Agency [51201-1]; VINNOVAVinnova [2019-04882]; Carl Tryggers Stiftelse [CTS 17:166, CTS 15:219, CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

The performance of lithium-sulfur batteries is deteriorated by the inferior conductivity of sulfur, the shuttle effect of lithium polysulfides (LiPSs), sluggish redox kinetics of polysulfide intermediates and serious volumetric expansion of sulfur. To overcome these challenges, we report a versatile route to prepare multi-functional nanocomposites with tuable hierarchical structure via ammonium hydroxide (NH3·H2O) induced self-assembly. The versatility of the system has been demonstrated that the organization of the hierarchical structure can be regulated by adding different amounts of NH3·H2O, and WS2 and Co9S8 with nitrogen-doped carbon coating (denoted as WS2@NC and Co9S8@NC) can be prepared by adding different precursor salts. When the as-prepared materials are applied for Li-S batteries, the WS2@NC composite exhibits a reversible capacity of 1107.4 mAh g−1 at 0.1C after 500 cycles and even 728.9 mAh g−1 at 2C for 1000 cycles, which is significantly better than the Co9S8 counterpart and other reported WS2 sulfur hosts. Experimentally, the advantageous performance of WS2 could be attributed to its higher surface area and total pore volume, giving rise to the easier access to electrolyte and better ability to buffer the volume change during the charge/discharge process. Theoretically, the density function theory (DFT) calculation reveals that the as-prepared WS2 has a higher binding energy towards LiPSs as well as a lower energy barrier for Li+ diffusion on the surface than Co9S8. More significantly, the density of states (DOS) analysis further confirms that the superior performance is mainly ascribed to the more prominent shifting and the more charge compensation from d band of W than Co, which increase electronic concentration and give more hybridization of d-p orbitals in the Fermi level of the adsorbed Li2S4 to accelerate the lithium polysulfide interfacial redox and conversion dynamics in WS2. By proposing this mechanism, this work sheds new light on the understanding of catalytic conversion of lithium polysulfides at the atomic level and the strategy to develop advanced cathode materials for high-performance lithium-sulfur batteries.

In the current study, by employing first-principles computations, the adsorption behavior of letrozole (LET) was investigated on the pristine graphdiyne nanosheet (GDY) as well as Si-doped graphdiyne (SiGDY). According to the adsorption energy, charge transfer value, and the change in the bang gap energy, the tendency of the pristine GDY towards LET is insignificant. However, the interaction of LET with SiGDY was strong and the adsorption energy was approximately − 19.20 kcal/mol. In addition, the associated electrical conductivity with SiGDY increased by approximately 23.53 % following the adsorption of LET. The results show that SiGDY can be employed as an electronic sensor to detect LET. Furthermore, LET is detected by SiGDY in the water phase based on the magnitude of solvation energy. Finally, a considerable charge-transfer between LET and SiGDY is a precondition for the adsorption of the LET molecule with proper binding energies, which delivers the Si atoms with a significant positive charge.

The hydrogen binding efficiency of multiple metal-ion (Be2+, Mg2+)-decorated “First Generation” Sulflower (C16S8) systems has been investigated for the first time using density functional ω-B97XD method and 6311++G(d,p) basis set. Our calculations show that the central ring of the aforesaid system can be decorated by a single di-positive metal ion, followed by favorable decoration of at most one pair of metal ions (di-positive each) on the peripheral five-membered rings, both on same and opposite faces with certain preferences. All of the metal ion-decorated complexes are capable of efficient hydrogen binding. Be2+ and Mg2+-decked single ion complexes effectively bind six and four H2 molecules respectively. Moreover, each of the double ion-decorated systems can adsorb ten H2 molecules irrespective of the facial orientation of the metal ions. The average interaction energy (ΔE) between sulflower and metal ions (single and double ions) as well as the average binding energy (ΔBE) per molecular hydrogen of the concerned metal-ion-decorated complexes is found to be much higher for Be2+-decked systems. The nature of interaction between hydrogen molecules and metal ions is explicated by the topological analysis (AIM Analysis) and NBO formalisms. In case of Be2+-decked systems, the amount of charge transfer from H2 bonding orbital to metal anti-bonding orbital is much higher than analogous Mg2+-decorated systems. The Natural Population Analysis (NPA) evaluates the charge variation on the acceptor metal ions due to hydrogen adsorption. In short, our theoretical study gives a comprehensive account of the relationship between the metal ion-decorated sulflower systems and hydrogen molecules, which will further motivate researchers in the field of efficient hydrogen storage materials.

High-purity fused silica has been implanted with 60-keV helium ions at the fluence of 1.5·1017 cm–2. The effects of helium-ion implantation on optical properties of silica samples before and after helium implantation have been investigated by infrared (IR), photoluminescence (PL), and ultraviolet-visible (UV-vis) spectrophotometer. After helium-ion implantation, X-ray photoelectron spectroscopy (XPS) results indicate that Si 2p peak is shifted to higher binding energy. An obvious PL band at 500 nm is observed, and the PL intensity is significantly decreased. However, the intensity of IR and optical absorption is increased greatly by ion implantation. A mechanism for the effects of helium implantation on optical properties of fused silica is discussed.

Silicon purification with Al–Si solvent refining is a potential method to obtain solar grade silicon (SoG-Si). Hydrogen is a helpful element to enhance the removal of impurity boron during the Al–Si solvent refining. However, the interaction mechanism between hydrogen and boron is not very clear. In this paper, the ab initio calculation method, which is based on the density functional theory (DFT), was adopted to further understand the interaction behavior of hydrogen and boron. The structure properties, bonding energy, energy band structure and density of states (DOS) of BH2, BH3, B2H6, SiH4 and AlH3 were calculated and analyzed using the CASTEP module in Materials Studio. The results show that BH2 has the feature of semiconductor, while BH3, B2H6, SiH4 and AlH3 belong to insulator. Additionally, the order of binding energy for hydrides from large to small is B2H6, BH3, SiH4, BH2 and AlH3, indicating that B2H6 is the most stable compounds among the hydrides. The DOS and partial density of states (PDOS) analysis show that the valence band of B2H6 contains four parts, which are contributed by H-1s and B-2s states, H-1s, B-2s and B-2p states, H-1s and B-2p states, H-1s and B-2p states, respectively. To verify the calculation results, an experiment and a thermodynamic analysis were carried out, and both of them proved that the calculation results agree well with the experimental results.