Systematic DFT Calculations Research Articles

Facile one-pot synthesis of Co3Mo3N-loaded inside hierarchical porous bead-on-string as cathode host material for high-performance lithium-sulfur batteries

A critical factor impeding the development of lithium-sulfur batteries is the deleterious shuttle effect. To address the issue, we devise a facile electrospinning approach to integrate catalysts and hierarchically porous structures into bead-on-string carbon host material as the host material. Compared to the traditional preparation of hierarchical porous structures, the upgraded electrospinning eliminates the need for etching templates, providing a larger specific surface area (333.39 m2 g−1) and tremendous potential for large-scale production. The cathode utilizing bead-on-string Co3Mo3N as host material exhibits a remarkable capacity of 1257 mAh g−1 at 0.2 C and maintains a capacity retention rate of 90 % after 100 cycles. Even at 4.0 C, the capacity remains at 648 mAh g−1 with minimal capacity loss. Under harsh conditions (including high sulfur loading, high areal loading, and lean electrolyte), the composite cathode consistently delivers a capacity of 8 mAh cm−2. Simultaneously, systematic electrochemical testing, in-situ assessments, and DFT calculations unveil the dual-metal synergistic effects of Co3Mo3N in suppressing the shuttle effect and catalyzing the conversion of lithium polysulfides. Co3Mo3N provides chemical adsorption to significantly promote the reaction kinetics of polysulfides. This work establishes a neoteric technique and a theoretical strategy for exploring the catalytic efficacy of dual-metal nitrides for Li-S batteries.

Revealing operando surface defect–dependent electrocatalytic performance of Pt at the subparticle level

Understanding the operando defect-tuning performance of catalysts is critical to establish an accurate structure-activity relationship of a catalyst. Here, with the tool of single-molecule super-resolution fluorescence microscopy, by imaging intermediate CO formation/oxidation during the methanol oxidation reaction process on individual defective Pt nanotubes, we reveal that the fresh Pt ends with more defects are more active and anti-CO poisoning than fresh center areas with less defects, while such difference could be reversed after catalysis-induced step-by-step creation of more defects on the Pt surface. Further experimental results reveal an operando volcano relationship between the catalytic performance (activity and anti-CO ability) and the fine-tuned defect density. Systematic DFT calculations indicate that such an operando volcano relationship could be attributed to the defect-dependent transition state free energy and the accelerated surface reconstructing of defects or Pt-atom moving driven by the adsorption of the CO intermediate. These insights deepen our understanding to the operando defect-driven catalysis at single-molecule and subparticle level, which is able to help the design of highly efficient defect-based catalysts.

Molecular geochemistry of radium: A key to understanding cation adsorption reaction on clay minerals

Adsorption reactions of various cations on clay minerals have different effects on their environmental behaviors depending on the molecular-scale adsorption structure. Some cations form outer-sphere complexes via hydration, while others create inner-sphere complexes through dehydration. This preference dictates their environmental impact. However, the factors controlling these complex formations remain unclear. Furthermore, research on the adsorption preferences of radium (Ra) is lacking. Thus, this study conducted the first EXAFS study of Ra2+ adsorbed on clay minerals and showed that Ra2+ forms inner-sphere complexes on vermiculite, which can be surprising because Ra2+ is a divalent cation and prefers to be hydrated. In order to investigate the factors controlling the complex formations, this study conducted systematic EXAFS measurements and DFT calculations for alkali and alkaline earth metal cations. The results showed the importance of the size-matching effect between the adsorbed cation and the cavity of the tetrahedral sheets and that the complex formation can be estimated by the combination of the ionic radius and hydration enthalpy of the adsorbed cation. Furthermore, this study also analyzed environmental core samples. Their results showed the fixation of Ra2+ by clay minerals and the controlling factors can effectively predict cation environmental behavior.

Synergistically activating nucleophile strategy enabled organocatalytic asymmetric P-addition of cyclic imines.

Herein, we present an attractive organocatalytic asymmetric addition of P-nucleophiles to five-membered cyclic N-sulfonyl imines facilitated by phosphonium salt catalysis, enabling the highly enantioselective synthesis of tri- and tetra-substituted cyclic phosphorus-containing benzosultams. With this protocol, various cyclic α-aminophosphonates were efficiently synthesized with high yields and exceptional enantioselectivities (up to >99% ee) under mild reaction conditions. The utility and practicality of this method were demonstrated through gram-scale reactions and straightforward elaborations. Notably, the success of this approach relies on the deliberate selection of a synergistic organocatalytic system, which helps circumvent foreseeable side effects while handling secondary phosphine oxides (SPOs). Systematic mechanistic studies, incorporating experiments and DFT calculations, have revealed the critical importance of judiciously selecting bifunctional phosphonium salt catalysts for effectively activating P-nucleophiles while stereoselectively controlling the P-attack process.

Constructing fast charge separation of ZnIn2S4 @CuCo2S4 p-n heterojunction for efficient photocatalytic hydrogen energy recovery from quinolone antibiotic wastewater

Dual-functional catalysts can realize effective photocatalysis for synergistic water remediation and H2 production by coupling reduction and oxidation reaction in one water-pollutant system. In this work, a novel ZnIn2S4 @CuCo2S4 nanoflower-like p-n heterojunction catalyst was successfully synthesized by a simple method and used for hydrogen generation from quinolone antibiotic wastewater. ZnIn2S4 @CuCo2S4 exhibited high hydrogen production activity of 0.36 mmol·g−1·h−1 in ofloxacin (OFL) solution. Simultaneously, the OFL removal efficiency and mineralization rate were up to 89.4 % and 92.24 %, respectively. The interface charge transfer mechanism was thoroughly investigated through systematic characterizations and DFT calculations. The results show that CuCo2S4 addition significantly improved the separation and transfer rate of photoinduced carriers. Additionally, the possible degradation pathways of OFL were analyzed using LC-MS. This study provides a new approach for simultaneous energy conversion and environmental pollution treatment, offering a new pathway for achieving sustainable energy development through the management of antibiotic wastewater.

Combined DFT and Machine Learning Study of the Dissociation and Migration of H in Pyrrole Derivatives.

Systematic DFT calculations of model coal-pyrrole derivatives substituted by different functional groups are carried out. The N-H bond dissociation energies (N-H BDEs) and H-transfer activation energies (H-TAEs) of pyrrole derivatives are fully evaluated to elucidate the effect of the type of substituents and their position on the molecular reactivity. The results indicate that compounds substituted with electron-donating groups (EDGs) are more prone to pyrolysis while those substituted with electron-withdrawing groups (EWGs) are difficult to pyrolyze. Furthermore, quantitative structure-property relationship (QSPR) models for N-H BDEs and H-TAEs about pyrrole derivatives are built with multiple linear regression (MLR) and support vector machine (SVM). The final results show that the SVM-QSPR model has better fitness, prediction, and robustness, while the MLR-QSPR model can express the physical meaning better. The effects of functional groups on pyrolysis are clarified by the models presented in this paper, which will support the optimization of ultra-low NOx combustion.

Strong Electronic Metal–Support Interaction Augments Hydrogen Evolution over hcp-Ni/In2O3 with Ultrasound-Assisting Dehydrogenation of Ammonia Borane

Rational design of highly efficient catalysts for the dehydrogenation of ammonia borane (AB) to produce hydrogen is still challenging. The size and shape effects of catalysts on the performance have been well documented in the past decades. Nevertheless, there is still much space for study on the crystal structure-dependent catalytic performance. Herein, In2O3-supported hexagonal-close-packed (hcp) Ni (hcp-Ni/In2O3) has been prepared via impregnation of corresponding nanoparticles onto In2O3. The stronger electronic metal–support interaction in hcp-Ni/In2O3 than in fcc-Ni/In2O3 endows it with high capacity to activate AB molecules. It exhibits excellent hydrogen evolution activity from catalytic dehydrogenation of AB with a rate of 7.5 molH2 mol–1Ni min–1, which is 1.7 times that of the supported fcc sample. The systematic experiments and DFT calculations demonstrate that the hcp catalyst possesses stronger hydrophilicity and lower activation energy for the dissociation of H2O than the fcc counterpart. Moreover, the assistance with sonication enhances the process of mass and heat transfer and accelerates the reaction. This work provides a new way for the achievement of efficient metastable catalytic systems and promotes the construction of advanced devices toward various applications.

Modulation of the morphology and electronic structure of Ni3S2 nano-forests via P and Mo co-doping in polyoxometalates to promote the urea oxidation reaction

The P–Mo–Ni3S2@NF electrode with nanoforest morphology is synthesized and analyzed by systematic experiments and DFT calculations, which shows superior electrocatalytic activity toward the urea oxidation reaction.

Fluorescent styryl pyridine-N-oxide probes for imaging lipid droplets.

Lipid droplets (LDs) have emerged as major regulators of cellular metabolism, encompassing lipid storage, membrane synthesis, viral replication, and protein degradation. Exclusive studies have suggested a direct link between LDs and cancer, as a notable abundance of LDs is found in cancerous cells. Therefore, monitoring the location, distribution, and movements of LDs is of paramount importance for understanding their involvement in biological processes. To target LDs, we designed and synthesized fluorophores with a styryl scaffold bearing electron-donating amino groups and pyridine-N-oxide, a zwitterionic acceptor moiety. We explored their photophysical properties in various solvents and conducted systematic DFT calculations on the synthesized fluorescent molecules, comparing them with neutral pyridine and cationic pyridinium styryl dyes. The results demonstrate that diphenylaminostyryl pyridine-N-oxide (TNO) shows excellent imaging of LDs, in contrast to the behavior of cationic styrylpyridinium (TNC), which primarily localizes within the mitochondria. Notably, pyridine N-oxide offers several benefits: an increased dipole moment facilitating charge separation between donors and acceptors, substantial HOMO and LUMO stabilization, improved water solubility, favorable redox properties, and bathochromic-shifted absorption/emission spectra, showing promise as a fluorescent tool for probing the cellular-biological realm.

Effects of oxygen functionalities on hydrous hydrazine decomposition over carbonaceous materials.

Metal-free heterogeneous catalysis is promising in the context of H2 generation. Therefore, establishing structure-activity relationships is a crucial issue to improve the development of more efficient catalysts. Herein, to evaluate the reactivity of the oxygen functionalities in carbonaceous materials, commercial functionalized pyrolytically stripped carbon nanofibers (CNFs) were used as catalysts in the liquid-phase hydrous hydrazine decomposition process and its activity was compared to that of a pristine CNF material. Different oxygenated groups were inserted by treating CNFs with hydrogen peroxide for 1 h (O1-H2O2) and HNO3 for 1 h (O1-HNO3) and 6 h (O6-HNO3). An increase in activity was observed as a function of the oxidizing agent strength (HNO3 > H2O2) and the functionalization time (6 h > 1 h). A thorough characterization of the catalysts demonstrated that the activity could be directly correlated with the oxygen content (O6-HNO3 > O1-HNO3 > O1-H2O2 > CNFs) and pointed out the active sites for the reaction at carbon-oxygen double bond groups (CO and COOH). Systematic DFT calculations supported rationalization of the experimental kinetic trends with respect to each oxygen group (CO, C-O-C, C-OH and COOH).

A one-photon excitation pathway in 0D/3D CoS2/ZnIn2S4 composite with nanoparticles on micro-flowers structure for boosted visible-light-driven photocatalytic hydrogen evolution

Converting solar energy into hydrogen production is a promising approach to tackle the energy crisis. However, developing excellent photocatalytic materials with properties of positive visible light response, high efficiency and photostability remain a great challenge. Herein, we developed a one-photon excitation path system by coupling 3D ZnIn2S4 micro-flowers with 0D CoS2 nanoparticles for hydrogen evolution, with an optimal hydrogen evolution rate of 22.24 mmol h−1 g−1. The systematic characterizations and DFT calculations disclose that the improved performance is ascribed to the construction of 0D/3D with multi-reflection and exposed reaction sites, as well as the incorporation of CoS2 and ZIS via a one-photon excitation pathway, achieving the acceleration of photoinduced charge separation and transfer. This work shed light on the design of 0D/3D photocatalysts with high hydrogen evolution performance via a one-photon excitation pathway.

1H NMR spectral analysis of structural features in a series of paramagnetic homoleptic binuclear triple-decker phthalocyaninato lanthanide complexes

The search for efficient methods of comparative structural investigations of coordination compounds in solid state and solutions is a very relevant task. In this study, structural assignments in a series of Ln2[(15C5)4Pc]3 complexes (where [(15C5)4Pc]2- is 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninato-dianion, Ln = Nd3+, Tb3+, Dy3+, Ho3+, Er3+ and Tm3+) was performed using NMR relaxation and paramagnetic lanthanide-induced shifts (LIS) data. Analysis of the paramagnetic chemical shifts and relaxation rates evidenced of isostructurality of the complete series of the investigated triple-decker complexes in the solutions. The performed systematic DFT calculations for a series of model complexes with methoxy-substituted ligands Ln2[(MeO)8Pc]3 demonstrate that the calculated geometrical factors are in agreement with characteristics extracted from experimental NMR data.

Accurate first-principles evaluation of structural, electronic, optical and photocatalytic properties of BaHfO3 and SrHfO3 perovskites

A reliable first-principles account of experimentally observed physical properties of perovskite oxides is crucial for realizing their employment in electronic and optical devices. In this context, SCAN meta-GGA functional of DFT offers good approximation for the exchange-correlation energy; facilitating accurate determination of structural and energetic properties. However, SCAN is unable to reproduce electronic and optical properties of wide bad gap materials. In the present study, we report systematic DFT calculations to show that structural, energetic, electronic and optical properties of hafnium based BaHfO3 and SrHfO3 perovskite oxides can be accurately determined through a combine application of SCAN and Tran-Blaha modified Becke-Johnson (TB-mBJ) meta-GGAs. The structural and energetic properties computed using SCAN functional for both BaHfO3 and SrHfO3 are found to be in good agreement with experimental data; achieving a level of accuracy comparable to computationally expansive hybrid DFT calculations. On the other hand, TB-mBJ calculated band gaps computed using the SCAN optimized lattice parameters provide better agreement with experimental data at a low computational cost. The optical properties, band edge potentials and effective masses of the charge carriers in BaHfO3 and SrHfO3 are also computed to examine the combined application of SCAN and TB-mBJ meta-GGAs in predicting the photocatalytic performance of these wide band gap materials. Our results clearly show that the combination of the two meta-GGAs provide a computationally economical route for evaluating the photocatalytic performance of alkaline-earth metal hafnates.

Basic physical behavior of impurity carbon in molybdenum for nuclear material: A systematical first-principles simulation

• Systematic DFT calculations for basic physical behavior of impurity carbon in Mo. • Defect vacancy can easily capture impurity carbon atoms to form C n V clusters. • The concentration distributions of impurity carbon and C n V clusters are calculated. • Synergistic diffusion effect between impurity carbon and C n V clusters. Based on first-principles simulations, we have systematically studied physical behavior of impurity carbon in molybdenum. A single carbon atom is preferable to occupy the octahedral interstitial position (oip) rather than the tetrahedral interstitial position (tip) in molybdenum. Two carbon atoms are inclined to bind each other at two neighbor oips along the 〈2 1 0〉 direction. A mono-vacancy captures up to four carbon atoms to form C n V ( n = 1–4) clusters. The C 2 V cluster is the most stable cluster owing to its most favourable capturing energy of −1.71 eV. The vacancy concentration in the form of C n V clusters dramatically raises owing to powerfully exothermic reactions of C n V clusters, in according with the experimental results. The diffusion activation energy of carbon/vacancy are 1.22/1.17 eV, agreeing with the experimental value of 1.20/1.35 eV. The C n V formations are ascribed to vacancy capturing mechanism. The C n V clusters are nearly immobile at lower temperature regime. When the temperature achieves a critical point ~1700 K, carbon atoms and vacancy are separating from C n V cluster to produce the isolated interstitial carbon atoms and an individual vacancy, respectively. All C n V clusters do not exist anymore when the temperature exceeds ~1700 K. These C n V clusters do not nearly have the effect on interstitial carbon diffusion.

Mechanistic Insights into the Dual Directing Group-Mediated C-H Functionalization/Annulation via a Hydroxyl Group-Assisted MIII-MV-MIII Pathway.

The experimental investigations on the catalyst [Cp*Rh(OAc)2 and Cp*Ir (OAc)2)]-controlled [3 + 2] and [4 + 2] annulations of oximes with propargyl alcohols have been finished in our previous work and a supposed dual directing group-mediated reaction pathway has been deduced for the chemodivergent product synthesis. However, the detailed interaction modes of the dual directing groups binding with the corresponding metal center to achieve the above observed chemoselectivity remain unclear and even contradict. For instance, the calculational traditional dual direct coupling transition states suggested that both Cp*Rh(OAc)2- and Cp*Ir(OAc)2-catalyzed reactions would generate five-membered indenamines as the dominant products via [3 + 2] annulation. To address this concern, herein, systematic DFT calculations combined with proof-of-concept experiments have been carried out. Accordingly, a novel and more favorable MIII-MV-MIII reaction mechanism, which involves an unprecedented HOAc together with a hydroxyl group-assisted reaction pathway in which the hydroxyl group acts as double effectors for the formation of M–O coordination and [MeO···H···O(CCH3)O···H···O] bonding interactions, was deduced. Taken together, the present results would provide a rational basis for future development of the dual directing group-mediated C–H activation reactions.

Strengthening in Al-, Mo- or Ti-doped CoCrFeNi high entropy alloys: A parallel comparison

• Provided opportunities to identify the sole compositional effects on the strengthening of cocrfeni alloy. • Mo provides more pronounced solid solution strengthening than al and Ti. • Al and ti are more effective than mo in increasing grain boundary strengthening. • The labusch parameter f was quantified and a close SFE- k HP relation was observed. • Current findings present significant values toward novel alloy design. In the current work, a parallel comparison of the influence of Al, Mo and Ti, on the microstructure and strengthening of the CoCrFeNi alloy was conducted. To achieve this, inconsistencies on variables including the extent of alloying, thermomechanical processing and property-evaluation method were avoided. Microstructurally, following cold-rolling, annealing of the 4 at.% Al-doped alloys at 800–1000 °C did not result in phase separation; nevertheless, that of the 4 at.% Mo- and Ti-doped alloys led to the respective formation of σ and η phase and, consequently, caused extra strengthening through the Orowan dislocation bypassing mechanism. Our systematic qualitative analysis and DFT calculations showed that Al and Ti are more effective than Mo in reducing the stacking fault energy (SFE) of the CoCrFeNi alloy, because they can induce more considerable deformation of electronic density, making the gliding of atomic layers easier. Following identical thermomechnical processing, Al-, Mo-, and Ti-doping causes different extent of solid solution strengthening and grain boundary strengthening. Mo causes the most pronounced solid solution strengthening but does not benefit the grain boundary strengthening; in contrast, the effectiveness of grain boundary strengthening is boosted by the doping Al and Ti. Current analyses support that Labusch instead of Fleischer mechanism is applicable to explain the differences in solid solution strengthening, and the observed differences in grain boundary strengthening arise from the different tendency of Al, Mo and Ti to reduce the SFE of CoCrFeNi. In addition, we determined the value of the dimensionless parameter f in the Labusch model for CoCrFeNi-based alloys and observed a close relation between Hall-Petch slope and SFE. Although more in-depth studies are needed to provide full and mechanistic understandings, both these findings in fact presents significant values toward designing novel single-phase high-strength CoCrFeNi-based alloys through manipulating the solid solution and grain boundary strengthening by compositional tuning.

Regiospecific and Enantioselective Arylvinylcarbene Insertion of a C-H Bond of Aniline Derivatives Enabled by a Rh(I)-Diene Catalyst.

Asymmetric insertion of an arylvinylcarbenoid into the C-H bond for direct enantioselective C(sp2)-H functionalization of aniline derivatives catalyzed by a rhodium(I)-diene complex was developed for the first time. The reaction occurred exclusively at the uncommon vinyl terminus site with excellent E selectivity and enantioselectivities, providing various chiral γ,γ-gem-diarylsubstituted α,β-unsaturated esters with broad functional group compatibility under simple and mild conditions. It provides a rare example of the asymmetric C-H insertion of arenes with selective vinylogous reactivity. Synthesis applications of this protocol were featured by several versatile product transformations. Systematic DFT calculations were also performed to elucidate the reaction mechanism and origin of the uncommon enantio- and regioselectivity of the Rh(I)-catalyzed C(sp2)-H functionalization reaction. The measured and computed inverse deuterium kinetic isotope effect supports the C-C bond-formation step as the rate-determining step. Attractive interactions between the chiral ligand and substrates were also proposed to control the enantioselectivity.

Role of C-Defective Sites in CO Adsorption over ϵ-Fe2 C and η-Fe2 C Fischer-Tropsch Catalysts.

Herein, we report the crucial importance of C-defective sites on the CO adsorption over ϵ-Fe2 C and η-Fe2 C Fischer-Tropsch catalysts via systematic DFT calculations. The simulated XRD and Wulff construction show the significant differences in their equilibrium shapes and most exposed surfaces. It is observed that the ϵ-Fe2 C exposes a high proportion (89 %) of facets (1 1) with similar structure to that of η-Fe2 C (011) which has been proved to be the active surface of CO activation.

Cooperative bonding interactions of various oxygen species on the IB group metal anions

Series of MOx− (M = Cu, Ag, and Au; x = 1–3) complexes and one solitary kind of AgO5− were generated using a magnetron sputter cluster source, and their reactions with additional O2 were studied by combining a low temperature flow reactor and a time-of-flight mass spectrometer. The structures and bonding characters of these complexes were explored according to the observed reaction channels and systematic DFT calculations, in which OAgO−, OAg(η1-O2)−, and (η1-O3)Ag (η1-O2)− were newly observed complexes. The structure (η1-O3)Ag (η1-O2)− was further confirmed using the molecule tagging infrared photodissociation spectroscopy. The theoretical binding energies of oxygen species in MOx− (M = Cu, Ag, and Au; x = 1–3, and 5) are consistent with the experimental observations, which clearly show a cooperative effect of bonding interactions of various oxygen species on the Cu, Ag and Au anions. The contributions of (n-1)d, ns, and np components of the IB metals to their bonding interactions were discussed, which account for the above cooperative effect as well as the much stronger Cu–O bonds than corresponding Ag–O and Au–O bonds in MOx−.

Synthesis, anticancer activity, and molecular modeling of 1,4-naphthoquinones that inhibit MKK7 and Cdc25

Cell division cycle 25 (Cdc25) and mitogen-activated protein kinase kinase 7 (MKK7) are enzymes involved in intracellular signaling but can also contribute to tumorigenesis. We synthesized and characterized the biological activity of 1,4-naphthoquinones structurally similar to reported Cdc25 and(or) MKK7 inhibitors with anticancer activity. Compound 7 (3-[(1,4-dioxonaphthalen-2-yl)sulfanyl]propanoic acid) exhibited high binding affinity for MKK7 (Kd = 230 nM), which was greater than the affinity of NSC 95397 (Kd = 1.1 μM). Although plumbagin had a lower binding affinity for MKK7, this compound and sulfur-containing derivatives 4 and 6–8 were potent inhibitors of Cdc25A and Cdc25B. Derivative 22e containing a phenylamino side chain was selective for MKK7 versus MKK4 and Cdc25 A/B, and its isomer 22f was a selective inhibitor of Cdc25 A/B. Docking studies performed on several naphthoquinones highlighted interesting aspects concerning the molecule orientation and hydrogen bonding interactions, which could help to explain the activity of the compounds toward MKK7 and Cdc25B. The most potent naphthoquinone-based inhibitors of MKK7 and/or Cdc25 A/B were also screened for their cytotoxicity against nine cancer cell lines and primary human mononuclear cells, and a correlation was found between Cdc25 A/B inhibitory activity and cytotoxicity of the compounds. Quantum chemical calculations using BP86 and ωB97X-D3 functionals were performed on 20 naphthoquinone derivatives to obtain a set of molecular electronic properties and to correlate these properties with cytotoxic activities. Systematic theoretical DFT calculations with subsequent correlation analysis indicated that energy of the lowest unoccupied molecular orbital E(LUMO), vertical electron affinity (VEA), and reactivity index ω of these molecules were important characteristics related to their cytotoxicity. The reactivity index ω was also a key characteristic related to Cdc25 A/B phosphatase inhibitory activity. Thus, 1,4-naphthoquinones displaying sulfur-containing and phenylamino side chains with additional polar groups could be successfully utilized for further development of efficacious Cdc25 A/B and MKK7 inhibitors with anticancer activity.