Generalized gradient approximation for the exchange-correlation hole of a many-electron system

Vacancy engineering of single-layer lateral heterojunction for efficient Z-scheme photocatalytic water reduction

Optimizing the Z-scheme charge transmission of lateral heterojunction constructed by single-layer (SL) nanosheets is an appealing yet challenging tactics to boost photocatalytic efficiency for solar fuel production and environmental remediation. Herein, we reported the edge/corner-specific growth of SL ZnIn2S4-MoSe2 lateral heterojunction with intensified Z-scheme charge transmission through intimate Mo-S connection and S vacancies (VS) engineering. The Mo-S chemical bonds inside ZnIn2S4-MoSe2 heterojunction offer a speedy channel for Z-scheme charge transmission as confirmed via surface photovoltage spectroscopy, radical production, and in situ photo-irradiated X-ray photoelectron spectroscopy tests as well as density functional theory calculation, while VS engineering enlarges Fermi level difference between ZnIn2S4 and MoSe2 to strengthen internal electric field and driving force for photo-carriers transmission, resulting in an excellent photocatalytic H2 evolution (PHE) capability. Isotopic labeling experiment verified the photocatalytic water reduction by ZnIn2S4-MoSe2 heterojunction, which exhibited a visible-light-driven PHE rate up to 55.70 mmol g-1h-1 (or 550.70 μmol/10 mg/h) with an apparent quantum yield reaching 38.9 % at 400 nm. Moreover, the ZnIn2S4-MoSe2 heterojunction also possessed a robust stability during long-term photocatalytic reaction. The research findings could inspire new idea to enhance the photocatalytic capability of two-dimensional (2D) heterojunction by strengthening Z-scheme charge transmission at atomic level.

2D/3D hierarchical Zinc@Ti3C2Tx-MXene composite-coated copper foil as dendrite-free lithium host for stable lithium metal batteries

Lithium metal, with its ultrahigh theoretical capacity (3860 mAh g-1) and the lowest redox potential among metallic anodes (-3.04 V vs. SHE), is regarded as the ultimate anode for next-generation high-energy-density batteries. However, rampant dendrite growth and unstable solid electrolyte interphase (SEI) formation critically hinder its practical adoption. Herein, we design a hierarchical 2D/3D Zinc@MXene (Zn@M) composite-coated Cu current collector to stabilize lithium metal anodes. The MXene nanosheets (Ti3C2Tx) function as lithium-philic conductive channels to homogenize Li+ flux, while micrometer-sized Zn particles construct a porous scaffold that mitigates MXene restacking and provides preferential nucleation sites for lithium deposition. Benefiting from the strong interfacial bonding between MXene and Zn, the composite forms a robust dual-phase architecture with enhanced mechanical integrity and ion/electron transport efficiency. This synergy enables dendrite-free Li plating/stripping, as evidenced by the Li||Zn@M half-cell achieving a high average coulombic efficiency of 97.6 % over 450 cycles (1 mA cm-2/1 mAh cm-2) and symmetrical cells sustaining stable operation for 3300 h (1 mA cm-2/1 mAh cm-2). Remarkably, when paired with a high-loading LiFePO4 cathode (12.7 mg cm-2) in anode-free configuration, the Zn@M/Cu current collector demonstrates exceptional full-cell cyclability with 70 % capacity retention after 50 cycles. This work provides a universal interface engineering strategy for realizing dendrite-suppressive lithium hosts, paving the way toward practical high-energy lithium-metal batteries.

Interplay between Cation "Coloring" and Stereochemically Active Lone Pairs in AgBiS2 Thin Films

Solution-processed AgBiS2 thin films were fabricated using novel thiol-amine precursor inks to investigate the stereochemical activity of Bi3+ 6s2 lone pairs and their impact on the structure. A dual-space analysis combining Bragg diffraction and hard X-ray photoelectron spectroscopy (HAXPES) revealed a rock salt-like average structure with local distortions linked to cation coloring. Density functional theory (DFT) and crystal orbital Hamilton population (COHP) analyses confirmed that local Bi-rich and Ag-rich nanodomains amplify stereochemical activity, whereas more mixed and cation-order nanodomains are less stereochemically active. This local, nanoscopic mixing of segregated and ordered domains would indeed explain an average Fm3̅m structure that is rock salt-like and that does not manifest the full anharmonicity and noncentrosymmetry evidenced in canonical structures with stereochemical expression. These findings provide insights into the local structural and electronic complexities governing the optoelectronic properties of AgBiS2 thin films.

Dimensional reduction in Cs2AgBiBr6 enables long-term stable Perovskite-based gas sensing

Halide perovskite gas sensors have a low gas detection limit at room temperature, surpassing the performance of traditional metal oxide chemiresistors. However, they are prone to structural decomposition and performance loss due to the lack of coordination unsaturated surface metal ions and sensitivity to environmental factors such as water, oxygen, heat, and light. To address this issue, we present a general strategy: replacing the cation Cs+ in inorganic perovskite Cs2AgBiBr6 with long-chain alkylamines. This modification synthesizes perovskite sensor materials that effectively block moisture and exhibit excellent stability under real-working conditions. The chemiresistors show high sensitivity and stability to CO gas, with (BA)4AgBiBr8 detecting CO at a limit of 20 ppb, maintaining performance after 270 days of continuous exposure to ambient air. The exceptional performance of (BA)4AgBiBr8 is elucidated through density functional theory calculations combined with sum frequency generation spectroscopy, marking a significant breakthrough in halide perovskite-based gas sensing by surpassing the stability and sensitivity of traditional sensors.

Atomic-Scale Origins and Shielding-Corrected Dipole Predictions of Surface Electrostatic Potential Difference in Metal-TMDC Contacts

The atomic-scale origins and quantitative description of the surface electrostatic potential difference (ΔV) in metal-semiconductor contacts remain elusive, limiting rational interface barrier design. Through first-principles calculations on Au/Ag/Pt/Pd-transition-metal dichalcogenide (TMDC) contacts, we establish a robust linear correlation between ΔV and shielding-corrected dipole terms parametrized by atomic number (Z), valence electron count, and atomic radii. Three critical insights are identified. First, the dipole terms from metal-TMDC and TMDC-TMDC interfaces as well as TMDC layers dominate linearity with a contribution of about 90%-92%. Second, the interfaces and TMDC layers in closer proximity to the metal layer show reduced contributions due to suppression by the metallic free-electron region. Third, incorporating high-Z atomic shielding corrections collectively enhances linearity by 8%-10%, with a maximal correction from metal-TMDC interfaces. Using this correlation, interface barriers are predicted, matching those from band structures. This work clarifies the atomic origins of ΔV and establishes a predictive framework for designing metal-TMDC contact barriers.

Unveiling 2D Rb3Bi2I6Cl3 and Rb3Bi2I3Cl6 perovskites for optoelectronic, solar cell and photocatalytic applications

The removal of harmful lead from perovskite materials has led to a surge in interest in lead-free perovskite-based solar cells. Using density-functional theory (DFT) and a numerical simulation method using the solar cell capacitance simulator SCAPS-1D. This work aims to advance the field of lead-free perovskite solar cells by conducting a comparative analysis of lead-free perovskite materials. WIEN2k is employed to explore the structural, electronic and optical properties of the two dimensional (2D) halide perovskites Rb3Bi2I6Cl3 and Rb3Bi2I3Cl6, while their solar cell (SC) efficiency is estimated using SCAPS-1D. The reported structural properties are aligned with the experimental values. The electronic properties of Rb3Bi2I6Cl3 and Rb3Bi2I3Cl6 reveal their direct band gap semiconducting nature with band gaps of 2.02 and 1.99 eV, respectively. Their optical properties reveal that the compounds are activated under visible light, making them ideal for optoelectronic device and SC applications. To model the efficiency of these compound-based solar cells, MoO3 is optimized as an electron transport layer (ETL); TiO2-SnS2 is optimized as a hole transport layer (HTL), and the respective thickness of the ETL, HTL and absorber are optimized as 180, 150 and 900 nm, respectively. Rb3Bi2I6Cl3 and Rb3Bi2I3Cl6 are used as the absorber layer (AL). Optimized solar cell devices based on FTO/TiO2-SnO2/Rb3Bi2I6Cl3 and Rb3Bi2I3Cl6/MoO3/Ni achieved short-circuit current densities of 9.02 and 10.11 mA cm-2, open-circuit voltages of 1.41 and 1.35 V, fill factors of 84.69% and 83.93%, and power conversion efficiencies (PCE) of 11.39% and 11.52%, respectively. Additionally, photocatalytic analysis demonstrates that all of the materials can evolve H2 from H+ and O2 from H2O/O2. Additionally, the compound under study can reduce CO2 to produce HCOOH, CO, HCHO, CH4OH and CH4. Based on these findings, 2D perovskites could be used in optoelectronic devices, photovoltaics, and photocatalysis-especially for water splitting and CO2 reduction driven by visible light. These results facilitate future studies aimed at developing fully inorganic lead-free perovskite-based photovoltaics and photocatalysts.

Activation of C(sp2)-X and C(sp3)-X σ-Bonds (X = F, Cl, Br, and OMe) by Rhodium Complex with Pincer-Type Aluminyl Ligands: Theoretical Insight into High Reactivity and Flexible Reaction Mechanism

C(sp2)-X (X = F, Cl, Br, and OMe) σ-bond activation of halo- and methoxybenzenes and C(sp3)-X (X = F and Cl) σ-bond activation of fluoro- and chloromethanes by a rhodium complex with pincer-type aluminyl ligand (named Rh(PAlP)) are theoretically studied. Rh(PAlP) exhibits high reactivity in difficult σ-bond activations and flexible dependence of reaction mechanism on substrate and solvent. In the gas phase and cyclohexane solvent, all the C(sp2)-X σ-bond activations occur via cooperative activation by the Rh-Al moiety (Pathway 1) with moderate Gibbs activation energy (ΔG°‡). In polar THF solvent, C(sp2)-Cl and C(sp2)-Br σ-bond activations occur via nucleophilic attack of Rh to the phenyl group (Pathway 3) with a moderate ΔG°‡ value, whereas even in THF solvent, C(sp2)-F and C(sp2)-OMe σ-bond activations occur via Pathway 1. Concerted oxidative addition to the Rh atom (Pathway 2) is not preferred in these substrates. C(sp3)-F σ-bond activation of fluoromethane occurs via Pathway 1 in the THF solvent, while C(sp3)-Cl σ-bond activation occurs via Pathway 2. The transition state of Pathway 3 could not be optimized in the halomethane case. The reactivity of Rh(PAlP) and flexible dependence of the reaction mechanism on the substrate and solvent result from the presence of a Rh-Al direct bond, Alδ+···Xδ- attractive interaction, and the strongly donating nature of the aluminyl ligand.

Sub-unit-cell-segmented ferroelectricity in brownmillerite oxides by phonon decoupling

The ultimate scaling limit in ferroelectric switching has been attracting broad attention in the fields of materials science and nanoelectronics. Despite immense efforts to scale down ferroelectric features, however, only few materials have been shown to exhibit ferroelectricity at the unit-cell level. Here we report a controllable unit-cell-scale domain in brownmillerite oxides consisting of alternating octahedral/tetrahedral layers. By combining atomic-scale imaging and in situ transmission electron microscopy, we directly probed sub-unit-cell-segmented ferroelectricity and investigated their switching characteristics. First-principles calculations confirm that the phonon modes related to oxygen octahedra are decoupled from those of the oxygen tetrahedra in brownmillerite oxides, and such localized oxygen tetrahedral phonons stabilize the sub-unit-cell-segmented ferroelectric domain. The unit-cell-wide ferroelectricity observed in our study could provide opportunities to design high-density memory devices using phonon decoupling.

Transition Metal-Decorated Biphenylene Sheet for Dioxin Detection: A First-Principles Investigation

Detecting highly toxic environmental pollutants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is crucial for environmental safety. However, current sensors often lack the necessary sensitivity and efficiency for rapid detection and reusability. In this study, we explore the potential of biphenylene (BPh), a 2D carbon allotrope, for TCDD detection by using density functional theory (DFT). To enhance the performance of BPh monolayers, we introduced metal decoration using Sc, Co, and Pd. Our analysis includes geometric structure, adsorption energy, partial density of states (PDOS), charge transfer mechanisms, and work function evaluation. The results reveal that while TCDD weakly adsorbs onto pristine BPh, metal decoration significantly improves the adsorption strength by enhancing charge transfer between TCDD and the BPh monolayer, leading to stronger orbital hybridization and more stable adsorption configurations. The Co-decorated BPh system exhibits the highest adsorption energy at -1.95 eV, followed by Pd (-1.77 eV) and Sc (-1.48 eV), with Co and Pd systems showing strong interactions but limited reusability due to prolonged desorption times. In contrast, the Sc-decorated BPh monolayer balances strong adsorption and efficient desorption, making it the most practical candidate for sensing applications. The recovery time for the Sc-decorated system at 500 K was calculated to be 1.59 s, and under UV light, it reduced to 89.2 ms, indicating optimal desorption efficiency. These findings suggest that Sc-decorated BPh monolayers hold promise for developing practical, reusable sensors for TCDD detection, providing both high sensitivity and reusability.

Dissecting the Diverse Reactivity of β-Diketiminate Aluminum(I) Compound towards Azaarenes: Insight From DFT Calculations

Interest in aluminum(I) complexes has surged in recent decades due to the unusual role of electropositive aluminum as donor atoms in ligands. Numerous Al(I) complexes, which were previously considered too unstable, have been isolated. Among these, β-diketiminate aluminum(I) complex, NacNacAl(I), stands out for its unique reactivities including oxidative addition and π-bond activation. However, the understanding of reactions involving NacNacAl(I) has not yet been fully established. This study unveils the mechanisms behind the diverse reactivity of NacNacAl(I) with five structurally similar azaarenes through DFT calculations. Interestingly, computational results indicate that some of the five reactions can proceed via radical processes. A holistic comparison of all results highlights the mechanistic differences between monocyclic and bicyclic azaarenes. In the initial step with NacNacAl(I), monocyclic azaarenes form Al(I)-azaarene adducts, whereas bicyclic azaarenes generate Al(II)-azaarene biradicals. These intermediates are critical for understanding their distinctive reactivity. For monocyclic azaarenes, electronic effects of their substituents on the azaarene adducts result in varying reaction outcomes, while for bicyclic azaarenes, subsequent intermolecular or intramolecular coordination of biradicals leads to different products. This study provides deeper mechanistic insights into reactions associated with NacNacAl(I) complexes, thereby contributing to a more comprehensive understanding of these reactions.

Theoretical investigation of the ultralow thermal conductivity of 2D PbTe via a strain regulation method

To systematically develop an efficient computational protocol for discovering high-performance materials with desirable thermal conductivity, it is essential to theoretically understand the key factors influencing their heat transport capacity. Recent advancements in first-principles based calculations have significantly facilitated the exploration of structural and electronic properties of nanoscale devices. Efficient identification of the dominant factors impacting the materials' inner heat transport is crucial for their applications in real practice. In this study, we optimized our computation protocol originally proposed for thermal conductivity investigations and extended it to explore heat transport within a 2-dimensional (2D) alloying material, PbTe. We delved into the structural and electronic properties of PbTe in detail. Additionally, to assess the thermodynamic stability and describe the bonding network of this 2D alloying material, we calculated its phonon dispersion at different strains. The heat transport mechanism within PbTe has been systematically investigated. The insights gained from this work are instructive for future studies, particularly those focusing on the evaluation of 2D materials' thermoelectric performance. This research contributes to a broader understanding of how structural and electronic properties influence the inner heat transport of 2D materials, establishing a theoretical foundation for the development of high-performance thermal devices.

Optimally tuned range-separated hybrid van der Waals density functional for molecular binding and quasiparticle characterizations

We introduce and illustrate use of two closely related range-separated hybrid (RSH) van der Waals density functionals (vdW-DFs), denoted AHBR-mRSH and AHBR-mRSH*, for total-energy and quasiparticle characterizations of molecules using generalized Kohn-Sham (gKS) density functional theory (DFT). For comparison, we also introduce and document a traditional design for a long-range corrected (LRC) vdW-DF, denoted 'B86R-LRC'. All three new vdW-DFs set the exchange potential as free of asymptotic screening in the coupling between the electron and its associated exchange hole. Our two AHBR-mRSHs are key members of a broader class 'AHBR-mRSH(γ)' defined by an inverse length scaleγfor a crossover in weighting short- and long-ranged exchange contributions; we obtain a highly accurate predictor of general molecular-energy differences by keepingγ = 0.106 (inverse Bohr) deliberately fixed in AHBR-mRSH. We obtain an optimally tuned (OT) form AHBR-mRSH* = AHBR-mRSH(γ∗) by computing a plausible value ofγ∗for specific types of systems. This AHBR-mRSH* permits characterizations of molecular quasiparticles and generalizes (1) the existing 'OT-RSH' (Steinet al2010Phys. Rev. Lett.105266802; Rafaely-Abramsonet al2012Phys. Rev. Lett.109226405) approach by a systematic inclusion of truly nonlocal correlations, and (2) more traditional LRC forms (e.g. B86R-LRC) by setting the short-range exchange description as in vdW-DF2-ahbr (Shuklaet al2022Phys. Rev. X12041003).Importantly,we may view AHBR-mRSH and AHBR-mRSH* as internally consistent functionals for gKS-DFT, being simultaneously accurate on molecular energies and quasiparticles. This is possible because the 'AHBR-mRSH(γ)' class has enough transferability to almost always limit adverse impacts of tuningγ, as tested here on the GMTKN55 benchmark suite (Goerigket al2017Phys. Chem. Chem. Phys.1932184). We find that AHBR-mRSH generally outperforms B86R-LRC on molecular problems. To illustrate usage, we complete the OT design of an AHBR-mRSH* for nucleobases and show that it provides quasiparticle predictions that are in good agreement with both literature theory and experimental values for adenine, thymine, cytosine, and guanine.

Enantioselective Cobalt(III)-Catalyzed [4 + 1] Annulation of Benzamides: Cyclopropenes as One-Carbon Synthons

A chiral cyclopentadienyl cobalt(III)-catalyzed enantioselective [4 + 1] annulation of N-chlorobenzamides with cyclopropenes is reported. The cobalt catalyst engages in the C-H activation as well as promotes the C-C bond cleavage of the cyclopropene, rendering it as a one-carbon unit for the annulation. The reaction efficiently constructs biologically relevant chiral isoindolinones with selectivities of up to 99:1 er and >20:1 E/Z ratios. The cobalt(III) catalyst displays a unique orthogonal reactivity profile delivering [4 + 1] annulation products, whereas its rhodium(III) homologue engages in the more classical [4 + 2] annulation pattern. Computational studies reveal the origin of these reactivity divergences.

Hydrogen storage, optoelectronic, and structural properties of novel osmium hydrides

CONTEXT

In present study, the density functional theory (DFT) is employed to analyze the structural, electronic, optical, and hydrogen storage characteristics of double perovskite-type hydrides A2OsH6 (A = Mg-Ba). The reported findings related to the structural aspects are in good agreement with the experimental results. All these compounds exhibit the FCC structure and formation enthalpy Hf which demonstrate their thermodynamic stability. The estimated band gap values for these compounds are 3.4, 3.0, 2.43, and 1.86 eV respectively by using perovskite-modified Becke-Johnson potential (P-mBJ) plus U parameter. According to the results, as going from Mg to Ba, the band gap decreases because of the increase in atomic radii. Furthermore, all the understudy compounds hold direct band gap nature, and their tuned band gap values show significant agreement with available results on isotropic compounds. The Mg2OsH6 is ultraviolet sensitive, and Ca2OsH6, Sr2OsH6, and Ba2OsH6 possess excellent optical behavior in the visible region. The characteristic dielectric function, oscillator strength, energy loss function, excitation coefficient, refractive index, reflectivity, and optical conductivity of these double perovskites type hydride indicate that they are highly suitable for optoelectronic applications. However, in terms of hydrogen storage performance, the gravimetric storage capacity of Mg2OsH6 is 2.77 wt%, for Ca2OsH6 is 2.59 wt%, for Sr2OsH6 is 2.15 wt%, and for Ba2OsH6 is 1.22 wt% while the favorable desorption temperature for these compounds is 189.46, 220.76, 311.19, and 356.37 K respectively with the formation energy of 24.76, 28.85, 40.67, and 46.58 kJ/mol, which is feasible in actual application.

METHOD

In the current investigation, the FP-LAPW method is used which is executed in WEIN2k simulation code. The generalized gradient approximation and mBJ with Hubbard U are used to address the exchange and correlation potentials. The Kramar-Kroning relation is used for optical properties assessment. The analytical technique is used to find out the gravimetric hydrogen storage capacity for these compounds while all the plotting was performed using Xmgrace and Origen software.

Mitigating Strain Localization via Stabilized Phase Boundaries for Strengthening Multi-Principal Element Alloys

Multi-principal element alloys (MPEA) demonstrate exceptional stability during rapid solidification, making them ideal candidates for additive manufacturing and other high-design-flexibility techniques. Unexpectedly, MPEA failure often mimics that of conventional metals, with strain localization along phase or grain boundaries leading to typical crack initiation. Most strategies aim at reducing strain localization either suppress the formation of high-energy sites or dissipate energy at crack tips to enhance toughness, rarely achieving a synergy of both. Inspired by the microstructure of mouse enamel, nanoscale body-centered cubic (BCC) and face-centered cubic (FCC) phases into MPEAs are introduced, stabilized at phase boundaries to provide ample plastic space for dislocation-mediated deformation. This approach overcomes the local hardening limitations of nanoscale alloys and harmonizes traditional toughening mechanisms-such as crack deflection, blocking, and bridging-to mitigate strain localization. These mechanisms impart the alloy with ultra-high tensile strength (≈1458.1 MPa) and ductility (≈21.2%) without requiring heat treatment. Atomic calculations reveal that partial atomic plane migration drives continuous dislocation transfer across phases. This study uncovers fundamental but latent mechanical mechanisms in MPEAs, advancing understanding of ultra-strong bioinspired alloys.

Effect of Impurities on the Redox Properties of Goethite

Iron oxide minerals regulate the flux of electrons in the environment and are important hosts for trace and minor, yet critical, elements. Here, we present the first evidence of a direct link between the local coordination environments of Ni and Zn and the redox properties of their host phase goethite (α-FeOOH), the most abundant Fe(III) (oxyhydr)oxide at Earth's surface. We used aqueous redox measurements to show that the redox potential EH0, and hence the mineral's stability, follows the order: pure goethite ≥ Zn-goethite > Ni-goethite. Parallel X-ray absorption and scattering measurements demonstrate, using quantum-informed analysis, that the local coordination environment of the smaller impurity, Ni, causes more bulk strain energy than Zn, which nearly accounts for the difference in EH0 between Ni- and Zn-goethite. Our theory-informed, experimental study reveals how two common impurities affect the stability of goethite with implications for the biogeochemical reactivity of Fe(III) (oxyhydr)oxide in mediating elemental and electron fluxes in the environment.

Enhanced electrocatalytic hydrogen evolution via nitrogen-induced electron density modulation in ReSe2/2D carbon heterostructures

The synthesis of heterostructures composed of transition metal dichalcogenides (TMDs) and carbon nanostructures has garnered a lot of attention in recent years. This is due to the synergistic effects that arise from these heterostructures that are advantageous in various applications. This includes but is not limited to the improvement in electron conductivity of TMDs that are grown on carbon nanostructures. This improvement in electron conductivity can increase the catalytic activity of TMDs towards the hydrogen evolution reaction (HER). Therefore, it is crucial to understand the formation of these heterostructures and how the interaction of the component materials can improve their performance as electrocatalysts in the HER. This study highlights how surface chemistry affects heterostructure formation and the catalytic performance of heterostructures in the HER. ReSe2 nanocrystals were grown on 2D carbon nanostructures, specifically reduced graphene oxide (rGO), nitrogen doped reduced graphene oxide (N-rGO), and graphitic carbon nitride (g-C3N4). FTIR, XPS, and TEM analyses showed that functional groups on carbon surfaces play a key role in the formation of the heterostructures. Among the materials tested, rGO had the highest ReSe2 loading due to the availability of oxygen containing functional groups on the surface of rGO. However, the performance of the heterostructures as catalysts in the HER showed that ReSe2-N-rGO had the highest catalytic activity with the lowest onset potential (115 mV), Tafel slope (72 mV dec-1), and overpotential (218 mV). The enhanced performance of the ReSe2-N-rGO catalyst was due to the modulation of rGO by nitrogen doping which improved the electron transfer between ReSe2 and N-rGO, this was further confirmed using computational studies and by ReSe2-N-rGO having the lowest R ct (65 Ω).

Computational study of carboplatin interaction with PEG-functionalized C60 fullerene as a drug carrier using DFT and molecular dynamics simulations

In this research, the interaction of carboplatin with polyethylene glycol (PEG) functionalized iron-encapsulated fullerene (Fe@C60) molecule was investigated using Density Functional Theory (DFT) and molecular dynamics simulations (MD). Our results indicate that the inclusion of PEG enhances the stability of the Fe@C60 molecule, leading to a shift in the formation energy of the structures from approximately - 3.4 to - 4.77 eV/atom in correlation with the quantity of surface polyethylene glycols. Additionally, the electric dipole moment of the Fe@C60 structure increases following the surface modification with PEG molecules, fostering a more efficient interaction with carboplatin. The optical absorption spectrum reveals several peaks within the 200-600 nm range for Fe@C60:PEG. Particularly noteworthy is the impact of the interaction with carboplatin on the optical properties of the structure, providing valuable insights into the assessment of drug adsorption behavior. Furthermore, the adsorption energy computations demonstrate that the complexes formed between Fe@C60 and carboplatin exhibit stability, with physical adsorption energies falling within a range conducive for the loading and release of carboplatin. Detailed analyses, including IR frequencies and molecular dynamics simulations, provide further insights into the structural and dynamic properties of this complex system, shedding light on its potential applications in drug delivery and related fields.

Copula methods for modeling pair densities in density functional theory

We propose a new approach toward approximating the density-to-pair-density map based on copula theory from statistics. We extend the copula theory to multi-dimensional marginals and deduce that one can describe any (exact or approximate) pair density by the single-particle density and a copula. We present analytical formulas for the exact copula in scaling limits, numerically compute the copula for dissociating systems with two to four particles in one dimension, and propose accurate approximations of the copula between equilibrium and dissociation for two-particle systems.

The Interplay Between Component Denticity and Flexibility Promotes the Formation of [AgI⋅⋅⋅AgI]-stabilised Links and Knots

A subtle interplay between the flexibility of the 2,2'-bipyridyl-based diamine and the denticity of the coordination domain formed upon self-assembly enabled the formation of four distinct topologies stabilised by [Ag⋅⋅⋅Ag]2+ pairs. The reactions utilising 2,6-diformylpyridine resulted in the formation of silver(I)-stabilised molecular tweezer, trefoil knot, and Solomon link. The 1,8-naphthyridine-based dialdehyde promoted the formation of [2]catenanes and trefoil knot, demonstrating very close AgI⋅⋅⋅AgI distances. Two of the studied assemblies demonstrated interesting luminescent properties in the solid state.

Adsorption attributes of β-phosphoborophane nanosheets towards some vapors emitted from cosmetics-a first-principles study

CONTEXT

Recently, new two-dimensional (2D) materials have emerged and are used for various engineering applications. One such new 2D material is beta (β-)phosphoborophane. Initially, we ensured the structural and dynamic stability of β-phosphoborophane. The semiconducting behavior of β-phosphoborophane with an energy band of 1.252 eV reveals that it is a suitable material for chemical nanosensors. We used β-phosphoborophane as adsorbing material for some of the molecules emitted from cosmetics such as hydroxycitronellal and alpha isomethyl ionone. The adsorption of target molecules changes the energy band gap of β-phosphoborophane, inferred based on the results of band structure and projected density of states. Furthermore, the changes in the electronic properties of β-phosphoborophane upon adsorption of target molecules are observed with regard to charge transfer and electron density difference results. The chemo-resistive nature of β-phosphoborophane is revealed from the relative energy gap changes owing to hydroxycitronellal and alpha isomethyl ionone adsorption.

METHODS

The structural stability, dynamical firmness, electronic properties, and interaction behavior of hydroxycitronellal and alpha isomethyl ionone on β-phosphoborophane are explored within the framework of the DFT method. The hybrid GGA/B3LYP functional is used for optimizing the base material β-phosphoborophane. All the calculation in the research study is carried out by the QuantumATK simulation package. The result of the proposed work supports that β-phosphoborophane can be a suitable sensing material for hydroxycitronellal and alpha isomethyl ionone, which are found in cosmetics.

Metal-Translocation-Coupled Ligand-Binding/Release by Dinuclear Rhodium Sandwich Complexes

Switching the location of metal atoms or ions in a molecule has been of great interest as a behavior of molecular machines. We describe herein that the reversible metal translocation can be coupled with the ligand-binding/release of organometallic complexes. The two rhodium moieties sandwiched between arylpolyene ligands exhibit metal-assembly and disassembly through reversible migration between the arene site and the olefin site, in response to the association and dissociation of additional ligands. This occurs either with bridging or even non-bridging ligands, where the latter involves oxidative π-addition of the unsaturated hydrocarbon binder to the metal moieties. The assembling- and disassembling states were characterized by NMR and X-ray diffraction analysis.

Dynamic in-situ reconstruction of active site circulators for photo-Fenton-like reactions

Developing efficient and stable heterogeneous catalysts for the continuous activation of oxidants is crucial to mitigating the global water resource crisis. Guided by computational predictions, this research achieved this goal through the synthesis of a modified graphitic carbon nitride with enhanced catalytic activity and stability. Its intrinsic activity was further amplified by dynamic in-situ reconstruction using the I-/I3- redox mediator system during photoreactions. Impressively, this reconstructed catalyst demonstrated the capability for at least 30 regeneration cycles while maintaining high purification efficacy. The mechanism underlying the in-situ reconstruction of active sites for periodate functionalization was elucidated through theoretical calculations, coupled with semi-in-situ X-ray photoelectron spectroscopy (XPS) and electrochemical analyses. The system's capacity to detoxify recalcitrant pollutants was demonstrated through successful Escherichia coli cultivation and Zebrafish embryo experiments. The economic feasibility and environmental impacts are quantitatively assessed by the Electrical Energy per Order (EE/O) metric and Life Cycle Assessment (LCA), confirming the system's scalability and applicability in real-world scenarios. This dual-site constrained interlayer insertion, and controllable in-situ catalyst reconstruction achieve durable robustness of the photocatalyst, paving the way for the development of sustainable catalytic water purification technologies.

Ligand-Assisted Colloidal Synthesis of Alkali Metal-Based Ternary Chalcogenide: Nanostructuring and Phase Control in Na-Cu-S System

The development of sustainable and tunable materials is crucial for advancing modern technologies. We present a controlled synthesis of colloidal Na-Cu-S nanostructures. To overcome the reactivity difference between Na and Cu precursors toward chalcogens in a colloidal synthesis and to achieve metastable phase formation, we designed a single-source precursor for Cu and S. The decomposition of this precursor creates a Cu-S template into which Na ions diffuse to form metastable Na-Cu-S. By leveraging the reactivity of sulfur precursors, we synthesized Na3Cu4S4 (orthorhombic) and Na2Cu4S3 (monoclinic) nanocrystals with distinct properties. A mechanistic investigation reveals a predictive pathway previously unobserved in alkali-metal-based ternary chalcogenide systems. Further, computational DFT calculations demonstrate that Na3Cu4S4 exhibits metallic characteristics while Na2Cu4S3 is semiconducting, with an optimal band gap for photovoltaic applications. This research advances our understanding of ternary chalcogenide systems and establishes a framework for the rational design of complex nanomaterials.

Pt nanocluster-Fe single atom pairs dual-regulate charge extraction and interfacial reaction for enhanced photoelectric response

Energy level mismatches between semiconductors and cocatalysts often induce carrier recombination, limiting photocatalytic and photoelectrochemical (PEC) efficiency. Here, we integrate Pt nanocluster-Fe single-atom pairs with CuO to regulate both solid-solid and solid-liquid interfaces in PEC systems. Experimental and theoretical analyses reveal that an Ohmic contact at the CuO/Pt interface accelerates electron extraction, while Pt-to-Fe charge transfer enhances oxygen reduction at Fe sites, collectively boosting reaction kinetics. Leveraging this, we construct a PEC biosensor exploiting chelating effect of glyphosate on CuO to impede electron transfer, achieving a detection limit of 0.41 ng/mL. This interface engineering strategy advances cocatalyst design for enhanced energy conversion and sensing applications by simultaneously addressing carrier dynamics and interfacial reaction barriers.

Combined insights from DFT and microkinetics into NO reduction by CO over an LaFeO3 perovskite

Herein, the relationship between the selective catalytic activity of CO in the reduction of NO and the active site of LaFeO3 perovskite was established through the combination of density functional theory and microkinetic studies. A reaction network consisting of various possible elementary reactions was built to reveal the pathway of CO2, N2 and N2O formation during CO-SCR on LaFeO3. The results indicated that the Fe site was active for reactant adsorption, which followed a chemisorption mechanism. The intermediate N2O2-mediated path was dominant for CO-SCR. Firstly, N2O2* was produced via the bimolecular reaction of NO-coupling with an energy barrier of 0.26 eV. Subsequently, N2O2* easily reacted with the adsorbed CO molecules to form an N2O2CO* intermediate (N2O2* + CO* → N2O2CO* + *), which required an activation energy of 0.65 eV. Finally, the formed N2O2CO* intermediate was reduced by CO* to generate N2 and CO2 (N2O2CO* + CO* → 2CO2 + N2 + 2*) with an energy barrier of 1.22 eV. Besides, the formation and decomposition of N2O were considered. N2O might have been formed via N-NO disproportionation reaction (NO* + N* → N2O + 2*) and decomposition of N2O2CO* (N2O2CO* → N2O + CO2 + *). Microkinetic results indicated that the conversion rate of CO and NO and the temperature showed a volcanic curve, and the N2 selectivity reached 100% at temperatures between 200 and 420 K. Thus, this work provides a detailed description of the CO-SCR reaction mechanism and lays the foundation for the development of high-performance LaFeO3 catalysts.

Implicating the Role of Au-H Bonds in Photochemical N2 Fixation by Ruthenium-Doped Gold Clusters

Dinitrogen fixation through the Nitrogen Reduction Reaction (NRR) under mild conditions without the use of sacrificial agents has its share of formidable hurdles. It has been shown recently that Ru-doped Au nanoclusters can reduce N2 molecules to NH3 only in the presence of UV-Vis light in aqueous medium. Herein, using theoretical techniques (Density Functional Theory), we shed light on the mechanistic avenues traversed to achieve this prodigious chemical feat. Our findings suggest that the bimetallic Au22Ru6 cluster successfully accomplishes the NRR process under ambient pressure and temperature conditions by the virtue of its bifunctional nature. Contrary to the existing views, we find that NRR propagates through an alternative associative pathway, where the Ru dopant assists in N2 adsorption while the Au-H bonds formed from Au-assisted water splitting are implicated in facilitating NRR.

Sulfite-Induced Release and Oxidation of Cr(III) in Reduced Chromite Ore Processing Residue under Visible Light: The Critical Role of Fe(IV) Intermediates

Reduced chromite ore processing residue (rCOPR) is vulnerable to the surrounding conditions in environments, which can induce the release and oxidation of Cr(III). This work found the synergistic effect of light and sulfite on destroying rCOPR stability, causing the significant release of Cr(VI), which was 4∼7 times higher than that under single factor action. In CrxFe1-x(OH)3/sulfite/light system, Cr(VI) release rate could reach 11.11 × 10-7 M min-1 g-1, because of the rapid formation of ·OH, O2·-, SO4·-, and quadrivalent iron [Fe(IV)]. In addition, this study found that the oxidized chromium residue could continuously release Cr(III) after being transferred to the dark environment. This should be attributed to the obvious change in the iron coordination structure of rCOPR caused by the catalytic reaction of sulfite with light, which greatly weakened the ability of the Fe-O structure to encase chromium elements in a solid. These insights are crucial for predicting the environmental risks of rCOPR in the presence of visible light and sulfur-containing compounds.

Computational Analysis of Diastereoselectivity and Carbene Reactivity in Pt- and Au-Catalyzed 1,5-Enyne Cycloisomerization to Bicyclo[3.1.0]hexane

Bicyclo[3.1.0]hexane is a structural motif of the bioactive, naturally occurring cryptotrione and could be realized via a Pt- or Au-catalyzed reaction on 1,5-enyne with good control of the diastereoselectivity. In this work, we perform a density functional theory (DFT) study that provides mechanistic insight into this intriguing reaction and discloses the origin of the diastereoselectivity and reactivity. Distortion/interaction analyses and computational models reveal that the diastereoselective cyclization of the [Pt]-catalyzed β-enyne favors a transition state with stronger hydrogen bonding, CH···π interactions, and less steric repulsion. The degree of back donation of the platinum carbene determines the activation barrier of the rate-determining hydride migration step. In the diastereoselective transition states of the [Au]-catalyzed reaction of α-enyne, the degree of out-of-plane distortion of the alkenyl moiety and the bending of the alkynyl group determine the preference. DFT calculations provided insight into transition states and intermediates that are difficult to detect experimentally, revealing structural factors that control the selectivity and reactivity.

Enhanced Simulation of Complicated MXene Materials with Graph Convolutional Neural Networks

MXene, a notable two-dimensional transition metal carbide, has attracted increasing attention in materials science due to its unique attributes, driving innovations in energy storage, sensors, catalysts, and electromagnetic shielding. The property and application performance are determined by the electronic structure, which can be described based on the density of states (DOS). The conventional density functional theory (DFT) calculation is able to provide the DOS spectrum of a specific atomic structure. However, for complicated composition, such as the recently reported high entropy MXene, the DFT calculations in exhaustive structure space are resource-intensive. In this study, machine learning (ML) technique, specifically the crystal graph convolutional neural networks (CGCNN) model, is applied to generate DOS of these MXene models with complex compositions. By using calculations on M3C2 and M4C3 structures as training sets, the DOS of the complex high entropy MXene is well reproduced according to the atomic structure. Moreover, the adsorption energy of lithium is precisely predicted based on the DOS, which can be further employed to screen the potential electrode materials for lithium batteries. Herein, ML method not only streamlines predictions but also enhances the understanding of MXene's intrinsic properties.

Highly Symmetrical Palladium Cluster Complexes with Either Anticuboctahedral or Cuboctahedral Pd13 Core: Theoretical Insight into Factors Determining Symmetrical Structure

One of the important open questions is what factor(s) determines the symmetry of the structure of the metal nanocluster complex. [Pd13(μ-Cl)3(μ4-C16H16)6]+ (Anti-μ4; C16H16 = [2.2]paracyclophane) has an anticuboctahedral Pd13 core unlike [Pd13(μ4-C7H7)6]2+ with cuboctahedral Pd13 core. DFT calculations show that Anti-μ4 is more stable than isomers, [Pd13(μ-Cl)3(μ3-C16H16)3(μ4-C16H16)3]+ and [Pd13(μ-Cl)3(μ2-C16H16)3(μ4-C16H16)3]+ with cuboctahedral Pd13 core (Cubo-μ3,μ4 and Cubo-μ2,μ4, respectively) and [Pd13(μ-Cl)3(μ3-C16H16)6]+ with distorted icosahedral Pd13 core (dis-Ih-μ3). Not the stabilities of [Pd13(μ-Cl)3]+ core and (C16H16)6 ligand-shell but rather the interaction energy (Eint) between [Pd13(μ-Cl)3]+ and (C16H16)6 ligand-shell determines stabilities of these complexes. μ4-C16H16 coordination bond is stronger than μ2- and μ3-coordination bonds, leading to a larger Eint value in Anti-μ4 than in isomers bearing μ2- or μ3-coordination bond. An icosahedral Pd13 core is not favorable for these Pd13 complexes because of the absence of a Pd4 plane. [Pd13(μ-Cl)3(μ4-C16H16)6]+ with cuboctahedral Pd13 (Cubo-μ4) is not stable despite the presence of six Pd4 planes, because its three Pd4 planes with μ-Cl ligand cannot form μ4-C16H16 coordination bond due to steric repulsion of C16H16 with the μ-Cl ligand. In contrast, Anti-μ4 is stable because it has six Pd4 planes with no Cl ligand to form strong μ4-C16H16 coordination bonds without steric repulsion. Also, discussion is presented on the difference in symmetry between [Pd13(μ-Cl)3(μ4-C16H16)6]+ and [Pd13(μ4-C7H7)6]2+.

Effects of Cu, Ag, and Au Elements Doping on the Electronic and Optical Properties of β-Ga2O3 via First-Principles Calculations

β-Ga2O3, as a semiconductor material with an ultrawide band gap (Eg > 4.8 eV), emerges as a promising candidate for ultraviolet (UV)-transparent semiconductors. Its distinctive property of high transparency from visible light to the ultraviolet region gives it broad application prospects in the fields of deep UV light-emitting diodes (LEDs), UV lasers, and electronic devices. This study employed first-principles calculations utilizing the generalized gradient approximation+ U (GGA+U) method to investigate the impact of doping β-Ga2O3 with transition metals including copper (Cu), silver (Ag), and gold (Au) on its electronic structure and optical properties. The findings reveal that under oxygen (O)-rich conditions, the formation energy of the doped system is lower compared to gallium (Ga)-rich conditions. And the Cu-doped β-Ga2O3 is demonstrated to possess the lowest formation energy, indicating an enhanced stability of the β-Ga2O3. Additionally, the intrinsic band gap of β-Ga2O3 is calculated to be 4.853 eV, whereas the band gaps of transition metal (TM)-doped β-Ga2O3 are significantly reduced. Specifically, the band gaps of Cu-doped, Ag-doped, and Au-doped β-Ga2O3 are 1.228, 0.982, and 1.648 eV, respectively. This reduction can be attributed to the introduction of impurity levels by the transition metals, which modify the electron distribution of gallium and oxygen atoms in the vicinity of the Fermi level. Remarkably, β-Ga2O3 exhibits superior ultraviolet light absorption performance, and the incorporation of transition metals such as Cu, Ag, and Au facilitates the expansion of the absorption region from the ultraviolet to the visible light range. This transformation not only enhances the material's light-harvesting capability but also improves the electron transition capability of the intrinsic β-Ga2O3, providing a crucial theoretical foundation for the development of novel β-Ga2O3-based optoelectronic devices.

Precise Manipulation on the Structural Defects of Poly (Triazine Imide) Single Crystals for Efficient Photocatalytic Overall Water Splitting

Conjugated polymers, represented by polymeric carbon nitrides (PCNs), have risen to prominence as new-generation photocatalysts for overall water splitting (OWS). Despite considerable efforts, achieving highly crystalline PCNs with minimal structural defects remains a great challenge, and it is also difficult to examine the exact impact of complex defect states on OWS process, which largely limits their quantum efficiency. Herein, we devise a 'in-situ salt flux' assisted copolymerization protocol by using nitrogen-rich and nitrogen-deficient monomers to precisely manipulate the structural defects of poly (triazine imide) (PTI) single crystals. Stoichiometric control between two comonomers enables continuous tunning of carbon- and nitrogen-vacancies within PTI, allowing the construction of a series of PTI crystals with different defect states. Theoretical and experimental results unveil the carbon vacancies are related with the radiative decay of excitons, while the nonradiative decay is mainly derived from the nitrogen vacancies. Owing to the effective suppression of both radiative and nonradiative losses, the as-synthesized PTI achieves a record apparent quantum efficiency of 37.8 % by one-step-excitation OWS. This work highlights the significance of rational control of the structural defects and describes clear structure-property-activity relationships in PTI photocatalyst, offering guidance for the development of polymer photocatalysts for solar fuel production.

In/Outside Catalytic Sites of the Pore Walls in One-Dimensional Covalent Organic Frameworks for Oxygen Reduction Reaction

Pore channels play a decisive role in mass transport in catalytic systems. However, the influences of the location of catalytic sites inside or outside of the pore walls on the performance were still under-explored due, because it is difficult to construct sites anchored in or outside of pore walls. Herein, one-dimensional covalent organic frameworks with precisely anchored active sites were used to explore the effects of channels on a typical oxygen reduction reaction (ORR) catalysis. Electrocatalytic evaluations showed that single Pt sites located inside of the channels exhibited higher kinetic activity compared to those anchored outside. The in situ spectroscopic analysis revealed that local reconstruction of Pt-Cl breaking and potential-induced anion transport occurred more effectively inside the channels. The superior anion transportability and kinetic activity of the inside-channel active sites also facilitated *OH desorption during the ORR process outperforming their outside-channel counterparts. The results of this study provide strategies for designing active sites in porous catalysts for heterogeneous catalysis.

Observation of Extraordinary Vibration Scatterings Induced by Strong Anharmonicity in Lead-Free Halide Double Perovskites

Lead-free halide double perovskites provide a promising solution for the long-standing issues of lead-containing halide perovskites, i.e., the toxicity of Pb and the low stability under ambient conditions and high-intensity illumination. Their light-to-electricity or thermal-to-electricity conversion is strongly determined by the dynamics of the corresponding lattice vibrations. Here, the measurement of lattice dynamics is presented in a prototypical lead-free halide double perovskite(Cs2NaInCl6). The quantitative measurements and first-principles calculations show that the scatterings among lattice vibrations at room temperature are at the timescale of ≈1 ps, which stems from the extraordinarily strong anharmonicity in Cs2NaInCl6. Further the degree of anharmonicity of each type of atom is quantitatively characterized in the Cs2NaInCl6 single crystal, which stems from the interatomic forces, and demonstrate that this strong anharmonicity is synergistically contributed by the bond hierarchy, the tilting of the NaCl6 and InCl6 octahedral units, and the rattling of Cs+ ions. Consequently, the crystalline Cs2NaInCl6 possesses an ultralow thermal conductivity of ≈0.43 W mK-1 at room temperature, and a weak temperature dependence of T -0.41. These findings uncovered the underlying mechanisms behind the dynamics of lattice vibrations in double perovskites, which can largely benefit the design of optoelectronics and thermoelectrics based on halide double perovskites.

Minute-Level Room-Temperature Switching and Long Cycle Stability of Thermochromic Inorganic Perovskite Smart Windows

Perovskite smart windows (PSWs) are widely investigated owing to excellent thermochromic properties, while restricted by poor transition performance and cycle stability. Herein, dimethyl sulfoxide vapor is utilized as an induction reagent for rapid reversible switching at room temperature between the colored and bleached phases. To obtain PSWs with different optical properties and transition performance, red CsPbIBr2, yellow Rb0.5Cs0.5PbIBr2 and brown CsSn0.1Pb0.9IBr2 are prepared through alloying. The perovskites can exhibit reversible switching at 27.4-34.3 °C within 1.9-5.1 min. Even after 100 cycles, they exhibit remarkable stability of luminous transmittance (retention ≥97.4%) and transition time (retention ≥97.6%). Experimental characterization proves that the reversible switching occurs between colored three-dimension perovskite phase and bleached zero-dimension perovskite phase. In the field test (air temperature = 21.6-26.5 °C), model houses with PSWs exhibit a maximum indoor temperature drop of 4.2 °C. Furthermore, they exhibit considerable temperature modulation ability up to 7.9 °C under a solar simulator (temperature of the control model house = 60 °C). The decrease in the luminous transmittance of the PSWs after 20 days is 2.9%, indicating excellent long-term stability. This study offers PSWs with prominent transition performance and long cycle stability.

Vacancies in sulfides facilitate fluid-induced solid-state diffusion and critical metals accumulation

Understanding elements uptake and release from minerals in source rocks is crucial for comprehending critical metals accumulation, yet the mechanisms and kinetics of element mobilization at the atomic scale remain mostly unknown. Here, we analyzed the distribution of cobalt (Co) in natural pyrite from a Cu-Co ore deposit and found that metals distribution is best described by steady-state diffusion with constant flux and concentration-dependent diffusivities, rather than transient-state diffusion with time-evolving concentrations. First-principles calculations and diffusion modelling further demonstrate that this diffusion is accelerated by vacancy pathways and is far more efficient than traditional vacancy-mediated lattice diffusion, with element transfer rates higher by almost two orders of magnitude. We conclude that steady-state lattice diffusion induced by vacancies in the presence of fluid can be an efficient mechanism promoting the preferential release of metals into ore fluids and the accumulation of metals during ore formation.

Exploring atom-pairwise and many-body dispersion corrections for the BEEF-vdW functional

The Bayesian error estimation functional (BEEF-vdW) is widely used in surface science and catalysis, because it provides a balanced description of molecular, surface, and solid state systems, along with reliable error estimates. However, the nonlocal van-der-Waals density functional (vdW-DF2) employed in BEEF-vdW can be computationally costly and displays relatively low accuracy for molecular systems. Therefore, this work explores whether atom-pairwise and many-body dispersion treatments represent viable alternatives to using the vdW-DF2 functional with BEEF-vdW. To this end, we investigate the performance of commonly used atom-pairwise corrections [i.e., the Tkatchenko-Scheffler (TS) and the exchange-hole dipole moment (XDM) approaches] and many-body dispersion (MBD) treatments for molecular, surface, and solid-state systems. The results indicate that atom-pairwise methods such as TS and particularly XDM provide a good balance of cost and accuracy across all systems.

Alkyne dichotomy and hydrogen migration in binuclear cyclopentadienylmetal alkyne complexes

The structures and energetics of the binuclear cyclopentadienylmetal alkyne systems Cp2M2C2R2 (M = Ni, Co, Fe; R = Me and NMe2) have been investigated using density functional theory. For the Cp2M2C2(NMe2)2 (M = Ni, Co, Fe) systems the relative energies of isomeric tetrahedrane Cp2M2(alkyne) structures having intact alkyne ligands and alkyne dichotomy structures Cp2M2(CNMe2)2 in which the C[triple bond, length as m-dash]C triple bond of the alkyne has broken completely to give separate Me2NC units depending on the central metal atoms. For the nickel system Cp2Ni2C2(NMe2)2 as well as the related nickel systems Cp2Ni2(MeC2NMe2) and Cp2Ni2C2Me2 the tetrahedrane structures are clearly preferred energetically consistent with the experimental syntheses of several stable Cp2Ni2(alkyne) complexes. The tetrahedrane and alkyne dichotomy structures have similar energies for the Cp2Co2C2(NMe2)2 system whereas the alkyne dichotomy structures are significantly energetically preferred for the Cp2Fe2C2(NMe2)2 system. The potential energy surfaces for the Cp2M2(MeC2NMe2) and Cp2M2C2Me2 systems (M = Co, Fe) are complicated by low-energy structures in which hydrogen migration occurs from the alkyne methyl groups to one or both alkyne carbon atoms to give Cp2M2(C3H3NMe2) and Cp2M2(C3H3Me) derivatives with bridging metalallylic ligands, Cp2M2(CH2[double bond, length as m-dash]C[double bond, length as m-dash]CHNMe2) and Cp2M2(CH2[double bond, length as m-dash]C[double bond, length as m-dash]CHMe) with bridging allene ligands, as well as Cp2M2(CH2[double bond, length as m-dash]CH-CNMe2) and Cp2M2(CH2[double bond, length as m-dash]CH-CHMe) with bridging vinylcarbene ligands. For the Cp2M2C2Me2 (M = Co, Fe) systems migration of a hydrogen atom from each methyl group to an alkyne carbon atom can give relatively low-energy Cp2M2(CH2[double bond, length as m-dash]CH-CH[double bond, length as m-dash]CH2) structures with a bridging butadiene ligand. Five transition states have been identified in a proposed mechanism for the conversion of the Cp2Co2/MeC[double bond, length as m-dash]CNMe2 system to the cobaltallylic complex Cp2Co2(C3H3NMe2) with intermediates having agostic C-H-Co interactions and an activation energy barrier sequence of 13.1, 17.0, 15.2, and 12.0 kcal mol-1.

Polarization-mediated electronic characteristics in Sc2CO2-based 2D metal-ferroelectric heterostructures

The preparation of two-dimensional (2D) monolayer Sc2CO2ferroelectric semiconductor materials provides a promising material candidate for the development of high-performance electronic devices. However, the Schottky barrier present at the electrode/Sc2CO2interface significantly hinders the efficiency of charge injection. In this work, we propose the utilization of 2D metallic materials as electrodes to form van der Waals (vdW) contacts with ferroelectric Sc2CO2monolayers, aiming to achieve reduced Fermi-level pinning at the interface. By leveraging the ferroelectric polarization reversal in Sc2CO2, we demonstrate a controllable transition from Schottky to Ohmic contact, which is critical for optimizing charge injection efficiency. Additionally, we systematically investigate the polarization-mediated electronic properties of 2D metal/Sc2CO2interfaces through first-principles calculations. The findings indicate that a transition from Schottky to Ohmic contact can be induced within these heterostructures by manipulating the polarization reversal of Sc2CO2ferroelectric layers. Notably, the NbS2/Sc2CO2heterojunction, particularly in the upward polarization state, exhibits the highest carrier tunneling probability among the investigated heterojunctions, making it an optimal electrode for Sc2CO2. These findings are essential for regulating Schottky barriers in 2D metal/ferroelectric semiconductor heterostructures and provide theoretical guidance for designing high-performance field-effect transistors based on 2D metal/Sc2CO2vdW heterostructures.

Room-temperature Magnetocapacitance Spanning 97K Hysteresis in Molecular Material

Magnetic capacitor, as a new type of device, has broad application prospects in fields such as magnetic field sensing, magnetic storage, magnetic field control, power electronics and so on. Traditional magnetic capacitors are mostly assembled by magnetic and capacitive materials. Magnetic capacitor made of a single material with intrinsic properties is very rare. This intrinsic property is magnetocapacitance (MC). The studies on MC effect have mainly focused on metal oxides so far. No study was reported in molecular materials. Herein, two complexes: (CETAB)2[CuCl4] (1) and (CETAB)2[CuBr4] (2) (CETAB=(2-chloroethyl)trimethylammonium) are reported. There exist strong H-Br and Br-Br interactions and other weak interactions in complex 2, so the phase transition energy barrier is high, resulting in the widest thermal hysteresis loop on a molecular level to date. Furthermore, complexes 1 and 2 show large MC parameters of 0.247 and 1.614, respectively, which is the first time to observe MC effect in molecular material.

Methane to Methanol Transformation on Cu2+/H-ZSM-5 Zeolite. Characterization of Copper State and Mechanism of the Reaction

Cu-modified zeolites provide methane conversion to methanol with high selectivity under mild conditions. The activity of different Cu-sites for methane transformation is still under discussion. Herein, ZSM-5 zeolite has been loaded with Cu2+ cations (1.4 wt % Cu) as characterized by UV-vis DRS, EPR, EXAFS, and 1H MAS NMR. It is inferred that Cu2+ cations, attached to the cation-exchange Al-O--Si sites of the zeolite framework, can exist in the form of either isolated or paired Cu2+ sites. The transformation of methane to methanol on Cu2+/H-ZSM-5 has been verified by the observation of the methoxy species formation with 13C MAS NMR and FTIR spectroscopy. The related mechanisms have been analyzed by DFT calculations. The calculations show that the paired Cu2+ sites enable heterolytic C-H bond dissociation via the "alkyl" pathway resulting in methylcopper species, which however are not detected experimentally due to further rapid transformation to surface methoxy species through methyl radical formation and recombination with Si-O-Al site. Based on the obtained data, it has been concluded that methane transformation to methanol on paired Cu2+ sites, having no extra-framework oxygen ligand, is possible in Cu-modified zeolites. The pathways of Cu2+ cations regeneration with O2 and H2O have been experimentally explored.

Polarization-Sensitive Solar-Blind Ultraviolet Photodetectors Based on Semipolar (112̅2) AlGaN Film

Wide bandgap semiconductor AlGaN alloys have been identified as key materials to fabricate solar-blind ultraviolet photodetectors (SBUV PDs). Herein, a self-driven SBUV polarization-sensitive PD (PSPD) based on semipolar (112̅2)-oriented AlGaN films is reported. Using the flow-rate modulation epitaxy method, the full widths at half maximum (FWHMs) for the obtained (112̅2) AlGaN along [112̅3̅] and [11̅00] rocking curves are 0.205° and 0.262°, respectively, representing the best results for heteroepitaxial semipolar AlGaN so far. Density functional theory calculations and experimental results reveal that semipolar AlGaN possesses in-plane anisotropy. The self-driven (112̅2) AlGaN PSPDs exhibit strong polarization-sensitive photoresponse with a polarization ratio of 1.54 at 266 nm and rapid response of 450/450 ms compared to other low-dimensional semiconductor materials. More interestingly, we observe positive and negative photoresponse behaviors under UV light illumination due to surface states and charge transfer. Our results may enable potential applications in multifunctional SBUV optoelectronic devices.

Rashba effect originates from the reduction of point-group symmetries

The Rashba effect in a nonmagnetic condensed-matter system is described by the reduction of point-group symmetries. The inversion, two-fold rotation, and reflection symmetries transforming the wavevector k to -k are identified as the origin of a degenerate state according to the time-reversal symmetry. The lack of these symmetries in a bulk system or the breaking of these in a surface system is then identified as the origin of a nondegenerate state. The surface systems Au(111), Au(110), and W(110) are assessed. The bulk system BiTeI is demonstrated for the existence of a nondegenerate state on the basis of first-principles calculations. The related issues of the heterostructure GaAs/AlGaAs and the spin Hall effect are also presented.

Combining Brillouin Light Scattering Spectroscopy and Machine-Learned Interatomic Potentials to Probe Mechanical Properties of Metal-Organic Frameworks

The mechanical properties of metal-organic frameworks (MOFs) are of high fundamental and practical relevance. A particularly intriguing technique for determining anisotropic elastic tensors is Brillouin scattering, which so far has rarely been used for highly complex materials like MOFs. In the present contribution, we apply this technique to study a newly synthesized MOF-type material, referred to as GUT2. The experiments are combined with state-of-the-art simulations of elastic properties and phonon bands, which are based on machine-learning force fields and dispersion-corrected density functional theory. This provides a comprehensive understanding of the experimental signals, which can be correlated to the longitudinal and transverse sound velocities of the material. Notably, the combination of the insights from simulations and experiments allows the determination of approximate values for the components of the elastic tensor of the studied material even when dealing with comparably small single crystals, which limit the range of accessible experimental data.

Modeling the Carbothermal Chlorination Mechanism of Titanium Dioxide in Molten Salt Using a Deep Neural Network Potential

The molten salt chlorination method is one of the two main methods for producing titanium tetrachloride, an important intermediate product in the titanium industry. To effectively improve chlorination efficiency and reduce unnecessary waste salt generation, it is necessary to understand the mechanism of the molten salt chlorination reaction, and consequently this paper conducted studies on the carbon chlorination reaction mechanism in molten salts by combining ab initio molecular dynamics (AIMD) and deep potential molecular dynamics (DeePMD) methods. The use of DeePMD allowed for simulations on a larger spatial and longer time scale, overcoming the limitations of AIMD in fully observing complex reaction processes. The results comprehensively revealed the mechanism of titanium dioxide transforming into titanium tetrachloride. In addition, the presence form and conversion pathways of chlorine in the system were elucidated, and it was observed that chloride ions derived from NaCl can chlorinate titanium dioxide to yield titanium tetrachloride, which was validated through experimental studies. Self-diffusion coefficients of chloride ions in pure NaCl which were acquired by DeePMD showed good agreement with the experimental data.

Impact of N-Doping on MoSe2 Monolayer for PH3, C2N2, and HN3 Gas Sensing: A DFT Study

In this research, the different characteristics of MoSe2 and N-doped MoSe2 monolayers were studied using density functional theory calculations. The negative cohesive energy (-5.216 eV for MoSe2 and -5.333 eV for N-MoSe2) verified their energetical stability. The variation of structural, electronic, and optical properties of MoSe2 and N-MoSe2 via adsorption of PH3, C2N2, and HN3 gases are studied. The N-doping results in a stronger adsorbent-gas interaction, resulting in maximum adsorption energy of -0.036, -0.033, and -0.198 eV for the selected gases. The MoSe2 and N-MoSe2 monolayers showed a direct band gap of 1.48 eV and 1.09 eV, respectively. However, upon interaction with the gases, a notable shift in the band gap of both adsorbents is observed. N-MoSe2 showed semiconductor-to-conductor transition via C2N2 and HN3 adsorption. The sensitivity of MoSe2 for the selected gases has improved remarkably via N-doping. Also, HN3 gas can be easily detected by the N-MoSe2 monolayer due to the greater changes in work function (0.45 eV). The absorption coefficient of both adsorbents is over 105 cm-1 order in the UV region, which suffers a mild peak shifting due to gas adsorption. This study suggests that N-MoSe2 can be a potential candidate for selected gas sensing.

Anisotropically Epitaxial P-N Heterostructures Actuating Efficient Z-Scheme Photocatalytic Water Splitting

Crafting anisotropically epitaxial p-n heterostructures with Z-scheme charge transmission is a promising avenue toward excellent photocatalytic efficiency, yet the large lattice mismatch and diverse crystal growth habits between components have often arisen as a big challenge to this goal. Here, anisotropically epitaxial p-n heterostructures with 19.8% lattice mismatch are obtained via a dynamics-mediated seeded growth tactic under reaction temperature as low as 60 °C. Structural analyses reveal the epitaxy of hexagonal CuS nanoplates onto CdS nanowires through forming misfit dislocations at {101̄0} interface and stacking faults inside CuS nanoplates. Experimental and density functional theory calculation results verify the Z-scheme photo-carriers transfer in epitaxial CdS-CuS heterostructures, which exhibit a much enhanced visible-light-driven H2 generation capability than non-epitaxial CdS/CuS counterpart, and the site-specified NiOOH photo-deposition over CdS-CuS heterostructures leads to a distinguished H2-evolving activity ≈65 and 36 times promotion compared to those of pristine CdS and Pt-loaded (3 wt.%) CdS, respectively. The study can enlighten new thinking to the steerable synthesis of epitaxial nanostructures with large lattice mismatch for various promising applications.

Theoretical screening of single-atom catalysts (SACs) on Mo2TiC2O2 MXene for methane activation

Producing value-added chemicals and fuels from methane (CH4) under mild conditions efficiently utilizes this cheap and abundant feedstock, promoting economic growth, energy security, and environmental sustainability. However, the first CH bond activation is a significant challenge and requires high energy. Efficient catalysts have been sought for utilizing CH4 at low temperatures including emerging single-atom catalysts (SACs). In this work, we screened fourteen transition metals (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Pt) doped at a single oxygen vacancy in Mo2TiC2O2 (TMSA-Mo2TiC2O2 SACs) for methane activation using density functional theory (DFT) calculations. Our results reveal that methane adsorption is thermodynamically stable on all simulated TMSA-Mo2TiC2O2 SACs, with the adsorption energies (Eads) ranging from -0.92 to -0.40 eV. For the CH activation process, Ru-SAC exhibits the lowest activation barrier (Ea) of 0.22 eV. In summary, Ru-, Rh-, Co-, V-, Cr-, Ti-, and Pt-SACs demonstrate promising catalytic properties for methane activation, with Ea values below 1.0 eV and an exothermic nature. Our findings pave the way for the design and development of novel single-atom catalysts in MXene materials, applicable not only for methane activation but also for other alkane dehydrogenation processes.

In Situ Programmable, Active, and Interactive Crystallization by Localized Polymerization

Additive manufacturing has sought active and interactive means of creating predictable structures with diverse materials. Compared to such active manufacturing tools, current crystallization strategies remain in statistical and passive programs of crystals via macroscale thermodynamic controllers, commonly lacking active means to intervene in crystal growth in a spatiotemporal manner. Herein, a strategy toward active and interactive programming and reprogramming of crystals, realized by real-time tangible feedback on growing crystals by delicately controlling the degree of in-situ, localized photopolymerization of polymeric structures via additive manufacturing is presented. Using this strategy, crystals can be seeded, guided, and even reprogrammed in a supersaturated liquid resin. In principle, the localized formation of sparse polymeric networks within supercooled resins can induce density fluctuation to trigger seed nucleation instantaneously, whereas the formation of dense networks can lower molecules' mobilities to inhibit crystal growth. Assisted by these active triggers and deterministic procedural aspects in additive manufacturing, growing crystals can be tangibly interacted through programmed polymeric structures, strengthening deterministic characteristics in crystal growth. It is suggested that crystal growth can be programmable with deterministic hierarchies within the created crystal's morphologies within the background of inherent stochasticity in crystallization, launching an era of convolutional growth of crystals.