ABSTRACT Nitrate (NO 3 − ) pollution threatens aquatic ecosystems and drinking water safety, while electrocatalytic nitrate reduction to ammonia (NO 3 RR) offers a route for pollutant removal and nitrogen recovery. Here, density functional theory calculations were used to screen 100 graphene‐supported asymmetric M1N 3 ─M2N 4 dual‐atom catalysts (M1, M2 = 3 d transition metals) by considering stability, pristine‐site availability, reaction pathways, and ammonia desorption. Single‐H adsorption free energy alone was insufficient to describe competition with the hydrogen evolution reaction in dual‐site systems; *2H and *OH surface states should also be considered when determining catalyst‐specific electrochemical potential windows. NO 3 − mainly adopted side‐on@bridge and side‐on@M1 configurations, leading to site‐dependent pathway branching. Zero or near‐zero U L values often coincide with strong NH 3 binding. NiN 3 ─ZnN 4 ‐P1 and CuN 3 ─CoN 4 ‐P2 displayed balanced profiles, with limiting potentials of −0.29 and −0.23 V and NH 3 desorption free energies of 0.12 and 0.35 eV, respectively. These results provide theoretical guidance for evaluating and designing asymmetric dual‐site NO 3 RR catalysts by jointly considering site availability, pathway thermodynamics, and product release.

The unique structural features of the frustrated Lewis pairs (FLPs) have made them highly attractive for small molecules activation. In this study, the -C₆F₅ groups of the archetypal Lewis acid B(C₆F₅)₃ were substituted with -H, -C₆Cl₅, -C₆Br₅ and -C₆I₅ groups. And the resulting analogues were paired with the Lewis base I t Bu to construct a series of FLPs, which were subsequently investigated via theoretical calculation methods. The intrinsic nature of the substituent effects on the binding energy of FLPs was elucidated through the analyses of energy decomposition (sobEDA), orbital, and molecular fragment density difference (MFDD). These results demonstrate that the interaction strength of the hydrogen-substituted B(C₆F₅)₂H-I t Bu is significantly enhanced, which stems from its relatively low steric hindrance effect. For B(C₆F₅) x (C₆Y₅) 3-x -I t Bu (x = 0, 1; Y = Cl, Br, I), the coexistence of ligand effects and dispersion effects ensures that their interaction strengths remain larger than that of B(C₆F₅)₃-I t Bu, despite the presence of strong steric hindrance effects. However, for B(C₆F₅)₂(C₆Y₅)-I t Bu (Y = Cl, Br, I), the interaction is weakened by the combination of a weak ligand effect and significant steric hindrance. Consequently, B(C₆F₅)₂(C₆Y₅)-I t Bu (Y = Cl, Br, I) exhibits promising potential as catalysts for small molecules activation, offering a theoretical foundation for designing high performance FLPs.

Quantum chemical calculation using density functional theory at the BP86-D3(BJ)/def2-TZVPP level and ab initio theory at the CCSD(T)/def2-TZVPP level have been carried out for the homoleptic and heteroleptic borylones L1-B(Ph)-L2 with the ligands L1, L2 = PPh3, SPh2, N2, CO, CS, NHCMe, CAACMe. The computation of the bond dissociation energy suggests that all borylones considered in this work should be stable enough to be observed experimentally. A surprising result is the finding that the homoleptic borylones B(Ph)(N2)2 and B(Ph)(SPh2)2 have a higher BDE than the corresponding carbones. It seems possible that bis-dinitrogen borylones can be synthesized and structurally characterized under appropriate conditions. The boron-ligand bonds of the heteroleptic borylones L1-B(Ph)-L2 influence each other, so that one bond becomes stronger and the other weaker, but to different degrees. The BDEs do not always show the same trend, as the electronic and geometric relaxation of the fragments can strongly influence the energy change due to bond breaking, which affects the thermodynamic stability of the compounds. The EDA-NOCV results show that Pauli repulsion is often the strongest energy component of the chemical bond, determining the bond strength and bond length.

Passivating defects and enhancing the stability of perovskite materials are key focuses in perovskite solar cell research, particularly the simultaneous passivation of A-site vacancies and undercoordinated B-sites. This study designs a four-end zwitterionic amino acid (ZAA), with two ammonium arms and two carboxylate arms around the central carbon symmetrically. Through NH3+ occupying A-sites and COO- passivating B-sites, ZAA forms a stable "quadrupedal anchoring" mode on the perovskite surface. Selective fluorination of ZAA yields four derivatives, which are classified into two categories: ZAA-1 (ZAA(allH) and ZAA(CF)) and ZAA-2 (ZAA(NF) and ZAA(allF)). ZAA-1 passivates undercoordinated Pb, reducing surface states and modulating the band gap to a value close to that of pristine MAPbI(3), while ZAA-2 with excessively long Pb & ctdot;O distances introduces oxygen-derived impurity states near the Fermi level, causing severe band gap reduction. Furthermore, ZAA-1 increases the formation energies of both surface Pb and I vacancies and provides robust resistance against water invasion. Compared to ZAA(allH), ZAA(CF) exhibits superior overall protective performance, as it does not undergo significant displacement upon H2O adsorption due to the absence of strong attractive interactions with water. Additionally, the ZAA(CF)-modified system demonstrates comparable performance to the pristine material in photovoltaic device simulations. This work presents an effective strategy of employing a bifunctional four-end ZAA to construct a protective layer that concurrently addresses defect passivation and stability enhancement in perovskite materials.

The mechanical performance of electrospun polyacrylonitrile (PAN)-derived carbon nanofibers (CNFs) is intrinsically linked to the thermochemical transformation pathways governing polymer-to-carbon conversion. Although oxidative stabilization and carbonization are recognized as essential processing steps, their coupled role in directing structural evolution and mechanical integrity remains insufficiently resolved. This study systematically elucidated how stabilization history constrained carbonization behavior and thereby controlled the mechanical response of PAN-derived CNFs. The results demonstrated that stabilization played a decisive role on mechanical performance, with tensile strength exhibiting strong sensitivity to stabilization temperature and elastic modulus primarily influenced by stabilization duration. Insufficient stabilization preserved residual linear chain segments that underwent uncontrolled scission during carbonization, leading to structural collapse and mechanical degradation. Conversely, optimal stabilization promoted the formation of a densely crosslinked heterocyclic ladder architecture that provided a thermostable structural template. During carbonization, this stabilized framework underwent aromatization and polycondensation to form turbostratic graphite structures, while the degree of graphitic ordering remained limited by the precursor architecture. These findings highlight a pathway-dependent structural inheritance in PAN-to-carbon conversion and emphasize the critical role of stabilization in shaping the mechanical potential of CNFs, offering broader insights into the formation of mechanically robust carbon materials for advanced structural and functional applications.

This study aims to systematically investigate the influence of substituent effects on the strength of Lewis acid–base interactions in frustrated Lewis pairs (FLPs). Specifically, -C6F5 groups of the classical Lewis acid B(C6F5)3 are sequentially replaced with -C6Cl5, -C6Br5, and -C6I5 groups, and the Lewis acids are paired with the Lewis base 1,3-disubstituted imidazol-2-ylidene (ItBu) to form FLPs. Further energy decomposition analysis (sobEDA), orbital analysis, and molecular fragment density difference (MFDD) analysis reveal the nature of the substituent effect on the interaction energy (∆Eint) of the FLPs. The research findings indicate that the ∆Eint of B(C6F5)3-ItBu, B(C6F5)x(C6Y5)3−x-ItBu (x = 0, 1, 2; Y = Cl, Br, I) originates mainly from the interaction between the outermost halogen atom of the Lewis acid and the central carbon (C) atom of the Lewis base, rather than from the interaction between the central atoms boron (B) and carbon (C). This mechanism ultimately leads to a ∆Eint for B(C6F5)2(C6Y5)-ItBu (Y = Cl, Br, I) that is comparable to that of B(C6F5)3-ItBu. This indicates that modified B(C6F5)2(C6Y5) (Y = Cl, Br, I) exhibits greater potential for the construction of novel FLPs.

The catalytic activation and reduction of N2 for ammonia synthesis have attracted substantial research interest due to their pivotal role in sustainable nitrogen utilization. Herein, density functional theory (DFT) is employed to systematically investigate the adsorption and reduction of N2 on planar four-metal-atom clusters (M2Cu2, M = Sc, Y, Ti, Zr, Hf, Sn, Pd, Pt, Ag, Au, Zn, Ga) supported by two-dimensional substrate C5N2H2. In the twelve catalysts, four metal atoms exhibit two unique coordination modes with the substrate: 31-type (each M coordinates to three N atoms; each Cu to one N atom) and 22-type (each M and Cu both coordinate to two N atoms), with the 31-type ones having a higher symmetry. All these catalysts can form stable structures, and generally the 31-type ones have more negative formation energies and binding energies of metal atoms on the substrate. The 31-type catalysts adsorb N2 more strongly, with the Zr2Cu2@C5N2H2 catalyst showing the highest adsorption energy of -1.39 eV. The M metal dominates N2 adsorption in the 31-type catalysts, while Cu also plays a prominent role in 22-type ones. By evaluating N2 and H adsorption energies, three 31-type catalysts (Zr, Y, and Hf) were selected for further protonation pathway analysis. The Zr2Cu2@C5N2H2 catalyst exhibits optimal performance for the nitrogen reduction reaction (NRR) with the lowest rate-determining step energy barrier of 0.84 eV (*NH2NH3 -> *NH3NH3) across both enzymatic and consecutive mechanisms. Notably, a pronounced Metal-site Charge Transfer Effect (MCTE) is observed, where substantial electron gain by the active metal atoms correlates with elevated energy barriers in each hydrogenation step. These findings demonstrate that planar fourmetal-atom cluster catalysts M2Cu2@C5N2H2, with unique coordination environments, particularly the 31-type ones, provide an effective strategy for boosting N2 activation and NRR performance.

DFT calculations were utilized to explore the electrocatalytic nitrogen reduction reaction (NRR) mechanisms catalyzed by trimetallic clusters M3 (M = Ti, Zr, V, and Nb), both unsupported and supported by bowl-shaped sumanene. The substrate enhanced N2 adsorption and activation but hindered hydrogenation due to more negative adsorption energies. The substrate promoted hydrogenation of nitrogen, reducing the interference of the hydrogen evolution reaction (HER) and enhancing the NRR selectivity. Three fundamental and three mixed pathways were investigated, and the rate-determining step (RDS) was identified for each pathway. Through a consecutive pathway, V3 exhibits the best catalytic performance with the free energy change of the RDS (ΔGRDS) as 0.82 eV, while the optimal supported catalyst, Nb3 supported on sumanene, has a ΔGRDS of 1.43 eV. The introduction of the substrate generally increased ΔGRDS by 0.3-0.8 eV. The substrate can effectively regulate the distance between metal atoms and reduce the change in geometric structures of M3 clusters during the reaction process, thereby enhancing the structural stability of the active sites in the NRR process. The substrate can reduce the reactivity differences among catalysts with different metal types. This so-called blurring effect allows cheap metals to partially replace noble metals while maintaining catalyst performance. A linear correlation between charge changes on M3 or M3 together with the substrate and ΔG was observed, providing a potential method for optimizing the catalyst performance and designing new catalysts.

Structural DNA Nanotechnology facilitates the precise and versatile fabrication of nanomaterials possessing complex geometries and functionalities. DNA-silica composites (DSCs), as representative hybrid materials, demonstrate distinctive application potential in emerging fields such as nanophotonics and nanoelectronics. However, achieving precise control over the silica shell thickness remains a significant challenge in silicification processes utilizing DNA nanostructure templates. This study investigates the effect of organoalkoxysilanes (OASs), varying in substituent type and quantity, on DNA-templated silicification. We identify a negative correlation between the number of substituents on the OAS precursor and the resulting silica shell thickness, enabling nanometer-scale control. Compared to conventional tetraethyl orthosilicate (TEOS), the tailored OAS variants significantly reduce silica shell thickness while simultaneously enhancing DSC monodispersity, achieving values up to 76.7% following 24-h reactions. Furthermore, a positive correlation is established between the substituent steric occupancy ratios and the monodispersities of DSCs. Our approach also enables effective diversification of the surface functionalities of DSCs. These advances provide critical foundational support for the application of DSCs in nanofabrication, photonic crystal engineering, and interdisciplinary domains.

Many radical-involving palladium-catalyzed organic transformations are proposed to proceed via mononuclear palladium(I) halide intermediates. However, isolable palladium(I) complexes of this type remain elusive, casting doubt on these mechanistic hypotheses. In this work, we demonstrate that using the bulky bisphosphine ligand bis(di-tert-butylphosphino)ferrocene (dtbpf) enables the one-electron reduction of palladium(II) halide complexes Pd(dtbpf)X2 (X = Cl, Br, I) to yield isolable mononuclear palladium(I) halides [Pd(dtbpf)X] (X = Cl, Br, I) in high yields. These palladium(I) complexes have been characterized by paramagnetic 1H NMR spectroscopy, single-crystal X-ray diffraction, electron paramagnetic resonance (EPR) spectroscopy, and Pd K-edge X-ray absorption spectroscopy. Theoretical studies revealed that [Pd(dtbpf)X] (X = Cl, Br, I) in their doublet ground states have their single-occupied molecular orbitals in antibonding character and that their Pd-X bonds are polar covalent bonds. Furthermore, speciation studies confirmed the formation of palladium(I) halide species in reactions of the palladium(0) complex [Pd(dtbpf)(norbornene)] with benzyl halides and perfluoroalkyl iodide, as well as in the thermal and photoirradiated decomposition of the aryl palladium(II) complex [Pd(dtbpf)(C6H4-p-Me)]I. These findings provide compelling evidence for the involvement of palladium(I) halide intermediates in relevant palladium-catalyzed transformations.

In recent years, halide perovskites have made great progress due to their excellent optoelectronic properties. Taking advantage of the excellent elemental tunability of perovskites, a novel perovskite is designed as DAPPb2I6, where DAP indicates NH3(CH2)5 NH32+ The geometry, stability, electronic structure, and optical properties of DAPPb2I6 are investigated based on first principles calculations. Doping effects are taken into account by replacing I by Br. The ab initio molecular dynamics (AIMD) simulations show that these materials have high thermodynamic stability at room temperature. All DAPPb2(I1-xBrx)6 have indirect bandgaps with the calculated values of 2.22-2.72 eV, indicating that introducing of DAP increase the bandgap remarkably. The conduction bands are mainly contributed by Pb atoms, followed by halogen atoms, while the valence band part is mainly contributed by halogen atoms. These materials have high remarkable light absorption capacity with light absorption coefficients up to 4.5 x 105 cm-1 with wavelengths in the range of 200-450 nm. Doping of Br can increase the bandgap values and the cause blue-shift of the light adsorption. The newly designed DAPPb2(I1-xBrx)6 may serve as a promising wide bandgap perovskite material.

In this work, we conducted a detailed investigation of the catalytic mechanism of the electrocatalytic nitrogen reduction reaction (NRR) by density functional theory (DFT) calculations, focusing on fullerene (C 60 ) doped with single or dual Fe atoms. The results indicate that single or dual Fe atoms can be stably embedded within defective C 60 , yielding Fe 1 C 59 and Fe 2 C 58 , respectively. Both catalysts exhibit excellent performance in the adsorption and activation of N 2 , with Fe 2 C 58 demonstrating a certain degree of superiority. Based on the investigation of the NRR reaction pathways on these catalysts, it has been found that, despite varying pathways in different systems, the ratedetermining step (RDS) is consistently the first hydrogenation step *N 2 → *NNH. Both thermodynamic and kinetic analyses indicate that Fe 2 C 58 exhibits superior catalytic performance compared to Fe 1 C 59 . Specifically, the energy barrier for the RDS of the optimal reaction pathway on Fe 2 C 58 is only 0.690 eV. Additionally, Fe 2 C 58 also demonstrates an advantage in suppressing the competitive hydrogen evolution reaction (HER). The present work demonstrates that a catalyst composed of C 60 doped with dual Fe atoms exhibits superior stability, electrocatalytic activity, and selectivity for NRR compared to a catalyst doped with a single Fe atom. This research provides a foundation for the design and synthesis of other heteroatom-doped fullerene catalysts.

MgH2 is widely considered a great potential solid hydrogen storage material along with hydrogen energy and is recognized as a kind of renewable energy.However,its poor hydrogen absorption and desorption kinetics and high thermodynamic stability limit its application.In this work,CeO2@NC(Nano-Carbon supported CeO2 particles)nanosphere catalysts were synthesized by a one-step hydrothermal method,and the particle size of CeO2 was about 7 nm and MgH2+x wt.％CeO2@NC(x=0,2,4,6,8)com-posites were prepared by ball milling.It was found that the generation of oxygen vacancy defects and the multivalent environment of carbon-supported Ce can play the role of hydrogen pump and synergis-tically catalyze MgH2.Adding a carbon layer prevents nano-effect generation to a certain extent,which makes H atoms diffuse rapidly.The results show that MgH2+6 wt.％CeO2@NC can release 5.89 wt.％H2 in 50 min at 593 K,and MgH2 without catalyst can only release 0.31 wt.％H2.As the amount of catalyst added increases,the dehydrogenation activation energy of the composite material decreases by 31.11 kJ/mol H2.Through density functional theory calculation,it was found that the adsorption energy of the material increased by 1.21 eV after the addition of the catalyst,and the Fermi level of the density of states of the composite increased,which accelerated the electron transfer rate.This study can help work-ers catalytically modify the hydrogen storage performance of MgH2.Introducing oxygen vacancy defects in carbon-based supported multivalent transition metal oxide catalysts gives them a unique electronic structure and excellent catalytic activity.

Palladium (Pd), the second most abundant platinum group metal, exhibits excellent electrochemical activity but remains understudied for electrochemical oxidative disinfection. Consequently, this study employed Joule heating deposition to develop a palladium oxide-coated titanium electrode (Pd/Ti-TiO2) for efficient electrochemical disinfection. This system demonstrated rapid inactivation effects on both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at low current densities. In 30 mM NaCl solution with an applied current density of 3 mA/cm2, the reaction vessel efficiently eliminated 107 CFU/mL E. coli within 1 min and 107 CFU/mL S. aureus within 0.5 min. Medical wastewater treatment validated practical applicability, achieving over 99.99% microbial inactivation within 20 min at 5 mA/cm2. Mechanistic studies revealed that reactive chlorine species (RCS) generated during the electrolysis process were the primary cause of bacterial inactivation, leading to cell membrane rupture, enzyme inactivation, and DNA degradation. Compared with conventional RuO2-IrO2 electrodes (161 Wh/m3), this electrode reduced the energy requirement for complete inactivation to 38.9 Wh/m3. This study highlighted the potential of Pd electrodes for sustainable water disinfection, characterized by high efficiency and adaptability to complex wastewater environments.

This study outlines a detailed reaction mechanism for the Pd-catalyzed β-C(sp3)-H arylation of free carboxylic acids, which unfolds through three distinct stages: (i) ligand-driven β-C(sp3)-H activation, leading to the formation of the five-membered-ring intermediate IM2; (ii) oxidative addition of ArI to Pd of IM2, resulting in the Pd(IV) complex IM4; and (iii) reductive elimination, which produces the desired arylated product and regenerates the active species for the next catalytic cycle. Notably, the oxidative addition step, with a free energy barrier of 28.5 kcal/mol, is identified as the rate-determining step (RDS) of the entire catalysis. EDA-NOCV analysis revealed that the RDS is governed by a combination of intrinsic energy (ΔEint) and preparation energy (ΔEprep). Building on these mechanistic insights, we further explored a series of bidentate pyridone ligands (L2-L12) aimed at lowering the free energy barrier of the RDS. Among them, ligand L9 exhibits exceptional potential in promoting the overall reaction efficiency. Furthermore, L9 possesses computational potential in facilitating remote γ-C(sp3)-H arylations. These findings offer valuable mechanistic insights into both β- and γ-C(sp3)-H arylations, providing a theoretical guide for improving current catalytic systems and advancing the development of new arylation methodologies for free carboxylic acids.

The development of single chiral source-derived ligands to fine-switch enantioselectivity has been a key aspect in asymmetric catalysis. Herein, in this study, using the same chiral source l-prolinamide as the starting material, we synthesize 14 new diphenyl ether bridged C2-symmetric rigid chiral tertiary amine-derived dioxide ligands (abberviated as BPE-2NO) and 9 new m-phenylene bridged C2-symmetric rigid chiral tertiary amine-derived dioxide ligands (abberviated as Phe-2NO); their effectiveness was demonstrated in the first switch of enantioselectivity in palladium(II)-catalyzed Friedel-Crafts alkylation. In the presence of palladium acetate as the Lewis acid, both enantiomers of indole derivatives can be prepared in good-to-excellent yields and enantioselectivities by using the single chiral source-derived Eagle-shaped BPE/Phe-2NO ligands. Control experiments and density functional theory calculations provide a rational explanation for the above observations. This study was the first switch of enantioselectivity in palladium(II)-catalyzed Friedel-Crafts alkylation by using the single chiral source-derived ligands.

The foam drainage technique is considered to be a promising measure for solving the problem of liquid accumulation in natural gas wells and gathering pipelines. However, differences in gases can greatly affect the performance of surfactant foam, thus limiting the application of this technology. To elucidate the mechanism of natural gas components influencing foam properties, the interfacial properties of hydrocarbon gas-surfactant-water system were analyzed thermodynamically and kinetically by combining molecular dynamics simulations and foaming experiments. The results show that with the increasing alkane chain length, the foaming volume and half-life of the foam are gradually rising, while the gas–liquid interfacial tension is decreasing, which is consistent with the results of molecular dynamics simulations. Compared with air, hydrocarbon gases are more beneficial for foam generation and stabilization. The interfacial adsorption of alkane molecules and the interaction between alkanes and surfactants are the main factors affecting the interfacial tension and film stability of different systems.

The boron atom is a highly electrophilic reagent due to the presence of its empty p orbital, making it prone to undergo electrophilic addition reactions with the carbon-carbon double bonds of olefins. In this study, the classical C-C reaction pathway occurs when a boron atom attacks the C-C bond of cyclohexene, resulting in the formation of the eta(2) (1,2)-BC6H10 complex (A) that contains a borirane radical subunit. This complex can further undergo photoisomerization, leading to the formation of a 3,4,5,6-tetrahydroborepine radical (C) through the cleavage of C-C bonds. In addition, two 1-boratricyclo[4.1.0.02,7]heptane radicals with chair (B) and boat (B ') conformations were observed through alpha C-H cleavage reactions. Bonding analysis indicates that these radicals involve a four-center-one-electron (4c-1e) bond. Under UV light irradiation, these two radicals undergo ring-opening and rearrangement reactions, resulting in the formation of a 1-cyclohexen-1-yl-borane radical (D), which is a sp(2) C-H activation product. These findings delineate a potential pathway for the synthesis of organoboron radicals through boron-mediated C-H and C-C bond cleavage reactions in cycloolefins.

The prohibitive risk of isolated tricuspid valve (TV) surgery encouraged rapid development of a transcatheter solution for tricuspid regurgitation (TR). The favorable results of these devices informed recent guidelines to recommend considering transcatheter treatment of symptomatic secondary severe TR in inoperable patients. Transcatheter TV repair systems usually reduce TR through leaflet approximation and direct annuloplasty. Orthotopic transcatheter TV replacement (TTVR) devices generally rely on radial force and tricuspid leaflet engagement for implantation and stability. The LuX-Valve is a novel radial force-independent orthotopic TTVR device that is operated through the trans-atrial approach. Its radial force-independency is achieved through an interventricular septal anchor tab (septal insertion) and two leaflet graspers (leaflet engagement). Such a unique design makes the intraprocedural imaging different from that of other currently available TTVR systems. The latest generation of this device, the LuX-Valve Plus, comes with a newly designed delivery system through the transjugular approach, which makes the intraprocedural monitoring and adjustment of the device even more complex for successful implantation. However, its unique imaging needs for intra-procedural guidance and post-operative evaluation have not been described before. Therefore, we aimed to elaborate the key steps of transesophageal echocardiography (TEE) to guide this novel procedure. Herein, the primary 2-dimensional (2D) and 3-dimensional (3D) echocardiographic work planes are proposed and the critical steps are emphasized for better communication between imagers and interventionists. The suitability of 2D and 3D echocardiography to guide this procedure is also discussed to increase the flexibility of choice during the implantation.