Regulation of the CO2 hy-drogenation process to ob-tain highly selective target products is a challenging and important research topic.In this study,we re-port the key role of PO43-anions modified on the Ru/TiO2 catalyst surface in regulating the CO2 hy-drogenation process.Ion chromatography,X-ray diffraction,X-ray photoelectron spec-troscopy,and transmission electron microscopy confirmed the successful preparation of the Ru/TiO2 catalyst modified by PO43-anions.The original Ru/TiO2 catalyst showed poor catalytic activity in CO2 hydrogenation,and the main hydrogenation product was CO.With the PO43-anion-modified Ru/TiO2 catalysts,the conversion of CO2 was clearly im-proved,and the hydrogenation product changed from CO to CH4.XPS characterization and DFT theoretical calculations confirmed that the modified PO43-anions interacted mainly with the Ru metal site on the Ru/TiO2 catalyst surface,effectively regulating the surface electronic properties of the Ru metal,which affected the conversion efficiency of CO2.In addition,CO temperature-programmed desorption and diffuse reflectance infrared Fourier transform spectroscopy characterization revealed that the adsorption of CO inter-mediates improved after the Ru metal surface was modified with PO43-anions,which was beneficial for further CO hydrogenation and the formation of CH4 products.Our work ex-pands the research strategies of anion-modified metal-based catalysts that regulate the hy-drogenation performance of CO2 and provides a new direction for further understanding the influence mechanism of the catalyst surface structure on hydrogenation performance.
Based on the transforma-tion between different phase structures,lead halide perovskite materi-als can achieve interest-ing fluorescence response to water,heat,and pres-sure.Here,we achieve a novel fluorescence response to solvents on a three-dimensional perovskite(3D,CsPbBr3)that is transformed from zero-dimensional perovskite(0D,Cs4PbBr6).The phase transfor-mation process is realized by extracting excess CsBr from Cs4PbBr6 by tungstosilicic acid(TSA).The phase transformation product(U-CsPbBr3)with more surface defects shows weak photoluminescence(PL)emission,but shows bright green PL emission immediately when it is wetted with some solvents such as methyl acetate,acetone,tetrahydrofuran,and acetonitrile.Repeatable and time-controlled fluorescence response can be achieved by ad-justing solvents with different volatility.This unique property can be possibly used in anti-counterfeiting or electrowetting display,etc.
The photodissociation of H2 near its second dissociation threshold yields two competing channels:H(1s)+H(2s)and H(1s)+H(2p).While cosine oscillations in the branching ratio,signatures of quantum interference between the two pathways,were previous-ly observed in HD and D2,they remained undetected in H2 due to the rotational state distribution of conventional molecular beams.Here,we isolate the ground rotational state(J"=0)of para-H2 and combine delay-time-curve measurements with velocity map imaging to directly resolve the branching ratios,confirming universal quantum interference across all isotopologues.The oscillations are quantitatively described by a p-wave scattering model with effective spherical potentials,where fitted parameters for H2 agree with those derived from HD,D2,and ab initio calculations.The interference arises from a phase difference between two dissociation channels,which is determined by the product of the fragment wavevector and the width difference between the two effective potentials.These results establish quantum interference as a fundamental driver of molecu-lar dissociation and provide benchmark data for refining theoretical models of multichan-nel dynamics.
Traditional receptor-ligand theo-ry prioritizes equilibrium affinity,but kinetic factors—especially the energy barriers for association and dissociation—are often important.Here,we hypothesize that protein-ligand dissociation pro-ceeds via a well-defined activation barrier that can be quantified through physically realistic simula-tions.We employ a temperature-coupled molecular dynamics(TCMD)protocol that selec-tively heats the ligand while maintaining the protein near physiological temperature,there-by promoting unbiased dissociation events without sacrificing structural integrity.The re-sulting temperature-dependent off-rate follows a theoretically consistent trend,allowing ro-bust extraction of activation energies.Applied to streptavidin-biotin benchmarks,TCMD reproduces experimental dissociation activation barriers with a mean absolute error of 1.2 kcal/mol.Beyond numerical agreement,TCMD provides high-resolution mechanistic in-sight by showing how interaction-energy fluctuations,hydrogen-bond reordering,and dis-crete conformational changes shape the exit pathway,thereby linking the estimated barrier to its structural origins.These results establish,with near-experimental fidelity,the activa-tion barrier governing dissociation,encouraging a move beyond affinity-only perspectives.Furthermore,the unbiased trajectories provide a detailed,time-resolved view of contact re-organization during dissociation,offering a realistic framework for studying binding kinet-ics at atomic resolution.
We have successfully utilized noncollinear four-wave mixing in argon to generate～160 nm fem-tosecond laser pulses,which can serve as the vacuum ultraviolet pump laser for time-resolved measurements.By performing a femtosecond time-resolved pho-toelectron imaging experiment,the ultrafast decay dynamics of pyrrole following single-photon excitation at～160 nm is investigated.Two time constants of 50+17-12 and 250±50 fs are derived based on the analysis of the time-resolved photoelec-tron spectroscopy spectra and assigned to the excited-state lifetimes of high-lying valence and Rydberg states.In particular,the analysis of the photoelectron angular distributions clearly indicates that the initially prepared valence ππ* state(s)should be of mixed valence/Rydberg character.
Heterodyne-detected second harmonic genera-tion(HD-SHG)spec-troscopy was used to study the effects of po-tential and ionic strength on the struc-ture of water molecules at Pt electrode/LiClO4 electrolyte interface.The contribution from Pt electrode and the third-order nonlinear sus-ceptibility,x(3),contribution from water molecules in the electric double layer(EDL)were separated according to the SHG intensity and phase measurements of Pt/LiClO4 interface at different potentials.The results showed that the contributions from the Pt electrode and water molecules in the EDL both presented a parabolic relationship with the applied poten-tial,and the lowest point of the parabola was close to the potential of zero charge.Com-pared with the contribution from the Pt electrode,the x(3)contribution from water molecules in the EDL ranged from 0 to 22％.Moreover,the x(3)contribution from water molecules in the EDL increased with increasing interfacial potential,which was due to the more ordered arrangement of water molecules in the EDL.In addition,under open circuit potential,the SHG intensity and SHG phase measurements with different concentrations of LiClO4 showed that the x(3)contribution from water molecules in the EDL increased with the decrease of ionic strength,which was attributed to the increase of the number of or-dered water molecules in the EDL.These results provide quantitative information for the x(3)contribution of water molecules in the EDL to SHG signal at the electrode/dilute elec-trolyte interfaces.
Here we demonstrate the selective excita-tion and nanoscale imaging of vibronic cou-pling in artificially constructed molecular oligomers using 1-0 resonance tip-enhanced Raman spectroscopy(TERS).By tuning the laser energy to resonate with a specific vi-bronic transition(i.e.,|S0,v=0>→|S1,v=1>)of a single zinc phthalocyanine(ZnPc)molecule,we achieve selective enhancement of the corresponding vibrational mode by over-an-order of magnitude.Applying the 1-0 resonance TERS to an artificially constructed molecular dimer,we investigate the vi-bronic coupling of localized intramolecular vibrational modes with the delocalized excitonic modes.We find that the TERS enhancement is governed by the effective transition dipoles of the excitonic modes,with superradiant excitons yielding significantly stronger signals than subradiant ones.Spatially resolved TERS imaging patterns further reveal that the lo-cal Raman responses are dictated by the transition dipole configurations of the excitonic modes.Leveraging this knowledge,the 1-0 resonance TERS signal can be further increased with the growing number of molecules in a coherently coupled linear chain.Our findings es-tablish a powerful methodology for interrogating vibronic coupling effects in molecular ag-gregates at the single-molecule level and offer a new route toward designing high-perfor-mance,narrow-band molecular light sources and ultrasensitive vibrational sensors.
Criegee intermediates are highly reactive zwit-terionic species formed from alkene-ozone re-actions that play important roles in atmo-spheric oxidation chemistry.This study inves-tigates the kinetics of formaldehyde oxide(CH2OO)reactions with(E)-1,1,1,4,4,4-hex-afluoro-2-butene(CF3CH=CHCF3)and sul-fur hexafluoride(SF6)using time-resolved laser-induced fluorescence detection of OH radicals.For the CH2OO+CF3CH=CHCF3 re-action,we measured rate coefficients from 280 K to 323 K at 5-10 Torr,finding values ranging from(1.4±0.3)×10-14 to(3.0±0.5)×10-14 cm3·molecule-1s-1.The reaction shows posi-tive temperature dependence with an activation energy of(2.7±0.4)kcal/mol.Compared to non-fluorinated alkenes,the fluorinated compound reacts approximately 33 times faster,demonstrating the significant enhancement effect of trifluoromethyl groups.For CH2OO+SF6,no measurable reaction was observed at SF6 concentrations up to 6.5× 1017 molecule.cm-3,yielding an upper limit rate coefficient of 7×10-18 cm3.molecule-1s-1.These results expand the kinetic database for Criegee intermediates reactions with fluori-nated compounds and provide insights into atmospheric oxidation pathways involving these species.
Foams stabilized by surfactants play a pivotal role in industry, daily life, and fundamental research. However, the molecular mechanisms governing foam stability, particularly the interplay between surfactant structure and interfacial behavior, remain incompletely understood. Using molecular dynamics combined with advanced statistical analyses, we systematically explored the effects of alkyl trimethyl ammonium bromide (CnTAB) surfactants on the stability of foam film across a range of chain lengths and coverages. Our approach incorporated parallel simulations to ensure robust evaluation of fluctuating properties and employed methods such as sigmoid fitting and kernel density estimation to extract detailed insights into interfacial characteristics. The results reveal that increasing surfactant coverage significantly reduces interfacial tension via enhanced molecular packing, while chain length primarily influences structural properties, such as Gibbs dividing surface thickness and molecular orientation. Longer chains, particularly at high coverage, promote denser packing and resist penetration into the aqueous phase due to steric hindrance and hydrophobic interactions. These findings provide a molecular-level understanding of surfactant-stabilized interfaces and establish a robust framework for analyzing interfacial systems, offering insights for optimizing foam formulations in industrial applications.
Molecular potential energy predic-tion is fundamental to molecular dy-namics simulations.Recent ad-vances in geometric deep learning have yielded numerous models that balance speed and accuracy.Howev-er,existing approaches often strug-gle with limited feature extraction and suboptimal function fitting.Enhancing prediction accuracy remains a critical challenge.In this study,we introduce RAKAN,a novel residual-connected graph neural network that leverages attention mechanisms and Kolmogorov-Arnold representation to improve feature extraction and prediction precision.RAKAN surpasses the existing state-of-the-art approaches on the MD17 benchmark dataset and demonstrates superior performance in predicting chemical properties on the QM9 dataset.These results demonstrate RAKAN's superior accuracy and robust feature learning capabilities,advancing the field of molecular potential energy prediction.
The phase transition behavior of al-loys can be modulated by magnetic fields,which affects the phase transi-tion process by arranging magnetic moments,thereby changing the ther-modynamic and kinetic behaviors of the phase transition.In this work,based on our previous works,we have successfully simulated the process of the phase transition of Fe-Co alloys combining molecular dynamics and spin-lattice dynamics,under a machine-learning force field,with magnetic interaction parameters obtained from the first-principles density func-tional theory,with and without external magnetic field.From the simulated results,we have demonstrated the mechanism of both its solid-solid and solid-liquid phase transitions,under either 0 T or 10 T external magnetic field.
Nowadays,methylamine lead iodine(MAPbI3)perovskite materials with ex-cellent photoelectric properties have been widely concerned.However,the poor material stability and the unde-sired film quality of MAPbI3 per-ovskites in ambient air seriously ham-per their further development.Hence,we fabricated a series of Cs+-or Cl--doped CsxMA1-xPbI3 and MAPbI3-yCly films by one-step solution deposition method under open-air conditions to improve the thermal stability and crystallinity of MAPbI3 films,and systematically investi-gated the influence of doping ions.Results indicate that a small amount of Cs+can im-prove the thermal stability of the MAPbI3 film and the power conversion efficiency(PCE)of the perovskite solar cells(PSCs).However,excessive Cs+doping may induce phase segre-gation,leading to the formation of 8-phase CsPbI3 and consequently deteriorating the per-formance of PSCs.Meanwhile,minor Cl-incorporation markedly enlarges the grain size in MAPbI3 films.After optimizing the doping contents of Cs+and Cl-,we obtained the best Cs0.1MA0.9PbI3 and MAPbI2.95Cl0.05 PSCs,showing a maximum PCE of 19.61％and 19.56％,respectively.Subsequently,we further improved the performance of MAPbI3 films by co-doping with optimal concentrations of Cs+and Cl-.Results indicate that,compared with MAPbI3-based devices,the Cs0.1MA0.9PbI2.95Cl0.05-based devices exhibit a longer car-rier lifetime and a lower defect density.Consequently,the best-performance Cs0.1MA0.9PbI2.95Cl0.05 PSCs attain a remarkable PCE of 20.10％and a open-circuit volt-age(Voc)of 1.14 V in air,surpassing the PCE of devices with either Cs+or Cl-incorpora-tion alone.Moreover,the thermal stability of the Cs0.1MA0.9PbI2.95Cl0.05-based devices was also significantly improved compared to that of MAPbI3.Furthermore,by optimizing the thickness and sputtering process of the indium-doped zinc oxide(IZO)transparent elec-trode,we successfully fabricated semi-transparent perovskite solar cells(ST-PSCs)with a PCE of 17.73％.
Single-atom catalysts(SACs)possess unique catalytic properties due to their low-coordination and unsaturated active sites,and are widely applied in the field of the oxygen evolution reaction(OER).Limited by the same type of active sites and their associated adsorption-evolution mechanism(AEM),introducing new active sites and synergistic reaction mechanisms can effec-tively enhance the activity of SACs.Herein,density functional theory was used to study the possibility of carbon atoms serving as synergistic sites in the CoN4 embedded graphene system.The results show that the intermediate*Oc on the carbon site can accept protons from*OOH formed on the Co site.Through the synergistic evolution of the dual-sites,the overpotential is reduced to 0.27 V.Subsequently,by doping with graphitic N species,the activity of the system is further enhanced,and the overpotential approaches the theoreti-cal limit.Our work reveals the remarkable potential of carbon atoms as synergistic sites in carbon-based catalysts for oxygen electrocatalysis,providing new ideas for the develop-ment of more single-atom carbon-based catalysts in the future.
Incorporating metal fluorides is an effective strategy for increasing Li+transference number(tLi+)in solid polymer electrolytes(SPEs)through coordination of metal cations with migrating anions,allowing for allevi-ating concentrated polarization and improving rate performance in lithium batteries.However,a higher charge quantity of the metal cation can not translate into a more significant increase in tLi+.In this work,we uti-lize the ionic potential(Z/r,the ratio of charge quantity to ionic radius)to generalize the anoin trapping capability of metal fluorides.By incorporating MnF2,FeF3 or NbF5 with metal ionic potential of 2.99 Å-1,4.65 Å-1,and 7.81 Å-1,respectively,tLi+of polymerized vinyl ethylene carbonate and 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol diacrylate monomers increase from 0.35 to 0.52 for MnF2,0.61 for FeF3,and 0.67 for NbF5 at 25 ℃.Corre-spondingly,the assembled LiCoO2‖Li batteries with a cutoff voltage of 4.45 V at 25 ℃based on NbF5-SPE delivers discharge capacity of 153.81 mAh·g-1 at 5 C and capacity re-tention of 86％for 5 C/0.2 C,significantly higher than 146.59 mAh·g-1,81.5％based on MnF2,and 143.95 mAh·g-1,83.6％based on FeF3.This work provides a promising design guideline of high tLi+SPE as well as high-rate lithium batteries.
The Am(Ⅲ)and Eu(Ⅲ)in high-level liquid waste exhibit similar physicochemical proper-ties,which makes their extraction and sepa-ration rather challenging.Ten symmetric and asymmetric furan-based N,O-hybrid extrac-tants were constructed from the furan skele-ton and the side chains of pyridine,pyri-dazine,pyrimidine and pyrazine.The density functional theory method was employed to evaluate the coordination structures and bonding properties of the ligands with the Am(Ⅲ)and Eu(Ⅲ)ions;the thermodynamic parameters of the two-phase extraction process were calculated to explore the extraction ability and separation performance of the ligands for the Am(Ⅲ)and Eu(Ⅲ)ions.The natural bond orbitals and QTAIM analyses show that there is a weak closed-shell interaction between Am(Ⅲ),Eu(Ⅲ)and the ligand,and the Am-ligand bonds have more covalent character than the Eu-ligand bonds since the Am-5f orbitals are more involved in bonding with the ligand than the Eu-4f orbitals.Thermody-namic analysis shows that the solvents cyclohexanone and n-dodecane of the organic phase have some impact on the extraction and separation,the ligand was more likely to bind with the metal in the cyclohexanone solvent,while some ligands have better separation effects in the n-dodecane solvent.In either solvents,the asymmetric extractant L9 has the most ex-cellent separation performance for the two metal ions,and the asymmetric ligands L5 and L8 also have good separation effect.This work contributes to a deeper understanding of the selectivity differences of similar furan-based flexible ligands and provides more abundant theoretical bases and insights for the design of new extractants required for the separation of Am(Ⅲ)and Eu(Ⅲ).
PyQED is an open-source Python package designed for the numerical simulation of strongly coupled elec-tron-nuclear quantum dynamics,in particular,conical intersection dy-namics.Besides conventional nona-diabatic wavepacket dynamics methods based on the Born-Huang representation and mixed quantum-classical Ehrenfest dynamics,PyQED implements the geometric quantum dynamics based on the local diabatic representation,which provides a numerically exact framework for nonadiabatic quantum molecular dynamics.It differs from the conven-tional Born-Huang representation in that all non-Born-Oppenheimer effects are accounted for by a single electronic overlap matrix between adiabatic states,therefore removing the sin-gular derivative couplings.The complete workflow for ab initio modeling of conical intersec-tion dynamics is illustrated through the internal conversion dynamics in the H3+cation.PyQED provides a powerful and user-friendly computational platform for first-principles quantum dynamics,with applications to photochemical and photophysical processes.
Although previous IRMPD(infrared multiple photon dissociation)experi-ments proposed the presence of proto-nation of the C=O peptide bond in certain tripeptides with lower energy than traditional amino protonation,subsequent theoretical calculations have revealed that their conclusions are unreliable.Therefore,it has become imperative to ex-plore the existence of such molecules.In this study,based on reasonable speculation,four dipeptides and four tripeptides were selected and their protonated configurations were sys-tematically searched.High-level theoretical calculations using the composite CBS-QB3 method indicated that at least two dipeptides,GP and GV(G:glycine,P:proline,V:valine),have been identified as the candidate molecules with protonation at the amide oxygen as the global minimum.GP is also identified as the smallest dipeptide with the cis-peptide confor-mation as the global minimum.The electrostatic potentials and the transition states between the two protonated forms have been calculated to uncover the determining mechanism for the predominance of peptide bond protonation.In addition,the chemical(infrared,IR)and elec-tronic(X-ray photoelectronic spectroscopy and near-edge X-ray absorption fine structures,XPS and NEXAFS)structural calculations were performed to distinguish between these dif-ferent protonated forms in future experiments.This study provides valuable insights into the competitive coexistence between the two protonated forms of short peptides and deepens our understanding of the protonation process in the early stage of protein synthesis.
KSSOLV(Kohn-Sham solver)is a MAT-LAB(Matrix Laboratory)toolbox de-signed for solving the Kohn-Sham density functional theory(DFT)equations by us-ing the plane-wave basis set.Leveraging the powerful capabilities of MATLAB's parallel computing toolbox and an ad-vanced,optimized calculation workflow,KSSOLV uniquely enables efficient graph-ics processing unit(GPU)acceleration,making DFT calculations accessible on standard personal computing hardware.Here,KSSOLV-GPU 2.0,as the latest release,demonstrates substantial computational gains.In benchmarks,particularly involving calculations such as hybrid functionals and spin-polar-ized systems for complex band structure analysis,KSSOLV-GPU 2.0 achieves a speedup of more than an order of magnitude compared to conventional central processing unit based im-plementations.This significant acceleration marks a pivotal advancement in performing com-plex materials simulations,making KS-DFT increasingly accessible on personal computing platforms.
Comprehensive analysis of the connection between surface metal species and the mechanism of hydrogen (H-2) generation on TiO2 provides important new information for the development of more effective catalysts for H-2 production. We have systematically investigated the mechanism of catalytic H-2 generation on the Cu-10/TiO2, Au-10/TiO2, Au8Cu2/TiO2 and Cu-1/Au8Cu2/TiO2 surfaces using density functional theory. Our results demonstrate an O-H delta+ & mldr; H delta--M type transition state for H-2 production, and the Au8Cu2 (0.54 eV) bimetallic cluster catalyst exhibits more activity in comparison to the Cu-10 (0.63 eV) and Au-10 (0.88 eV) cluster catalysts on the TiO2 surface. On the Cu-1/Au8Cu2/TiO2 surface, we found that Au8Cu2 clusters act as electron donors, while Cu single atom acts as an electron acceptor. Therefore, the Au8Cu2 bimetallic catalyst has a low energy barrier (0.58 eV) in the reductive reaction of H-2 production in water, but Cu single atom as the catalytic center has a higher energy barrier (1.49 eV). This implies that bimetallic catalysts may be able to catalyze the water dehydrogenation reaction more successfully, which would be important knowledge for comprehending and refining the photocatalytic H-2 generation process.
Accurate simulation of combus-tion reactions is crucial for un-derstanding combustion mecha-nisms.Reactive force fields(ReaxFF)offer a computation-ally efficient approach to simu-lating complex combustion pro-cesses,but their accuracy de-pends critically on parameteri-zation.This work presents a comprehensive optimization of ReaxFF parameters for gas-phase combustion reactions using a machine learning driven ap-proach.We constructed a dataset of 33 reactions,encompassing key reaction types in combus-tion.High-level double hybrid DFT calculations served as a benchmark to evaluate the per-formance of various density functionals,the semi-empirical PM7 method,and existing ReaxFF parameter sets.We then employed the JAX-ReaxFF framework to optimize the CHO2008 parameters,leveraging its efficient local gradient-based optimization algorithms.The optimized ReaxFF significantly improved the accuracy of potential energy and atomic force predictions,with the mean absolute error(MAE)for energy approaching that of PM7.Analysis of reaction pathways and potential energy surfaces further demonstrated the en-hanced performance of the optimized force field,particularly near transition states.This opti-mized ReaxFF provides a good tool for simulating a wide range of combustion systems,and the presented methodology offers a general strategy for developing system-specific ReaxFF parameters.
