Direct methanol fuel cells (DMFCs) offer a promising power source by utilizing liquid-state methanol as fuel, providing easy storage and transportability. Currently, DMFCs commonly employ perfluorosulfonic acid membranes, such as the well-known Nafion membrane, as proton exchange membranes. However, perfluorosulfonic acid membranes have significant drawbacks in DMFCs, including a high crossover rate, substantial swelling, poor thermal stability, and elevated costs. The crossover of methanol fuel to the cathode side is particularly detrimental as it can poison the precious Pt catalyst, leading to damage in the fuel cell system. In this manuscript, we propose a non-ionic proton exchange membrane based on the polycarbonate track etched (PCTE) membrane. The aligned nanopores in pristine PCTE, with a regular diameter, facilitate proton passage while mitigating the crossover of methanol molecules. This results in satisfactory proton conductivity and selectivity comparable to that of the commercial Gore membrane. By adding a layer of graphene treated with oxygen plasma for 10 seconds, methanol permeation can be reduced by 16.44%, while achieving a 42.11% increase in proton conductivity compared to the commercial Gore membrane. Furthermore, PCTE material offers a more cost-effective alternative to Gore membrane, with a 18.37% lower swelling ratio and significantly higher stability. These characteristics make PCTE a promising choice for DMFCs, offering potential improvements in performance and cost-effectiveness.

Motivated by the exceptional optoelectronic properties of 2D Janus layers (JLs), we explore the properties of group Va antimony-based JLs SbXY (X = Se/Te and Y = I/Br). Using Bader charges, the electric dipole moment in the out-of-plane direction of all the JLs is studied and the largest dipole moment is found to be in the SbSeI JL. Our results on the formation energy, phonon spectra, elastic constants, and molecular dynamics (AIMD) simulation provide insights into the energetic, vibrational, mechanical, and thermal stability of JLs. After confirming the stability, the three-dimensional phase diagram is investigated to propose the experimental conditions required to fabricate the predicted JLs. Then, the electronic band structure is calculated using different levels of theory, namely, the generalized gradient approximation (GGA), GGA + spin-orbit coupling (GGA + SOC), hybrid Heyd-Scuseria-Ernzerhof (HSE) functional, and many-body perturbation theory-based Green's function method (GW). According to the HSE results, JLs show band gaps between 1.653 and 1.852 eV. The GGA + SOC calculations reveal Rashba spin splitting in these JLs. The calculated carrier mobility using deformation potential theory shows that the electrons have exceptionally high mobility compared to holes, which assists the spatial separation of both charge carriers. The optical spectra are determined using GGA, HSE, and GW methods. With respect to GGA results, HSE and GW optical spectra show a blue shift. More accurate calculations using the GW-Bethe Salpeter equation (BSE) yield optical absorption spectra that are dominated by strong excitonic effects with the excitonic binding energy (BE) in the range of 550-800 meV. Compared to the GW-BSE method, the Mott-Wannier (MW) model predicts a lower BE. A strong e-h coupling is observed for dispersions along K-M in the Brillouin zone from the fat band analysis. Our study suggests that the SbSeI JL is a potential candidate for photocatalytic and photovoltaic applications due to its largest dipole moment and low excitonic binding energy.

Glutathione is a biologically abundant and redox active tripeptide that serves to protect cells from oxidative stress and rid the body of toxic heavy metals. The present study examines the coordination complexes of glutathione (GSH) with metals that are central to redox processes in biology, Zn, Cu, and Fe, using infrared multiple photon dissociation (IRMPD) action spectroscopy with a free electron laser. For all three metals, a complex between the metal dication and deprotonated GSH was formed, M(GSH-H). The experimental IRMPD spectra were compared to scaled harmonic vibrational spectra calculated at the MP2/6-311+G(d,p) level of theory after thorough exploration of conformational space using a simulated annealing protocol. Interestingly, spectra calculated at the B3LYP or ωB97XD level do not match experiment as well. These findings offer the first gas-phase spectroscopic evidence for how the biologically relevant metal ions coordinate with glutathione. There are spectral features that are common to all three metals, however, noting the differences in the strengths of the common features between the three metals enables an assessment of the preference or specificity that each individual metal has for a given coordination site. Additionally, all three metals form structures where the deprotonated thiol of the cysteine side chain coordinates with the metal center, which is consistent with the involvement of the thiol site in biologically relevant redox chemistry.

Metalized-film dielectric capacitors provide lump portions of energy on demand. While the capacities of various capacitor designs are comparable in magnitude, their stabilities make a difference. Dielectric breakdowns - micro-discharges - routinely occur in capacitors due to the inevitable presence of localized structure defects. The application of polymeric dielectric materials featuring flexible structures helps obtain more uniform insulating layers. At the modern technological level, it is impossible to completely avoid micro-discharges upon device exploitation. Every micro-discharge results in the formation of a soot channel, which is empirically known to exhibit a semiconductor behavior. Because of its capability to conduct electricity, the emerged soot channels harm the subsequent capacitor performance and decrease the amount of stored energy. The accumulation of the soot throughout a dielectric capacitor ultimately results in irreversible overall failure. We have developed a universal method for predicting the composition and evaluating the properties of the decomposition products obtained after the dielectric breakdown of a metalized film capacitor. This method applies to both existing and newly developed designs of capacitors. In our work, we compared samples based on polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), and Kapton. We found that the decomposition of the PP-based composition yields the greatest number of gaseous products. The corresponding soot has the lowest electrical conductivity compared to other samples. The smallest fraction of gaseous products and the highest conductivity corresponded to the Kapton-based system. According to the electrical conductivity, the obtained soot samples have been ranked in the following order: PP < PET < PC < Kapton. The resulting gas phase content is as follows: PP (12.3 wt%) > PC (6.4 wt%) > PET (6.2 wt%) > Kapton (5.1 wt%). The obtained results are in agreement with the experimental data on the self-healing efficiency of metalized-film capacitors. The novel method qualitatively correctly rates the performances of the known capacitors. The method relies on various electronic-structure simulations and potential landscape explorations. The reported advances open an impressive avenue to computationally probe thousands of hypothetical capacitor designs and boost engineering practices.

We present a comprehensive theoretical analysis of the structural and electronic properties of a van der Waals heterostructure composed of CdS and α-Te single layers (SLs). The investigation includes an in-depth study of fundamental structural, electronic, and optical properties with a focus on their implications for photocatalytic applications. The findings reveal that the α-Te SL significantly influences the electronic properties of the heterostructure. Specifically, the optical properties of the heterostructure are notably dominated by the contribution of α-Te. The layer-resolved density of states analyses indicate that the valence and conduction bands near the Fermi level are mainly determined by the α-Te SL. Band edge analyses demonstrate a type-I band alignment in the heterostructure, causing charge carriers (electrons and holes) to localize within α-Te. The electronic properties can be further modulated by external strain and electric fields. Remarkably, the CdS-α-Te heterostructure undergoes a transition from type-I to type-II band alignment when subjected to biaxial strain and an external electric field. This may be interesting for the application of the heterostructure for photocatalysis.

Developing the multipolar-polarizable AMOEBA force field for large molecules presents its own set of complexities. However, by segmenting the molecules into smaller fragments and ensuring that each fragment is transferable to other systems, the process of parameterizing large molecules such as fatty acids can be simplified without compromising accuracy. In this study, we present a fragment-based AMOEBA FF development for long-chain fatty acid ionic liquids (LCFA-ILs). AMOEBA enables us to incorporate polarization to measurably enhance the precision in modeling these large highly charged systems. This is of significant importance since the computational investigation of ILs needs accurate modeling. Additionally, to leverage the tunability of ILs, it is essential to test numerous anion and cation combinations to identify the most suitable formulation for each application. However, conducting such experiments can be resource-intensive and time-consuming, but accurate molecular modeling can expedite the exploration process. Here, the newly developed parameters were evaluated by comparing the decomposed intermolecular interaction energies for ion pairs with energies determined by quantum mechanics calculations as a reference. By employing this FF in molecular dynamics simulations, we predicted bulk and structural properties including density, enthalpy of vaporization, diffusion coefficient, structure factor and radial distribution function of diverse LCFA-ILs. Notably, the good agreement between the experimental data and those calculated using our parameters validates the accuracy of our methodology. Therefore, this new procedure provides an accurate approach to parameterizing large systems, paving the way for studying more complicated systems such as lipids, polymers, micelles and membrane proteins.

The phase transition from supercooled water to ice is closely related to the electrochemical performance and lifetime of an energy device at sub-zero temperatures. In particular, fuel cells for passenger cars face this issue because they are frequently started and stopped under sub-zero conditions during the winter season. However, there is a lack of visual information regarding the processes that occur within the fuel cell stack, and insight into how to improve the safety and performance during cold starts is lacking. In this study, we developed an neutron imaging system to visualise the water distribution inside an automotive single cell simulating a fuel cell stack during cold starts. This was achieved using a rapid heating unit. In addition, we showcased cold-start tests at three different sub-zero temperatures, and the obtained results suggest that pre-conditioning residual water and post-cold-start meltwater have an impact on the rapid cold-start performance.

Based on first-principles calculations, we have predicted a novel group of 2D p-state Dirac half-metal (DHM) materials, YX (Y = Li, Na; X = Se, Te) monolayers. All the monolayers exhibit intrinsic ferromagnetism. Among them, LiTe and NaSe open topologically nontrivial band gaps of 4.0 meV and 5.0 meV considering spin-orbit coupling (SOC), respectively. The Curie temperature of LiTe is 355 K. The non-zero Chern number and the presence of edge states further confirm that the LiTe monolayer is a room-temperature ferromagnetic material and a quantum anomalous Hall (QAH) insulator. Additionally, it is found that YX (Y = Li, Na; X = Se, Te) monolayers exhibit strong robustness against strain and electric fields. Finally, we have proposed the growth of YX (Y = Li, Na; X = Se, Te) monolayers on h-BN substrates, which shows promise for experimental synthesis. Our research indicates that YX (Y = Li, Na; X = Se, Te) monolayers exhibit strong robustness as DHMs, showcasing significant potential for realizing the intrinsic quantum anomalous Hall effect (QAHE).

Expanding on the comprehensive research conducted by previous scholars, herein, we aim to elucidate the intrinsic piezoelectricity of tetragonal Pb(ZrTi)O (PZT), by focusing on the local atomic distribution which was neglected for a long time, through the supercell approach based on colour symmetry. Density functional theory (DFT) was employed to perform first-principles calculations on the electronic, phononic structures and piezoelectricity of various tetragonal PZT supercells. Building upon the evaluation of the piezoelectric properties of 22 distinct distributions, classical Monte Carlo methods were utilized to explore the statistical macroscopic properties at the morphotropic phase boundary (MPB). The results reveal that at = 0.5 and = 0.55, the reached 957 pm V and 893 pm V, respectively. The analysis of phonon vibration modes exposed significant disparity between different colour symmetries. The supercells of lower symmetry contain B-site atoms in asymmetric positions, and they exhibit softer vibrational frequencies in the phonon spectrum. These soft phonon vibration modes resulting from colour symmetry breaking were previously unknown. The weakening and reorientation of the covalent bonds between the O 2p and d orbitals were found in electronic structures. The free energy flattening in the polarization rotation path is the origin of the high piezoelectricity of this type of supercell. The analysis of the electronic structure is consistent with the experimental observations. Finally, colour symmetry proved to be an effective and accurate way to describe the local atomic distribution in supercells. It will also bring new perspectives to understanding the structure of domain walls, phase boundaries,

Electron-counting rules are promising for determination of chemically stable complexes for various elemental groups. While the 18-electron rule has been established for transition metals, recent experiments have discovered that alkaline-earth metals may follow a 20-electron rule when coordinated with CO or benzene. Herein, by employing first-principles calculations at the level of the generalized gradient approximation functional combined with the def2-SVP basis set, we theoretically predict a series of stable 20-electron exohedral alkaline-earth metallofullerenes, in which each alkaline-earth metal is η-coordinated with three Cs, leading to stable trigonal pyramidal structures. Molecular orbital calculation and energy decomposition analysis indicate that not only ()s orbitals but also ( - 1)d()p orbitals of the alkaline-earth metal atoms participate in bonding interactions with the fullerenes. Energy decomposition analysis reveals that the bonding between metal atoms and C can be divided into weak donation from C to metal d orbitals and strong back-donation from the metal d orbitals to C, consistent with 20-electron metal complexes. Based on stable trigonal pyramidal building blocks, we designed a series of two-dimensional assembled materials with fullerenes forming a Kagome sublattice and metals forming a honeycomb sublattice, possessing topologically nontrivial flat bands with exotic quantum properties.

Efficient formation of excited triplet states on metal-free photosensitizer dyads, bodipy-phenoxazine (BDP-PXZ) and tetramethylbodipy-phenoxazine (TMBDP-PXZ), was investigated using calculations. We revealed the reason why two different triplet transient species, CT and BDP, can co-exist only for BDP-PXZ as observed in the previous study with the TR-EPR measurements. It was found that the state mixing of CT enables the transition from CT to CT and BDP states only for BDP-PXZ. This mixing effect is commonly seen in the singlet states of twisted intermolecular charge transfer molecules, though the key factor that determines the mixing of the excited states of the dyes was found to be the electron-donating ability of the substituents rather than their steric hindrance. This mechanism was corroborated by comparing the spin polarization ratio of the triplet spin-sublevels measured by TR-EPR with the theoretical predictions. The spin polarization ratio of the triplets should contain information about the transition intersystem crossing, the twisted angle of two chromophores of the dyad, and thus it can be a powerful tool to analyze the molecular mechanism of photochemical processes at the electronic structure level. These insights on the molecular structures' effect provided by this theoretical study would be a compass to molecular design of metal-free triplet photosensitizers.

We propose a new, simple and efficient procedure of light-driven deoxygenation of solutions based on hydroperoxides formation upon irradiation. Efficient and fast removal of molecular oxygen is caused by photosensitized generation of singlet oxygen, which then reacts with the solvent (2-methyltetrahydrofuran or tetrahydrofuran). Oxygen depletion makes it possible to observe processes normally undetectable in non-degassed liquid samples at room temperature, such as phosphorescence and triplet-triplet annihilation. The potential of the proposed protocol is demonstrated by recording of previously unknown phosphorescence of palladium complex of octaethylporphycene.

The 1,2-addition reactions involving CS and oxygen-bridged intramolecular G13/P-based (G13 = group 13 element) and B/G15-based (G15 = group 15 element) frustrated Lewis pairs (FLPs) have been theoretically analyzed through density functional theory (DFT). Our DFT calculations suggest that of the nine FLP-assisted compounds, only B/P-Rea, Al/P-Rea, Ga/P-Rea, and In/P-Rea can kinetically and thermodynamically initiate energetically favorable 1,2-addition reactions with CS, forming five-membered heterocyclic adducts. Our findings from the activation strain model suggest that the atomic radius of the Lewis acceptor (G13) and donor (G15) is critical in setting the barrier heights needed for optimal orbital interactions between G13/P-Rea, B/G15-Rea, and CS. The EDA-NOCV (energy decomposition analysis-natural orbitals for chemical valence) analysis we conducted indicates that donor-acceptor bonding (singlet-singlet) plays a more dominant role than electron-sharing bonding (triplet-triplet) in the transition states G13/P-TS and B/G15-TS. Based on frontier molecular orbital theory and EDA-NOCV analyses, the bonding in the 1,2-addition reactions of oxygen-bridged intramolecular G13/P-Rea and B/G15-Rea with CS is primarily influenced by the forward interaction (lone pair (G15) → p-π*(CS)), while the backward interaction (p-π*(G13) ← p-π(CS)) has a relatively minor influence. Several significant findings derived from the current theoretical analyses are discussed in this work.

Most of the known methods for the chemical production of nickel nano- and microparticles, nickel oxides and hydroxides use various reducing agents and solvents, which are often toxic to the environment. As a rule, these methods are energy-consuming, lengthy and multi-stage, requiring complex equipment. Therefore, the development of a simple and "green" process for the synthesis of nickel-containing particles, including those with magnetic properties, remains one of the priority tasks. In this paper, a new physicochemical method for oxidation-reduction contact deposition of nickel(II) hydroxide nano-microparticles on the surface of magnesium particles from aqueous solutions of nickel-containing electrolyte is proposed. This method is based on the local corrosion of microgalvanic cells' formation with predominant hydrogen depolarization. The proposed method was used to obtain nickel(II) hydroxide samples and study their morphology using SEM, as well as their phase composition using XRD analysis. It has been proven that the shape and structure of the resulting Ni(OH) particles depend on the contact deposition conditions: depending on the surface state of the magnesium particles as a reducing agent, it is possible to obtain both plate-shaped α/β-Ni(OH) particles and three-dimensional β-Ni(OH) "flowers" with different degrees of crystallinity.

In this study, an efficient route to compute the multidimensional potential energy surfaces (PESs) for the description of quantum anharmonic molecular vibrations is presented. For large molecular systems, where the number of inter mode coupling terms are substantial, a tailor-made construction of truncated PESs is suggested which suitably avoids computation of full PESs by quantitative assessment of the atomic displacements during the normal mode of vibrations. It is shown that, typically, when two normal modes of vibrations are sharing the same atoms, the mode-mode coupling strength is generally large and can be included for truncated PESs. Since the calculations of these terms are the main computational bottleneck, the guided construction of tailor-made PESs can remarkably speed up the calculation by many folds against the expense of little accuracy for peak positions and intensities. This protocol is applicable to any anharmonic vibrational algorithm and more appropriate for large molecules where exploration of chemically important small fragments is more significant compared to that of the entire molecule. A systematic study for -butanol and a dipeptide in the framework of the VSCF-PT2 method shows that for a group of target modes, inclusion of a set of 5-6 other associated important modes is sufficient to offer good accuracy with an error of ∼5-20 cm against the full PES and computationally faster by ∼10-20 times. Finally, a prescription is given on the choice of such tailor-made PESs to compute anharmonic vibrational spectra accurately and efficiently without calculating the full PES.

The conformational dynamics of the pyrene excimer play a critical role in its unique fluorescence properties. Yet, the influence of multiple local minima on its excited-state behavior remains underexplored. Using a combination of time-dependent density functional theory (TD-DFT) and unsupervised machine learning analysis, we have identified and characterized a diverse set of stable excimer geometries in the first excited state. Our analysis reveals that rapid structural reorganization towards the most stable stacked-twisted conformer dominates the excimer's photophysics, outcompeting radiative relaxation. This conformer, which is primarily responsible for the characteristic red-shifted, structureless fluorescence emission, reconciles experimental observations of long fluorescence lifetimes and emission profiles. These findings provide new insights into the excited-state dynamics of excimers. They may inform the design of excimer-based materials in fields ranging from organic electronics to molecular sensing.

Using first-principles calculations, this study unveils a spherically aromatic core-shell B@B structure featuring a B icosahedral core, which is the smallest complete coating icosahedral B core-shell B cluster to date. Detailed orbital and bonding analyses reveal that the icosahedral B core exhibits prominent superatomic behavior with the electronic configuration 1S1P1D1F.

The development of chiral compounds exhibiting circularly polarized luminescence (CPL) has advanced remarkably in recent years. Designing CPL-active compounds requires an understanding of the electric transition dipole moment () and the magnetic transition dipole moment () in the excited state. However, while the direction and magnitude of can, to some extent, be visually inferred from chemical structures, remains elusive, posing challenges for direct predictions based on structural information. This study utilized binaphthol, a prominent chiral scaffold, and achieved CPL-sign inversion by strategically varying the substitution positions of phenylethynyl (PE) groups on the binaphthyl backbone, while maintaining consistent axial chirality. Theoretical investigation revealed that the substitution position of PE groups significantly affects the orientation of in the excited state, leading to CPL-sign inversion. Furthermore, we propose that this CPL-sign inversion results from a reversal in the rotation of instantaneous current flow during the S → S transition, which in turn alters the orientation of . The current flow can be predicted from the chemical structure, allowing anticipation of the properties of and, consequently, the characteristics of CPL. This insight provides a new perspective in designing CPL-active compounds, particularly for -symmetric molecules where the S → S transition predominantly involves LUMO → HOMO transitions. If represents the directionality of electron movement during transitions, , the "difference" in electron locations before and after transitions, then could be represented as the "path" of electron movement based on the current flow during the transition.

Goldene, a one-atom-thick gold sheet, is an emerging graphene-like flat 2-dimensional material. In this study, the geometrical and electronic properties, as well as CO adsorption characteristics, of the pristine, vacancy-containing, and X-doped (X = Al, B, S, P and N) goldene sheets have been investigated by employing first-principles calculations based on the density functional theory. The distribution of energy levels and interaction between the CO molecule and goldene (pristine, partially vacant, and doped) is discussed through the projected density of states (PDOS), electronic band structure (EBS), and Bader charge analysis. We found that CO adsorbs physically on pristine goldene (PG) with an adsorption energy of -24.6 kJ mol, while the creation of a mono-vacancy (MG), di-vacancy (DG) or tri-vacancy (TG) results in only marginal increases in the binding strength of CO with the goldene, and the nature of the interaction remains physisorption. The calculated adsorption energies of CO at MG, DG and TG are -25.60, -25.10, and -30.90 kJ mol respectively. Among a range of dopants considered in this work, doping by boron and nitrogen atoms causes goldene to absorb CO chemically, with relatively large adsorption energies of -138.9 and -163.7 kJ mol and Bader charge transfers of -1.22 e and 0.66 e respectively. Our findings provide an in-depth understanding of the electronic properties of pure, vacancy-containing, and doped goldene, which can aid their potential application in CO activation and conversion.

The conversion of the highly selective CO reduction reaction (CORR) into desired value-added multicarbon compounds, like CH, is crucial, but it is mainly constrained by the high energy barrier for C-C coupling and the multi-electron transfer process. Herein, M/TiO and M/TiO-V (M = Cu, Pd, CuPd, and V refers to the surface oxygen vacancy) catalysts were designed to study the CORR towards CH by using density functional theory (DFT). We found that the surface oxygen vacancy enhances the adsorption ability of studied catalysts. The CO molecule is strongly adsorbed at the metal-surface interfaces of Cu/TiO-V, Pd/TiO-V and CuPd/TiO-V catalysts with adsorption energies of -1.79, -1.75 and -1.71 eV, respectively. Furthermore, the C-C coupling reaction does not occur on the Cu and PdCu cluster sites of the M/TiO-V catalysts, indicating the inactivity of these sites for C products. However, Pd/TiO, CuPd/TiO and M/TiO-V interfaces favor the C-C coupling reaction and therefore have the potential to reduce CO to C products. Additionally, the Gibbs free energy calculations reveal that the surface oxygen vacancy improves the OCCO hydrogenation to CH at the CuPd/TiO-V interface.

Magnetic field-assistance holds the promise of becoming a new or complementary approach to enhance the efficiency of atmospheric pressure plasma jet (APPJ), but there is currently a lack of research on the effect of the assistance region between magnetic field and plasma on application of APPJ. Herein, using a 130 mT perpendicular magnetic field to assist APPJ in treating deionized water to prepare plasma activated water (PAW) as a model, we studied the effect of the magnetic field-assisted region on the performance of PAW produced by APPJ, and found that introducing a magnetic field could always enhance the performance of the prepared PAW with higher concentrations of HO, NO, and NO and lower concentrations of O and lower pH values, but this enhancement effect was related to the magnetic field-assisted region relative to the APPJ, where the optimized PAW performance was achieved when the magnetic field did not act on the jet tube wall (only assisting plasma plume). To reveal the underlying physicochemical mechanism behind the differences in the enhanced performance of PAW in different magnetic field-assisted regions, a plasma reaction network involving physical parameters and chemical products was considered. The results showed that the magnetic field-assisted region modulated the equilibrium between the confinement effect and the recombination loss of magnetized electrons, and subsequently altered the reactive species in PAW a plasma reaction network mediated by electron density and electron excitation temperature without remarkably changing the discharge intensity, discharge power, plasma plume, and gas temperature . These insights contribute to understanding the mechanism of the magnetic field-assisted region effect on APPJ, which provides guidance for optimizing discharge activity and promotes the development of applications.