Silver nanoparticle (AgNP) assemblies combined with electrode surfaces have a myriad of applications in electrochemical energy storage and conversion devices, (bio)sensor development, and electrocatalysis. Among various nanoparticle synthesis methods, electrochemical deposition is advantageous due to its ability to control experimental parameters, enabling the formation of low-nanoscale (<10 nm) particles with narrow size distributions. Herein, we report the electrodeposition of AgNPs on a unique electrode platform based on carbon ultramicroelectrode arrays (CUAs), exploring several experimental variables including potential, time, and silver ion concentration. Extensive scanning electron microscopy analysis revealed that more reductive deposition potentials resulted in higher counts of smaller-sized AgNPs. While previous studies have employed planar, macro-sized electrodes with millimolar silver ion concentrations and minute-long times for AgNP electrodeposition, our results demonstrate that lower Ag+ concentrations (50-100 µM) and shorter deposition times (15-30 s) are sufficient for successful AgNP formation on CUAs. These findings are attributed to enhanced mass transfer from the radial diffusion of the array-based CUAs. The quantity of deposited Ag was determined to be 1100 ± 200 nmol cm-2, consistent with AgNP-modified CUA electrocatalytic activity for hydrogen peroxide reduction. This study emphasizes the importance of carefully considering AgNP electrodeposition parameters on unconventional electrode surfaces.

Biophysical studies in the last two decades demonstrate that salts affect biomolecules in an ion-specific manner. Diverse biological processes such as protein folding, protein precipitation, protein coacervation and phase separation, and protein oligomerization, all show that this ion specificity directly relates to how individual ions interact with biomolecular surfaces. Interestingly, although ion-specific effects upon enzyme catalytic processes are well-known in the literature, a molecular level description of these effects is not yet available. This work addresses this need by investigating ion-specific effects upon the enzymatic activity and stability of RNase A. We have developed a robust framework to analyze and quantify ion-specific effects upon the RNase A catalyzed phosphate ring opening reaction of cCMP. Both the folding thermodynamics and the Michaelis-Menten kinetic parameters of this enzyme show ion-specificity. However, these effects are not necessarily directly related to each other. Ion-specific effects observed in protein folding reflects mostly how an individual ion interacts with the overall protein surface; while alternatively, ion-specific effects on enzyme activity indicate how a given ion interacts with the enzyme active site surface or alternatively, how ions interact with the substrate molecule as represented by changes in the substrate thermodynamic activity coefficient.

Here two A2B type corrole has been synthesized and solubilized in water via pluronic micelle system by avoiding the utmost mandatory multistep non-environment friendly strategies for bringing hydrophobic non-ionic corroles in aqueous medium. Both the corroles were extremely insoluble in water as no absorption spectra of corrole was available in water. However, corrole 2 in the aqueous solution of F127 exhibit characteristic Soret and Q bands due to efficient solubilization of corrole in F127, the micelles formed by block copolymer act as a "cargo hold" for the corrole molecules. Intense emission spectra were observed for both the corroles in the aqueous solution of F127. We further observed that fluorescence properties of corrole-F127 micelle systems are quenched in presence of graphene oxide (GO) without change in the wavelength or shape of the emission band. The possibility of a dynamic quenching is probed more quantitatively by recording the emission decay profiles of corrole-F127-GO system. This quenching of fluorescence intensity of graphene oxide dispersed corrole-F127 micellar system was partially re-established in the presence of bioanalytes such as dopamine, ascorbic acid. Therefore, the present work has a future potential application for analyzing the interaction with different bioanalytes in biological systems using corrole-GO composite.

Charge Transfer (CT) molecular complexes have recently received much attention in a broad variety of fields. The time-dependent density functional theory (TDDFT), which is essential for studying CT complexes, is a well-established tool to study the excited states of relatively large molecular systems. However, when dealing with donor-acceptor molecules with CT characteristics, TDDFT calculations based on standard functionals can severely underestimate the excitation energies. Here, we demonstrate that TDDFT can reliably be used for the calculations of the excitation energies of charge transfer molecular complexes, such as, Ar-TCNE (TCNE = tetracyanoethylene; Ar= benzene, naphthalene, anthracene, etc.) when using range-separated DFT and range-separated double-hybrid DFT functionals. The interactions between the donor-acceptor moieties of these molecular complexes are also studied and the relationship between the interaction and the charge transfer energies are shown here.

The molecular structure of a ferrocene derivative with adjacent centers of chirality, 1,1'-bis(tert - butylphosphino)ferrocene, has been examined in the gas phase using broadband microwave spectroscopy under the isolated and cold conditions of a supersonic jet. The diastereomers of 1,1'-bis(tert-butylphosphino)ferrocene can adopt homo- and hetero-chiral configurations, owing to the P-chiral substituents on the cyclopentadienyl rings. Moreover, the internal ring rotation of each diastereomer gives rise to four conformers with eclipsed ring arrangements, where the two tert-butylphosphino groups were separated by dihedral angles of approximately 72◦, 144◦, 216◦, and 288◦ with respect to the two ring centers. The interconversion barriers between the conformations are below 2 kJ/mol, whereas the pyramidal inversion of the tert-butylphosphino groups is hindered by more than 140 kJ/mol, calculated at the B3LYP-D3(BJ)/def2-QZVP level of theory. In the experimental microwave spectrum, we unambiguously identified the two global-minimum diastereomers with 72◦ conformations. The absence of other conformers can be attributed to the relaxation dynamics in the supersonic jet, which transfers the high-energy conformers to the respective global-minimum geometries. Additionally, we discovered that London dispersion inter- actions between the two tert-butylphosphino groups play a crucial role in stabilizing the structures of this ferrocene complex.

CeO2/CuO heterojunction composite catalysts were synthesized using a one-step method, achieving the introduction of Ce species on nanoscale copper oxide (CuO) particles during the hydrothermal process. On one hand, this protects the nanostructure of the substrate from damage and prevents the agglomeration of CuO nanoparticles. On the other hand, the bimetallic synergistic effect between Ce and Cu effectively improves the conductivity and catalytic activity of the catalyst, significantly enhancing the selectivity of the catalyst for electrochemical reduction of CO2 to C2H4, while effectively suppressing the competing hydrogen evolution reaction (HER). By regulating the amount of CeO2 introducing, a series of CeO2/CuO composite catalysts were designed. The results showed that the 15% CeO2/CuO catalyst exhibited the best selectivity and catalytic activity for C2H4. At a low overpotential of -1.2 V, the 15% CeO2/CuO catalyst demonstrated a current density of 14.2 mA cm⁻² and achieved a Faradaic efficiency for ethylene as high as 65.78%, which is 2.85 times the current density (j = 4.98 mA cm⁻²) and 3.27 times the Faradaic efficiency for ethylene (FEC2H4 = 20.13%) of the undoped catalyst at the same potential. This work provides a feasible basis for achieving efficient CO2RR to C2 products, and even multi-carbon products.

Small gas-phase metal clusters serve as model systems for complex catalytic reactions, enabling the exploration of the impacts of the size, doping, charge state and other factors under clean conditions. Although the mechanisms of reactions involving metal clusters are known in many cases, they are not always sufficient to interpret the experimental results, as those can be strongly influenced by the chemical kinetics under specific conditions. Therefore, our objective here is to develop a model that utilizes quantum chemical computations to comprehend and predict the precise kinetics of gas-phase cluster reactions, particularly under low-pressure conditions. In this study, we demonstrate that master equation simulations, utilizing reaction paths computed through quantum chemistry, can effectively elucidate the findings of previous experiments. Furthermore, these simulations can accurately predict the kinetics spanning from low-pressure conditions (typically observed in gas-phase cluster experiments) to atmospheric or higher pressures (typical for catalytic experiments). The models are tested for simple elementary steps (Cu+H). We highlight the importance of the reaction mechanism simplification in Cu +H and provide an interpretation for the previously observed product branching in Pt+CH.

Retinal protonated Schiff base (RPSB), found in its all-trans conformer in Bacteriorhodopsin, undergoes barrier-controlled isomerization upon photoabsorption through polyene- chain torsion. The effects of the protein environment on the active vibrations during photoabsorption and their redistribution are still not understood. This paper reports on femtosecond time-resolved action-absorption measurements of cryogenically cooled gas-phase all-trans RPSB, which exhibit two coherent vibrational oscillations, 167(14) cm-1 and 117(1) cm-1, of the first excited state with dephasing times of ∼ 1 ps. The absence of the high-frequency vibration in solution and the low-frequency vibration in the protein indicates that these vibrations are sensitive to environments. An action-absorption spectrum of cryogenically cold all-trans RPSB, reveals a ∼ 310 cm-1 active vibration when using a hole-burning technique and 1500 cm-1 C=C stretching modes.

The formulation of safe electrolytes for supercapacitors based on phosphazene used as a flame-retardant (FR) is carried out. 3 molecules are used: hexafluorocyclotriphosphazene (FR1), (ethoxy)pentafluorocyclotriphosphazene (FR2) and pentafluoro(phenoxy)cyclotriphosphazene (FR3). A comparative study on the efficacy from a safety point of view is performed to determine the minimum percentages of each to be used in a conventional acetonitrile (ACN)/1.0 M tetraethylammonium tetrafluoroborate (Et4NBF4) electrolyte to make it non-flammable. Flammability tests have shown that 5%FR1, 15%FR2 or 20%FR3 are required to do that. The FTIR coupled to the TGA as well as the measurements of surface tensions and contact angles showed that the FRs tend to protect the surface of the electrolyte. The transport properties always remain good, superior to PC/1.0 M Et4NBF4 for example, and the electrochemical stability windows determined in 3-electrode cells with platinum or activated carbon are at least 2.5 V. The cycling performances are also interesting because the AC|AC EDLCs made in this study are compatible with these FRs, which makes it possible to operate devices providing energies and powers of 23.0 Wh.kg-1 and 3.7 kW.kg-1 with the electrolytes based on FR1 or FR2 between 0 and 2.5 V.

The synthesis of efficient oxygen evolution reaction (OER) catalysts that markedly reduce the overpotential over an extended period is crucial for electrolytic water splitting toward hydrogen production. A kind of Ni/Fe fluoride (hydroxide) nanocomposite OER catalyst is designed and prepared by a two-step method for the first time. The nanocomposite with the optimal OER performance (Ni:Fe precursor ratio of 9:1) is observed to possess a nanoparticle morphology with size of about 100 nm. Each nanoparticle hosts extensive nanoregions of Ni4OHF7, NiFeF5∙2H2O and Fe1.9F4.75∙0.95H2O phases. The optimal nanocomposite (Ni:Fe precursor ratio of 9:1) exhibits OER overpotential of merely 208 mV and 349 mV at 10 mA cm-2 and 100 mA cm-2 respectively, tafel slope of 53.1, and outstanding stability for 10 h duration at 100 mA cm-2. The superior OER catalytic performance of the optimal nanocomposite after CV activation is mainly ascribed to the comprehensive catalytic effect of multiple Ni, Fe active sites from three phases, the smaller charge transfer resistance achieved at this particular Ni:Fe precursor ratio. The abundant resources of Ni, Fe, F elements and the superior OER properties of the Ni/Fe fluorides (hydroxide) nanocomposite, makes it a good OER catalyst candidate for electrolytic water splitting toward hydrogen production.

Carbon capture, sequestration and utilization offers a viable solution for reducing the total amount of atmospheric CO2concentrations. On an industrial scale, amine-based solvents are extensively employed for CO2 capture through chemisorption. Nevertheless, this method is marked by the high cost associated with solvent regeneration, high vapor pressure, and the corrosive and toxic attributes of by-products, such as nitrosamines. An alternative approach is the biomimicry of sustainable materials that have strong affinity and selectivity for CO2. Bioinspired approaches, such as those based on naturally occurring amino acids, have been proposed for direct air capture methodologies. In this study, we present a database consisting of 960 dipeptide molecular structures, composed of the 20 naturally occurring amino acids. Those structures were analyzed with a novel computational workflow presented in this work that considers certain interaction sites that determine CO2 affinity. Density functional theory (DFT) and symmetry-adapted perturbation theory (SAPT) computations were performed for the calculation of CO2 interaction energies, which allowed to limit our search space to 400 unique dipeptide structures. Using this computational workflow, we provide statistical insights into dipeptides and their affinity for CO2 binding, as well as design principles that can further enhance CO2 capture through cooperative binding.

Highly emissive Zn-Ag-In-S nanocrystals have attracted attention as derivatives of I-III-VI2-type nanocrystals without the use of toxic elements. The wide tunability of their luminescence wavelengths is attributed to the controllable bandgap of the solid solution between ZnS and AgInS2. However, enhancement of the photoluminescence quantum yield (PL-QY) depending on the chemical composition has not been elucidated. Here, the luminescence mechanisms of Zn-Ag-In-S nanocrystals were studied from the perspective of ZnS doped with Ag and In, although previous research has proposed a hypothesis that Zn is a radiative recombination centre in the AgInS2 host. The Zn-Ag-In-S nanocrystals were synthesized by systematically varying the Zn, Ag, and In contents. The nanocrystals exhibit a structure in which a part of the Zn in the cubic ZnS is substituted with Ag and In. Luminescence was ascribed to a donor-acceptor pair (DAP) recombination between electrons trapped in In donors and holes trapped in Ag acceptors. The composition-dependent enhancement of PL-QYs was attributed to an increase in donor and acceptor concentrations. The DAP characteristics were maintained over a wide range of Ag and In contents because of the localized character of the band edge states dominated by Ag and In orbitals, as suggested formerly by simulation.

The emission control of harmful compounds and greenhouse gases and the development of alternative, sustainable fuel sources is a major focus in current research. A solution for this problem lies in the development of efficient catalytic materials. Here, gas phase model systems represent prominent examples for obtaining fundamental insights on reaction properties of prospective catalytic systems. In this work, we review results from studies of tantalum clusters and their oxides in the gas phase and discuss insights with a potential relevance for applied systems. We focus on reactions that are essential for sustainable chemistry in the future. In detail, we address the activation of methane, which may enable the transformation of a greenhouse gas to a chemical feedstock, and we discuss the activation of NH3, which may function as an alternative energy carrier whose unwanted emission needs to be curbed in future applications. Finally, we consider the activation of N2 as a third reaction, since reducing the high energy demand of ammonia synthesis still bears significant challenges. While tantalum may be an interesting catalytic material, the discussed studies may also serve as benchmark for investigations of other materials.

Graphene oxide (GO) is a widely used 2D material employed in various applications due to its tunable properties. Understanding its mechanical properties is crucial to develop polymeric nanocomposites. We employ reactive molecular dynamics simulations to understand the effects of surface and edge functionalization of carbon atoms on the mechanical strength and fracture morphology of graphene and GO. We vary the extent of functionalization of hydroxyl and epoxy groups between 0.1%-70% on the GO surface and find that the tensile strength decreases with increasing functionalization. Nevertheless, there exists an optimal level of surface functionalization of 15-20% where the tensile strength of pristine graphene is retained. Additionally, we find that functionalization alters the fracture morphology from brittle to mild ductile, which is desirable in engineering applications. We also show that the edge functionalization of finite-size graphene nanosheets transfers the failure nucleation sites from the edges to the bulk, although the tensile strength decreases due to increased buckling. Interestingly, the decrement in tensile strength due to surface functionalization is larger as compared to edge functionalization. Overall, this work highlights the possibility of customizing GO's mechanical properties through targeted surface and edge functionalization, paving the way for its controlled application in nanocomposites.

The interaction between two square palladium (II) dianions PdX42- (X = Cl, Br) is evaluated by crystal study and analyzed by quantum chemical means. The arrangement within the crystal between each pair of PdX42- neighbors is suggestive of a Pd···X noncovalent bond, which is verified by a battery of computational protocols. While the potential between these two bare dianions is computed to be highly repulsive, the introduction of even just two counterions makes this interaction attractive, as does the presence of a constellation of point charges. It is concluded that there is indeed a stabilizing Pd···X bond, but it is incapable of overcoming the strong coulombic repulsive force between two dianions. While the QTAIM, NBO, and NCI tools can indicate the presence of a noncovalent bond, they are unable to distinguish an attractive from a repulsive interaction.

It is shown that the exchange repulsion energy, Exr, can be rationalized by partitioning the respective energy expression for two systems with Hartree-Fock orbitals into physically meaningful contributions. A division of Exr into a positive kinetic and a negative potential part is possible, but these contributions correlate only poorly with the actual exchange repulsion energy. A more meaningful partitioning is derived, where all kinetic energy contributions are collected in a term that vanishes for exact Hartree-Fock orbitals due to their stationarity conditions. The remaining terms can be distinguished into an exchange integral contribution as well as contributions to the repulsion energy with two, three and four orbital indices. The forms, relationships and absolute sizes of these terms suggest an intuitive partitioning of the exchange repulsion energy into Molecular Orbital Pair Contributions to the Exchange repulsion energy (MOPCE). Insight into the analytic form and quantitative size of these contributions is provided by considering the 3Σ+u (1σg1σu) state of the H2 molecule, the water dimer, as well as an argon atom interacting with Cl2 and N2.

Safer and more environmentally friendly alternatives to lead-based perovskites include lead-free halide perovskites, which retain good optoelectronic capabilities while reducing environmental toxicity. They also align better with ecological and regulatory standards for green technologies. In this manuscript, we have presented the first principles analysis of the physical traits of A2InGaBr6 (A=K, Rb, Cs). The exchange-correlation effects are treated with mBJ potential. The structural characteristic of A2InGaBr6 (A=K, Rb, Cs) was assessed through the volume optimization curves, formation energies and tolerance factor. The elastic properties of the studied halides are analyzed through elastic constants. The electronic band structures revealed indirect bandgaps for K2InGaBr6, Rb2InGaBr6, and Cs2InGaBr6. The optical properties indicate promising potential in the fabrication of optoelectronic devices for A2InGaBr6 (A=K, Rb, Cs). The transport properties for the studied halides are computed using the BoltzTraP code, which reveals that these halides are promising candidates for thermoelectricity.

The adsorption of the radical α,γ-bisdiphenylene-β-phenylallyl (BDPA) molecule to the Cu(100) surface was studied using scanning tunnelling microscopy (STM), scanning tunnelling spectroscopy (STS), and density functional theory (DFT) calculations accounting for dispersion forces. BDPA on Cu(100) was observed to align preferentially along [[EQUATION]] directions due to weak Cu-C chemisorption between fluorenyl carbons with the underlying copper atoms. The curved shape of the BDPA molecule on Cu(100) can be ascribed to the lack of molecular orbital character on the phenyl substituent. A Kondo-like feature from differential conductance (dI/dV) measurements centered close to the Fermi energy ([[EQUATION]]) suggests the retention of an electron spin-½ state, which is corroborated by hybrid DFT calculations that place the SOMO below and SUMO above EF for Cu(100).

P2 Na2/3MnO2 can be used as a cathode material in sodium-ion batteries. Here, the electrochemical-temperature-dependent phase diagram of P2 Na2/3MnO2 is investigated using X-ray powder diffraction. The P2 Na2/3MnO2 powder under a N2 atmosphere shows evidence of the formation of a monoclinic C2/m phase, from about 450°C. The P2 Na2/3MnO2 electrode sealed in a capillary undergoes a sequence phase transitions from the as-prepared hexagonal P63/mmc to a secondary hexagonal P63/mmc phase followed by a transition to Mn3O4 and subsequently MnO. NaF also appears parallel to the formation of the secondary hexagonal phase. These transitions suggest a local reducing environment as the Mn oxidation state evolves from 3+/4+ to 2+. The samples at various states of charge show similar thermal evolution with the exception of the discharged (Na-inserted) state which features a slightly more complex evolution. Understanding the structure and thermal evolution at various states of charge and under various conditions provides insight into the stability of these potential cathode materials.

Three types of hydrogen bonds of coordinated glycine and water had been investigated: NH/O of α-amino group, O1/HO involving oxygen coordinated to the metal ion (O1), and O2/HO involving α-carbonyl oxygen (O2). Various glycine complexes were investigated: octahedral cobalt(III) and nickel(II), square pyramidal copper(II), and square planar copper(II), palladium(II), and platinum(II) complexes. Nature of these three hydrogen bond types was analysed using symmetry-adapted perturbation theory (SAPT) and variational energy decomposition analysis (EDA) method (TPSS-D3/def2-TZVPP). The results of the EDA decomposition are in good agreement with the reliable SAPT2+3/def2-TZVPP and its total interaction values with CCSD(T)/CBS energies. Electrostatic interaction is generally the dominant attractive energy term in most of the interactions, followed by orbital relaxation, and lastly dispersion as the weakest. We compared EDA results of various complexes to determine the effects of complex charge, metal oxidation, coordination, and atomic number on the energy decomposition terms. The complex charge influences the values of decomposition terms the most, followed by metal oxidation and coordination number, while atomic number effects them the least. All complex and metal changes have a more significant effect on the results of NH/O and O1/HO then O2/HO interactions, due to its location further away from the metal ion.

Benzopyrone is a popular fluorescent scaffold, but how chemical modifications affect its properties is less understood. We investigated this using halogenated 7-hydroxycoumarin, unsubstituted 4-methylumbiliferone, and ortho-chloro and bromo substitutions on the phenolic ring. Experimental charge density data and computational methods revealed that halogenation at the ortho position significantly reduced quantum yield (QY). Specifically, 7-hydroxycoumarin (1) had a QY of 70%, while ortho-chloro (2) and ortho-bromo (3) had QYs of 61% and 30%, respectively. Experimental data showed that all probes excited similarly, but the electrostatic potential and dipole moments indicated that 2 and 3 dissipated excitation energy more easily due to charge separation. The heavy-atom effect of Cl and Br did not fully explain the QY reductions, suggesting other radiative decay processes were involved. By incorporating spin-orbit coupling (SOC) effects, we estimated intersystem crossing (ISC) and phosphorescence rates, providing theoretical QYs of 78% for 1, 59% for 2, and 15% for 3. The large deviation for 3 was attributed to its higher SOC potential. Our findings indicate that 3's reduced QY results from a mix of SOC-induced ISC and charge dissipation, while 2's reduction is primarily due to charge separation. Further studies are needed to validate this approach with other scaffolds.