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Owing to their unique optical and electronic properties, vertical van der Waals heterostructures (vdWHs) have attracted considerable attention in optoelectronic applications, such as photodetection, light harvesting, and light-emitting diodes. To fully harness these properties, it is crucial to understand the interfacial charge transfer (CT) and recombination dynamics across vdWHs. However, the effects of interfacial energetics and defect states on interfacial CT and recombination processes in graphene-transition metal dichalcogenide (Gr-TMD) vdWHs remain debated. Here, we investigate the interfacial CT dynamics in Gr-TMD vdWHs with different chemical compositions (W, Mo, S, and Se) and tunable interfacial energetics. We demonstrate, using ultrafast terahertz spectroscopy, that while the photo-induced electron transfer direction is universal with graphene donating electrons to TMDs, its efficiency is chalcogen-dependent: the CT efficiency of S atom-based vdWHs is 3–5 times higher than that of Se-based vdWHs thanks to the lower Schottky barrier present in S-based vdWHs. In contrast, the electron back transfer process from TMD to Gr, which defines the charge separation time, is transition metal-dependent and dominated by the mid-gap defect level of TMDs: W transition metal-based vdWHs possess extremely long charge separation, well beyond 1 ns, which is significantly longer than Mo-based vdWHs with only 10 s of ps charge separation. This difference can be traced to the much deeper mid-gap defect reported in W-based TMDs compared to Mo-based ones, resulting in modified energetics for the back electron transfer from the trapped states to graphene. Our results shed light on the role of interfacial energetics and defects by tailoring chemical compositions of TMDs on the interfacial CT and recombination dynamics in Gr-TMD vdWHs, which is pivotal for optimizing optoelectronic devices, particularly in the field of photodetection. [ABSTRACT FROM AUTHOR]

The chemiresistive effect of an oxide significantly influences its electrical properties, which depend greatly on the interactions between the ambient gas molecules and the solid surface, including the gas adsorption and charge transfer still challenging to be clarified. In this work, we investigate the chemiresistive effect of the p-type delafossite CuScO2 microsheets by comparing their responses to various gaseous alcohols, which increase with an approximately linear relationship with the length of straight carbon chains from methanol to n-hexanol. A new mechanism is proposed to elucidate such a dramatic trend of observed chemiresistive change based on the first-principles calculations and test results. The increasing carbon chain length modulates the adsorption configuration and provides supplementary routes for electron transfer, which is assumed to account for the observed chemiresistive effect. This work may provide a novel perspective for the investigation and development of more advanced functional oxides for electrical applications. [ABSTRACT FROM AUTHOR]

Linker-assisted Ag-TiO2 nanocomposite (NC)-based photocatalysts have been successfully synthesized using thioglycolic acid (TGA) and 3-mercaptopropionic acid (MPA) as bifunctional linker molecules (LMs). The Ag–LMs–TiO2 composites showed greatly improved photocatalytic performance for the degradation of an organic dye mixture under direct sunlight over bare Ag–TiO2 NCs. The efficiencies estimated from the degradation curves for Ag–TiO2, Ag–MPA–TiO2, and Ag–TGA–TiO2 are found to be 82.9%, 90.2%, and 96.1%, respectively. Compared to Ag–MPA–TiO2, Ag–TGA–TiO2 NCs exhibit an enhanced photocatalytic activity, which can be attributed to the TGA molecule's shorter chain length and, hence, faster and more charge transfer, which is duly confirmed by photoluminescence (PL) quenching and TRPL decay curves. Furthermore, higher Stern–Volmer quenching constant values (Ksv) have been obtained for Ag–TGA–TiO2 NCs compared to the bare Ag–TiO2 and Ag–MPA–TiO2 NCs from the PL quenching and estimated Ksv values for Ag–TiO2, Ag–MPA–TiO2, and Ag–TGA–TiO2 are 1400, 1950, and 2560 l−1, respectively. Interestingly, the Ag–TGA–TiO2 recycling analysis confirmed high stability and fast photodegradation up to 40 cycles. From the obtained results, it is concluded that the interfacial electron transfer kinetics in Ag–LM–TiO2 assemblies rely on the length of the alkyl-containing molecular linkers; the shorter the length, the more the charge transfer will be, thereby improving the photocatalytic behavior of the NCs. [ABSTRACT FROM AUTHOR]

Accurate quantum dynamics simulations of nonadiabatic processes are important for studies of electron transfer, energy transfer, and photochemical reactions in complex systems. In this comparative study, we benchmark various approximate nonadiabatic dynamics methods with mapping variables against numerically exact calculations based on the tensor-train (TT) representation of high-dimensional arrays, including TT-KSL for zero-temperature dynamics and TT-thermofield dynamics for finite-temperature dynamics. The approximate nonadiabatic dynamics methods investigated include mixed quantum–classical Ehrenfest mean-field and fewest-switches surface hopping, linearized semiclassical mapping dynamics, symmetrized quasiclassical dynamics, the spin-mapping method, and extended classical mapping models. Different model systems were evaluated, including the spin-boson model for nonadiabatic dynamics in the condensed phase, the linear vibronic coupling model for electronic transition through conical intersections, the photoisomerization model of retinal, and Tully's one-dimensional scattering models. Our calculations show that the optimal choice of approximate dynamical method is system-specific, and the accuracy is sensitively dependent on the zero-point-energy parameter and the initial sampling strategy for the mapping variables. [ABSTRACT FROM AUTHOR]

Electron transfer reactions play an essential role in many chemical and biological processes. Fermi's golden rule (GR), which assumes that the coupling between electronic states is small, has formed the foundation of electron transfer rate theory; however, in short range electron/energy transfer reactions, this coupling can become very large, and, therefore, Fermi's GR fails to make even qualitatively accurate rate predictions. In this paper, I present a simple modified GR theory to describe electron transfer in the Marcus inverted regime at arbitrarily large electronic coupling strengths. This theory is based on an optimal global rotation of the diabatic states, which makes it compatible with existing methods for calculating GR rates that can account for nuclear quantum effects with anharmonic potentials. Furthermore, the optimal GR (OGR) theory can also be combined with analytic theories for non-adiabatic rates, such as Marcus theory and Marcus–Levich–Jortner theory, offering clear physical insights into strong electronic coupling effects in non-adiabatic processes. OGR theory is also tested on a large set of spin-boson models and an anharmonic model against exact quantum dynamics calculations, where it performs well, correctly predicting rate turnover at large coupling strengths. Finally, an example application to a boron-dipyrromethane–anthracene photosensitizer reveals that strong coupling effects inhibit excited state charge recombination in this system, reducing the rate of this process by a factor of 4. Overall, OGR theory offers a new approach to calculating electron transfer rates at strong couplings, offering new physical insights into a range of non-adiabatic processes. [ABSTRACT FROM AUTHOR]

We report the free energy barriers for the elementary reactions in the 2e− and 4e− oxygen reduction reaction (ORR) steps on Au(100) in an alkaline solution. Due to the weak adsorption energy of O2 on Au(100), the barrier for the association channel is very low, and the 2e− pathway is clearly favored, while the barrier for the O–O dissociation channel is significantly higher at 0.5 eV. Above 0.7 V reversible hydrogen electrode (RHE), the association channel becomes thermodynamically unfavorable, which opens up the O–O dissociation channel, leading to the 4e− pathway. The low adsorption energy of oxygenated species on Au is now an advantage, and residue ORR current can be observed up to the 1.0–1.2 V region (RHE). In contrast, the O–O dissociation barrier on Au(111) is significantly higher, at close to 0.9 eV, due to coupling with surface reorganization, which explains the lower ORR activity on Au(111) than that on Au(100). In combination with the previously suggested outer sphere electron transfer to O2 for its initial adsorption, these results provide a consistent explanation for the features in the experimentally measured polarization curve for the alkaline ORR on Au(100) and demonstrate an ORR mechanism distinct from that on Pt(111). It also highlights the importance to consider the spin state of O2 in ORR and to understand the activation barriers, in addition to the adsorption energies, to account for the features observed in electrochemical measurements. [ABSTRACT FROM AUTHOR]

Fullerene–chromophore dyads have attracted a great deal of research interest because these complexes can be potentially designed as nanoscale artificial photosynthetic centers, in which the chromophore and fullerene function as the electron donor and acceptor, respectively. The basic operation of this dyad-type artificial reaction center is photoinduced electron transfer from the donor to the acceptor. The fullerene and chromophore are usually covalently linked so that sufficient electronic coupling between these two moieties can facilitate the electron transfer. However, other deactivation pathways for the chromophore excited state, such as energy transfer to the fullerene, may reduce the quantum yield of the photoinduced electron transfer. Here, a series of C60-perylene dyads is exploited to interrogate the effect of the linkage on deactivation mechanisms of the chromophore excited state. For the C60-perylene dyads with a single or double bond bridge, we find that the decay of the singlet state of the chromophore is dominated by the electron transfer, and the corresponding time constant is determined to be 45 ps. On the other hand, for the dyad with a triple bond bridge, the singlet state of the chromophore is quickly quenched through energy transfer to fullerene, and the time constant is as short as 7.9 ps. Our finding suggests that the bond order of the bridge in the fullerene–chromophore dyads can be utilized to control the deactivation pathways of the excited state. [ABSTRACT FROM AUTHOR]

Uniquely, large-bipolarons' self-trapped holes occupy superoxygens, each comprising four oxygens circumscribed by four coppers in a CuO2 plane, formed as oxygens relax inward and coppers relax outward. Critically, concomitant oxygen-to-copper electron transfer eliminates copper spins. The d-symmetry of superoxygens' ground state molecular orbital tracks the superoxygens' predominant zero-point radial vibrations. These large bipolarons' distinctive charge transport, absorption, magnetism, local atomic vibrations, condensation into a liquid, and subsequent superconductivity are consistent with cuprate superconductors' long-established unusual properties. [ABSTRACT FROM AUTHOR]

We have investigated Interparticle Coulombic Electron Capture (ICEC) using an ab initio approach for two systems, H+ + H2O and H + H2O+. In this work, we have determined the contribution of virtual photon exchange and electron transfer to the total ICEC cross section as a function of the distance between the charged and neutral particles. Furthermore, we have shown that the relative orientation of the electron acceptor and neighbor systems affects the magnitude of the ICEC cross sections by at least two orders at relatively small distances. This geometry dependence, present even for distances as large as 10 a0, is due to the electron transfer contribution. The relative magnitude of each contribution to ICEC seems to depend on the system studied. By replacing the projectile electron with a positron, we have confirmed that electron transfer also takes place in positron collisions and that the charge of the projectile has a noticeable effect on the process, particularly at low scattering energies. [ABSTRACT FROM AUTHOR]

The efficient conversion of solar energy to chemical energy represents a critical bottleneck to the energy transition. Photocatalytic splitting of water to generate solar fuels is a promising solution. Semiconductor quantum dots (QDs) are prime candidates for light-harvesting components of photocatalytic heterostructures, given their size-dependent photophysical properties and band-edge energies. A promising series of heterostructured photocatalysts interface QDs with transition-metal oxides which embed midgap electronic states derived from the stereochemically active electron lone pairs of p-block cations. Here, we examine the thermodynamic driving forces and dynamics of charge separation in Sb2VO5/CdSe QD heterostructures, wherein a high density of Sb 5s2-derived midgap states are prospective acceptors for photogenerated holes. Hard-x-ray valence band photoemission spectroscopy measurements of Sb2VO5/CdSe QD heterostructures were used to deduce thermodynamic driving forces for charge separation. Interfacial charge transfer dynamics in the heterostructures were examined as a function of the mode of interfacial connectivity, contrasting heterostructures with direct interfaces assembled by successive ion layer adsorption and reaction (SILAR) and interfaces comprising molecular bridges assembled by linker-assisted assembly (LAA). Transient absorption spectroscopy measurements indicate ultrafast (<2 ps) electron and hole transfer in SILAR-derived heterostructures, whereas LAA-derived heterostructures show orders of magnitude differentials in the kinetics of hole (<100 ps) and electron (∼1 ns) transfer. The interface-modulated kinetic differentials in electron and hole transfer rates underpin the more effective charge separation, reduced charge recombination, and greater photocatalytic efficiency observed for the LAA-derived Sb2VO5/CdSe QD heterostructures. [ABSTRACT FROM AUTHOR]

Using the density functional theory, we conducted a study on the electrification upon contact between hydrophobic liquid molecules and water molecules, revealing localized characteristics of contact-electrification. These "localized features" refer to the specific microscale characteristics where electron transfer predominantly occurs at the contact regions, influenced by factors such as atomic distances and molecular orientations. Although the electrostatic potential and the highest occupied molecular orbital–lowest unoccupied molecular orbital gap offer substantial predictive insights for electron transfer across polymer interfaces, they fall short in capturing the complexities associated with the interaction between hydrophobic liquids and water molecules. The electronegativity of elements at the interface and the localization of molecular orbitals play a decisive role in electron transfer. Simultaneously, for liquid molecules with irregular structures, there is no correlation between the "contact area" and the amount of electron transfer. The "contact area" refers to the surface region where two different liquid molecules come into close proximity. It is defined by the surface area of atoms with interatomic distances smaller than the van der Waals radius. This study challenges traditional assumptions about contact-electrification, particularly in liquid–liquid interfaces, providing new insights into the localized nature of this phenomenon. [ABSTRACT FROM AUTHOR]

A generalized quantum master equation approach is introduced to describe electron transfer in molecular junctions that spans both the off-resonant (tunneling) and resonant (hopping) transport regimes. The model builds on prior insights from scattering theory but is not limited to a certain parameter range with regard to the strength of the molecule–electrode coupling. The framework is used to study the simplest case of energy and charge transfer between the molecule and the electrodes for a single site noninteracting Anderson model in the limit of symmetric and asymmetric coupling between the molecule and the electrodes. In the limit of elastic transport, the Landauer result is recovered for the current by invoking a single active electron Ansatz and a binary collision approximation for the memory kernel. Inelastic transport is considered by allowing the excitation of electron–hole pairs in the electrodes in tandem with charge transport. In the case of low bias voltages where the Fermi levels of the electrodes remain below the molecular state, it is shown that the current arises from tunneling and the molecule remains neutral. However, once the threshold is reached for aligning the fermi level of one electrode with the molecular orbital, a small amount of charge transfer occurs with a negligible amount of hopping current. While inelasticity in the current has a minimal impact on the shape of the current–voltage curve in the case of symmetric electrode coupling, the results for a slight asymmetry in coupling demonstrate complete charge transfer and a significant drop in current. These results provide encouraging confirmation that the framework can describe charge transport across a wide range of electrode–molecule coupling and provide a unique perspective for developing new master equation treatments for energy and charge transport in molecular junctions. An extension of this work to account for inelastic scattering from electron–vibrational coupling at the molecule is straightforward and will be the subject of subsequent work. [ABSTRACT FROM AUTHOR]

Solar fuels catalysis is a promising route to efficiently harvesting, storing, and utilizing abundant solar energy. To achieve this promise, however, molecular systems must be designed with sustainable components that can balance numerous photophysical and chemical processes. To that end, we report on the structural and photophysical characterization of a series of Cu(I)–anthraquinone-based electron donor–acceptor dyads. The dyads utilized a heteroleptic Cu(I) bis-diimine architecture with a copper(I) bis-phenanthroline chromophore donor and anthraquinone electron acceptor. We characterized the structures of the complexes using x-ray crystallography and density functional theory calculations and the photophysical properties via resonance Raman and optical transient absorption spectroscopy. The calculations and resonance Raman spectroscopy revealed that excitation of the Cu(I) metal-to-ligand charge-transfer (MLCT) transition transfers the electron to a delocalized ligand orbital. The optical transient absorption spectroscopy demonstrated that each dyad formed the oxidized copper–reduced anthraquinone charge-separated state. Unlike most Cu(I) bis-phenanthroline complexes where increasingly bulky substituents on the phenanthroline ligands lead to longer MLCT excited-state lifetimes, here, we observe a decrease in the long-lived charge-separated state lifetime with increasing steric bulk. The charge-separated state lifetimes were best explained in the context of electron-transfer theory rather than with the energy gap law, which is typical for MLCT excited states, despite the complete conjugation between the phenanthroline and anthraquinone moieties. [ABSTRACT FROM AUTHOR]

We study a moving adsorbate interacting with a metal electrode immersed in a solvent using the time-dependent Newns–Anderson–Schmickler model Hamiltonian. We have adopted a semiclassical trajectory treatment of the adsorbate to discuss the electron and energy transfers that occur between the adsorbate and the electrode. Using Keldysh Green's function scheme, we found a non-adiabatically suppressed electron transfer caused by the motion of the adsorbate and coupling with bath phonons that model the solvent. The energy is thus dissipated into electron–hole pair excitations, which are hindered by interacting with the solvent modes and facilitated by the applied electrode potential. The average energy transfer rate is discussed in terms of the electron friction coefficient and given an analytical expression in the slow-motion limit. [ABSTRACT FROM AUTHOR]

We present cross sections for the formation of positronium chloride (PsCl) in its ground state from the charge exchange between positronium (Ps) and chloride (Cl−) in the range of 10 meV–100 eV Ps energy. We have used theoretical models based on the first Born approximation in its three-body formulation. We simulated the collisions between Ps and Cl− using ab initio binding energies and positronic wave functions at both the mean-field and correlated levels extrapolated to the complete basis set limit. The accuracy of these ab initio data was benchmarked on the PsF system with the existing highly accurate results, including the very recent quantum Monte Carlo results. We have investigated Ps excited states up to n = 4. The results suggest that the channel Ps(n = 2) is of particular interest for the production of PsCl in the ground state and shows that an accurate treatment of correlation effects (i.e., electron–electron and electron–positron correlations) leads to a significant change in the magnitude of the PsCl production cross section with respect to the mean-field level. [ABSTRACT FROM AUTHOR]

We present cross sections for the formation of positronium chloride (PsCl) in its ground state from the charge exchange between positronium (Ps) and chloride (Cl−) in the range of 10 meV–100 eV Ps energy. We have used theoretical models based on the first Born approximation in its three-body formulation. We simulated the collisions between Ps and Cl− using ab initio binding energies and positronic wave functions at both the mean-field and correlated levels extrapolated to the complete basis set limit. The accuracy of these ab initio data was benchmarked on the PsF system with the existing highly accurate results, including the very recent quantum Monte Carlo results. We have investigated Ps excited states up to n = 4. The results suggest that the channel Ps(n = 2) is of particular interest for the production of PsCl in the ground state and shows that an accurate treatment of correlation effects (i.e., electron–electron and electron–positron correlations) leads to a significant change in the magnitude of the PsCl production cross section with respect to the mean-field level. [ABSTRACT FROM AUTHOR]

In view of the inherent pseudocapacitance, rich redox pairs (Nb5+/Nb4+ and Nb4+/Nb3+), and high lithiation potential (1.0–3.0 V vs Li/Li+), Nb2O5 is considered a promising anode material. However, the inherent low electronic conductivity of Nb2O5 limits its lithium storage performance, and the rate performance after carbon modification is still unsatisfactory because the intrinsic conductivity of Nb2O5 has not been substantially improved. In this experiment, taking the improvement of the intrinsic electrical conductivity of Nb2O5 as the guiding ideology, we prepared F-doped Nb2O5@fluorocarbon composites (F–Nb2O5@FC) with a large number of oxygen vacancies by one-step annealing. As the anode electrode of lithium-ion batteries, the reversible specific capacity of F–Nb2O5@FC reaches 150 mA g−1 at 5 A g−1 after 1100 cycles, and the rate performance is particularly outstanding, with a capacity up to 130 mA g−1 at 16 A g−1, which is far superior to other Nb2O5@carbon-based anode electrodes. Compared with other single conductivity sources of Nb2O5@carbon-based composites, the electrical conductivity of F–Nb2O5@FC composites is greatly improved in many aspects, including the introduction of free electrons by F− doping, the generation of oxygen vacancies, and the provision of a three-dimensional conductive network by FC. Through analytical chemistry (work function, UV–Vis diffuse reflectance spectroscopy, and EIS) and theoretical calculations, it is proved that F–Nb2O5@FC has high electrical conductivity and realizes rapid electron transfer. [ABSTRACT FROM AUTHOR]

The entanglement between system and bath often plays a pivotal role in complex systems spanning multiple orders of magnitude. A system–bath entanglement theorem was previously established for Gaussian environments in J. Chem. Phys. 152, 034102 (2020) regarding linear response functions. This theorem connects the entangled responses to the local system and bare bath properties. In this work, we generalize it to correlation functions. Key steps in derivations involve using the generalized Langevin dynamics for hybridizing bath modes and the Bogoliubov transformation that maps the original finite-temperature reservoir to an effective zero-temperature vacuum by employing an auxiliary bath. The generalized theorem allows us to evaluate the system–bath entangled correlations and the bath mode correlations in the total composite space, as long as we know the bare-bath statistical properties and obtain the reduced system correlations. To demonstrate the cross-scale entanglements, we utilize the generalized theorem to calculate the solvation free energy of an electron transfer system with intramolecular vibrational modes. [ABSTRACT FROM AUTHOR]

It is a novel-effective process for realizing high-efficiency sensing and continuous gas monitoring by introducing precious metals into metal–oxide–semiconductors (MOSs). In this study, Ag is exploited to prepare surface functionalized SnO2 nanoparticles (NPs) and innovative xAg@SnO2/CsPbBr3, activating and catalyzing the gas sensing reactions on semiconductors. The results show that the precious metal Ag NPs promote the directional transport of carriers, thus improving the gas sensing performances. In addition, innovative xAg@SnO2/CsPbBr3 composites originated from Ag@SnO2 NPs and 3-mercaptopropionic acid treated all-inorganic perovskite CsPbBr3 are constructed to further accelerate electron transfer on heterointerfaces, enabling continuous and efficient monitoring of ethanolamine (EA) at room temperature. The sensing properties of Ag@SnO2/CsPbBr3 on various volatile organic compounds are investigated. Compared with pure CsPbBr3, the EA response of as-prepared 2Ag@SnO2/CsPbBr3 is obviously improved by about sevenfold. The response/recovery time is greatly shortened, besides the good stability. Another interesting result for xAg@SnO2/CsPbBr3 is the lower limit of detection of 44.43 ppb. The work demonstrates that Ag modification facilitates the adsorption/desorption rate and the response. Furthermore, the catalytic activation of noble metal Ag NPs and the synergistic interaction of SnO2/CsPbBr3 nano-heterojunctions promote EA sensing performances at room temperature. [ABSTRACT FROM AUTHOR]

Diffusion of electrons over distances on the order of 100 μm has been observed in crystals of a small tetraheme cytochrome (STC) from Shewanella oneidensis [J. Huang et al. J. Am. Chem. Soc. 142, 10459–10467 (2020)]. Electron transfer between hemes in adjacent subunits of the crystal is slower and more strongly dependent on temperature than had been expected based on semiclassical electron-transfer theory. We here explore explanations for these findings by molecular-dynamics simulations of crystalline and monomeric STC. New procedures are developed for including time-dependent quantum mechanical energy differences in the gap between the energies of the reactant and product states and for evaluating fluctuations of the electronic-interaction matrix element that couples the two hemes. Rate constants for electron transfer are calculated from the time- and temperature-dependent energy gaps, coupling factors, and Franck–Condon-weighted densities of states using an expression with no freely adjustable parameters. Back reactions are considered, as are the effects of various protonation states of the carboxyl groups on the heme side chains. Interactions with water are found to dominate the fluctuations of the energy gap between the reactant and product states. The calculated rate constant for electron transfer from heme IV to heme Ib in a neighboring subunit at 300 K agrees well with the measured value. However, the calculated activation energy of the reaction in the crystal is considerably smaller than observed. We suggest two possible explanations for this discrepancy. The calculated rate constant for transfer from heme I to II within the same subunit of the crystal is about one-third that for monomeric STC in solution. [ABSTRACT FROM AUTHOR]

Experimental findings by others suggest that OH radicals are formed in unexpected abundance on or near surfaces of 1–50 µm microdroplets comprised of pure water, but the mechanism by which these radicals are generated is not yet fully resolved. In this work, we examine two possibilities using ab initio electronic structure methods: (1) electron transfer (ET) from a microdroplet surface-bound OH− anion to a nearby H3O+ cation and (2) proton transfer (PT) from such a H3O+ cation to a nearby OH− anion. Our findings suggest that both processes are possible but only if the droplet's underlying water molecules comprising the microdroplet provide little screening of the Coulomb interaction between the anion and cation once they reach ∼10 Å of one another. In the ET event, an OH radical is formed directly; for PT, the OH formation occurs because the new O–H bond formed by the transferred proton is created at a bond length sufficiently elongated to permit homolytic cleavage. Both the ET and PT pathways predict that H atoms will also be formed. Finally, we discuss the roles played by strong local electric fields in mechanisms that have previously been proposed and that occur in our two mechanisms. [ABSTRACT FROM AUTHOR]

Interfacial electron transfer (IET) through saturated single-linker and dual-linker groups from a perylene chromophore into nanostructured TiO2 films was studied by ultrafast spectroscopy. Perylene chromophores with one and two propanoic acid linker groups in the peri and ortho positions were investigated. In comparison to previously studied perylenes bound via unsaturated acrylic acid linkers, the chromophores with saturated linkers showed bi-exponential IET dynamics. Two distinct transfer times were observed that indicate the presence of two concurrent binding modes. A comparison between ortho- and peri-substituted sensitizers resulted in slower IET dynamics and weaker electronic coupling for ortho substitution. Finally, IET from sensitizers with saturated linker groups is neither promoted nor hindered by a second linker group. This indicates that only one of the two linkers binds covalently to the surface. This study reveals the importance of the anchor-binding mode and design considerations of the linker for regulating IET. [ABSTRACT FROM AUTHOR]

The activation volume, which quantifies the response of the chemical reactions to the applied stress, plays a central role in controlling the mechanochemical reactions for applications including lubricity, wear, and the topographic fabrication of the surfaces under stress. However, the physical interpretations of the activation volume remain scientifically intriguing and largely unexplored. Here, density functional theory calculations are used to investigate the general rules of charge transfer underlying activation volume in controlling the typically mechanochemical reaction process. It is found that the activation volume could be decoupled into the electronic contributions from interface chemistry and bulk physical deformation, which are commonly linear dependent on the contact pressure. Therefore, the activation volume may, indeed, be derived from the stress-driven charge transfer underlying cooperative competition between interfacial chemistry and the bulk region. This competition is related to the stiffness change from the bulk to slab. The magnitude of the stiffness change represents the degree to which the interface atoms modify the bulk properties, which is directly related to the contribution of different regions to the activation volume. This work may open up the understanding of the activation volume from dynamic electron transfer to engineer mechanochemical reactions, different from the existing insights into the geometric dimensionality of the contact configuration. [ABSTRACT FROM AUTHOR]

In recent years, organic–inorganic hybrid perovskite (PVK) devices have attracted widespread attention with their high absorption coefficient and low-cost fabrication process. Formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) have been reported to obtain high power conversion efficiencies (PCEs) due to the narrow bandgap. Zinc oxide (ZnO) has better electrical conductivity and high transmittance than tin (IV) dioxide (SnO2). However, the deprotonation behavior of ZnO limits its use in formamidinium (FA) or methylammonium (MA) devices, so it is mostly used in all-inorganic PSCs. In this work, to avoid the deprotonation behavior of ZnO, we prepared FAPbI3 PSCs using ZnO/SnO2 as bilayer electron transporting layers (ETLs), which improved the conductivity of the ETLs and promoted electron extraction and transfer. In addition, the decrease in the oxygen vacancy (Ov) on the bilayer ETLs contributed to the suppression of the non-radiative recombination of the device, thus enabling the achievement of a higher fill factor. As a result, the modified ETLs increased the PCE of FAPbI3 PSCs from 20.24% to 21.42% and improved the stability of the devices. The PCE of unpackaged devices increased steadily to 21.91% when stored in an N2 atmosphere for 183 days. [ABSTRACT FROM AUTHOR]

The ultrafast photoinduced electron or exciton transfer was investigated theoretically. The charge separation on the ultrafast time scale results in the unrelaxed vibrational modes that appear in the initial terms of the generalized master equations. Here, the impact of these initial terms on the electron transfer directionality in the open system was evaluated. Moreover, the role of unrelaxed vibrational modes in electron–hole separation was also examined. It was shown that the unrelaxed vibrational modes significantly increase the efficiency of electron–hole separation. This could play a crucial role in the remarkable efficiency of charge separation in biological systems. [ABSTRACT FROM AUTHOR]

The physical regions (domains or basins) within the molecular structure are open systems that exchange charge between them and, consequently, house a fractional number of electrons (net charge). The natural framework describing the quantum states for these domains is the density matrix (DM) in its grand-canonical version, which corresponds to a convex expansion into a set of basis states of an integer number of electrons. In this report, it is shown that the solution for these quantities is supported by the DM expansion into three states of different numbers of particles: the neutral and two (edge) ionic states. The states and the average number of particles in the domains (fractional occupation population) are determined by the coefficients of the expansion in terms of the fundamental transference magnitudes, revealing the donor/acceptor character of the domains by which the quantum accessible states are discussed. [ABSTRACT FROM AUTHOR]

Intramolecular electron transfer between two biphenyl groups linked by an androstane spacer and excitation of the pyridinium-N-phenolate betaine dye B30 to the first excited singlet state are studied by quantum/classical molecular-dynamics simulations at temperatures between 150 and 300 K in solvents with a range of polarities. Temperature dependences of the solvent reorganization energies, free energies, entropies, and the inhomogeneous broadening of B30's absorption band are examined. The variances of fluctuations of the energy gap between the reactant and product states do not have the direct proportionality to temperature that often is assumed to hold. An explanation for the observations is suggested. [ABSTRACT FROM AUTHOR]

Metal-reducing bacteria have adapted the ability to respire extracellular solid surfaces instead of soluble oxidants. This process requires an electron transport pathway that spans from the inner membrane, across the periplasm, through the outer membrane, and to an external surface. Multiheme cytochromes are the primary machinery for moving electrons through this pathway. Recent studies show that the chiral-induced spin selectivity (CISS) effect is observable in some of these proteins extracted from the model metal-reducing bacteria, Shewanella oneidensis MR-1. It was hypothesized that the CISS effect facilitates efficient electron transport in these proteins by coupling electron velocity to spin, thus reducing the probability of backscattering. However, these studies focused exclusively on the cell surface electron conduits, and thus, CISS has not been investigated in upstream electron transfer components such as the membrane-associated MtrA, or periplasmic proteins such as small tetraheme cytochrome (STC). By using conductive probe atomic force microscopy measurements of protein monolayers adsorbed onto ferromagnetic substrates, we show that electron transport is spin selective in both MtrA and STC. Moreover, we have determined the spin polarization of MtrA to be ∼77% and STC to be ∼35%. This disparity in spin polarizations could indicate that spin selectivity is length dependent in heme proteins, given that MtrA is approximately two times longer than STC. Most significantly, our study indicates that spin-dependent interactions affect the entire extracellular electron transport pathway. [ABSTRACT FROM AUTHOR]

Designing organic semiconductors for practical applications in organic solar cells, organic field-effect transistors, and organic light-emitting diodes requires understanding charge transfer mechanisms across different length and time scales. The underlying electron transfer mechanisms can be efficiently explored using semiempirical quantum mechanical (SQM) methods. The dimer projection (DIPRO) method combined with the recently introduced non-self-consistent density matrix tight-binding potential (PTB) [Grimme et al., J. Chem. Phys. 158, 124111 (2023)] is used in this study to evaluate charge transfer integrals important for understanding charge transport mechanisms. PTB, parameterized for the entire Periodic Table up to Z = 86, incorporates approximate non-local exchange, allowing for efficient and accurate calculations for large hetero-organic compounds. Benchmarking against established databases, such as Blumberger's HAB sets, or our newly introduced JAB69 set and comparing with high-level reference data from ωB97X-D4 calculations confirm that DIPRO@PTB consistently performs well among the tested SQM approaches for calculating coupling integrals. DIPRO@PTB yields reasonably accurate results at low computational cost, making it suitable for screening purposes and applications to large systems, such as metal-organic frameworks and cyanine-based molecular aggregates further discussed in this work. [ABSTRACT FROM AUTHOR]

The nitrogen-vacancy (NV) centers (NCVSi)− in 4H silicon carbide (SiC) constitute an ensemble of spin S = 1 solid state qubits interacting with the surrounding 14N and 29Si nuclei. As quantum applications based on a polarization transfer from the electron spin to the nuclei require the knowledge of the electron–nuclear interaction parameters, we have used high-frequency (94 GHz) electron–nuclear double resonance spectroscopy combined with first-principles density functional theory to investigate the hyperfine and nuclear quadrupole interactions of the basal and axial NV centers. We observed that the four inequivalent NV configurations (hk, kh, hh, and kk) exhibit different electron–nuclear interaction parameters, suggesting that each NV center may act as a separate optically addressable qubit. Finally, we rationalized the observed differences in terms of distinctions in the local atomic structures of the NV configurations. Thus, our results provide the basic knowledge for an extension of quantum protocols involving the 14N nuclear spin. [ABSTRACT FROM AUTHOR]

In this computational study, we describe a self-consistent trajectory simulation approach to capture the effect of neutral gas pressure on ion–ion mutual neutralization (MN) reactions. The electron transfer probability estimated using Landau–Zener (LZ) transition state theory is incorporated into classical trajectory simulations to elicit predictions of MN cross sections in vacuum and rate constants at finite neutral gas pressures. Electronic structure calculations with multireference configuration interaction and large correlation consistent basis sets are used to derive inputs to the LZ theory. The key advance of our trajectory simulation approach is the inclusion of the effect of ion-neutral interactions on MN using a Langevin representation of the effect of background gas on ion transport. For H+ − H− and Li+ − H(D)−, our approach quantitatively agrees with measured speed-dependent cross sections for up to ∼105 m/s. For the ion pair Ne+ − Cl−, our predictions of the MN rate constant at ∼1 Torr are a factor of ∼2 to 3 higher than the experimentally measured value. Similarly, for Xe+ − F− in the pressure range of ∼20 000–80 000 Pa, our predictions of the MN rate constant are ∼20% lower but are in excellent qualitative agreement with experimental data. The paradigm of using trajectory simulations to self-consistently capture the effect of gas pressure on MN reactions advanced here provides avenues for the inclusion of additional nonclassical effects in future work. [ABSTRACT FROM AUTHOR]

For a detailed understanding of many processes in nature involving, for example, energy or electron transfer, the theory of open quantum systems is of key importance. For larger systems, an accurate description of the underlying quantum dynamics is still a formidable task, and, hence, approaches employing machine learning techniques have been developed to reduce the computational effort of accurate dissipative quantum dynamics. A downside of many previous machine learning methods is that they require expensive numerical training datasets for systems of the same size as the ones they will be employed on, making them unfeasible to use for larger systems where those calculations are still too expensive. In this work, we will introduce a new method that is implemented as a machine-learned correction term to the so-called Numerical Integration of Schrödinger Equation (NISE) approach. It is shown that this term can be trained on data from small systems where accurate quantum methods are still numerically feasible. Subsequently, the NISE scheme, together with the new machine-learned correction, can be used to determine the dissipative quantum dynamics for larger systems. Furthermore, we show that the newly proposed machine-learned correction outperforms a previously handcrafted one, which, however, improves the results already considerably. [ABSTRACT FROM AUTHOR]

Investigating the role of chiral-induced spin selectivity in the generation of spin correlated radical pairs in a photoexcited donor–chiral bridge–acceptor system is fundamental to exploit it in quantum technologies. This requires a minimal master equation description of both charge separation and recombination through a chiral bridge. To achieve this without adding complexity and entering in the microscopic origin of the phenomenon, we investigate the implications of spin-polarizing reaction operators to the master equation. The explicit inclusion of coherent evolution yields non-trivial behaviors in the charge and spin dynamics of the system. Finally, we apply this master equation to a setup comprising a molecular qubit attached to the donor–bridge–acceptor molecule, enabling qubit initialization, control, and read-out. Promising results are found by simulating this sequence of operations assuming realistic parameters and achievable experimental conditions. [ABSTRACT FROM AUTHOR]

Exciplexes are excited-state complexes formed as a result of partial charge transfer from the donor to the acceptor species when one moiety of the donor–acceptor pair is electronically excited. The arene–amine exciplex formed between oligo-(p-phenylene) (OPP) and triethylamine (TEA) is of interest in the catalytic photoreduction of CO2 because it can compete with complete electron transfer to the OPP catalyst. Therefore, formation of the exciplex can hinder the generation of a radical anion OPP·− necessary for subsequent CO2 reduction. We report an implementation of a workflow automating quantum-chemistry calculations that generate and characterize an ensemble of structures to represent this exciplex state. We use FireWorks, Pymatgen, and Custodian Python packages for high-throughput ensemble generation. The workflow includes time-dependent density functional theory optimization, verification of excited-state minima, and exciplex characterization with natural transition orbitals, exciton analysis, excited-state Mulliken charges, and energy decomposition analysis. Fluorescence spectra computed for these ensembles using Boltzmann-weighted contributions of each structure agree better with experiment than our previous calculations based on a single representative exciplex structure [Kron et al., J. Phys. Chem. A 126, 2319–2329 (2022)]. The ensemble description of the exciplex state also reproduces an experimentally observed red shift of the emission spectrum of [OPP-4–TEA]* relative to [OPP-3–TEA]*. The workflow developed here streamlines otherwise labor-intensive calculations that would require significant user involvement and intervention. [ABSTRACT FROM AUTHOR]

In this research, we explore sequence-dependent chiral-induced spin selectivity (CISS) in double-stranded (ds)-DNA using time-correlated single-photon counting and electrochemical impedance spectroscopy supplemented by tight-binding calculations of the phenomenon for the first time. The average lifetime of the photo-excited electrons in a Quantum Dot-DNA system is influenced by the CISS effect generated by the DNA molecule, and the difference in average time decay of electrons was found to be 345 ps for opposite polarity ("UP" and "DOWN") of spins due to the CISS effect. Moreover, the yield of spin-polarized electrons due to the CISS effect was reduced by more than 35% from perfect DNA to DNA with point mutations. Remarkably, by employing a tight binding method combined with Green's function formalism for transport, simulations of the process support the observed experimental trends. Our results provide a basic understanding of the sequence-specific spin-dependent electron transfer through ds-DNA. These results would help to build spin-based next-generation DNA sensors. [ABSTRACT FROM AUTHOR]

Controlling matter at the level of electrons using ultrafast laser sources represents an important challenge for science and technology. Recently, we introduced a general laser control scheme (the Stark control of electrons at interfaces or SCELI) based on the Stark effect that uses the subcycle structure of light to manipulate electron dynamics at semiconductor interfaces [A. Garzón-Ramírez and I. Franco, Phys. Rev. B 98, 121305 (2018)]. Here, we demonstrate that SCELI is also of general applicability in molecule–semiconductor interfaces. We do so by following the quantum dynamics induced by non-resonant few-cycle laser pulses of intermediate intensity (non-perturbative but non-ionizing) across model molecule–semiconductor interfaces of varying level alignments. We show that SCELI induces interfacial charge transfer regardless of the energy level alignment of the interface and even in situations where charge exchange is forbidden via resonant photoexcitation. We further show that the SCELI rate of charge transfer is faster than those offered by resonant photoexcitation routes as it is controlled by the subcycle structure of light. The results underscore the general applicability of SCELI to manipulate electron dynamics at interfaces on ultrafast timescales. [ABSTRACT FROM AUTHOR]

Electron transfer (ET) is a fundamental process in chemistry and biochemistry, and electronic coupling is an important determinant of the rate of ET. However, the electronic coupling is sensitive to many nuclear degrees of freedom, particularly those involved in intermolecular movements, making its characterization challenging. As a result, dynamic disorder in electron transfer coupling has rarely been investigated, hindering our understanding of charge transport dynamics in complex chemical and biological systems. In this work, we employed molecular dynamic simulations and machine-learning models to study dynamic disorder in the coupling of hole transfer between neighboring ethylene and naphthalene dimer. Our results reveal that low-frequency modes dominate these dynamics, resulting primarily from intermolecular movements such as rotation and translation. Interestingly, we observed an increasing contribution of translational motion as temperature increased. Moreover, we found that coupling is sub-Ohmic in its spectral density character, with cut-off frequencies in the range of 102 cm−1. Machine-learning models allow direct study of dynamics of electronic coupling in charge transport with sufficient ensemble trajectories, providing further new insights into charge transporting dynamics. [ABSTRACT FROM AUTHOR]

We address the electron-spin-phonon coupling in an effective model Hamiltonian for DNA to assess its role in spin transfer involved in the Chiral-Induced Spin Selectivity (CISS) effect. The envelope function approach is used to describe semiclassical electron transfer in a tight-binding model of DNA at half filling in the presence of intrinsic spin–orbit coupling. Spin-phonon coupling arises from the orbital-configuration dependence of the spin–orbit interaction. We find spin-phonon coupling only for the acoustic modes, while the optical modes exhibit electron–phonon interaction without coupling to spin. We derive an effective Hamiltonian whose eigenstates carry spin currents that are protected by spin-inactive stretching optical modes. As optical phonons interact more strongly than acoustic phonons, side buckling and tilting optical base modes will be more strongly associated with decoherence, which allows for the two terminal spin filtering effects found in CISS. [ABSTRACT FROM AUTHOR]

An experimental study on the role of an external longitudinal magnetic field on the characteristics changes of pulsed plasma stream, produced in argon medium, is carried out at different time spans of its evolution. The spectroscopic observations are time integrated and are carried out at different times of plasma formation for pulsed discharge. This study gives insights into the recombination and diffusion phase of the plasma species in the presence of the magnetic field. The transition of plasma species from a dominant recombination phase to a diffusional phase is well revealed by the density profile during the time evolution. Moreover, the decrease in electron temperature and the increase in electron excitation temperature explain the energy transfer to electrons due to metastable quenching, and the system gradually approaches equilibrium. The magnetic field also affects the transitions of the ionized argon population between different energy levels. It is found that faster decay occurs for transitions of different plasma species to non-metastable states, while the populations of metastable states exist for a longer time. In addition, the time-resolved morphology changes of the plasma stream are also observed by high speed imaging, which shows the flow structure of the plasma stream at different time frames. The imaging of the plasma stream evolution shows the initial ejection of the plasma sheet from the electrode assembly, its detachment, the steady flow, and gradually its nature of dying out. [ABSTRACT FROM AUTHOR]

The coherent transfer of electron spin polarization to nuclei by means of a microwave pulse sequence is a promising new approach to enhancing the sensitivity of solid-state nuclear magnetic resonance (NMR). The development of pulse sequences for dynamic nuclear polarization (DNP) of bulk nuclei is far from complete, as is the understanding of what makes a good DNP sequence. In this context, we introduce a new sequence, termed Two-Pulse Phase Modulation (TPPM) DNP. We provide a general theoretical description for electron–proton polarization transfer by periodic DNP pulse sequences and find it in excellent agreement with numerical simulations. In experiments at 1.2 T, TPPM DNP generates a higher gain in sensitivity than existing sequences XiX (X-inverse-X) and TOP (Time-Optimized Pulsed) DNP but does so at relatively high nutation frequencies. In contrast, we find that the XiX sequence performs very well at nutation frequencies as low as 7 MHz. A combination of theoretical analysis and experimental investigation makes clear that fast electron–proton polarization transfer, due to a well-preserved dipolar coupling in the effective Hamiltonian, correlates with a short build-up time of the dynamic nuclear polarization of the bulk. Experiments further show that the performances of XiX and TOP DNP are affected differently by the concentration of the polarizing agent. These results constitute important reference points for the development of new and better DNP sequences. [ABSTRACT FROM AUTHOR]

Electron transfer at electrode interfaces to molecules in solution or at the electrode surface plays a vital role in numerous technological processes. However, treating these processes requires a unified and accurate treatment of the fermionic states of the electrode and their coupling to the molecule being oxidized or reduced in the electrochemical processes and, in turn, the way the molecular energy levels are modulated by the bosonic nuclear modes of the molecule and solvent. Here we present a physically transparent quasiclassical scheme to treat these electrochemical electron transfer processes in the presence of molecular vibrations by using an appropriately chosen mapping of the fermionic variables. We demonstrate that this approach, which is exact in the limit of non-interacting fermions in the absence of coupling to vibrations, is able to accurately capture the electron transfer dynamics from the electrode even when the process is coupled to vibrational motions in the regimes of weak coupling. This approach, thus, provides a scalable strategy to explicitly treat electron transfer from electrode interfaces in condensed-phase molecular systems. [ABSTRACT FROM AUTHOR]

Solar-driven water splitting for hydrogen production is a vital approach to mitigating the energy crisis and achieving carbon neutrality and peak carbon emissions. Cd 0.8 Mn 0.2 S holds significant potential for photocatalytic hydrogen evolution but faces severe challenges due to photogenerated carrier recombination. To address this, we employed ultrasonic self-assembly to tightly couple Cu 2 WS 4 nanosheets with Cd 0.8 Mn 0.2 S nanoparticles, forming an S-scheme heterojunction to reduce carrier recombination rates. In this configuration, Cd 0.8 Mn 0.2 S acts as the electron acceptor, and Cu 2 WS 4 serves as the electron donor. The Cd 0.8 Mn 0.2 S/Cu 2 WS 4 structure creates a closely spaced interface, providing the shortest transfer distance for electron migration. The S-scheme heterojunction strategy effectively suppresses the recombination of photogenerated carriers, promoting vectorial separation. Under 10 W white light irradiation, the Cd 0.8 Mn 0.2 S/Cu 2 WS 4 composite photocatalyst exhibited remarkable hydrogen evolution activity, with a hydrogen production rate of 39.83 mmol g−1 h−1. This S-scheme heterojunction strategy lays the foundation for the structural design and large-scale application of high-activity visible-light photocatalysts. • Recombination of photogenerated carriers is inhibited. • Facilitated vector separation of photogenerated carriers. • In situ irradiated XPS validates the S-scheme heterojunction charge transfer mechanism. [ABSTRACT FROM AUTHOR]

It is immensely meaningful to design efficient electrolysis for water electrolysis and realize green hydrogen production. Herein, a ruthenium dioxide modified CoFe-Layered double hydroxides (LDHs) catalyst (RuO 2 /CoFe-LDH/NF) was synthesized by combining the advantages of RuO 2 and CoFe-LDHs for driving alkaline water and seawater. RuO 2 /CoFe-LDH/NF display impressive activity and stability at 10 mA cm−2, which only need an overpotential of 59 and 270 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) respectively. Meaningfully, the catalyst only required a small cell voltage of 1.58 V as a bifunctional catalyst, what is superior to commercial RuO 2 /NF||Pt/C/NF (1.66 V). In addition, RuO 2 /CoFe-LDH/NF exhibited excellent HER and OER performance with overpotentials of 119 and 260 mv in alkaline seawater at 10 mA cm−2, respectively. Additionally, RuO 2 /CoFe-LDH/NF displays a larger corrosion potential, smaller corrosion and improved oxygen evolution capacity than CoFe-LDH/NF. Moreover, there is electron transfer between Ru and Co or Fe, which can improve the micro-coordination environment and enhance the stability for RuO 2 /CoFe-LDH/NF. The method with integration of RuO 2 and CoFe-LDH could be broadened to explore other robust bifunctional catalysts for water/seawater electrolysis. Trace RuO 2 decorated CoFe-LDH can not only provide much more active sites, but also stabilize the active site of CoFe-LDH, resulting in an enhance activity and stability [Display omitted] • RuO 2 nanoparticles modified CoFe-LDHs were prepared by a simple hydrothermal synthesis method. • RuO 2 /CoFe-LDH/NF displays excellent HER and OER performance in seawater electrolysis. • The interaction among various metals can establish a micro-environment to enhance stability. [ABSTRACT FROM AUTHOR]

The slow electron transfer rate and low temperature are the bottleneck in biological denitrification process, and quinone electron shuttle (e.g. AQDS) has been confirmed as a viable approach to improve the efficiency of biological denitrification by accelerating electron transport. In this study, we employed the eletrotrophic bio-cathode with cold-tolerant to explore the mechanisms of extracellular electron transfer (EET) mediated by AQDS in simultaneous nitrification and denitrification (SND) for the first time. The results indicated that adding 0.5 mmol/L AQDS increased NH 4 +-N removal rate and SND efficiency by 18.1% and 17.9%, respectively, and the optimal hydraulic retention time (HRT) was shortened from 5 d to 3 d. The potential mechanism was that AQDS resulted in a 1.47-fold increase in the relative abundance of cathodic electroactive microorganisms, and the relative abundance of functional genes such as cytochrome c , flavin, cold acclimation and translocator increased by about 1.15–300.42%, which accelerated the transfer of extracellular electron and significantly improved the energy metabolism efficiency. In addition, AQDS may act as an electron shuttle to accelerate the electronic transition in long-distance electron transfer. In summary, this study expands our understanding of the role of AQDS in the SND process by bio-cathode under low temperature and provides an insight into the EET of eletrotrophic microorganisms with cold-tolerant. [Display omitted] • AQDS enhanced the removal rate of NH 4 +-N and SND efficiency of electrotrophic bio-cathode at low temperature. • AQDS promoted the energy metabolism of eletrotrophic microorganisms with cold-tolerant. • AQDS increased the abundance of functional genes, ehancing electorn transfer. • AQDS immerged in EPS accelarated electorn hopping by act as an electron shuttle. [ABSTRACT FROM AUTHOR]

The low electrical conductivity and catalytic activity of transition metal sulfides have been identified as the primary factors limiting their application in the field of electrocatalytic water splitting. In this study, FeS 2 and Co-FeS x were initially synthesized through a hydrothermal method, followed by further annealing in an NH 3 atmosphere to obtain Co,N-FeS x. The introduction of Co led to adjustments in the electronic structure, resulting in the formation of FeS 2 /FeS (FeS x) heterojunctions that facilitated accelerated charge transfer. Simultaneously, Co element doping increased the electrochemical active surface area, providing more active sites for the reactions. N element doping, on the other hand, introduced sulfur vacancies, thereby enhancing electrical conductivity and improving charge transfer efficiency. As a result, Co,N-FeS x exhibited significantly higher activities for the oxygen evolution reaction (OER) and overall water splitting compared to FeS 2 , with overpotentials of 290 mV and 330 mV, respectively, at a current density of 10 mA cm−2. Furthermore, the catalyst demonstrated excellent stability. The designed structure of the catalyst provides theoretical support for the study of Fe-based catalysts in OER and overall water splitting. [Display omitted] • Co,N-FeS x were synthesized by hydrothermal and further annealing in NH 3 atmosphere. • Co and N co-doping is benefit to increase the exposed actives. • FeS/FeS 2 heterojunction can provide the rapid electron transfer. • Co,N-FeS x exhibited desirable OER and overall water splitting activity. [ABSTRACT FROM AUTHOR]

We have investigated the electronic properties of lithium, sodium, and potassium doped endohedrally on C20 fullerenes, through DFT calculations. The dipolar moment, average binding energies, cohesion energy, ‖HOMO–LUMO‖ energy gaps and NBO population analysis are expressed as functions of Li amount. The electrons transferred by lithium are distributed on the surface of the C20. The excess charge induces a decrease in the gap value, which allows the structure to behave like a semiconductor material. The obtained results indicate that the C20 fullerenes are highly efficient in adsorbing Li atoms, as the retention capacity of Li@C20, Na@C20, and K@C20 exceeds 1458.9, 1146.3, and 907.4 mA h g−1, respectively. The Li@C20 complex provides a maximum voltage of 1.1 V. The insertion of Na and K increases the adsorption energy, so the voltage also increases to 2.2 and 2.4 V. This makes them an alternative for energy storage. [ABSTRACT FROM AUTHOR]

Exploring the construction of an interface with bright emission, fabulous stability, and good function to develop high-performance electrochemiluminescence (ECL) biosensors for tumor biomarkers is in high demand but faces a huge challenge. Herein, we report an oriented attachment and in situ self-assembling strategy for one-step fabrication of CdTe QD-encapsulated Hf polymer membrane onto an ITO surface (Hf-CP/CdTe QDs/APS/ITO). Hf-CP/CdTe QDs/APS/ITO is fascinating with excellent stability, high ECL emission, and specific adsorption toward ssDNA against dsDNA and mononucleotides (mNs). These interesting properties make it an ideal interface to rationally develop an immobilization-free ECL biosensor for cancer antigen 125 (CA125), used as a proof-of-concept analyte, based on target-aptamer recognition-promoted exonuclease III (Exo III)-assisted digestion. The recognition of ON by CA125 leads to the formation of CA125@ON, which hybridizes with Fc-ssDNA to switch Exo III-assisted digestion, decreasing the amount of Fc groups anchored onto the electrode's surface and blocking electron transfer. As compared to the case where CA125 was absent, significant ECL emission recovery is determined and relies on CA125 concentration. Thus, highly sensitive analysis of CA125 against other biomarkers was achieved with a limit of detection down to 2.57 pg/mL. We envision this work will provide a new path to develop ECL biosensors with excellent properties, which shows great potential for early and accurate diagnosis of cancer. [ABSTRACT FROM AUTHOR]

A highly efficient ratiometric electrochemiluminescence (ECL) immunoassay was explored by bidirectionally regulating the ECL intensity of two luminophors. The immunoassay was conducted in a split-type mode consisting of an ECL detection procedure and a sandwich immunoreaction. The ECL detection was executed using a dual-disk glassy carbon electrode modified with two potential-resolved luminophors (g-C3N4-Ag and Ru-MOF-Ag nanocomposites), and the sandwich immunoreaction using glucose oxidase (GOx)-modified SiO2 nanospheres as labels was carried out in a 96-well plate. The Ag nanoparticles (NPs) acted as bifunctional units both for triggering the resonance energy transfer (RET) with g-C3N4 and for accelerating the electron transfer rate of the Ru-MOF-Ag ECL reaction. When the H2O2 catalyzed by GOx in the 96-well plate was transferred to the dual-disk glass carbon electrode, the doped Ag NPs in the two luminophors could be etched, thus destroying the RET between C3N4 and the accelerated reaction to Ru-MOF, resulting in an opposite trend in the ECL signal outputted from the dual disks. Using the ratio of the two signals for quantification, the constructed immunosensor for a model target, i.e. myoglobin, exhibited a low detection limit of 4.7 × 10–14 g/mL. The ingenious combination of ECL ratiometry, bifunctional Ag NPs, and a split-type strategy effectively reduces environmental and human errors, offering a more precise and sensitive analysis for complex samples. [ABSTRACT FROM AUTHOR]

The use of ultrasound in the presence of semiconductor materials is considered a novel technique for the degradation of hazardous organic pollutants in water. In this study, graphitic carbon nitride (g), graphene oxide (GO), and Cobalt ferrite, CoFe 2 O 4 (CF) nanoparticles were synthesized via soft-template-assisted synthesis, Hummer's, and hydrothermal methods, respectively. Subsequently, the hybrid magnetic g-C 3 N 4 /CoFe 2 O 4 /GO (g-CF1@GO, g-CF2@GO, g-CF3@GO, and g-CF4@GO) nanocomposites were prepared via a simple hydrothermal route at 180 °C. The crystallite structure, functional groups, morphology, and energy band gaps were characterized by XRD diffraction, FT-IR, TEM, and UV–vis DRS. The heterostructure nanocomposites were formed, as evidenced by the TEM data, with an average crystallite size of 13.4 nm and band gap energies of 2.19–1.80 eV, suggesting their suitability for sono/photo degradation processes. Pyrene, a tetracyclic polycyclic aromatic hydrocarbon (PAH) was chosen as a model pollutant to evaluate the performance of the prepared nanocomposites toward sonocatalytic degradation. The nanocomposites exhibited higher degradation performances than individual materials. The sonocatalytic degradation of pyrene revealed that the g-CF4@GO nanocomposite exhibited the highest sonocatalytic activity and achieved 86.7 and 92.3 % degradation efficiency for 10 and 5 mg/L of pyrene under ultrasonic irradiation (40 mg/L, 50 W and 20 kHz) in 120 min. In addition, the sonocatalytic degradation of pyrene is performed in the absence of any oxidant and follows a pseudo-first-order kinetics. Trapping experiments were carried out to investigate the sonocatalytic degradation mechanism, and the results showed that ●O 2 − was the major reactive species. The easily recoverable magnetic nanocomposite via a simple magnet was tested for its recyclability and reusability, and it was observed that it could degrade up to 78 % of pyrene in four cycles. [ABSTRACT FROM AUTHOR]

Visible light mediated decarboxylative functionalization of carboxylic acids and their derivatives has recently emerged as a novel and powerful toolkit for small molecule activation in diverse carbon–carbon and carbon–hetero bond forming reactions. Naturally abundant highly functionalized bench-stable carboxylic acid analogs have been employed as promising alternatives to non-trivial organometallic reagents for mild and eco-benign synthetic transformation with traceless CO2 by-products. In this highlight article, we focus on the development of various photodecarboxylative functionalization strategies along with intra/inter-molecular cyclization via concerted single electron transfer (SET) or energy transfer (ET) pathways. Moreover, widely explored carboxylic acids are systematically classified here into four categories; i.e., α-keto, aliphatic, α,β-unsaturated, and aromatic analogs for a concise overview to the readership. The association of decarboxylative radical species with coupling partners to construct C–C and C–N/O/S/P/X bonds for each analogous acid has been presented in brief. [ABSTRACT FROM AUTHOR]