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An efficient approach employing 4-dimethylaminopyridine and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as the coupling reagent is presented, which enables the functionalization of cotton linter paper substrates with the 19F spin label N-boc-cis-4-fluoro-l-proline. This spin label can be easily quantified by 19F magic angle spinning (MAS) NMR experiments to determine its loading on paper substrates. During the functionalization, the spin label stays intact, as confirmed by the 1H–19F heterocorrelation (1H → 19F CP MAS FSLG HETCOR) experiments. In combination with dynamic nuclear polarization (19F MAS DNP), the N-boc-cis-4-fluoro-l-proline spin label allows us to inspect 1 μmol/g and even lower molecule loadings on paper substrates, providing a highly sensitive local probe to analyze the structure of biofunctionalizations at the nanoscale on paper substrates in the future.

Photoelectrochemical water splitting is a promising strategy to harvest energy from the sun; it utilizes a photoactive material, coupled with a slight electrical input, to convert water into hydrogen and oxygen. These generated gases are stored as chemical energy and can later be used as fuels. Among many reported photoactive materials, tin disulfide (SnS2) offers unique advantages due to the earth abundance of tin and its appropriate bandgap. Here, we report the fabrication of high-density two-dimensional vertically aligned SnS2nanoflakes anchored on a conductive substrate for photoelectrochemical water splitting application. The as-fabricated nanoflakes were carefully studied, where crystalline, hexagonal SnS2flakes can clearly be observed; their crystal structure has been indexed with the assistance of high-resolution transmission electron microscopy. For photoelectrochemical testing, a Solartron potentiostat was used to perform the indicative electrochemistry tests, including linear polarization, electrochemical impedance spectroscopy, and potential static with a light on–off current. A Horiba Hal-320 solar simulator was used as a light source to illuminate the active samples placed in a 0.5 M Na3PO4aqueous electrolyte. The incident photon to converted electron figure was also calculated and was found to have 2.66% efficiency at zero bias (i.e., spontaneous evolution reaction) and 20.53% efficiency at 1 V bias. This high efficiency is probably due to both the high optical gap of ∼2.4 eV obtained from these 2D nanostructures and their physical structure that maximizes light trapping of the incident source.

Electrochemical measurement of pH on paper artifacts is a very important tool to assess the state of paper conservation. Different methods using different types of electrodes have been standardized to provide reproducible pH values of paper. One of these methodologies is not very invasive since it is made on the paper surface by means of a surface electrode in contact with the paper through a small layer of water previously added at the measurement point. This method is very convenient but suffers from the fact that the pH value given by the instrument is continuously changing during the measurement with a very fast rate in the first seconds and tending to reach a plateau value after very long time. Usually, the measure is taken at a time after which the rate of pH change is below a given value, i.e., when the value can be considered constant. This condition is usually signaled by an automatic instrumental alert provided to the operator. This pH value, however, is not the asymptotic one, which can be reached only at infinite time. Here we have investigated this behavior showing that it is simply due to the gradual diffusion of water away from the measurement region under the electrode. A theoretical model, which reproduces very well the time dependence discussed above, has been developed. The validity of the model has been completely proven by taking in consideration experiments where water diffusion is prevented in a simple confining apparatus. This work shows that it is possible to eliminate any factor affecting accuracy and reproducibility of the pH data for paper measured by the surface electrode method.

An electrostatic self-assembly method is used to synthesize FeSiCr/MXene, and the effect of MXene on the wave-absorbing properties is studied in this paper. The electromagnetic parameters of the composites are adjusted by optimizing the amount of MXene to improve the dielectric polarization and achieving impedance matching in order to enhance the microwave-absorbing properties. The lowest reflection loss (RLmin) of FeSiCr/MXene composites is −50.34 dB at 13.75 GHz. When the quantity of MXene composite is 15 wt % and the matching thickness is only 1.32 mm, the effective absorption bandwidth (EAB) at 2.00 mm approaches 11.05 GHz. The improved FeSiCr impedance matching, together with synergistic effects such as dielectric loss and interfacial polarization, results in outstanding microwave absorption performance for the FeSiCr/MXene composites. This paper proposes a new approach to developing and synthesizing materials with lightweight and efficient electromagnetic wave absorption.

This paper reports the synthesis of different crystalline phase-pure Co-vanadates (CVOs), CoV2O6, Co2V2O7, and Co3V2O8, in the same structure. Electrochemical performance experiments were conducted, and density functional theory calculation was used to study their crystalline properties. This paper finds that the supercapacitor performance of CVOs largely depends on the crystalline structure property and charge storage mechanism. Co2V2O7has the biggest tunnel size and thus exhibits the best electrochemical performance at a low rate. In the aspect of Co3V2O8, superior crystalline structure properties are attributed to excellent performance at a high rate. We anticipate that this study will make a contribution toward offering theoretical guidance for CVO supercapacitor electrode materials.

The synthesis, characterization, and computational modeling of AuCuNiPd nanoparticle alloys are reported in this paper. It was demonstrated that the AuCuNiPd alloys present dispersed atoms along the nanoparticles without any chemical order. The chemical analysis showed the alloys present a stoichiometry consistent with the Au35Cu35Ni15Pd15phase, at times showing segregation related to the Pd and Ni atoms. Molecular dynamics calculations were carried out to describe the stable phase of the nanoparticles, showing remarkable agreement with the experimental results. These findings are consistent with the high-entropy alloy predictions. Therefore, multimetallic nanoparticles with large enough sizes are an excellent model to study multimetallic alloys.

This paper presents a comprehensive mechanistic investigation into the partial oxidation of methane to methanol on bare and ZSM-5-supported Pd4clusters utilizing N2O as an oxidant. The study employs density functional theory (DFT) with ONIOM2 (QM: MM) (B3PW91/LANL2DZ/6-31G(d,p):UFF) with dispersion correction calculations to explore potential energy surfaces (PESs) associated with the methane-to-methanol conversion process in a ZSM-5-supported Pd4cluster. Two spin multiplicities (SM = 1, 3) were considered for the overall reaction pathway. The investigation reveals that C–H activation of methane takes place subsequent to the formation of Pd4O from the N2O decomposition step, which ultimately leads to methanol formation. The study indicates that in terms of activation barrier, the N–O and C–H activation steps exhibit a lower energy barrier in the singlet state, while the recombination step of CH3and OH moieties is preferable in the triplet spin state. However, the reaction process does not involve any spin crossover, as the triplet spin state consistently maintains the lowest energy pathway throughout the reaction. From the overall analysis of the reaction mechanisms for methane to methanol, it is evident that zeolite support and spin multiplicity play a significant role in lowering the activation barriers.

This study looks at energy-dispersive X-ray spectroscopy (EDX) maps of fluorine in NMC 622 cathodes and the efforts made to improve the spatial resolution of fluorine mapping. The transition to electric vehicles demands faster and efficient production of next-generation lithium-ion batteries. To achieve this goal, the industry needs to take advantage of state-of-the-art battery characterization techniques in the pursuit of gaining a greater understanding of electrode structure and production. The binder location within an electrode is critical to electrochemical performance and contains fluorine, yielding an opportunity to use it as a marker and a way to visualize binder distribution and therefore, better understand process-structure relations. However, fluorine is difficult to differentiate from cobalt and manganese in an EDX spectrum due to similar Kα energy. Fluorine also interacts with the electron beam, potentially leading to poor spatial resolution. This paper examines different EDX parameters and compares the spatial resolution of fluorine in the maps of lithium-ion cathode cross sections. Analysis of the EDX maps showed that reducing the accelerating voltage from 20 to 5 kV improved the spatial resolution of fluorine 10-fold, from 2553 to 238 nm, supported by CASINO simulations. The EDX maps also indicated that imaging for one long scan at a 2500 μs dwell time produced a higher spatial resolution than imaging for 10 scans at 250 μs. Repeated line scans of the sample showed the extent of fluorine mobility; fluorine-rich zones emit less, while fluorine-free zones begin to emit more fluorine X-rays. This work shows that the spatial resolution of fluorine maps can be increased by imaging at 5 kV and scanning for one pass at 2500 μs. This methodology can be used to create more representative EDX maps of the binder in the cathodes. Visual analysis or further processing with an image analysis can reveal binder distributions and potential binder gradients. This technique is useful in understanding how changes to electrode manufacturing can change the electrode structure and binder distribution.

Ammonia synthesis by nitrogen and water reaction is essentially a process of nitrogen and hydrogen ion coupling, with electrons forming an N–H bond. In this paper, friction can continuously provide electrons and hydrogen ions in the catalytic reaction of Si3N4to realize the nitrogen fixation process, so as to achieve high efficiency of friction catalytic nitrogen fixation at room temperature. For the direct nitrogen fixation of air and water to produce ammonia, the ammonia yield can reach 1273.4 μmol/g at 5 h, while the ammonia yield can reach 1865.2 μmol/g at 5 h under pure nitrogen and water nitrogen fixation. The rapid contact and separation between a PTFE rod, Si3N4particles, and a glass reactor causes continuous positive and negative charge formation on the surface of Si3N4. The positive charges react with the sacrificial agent methanol and water to generate hydrogen ions, which not only consumes the positive charges, inhibits the recombination of positive and negative charges, and improves the utilization rate of electrons but also provides a large number of hydrogen ion sources for the reaction. Based on the results of density functional theory (DFT) calculations, which indicate that silicon atoms on the surface of silicon nitride have no catalytic activity, while nitrogen atoms can effectively activate nitrogen molecules and catalyze the nitrogen fixation reaction, we designed a tribocatalysis process to continuously break the catalyst particles to expose more surface nitrogen atoms as active sites in situ to promote the nitrogen fixation reaction. In addition, the friction force can provide energy for the reaction in the instantaneous process, which is conducive to the activation of nitrogen molecules to promote the reaction, and together with the continuous charge provided by the friction process, it finally enables Si3N4to catalyze nitrogen fixation efficiently at room temperature.

Fast charging of lithium-ion batteries (LIBs) is now a critical challenge for the development of electric vehicles (EVs). The difficulty of achieving fast-charging LIBs arises from the sluggish Li-ion transport in both electrolytes and electrode materials and the sluggish charge transfer processes across the electrode–electrolyte interphases (EEIs). To overcome these obstacles, it is important to fully understand the transport mechanism of Li+in electrode materials, electrolytes, and EEIs. Spectroscopic techniques are useful tools to detect the structural changes and reveal the mass transport mechanism during the cycling of the batteries, which are helpful to guide the design of novel electrode materials and electrolytes as well as optimal interphases for fast-charging batteries. In this paper, recent advancements in the application of spectroscopic techniques for the development of fast-charging LIBs are reviewed. We focus on the key roles of spectroscopic techniques in revealing the reasons for improved fast-charging capabilities of LIBs, including their application in the fields of electrolyte engineering, interphase modification, Li-plating detection, and composition/structure optimization. Moreover, the application of electrospectroscopic techniques in exploring the interfacial reactions of the electrodes is also discussed. Finally, some perspectives and research directions for improving spectroscopic techniques to advance the development of fast-charging LIBs are provided.

Organic solar cells (OSCs) are lightweight, flexible, and highly transparent; however, their power conversion efficiency is currently subpar. This has motivated researchers to intensify their efforts to augment the performance of these devices. In non-fullerene-acceptor (NFA) OSCs, the impact of spin-triplet states has proved to be significant. In addition, it has been shown that the low exciton binding energies in NFAs, such as Y6, can lead to self-dissociation. These findings call for a deeper exploration. In this paper, we introduce an extended hot kinetic model that accounts for all spin states and the direct dissociation of local exciton states to evaluate their effects on OSC performance. The machine learning technique, specifically a regression neural network algorithm, is employed to handle the complex calculations related to the model. This algorithm generates the current density–voltage (J–V) curves for OSCs, from which three crucialfactors are identified out of 28 examined factors, and their influence on the OSC performance parameters is thoroughly investigated. The analysis indicates that improving charge carrier mobility enhances the fill factor (FF), raising the energy of singlet charge transfer states increases the open-circuit voltage (VOC), and thicker film generally boosts short-circuit current density (JSC) but reduces the FF. Additionally, we explore how these three parameters affect device performance collectively. This research offers fresh insights into designing more efficient OSC devices.

This paper reports the construction of a series of two-dimensional (2D) transition metal coordinated porphyrin-analogue catalytic materials and employs a combined strategy of the first-principles calculations and high-throughput screening to systematically investigate their catalytic activity and reaction mechanisms of electrocatalytic nitrogen reduction reaction (NRR). Ninety metal porphyrin-analogue catalysts are obtained by embedding 30 transition metals (3–5d series) into three classes of two-dimensional porphyrin-analogue substrates. High-throughput screening and full reaction pathway search reveal that MoPp-β-H-meso-Diyne, MoPp-meso-H-β-Ph and MoPp-meso-H-β-Py are the optimal catalysts via the distal pathway with onset potentials of −0.21, −0.26 and −0.28 V, respectively. WPp-meso-H-β-Py and RePp-β-H-meso-Diyne also exhibit good catalytic performance with onset potentials of −0.46 and −0.46 V, respectively. All five catalytic materials demonstrate good electronic conductivity and high stability. A volcano-shaped relationship is unveiled between the free energy change of the first protonation step (ΔG*N2→ *N2H) and the onset potential (Uonset), which can be utilized to describe the catalytic activity of NRR and guide the design and selection of efficient catalysts.

In this paper, we propose a strategy for screening multicomponent alloys using evidence theory and high-throughput density functional theory calculations. We demonstrate an electrochemical C2-selective CO2reduction reaction (eCO2RR) on multicomponent alloys as a practical study. The proposed strategy can screen potential C2-selective alloys from enormous element combinations without complicated structural descriptors or a complete data set. Therefore, this strategy is expected to effectively design multicomponent alloys with vast element combinations.

In this paper, we report on one of the first applications of fluorophore-induced plasmonic current (FIPC) developed, namely, the direct detection of analytes using turn-onfluorescent sensing probes. Recent work by our group has demonstrated the utility of various types of metal nanoparticle films and how these different films can provide the suitable spectral overlap for a wide range of fluorophores and chromophores to be directly detected “electrically”. In this article, we subsequently share our findings pertaining to the sensing of aqueous Fe3+ions via a turn-on fluorescent probe. The probe’s responses are compared between their typical fluorescence solution-based responses as well as their ability to sense Fe3+via the new FIPC transduction mechanism. Our results suggest a pathway for the development of FIPC-based detection of analytes vs using traditional fluorescence sensing techniques, albeit, with nearly identical sensing instrumentation.

In the present paper, we have investigated the evolution of structure followed by local structure-driven magnetic properties in CoxMn3-xO4nanoparticles synthesized through a facile coprecipitation technique. Rietveld refinement of the X-ray diffraction pattern reveals a structural phase transition from the coexistence of tetragonal and cubic to a pure cubic phase with increasing xfrom 1.00 to 2.00. Such transition is validated with local structure analysis where it is observed that while Mn3+and Co2+ions are distributed among B and A sites, respectively, in x= 1.00, with increase in x,Mn3+in the B site is replaced by Co3+ions. When x≥ 1.75, the additional presence of Mn4+is observed from extended X-ray absorption fine structure spectroscopy and confirmed by X-ray photoelectron spectroscopy. In accordance with two structural phases, for x= 1.00, two magnetic transitions Tc1and Tc2at 165 and 93 K, respectively, are observed. With an increase in x, Tc1grows at the expense of Tc2and finally, at x= 2.0, only Tc1is detected. Unusual temperature-dependent Hc is observed for the coexistence of the cubic and tetragonal phase. Such magnetic behavior is discussed based on the competition between magnetic ions occupying the tetrahedral and octahedral sites.

This paper reports X-ray chromophorebehavior: the substituents of an X-ray-absorbing atom (here phosphorus) were found to contribute consistent absorptions, in intensity and in relative peak position (transition energy). Linear relations for absolute peak position, as a function of the sum of the phosphorus neighbor-atom electronegativities (Σχ), have been found for ten chromophore peaks: P–F, P–O, P–Cl, P–N, P–CI, P–WI, P–CII(Ph), P–CII(pyr) P–CII(Fc), P–WII. The discovery was made by finding (i) surprisingly rich phosphorus K-edge X-ray absorption spectra [P X-ray absorption spectroscopy (XAS)] for several four-coordinate-phosphorus compounds, including four new ones involving the W(CO)5substituent, (ii) a vastly improved time-dependent (linear-response-based) density-functional-theory prediction method for P XAS which provides unprecedented XAS peak-assignment ability, and (iii) a fresh antibonding-orbital-based interpretive framework. The discovery, that selective X-ray excitation of substituents is possible, opens the door for studies of chemical reactivity implications (X-ray photochemistry), and improved studies of X-ray radiation exposure effects and damage.

Electrochemical water splitting is a promising strategy for reducing hydrogen production costs. However, the conventional phosphate buffer (PBS) electrolyte incurs a huge energy penalty in high overpotential ranges. This study investigates the hydrogen evolution reaction (HER) performance using two buffer electrolytes with different charge properties: H2PO4–/HPO42–(PBS pKa= 6.90) and IMZH+/IMZ (IMZS pKa= 7.03). On Pt microelectrodes, results reveal that the plateau current density of PBS correlates closely with the electrode potential, a trend not observed with IMZS. In addition, when using commercial Pt/C nanocatalysts loaded on carbon paper, the plateau current density phenomenon disappears in the IMZS electrolyte, which is attributed to the preconcentration effect of the positively charged hydrogen source. In situ Raman characterization indicates that the configuration of H2PO4–at the electrochemical interface changes as the electrode potential becomes progressively negative. In comparison, the adsorption configuration of IMZH+remains considerably stable across the tested potential range. The grand canonical density functional theory method with both implicit and explicit solvation models was further used to investigate the influence of electrode potential on the dissociation of a differently charged hydrogen source. Results indicate that when the electrode potential becomes progressively negative, H2PO4–is repelled from the electrode surface owing to electrostatic forces, increasing Gibbs free energy of dissociation accordingly. This phenomenon contributes to the inevitable energy penalty observed in the PBS electrolyte for the HER. In comparison, the Gibbs free energy of dissociation of IMZH+decreases monotonically with the progressive negative cathode potential. To explain this discrepancy, this study briefly examined the influence of electrode potential in two aspects: theoretical thermodynamics energy and the state of the hydrogen source near the electrode surface.

In our recent paper [Phys. Rev. B2023, 107, 184314], we introduced a Floquet electronic friction model to describe nonadiabatic molecular dynamics near metal surfaces in the presence of periodic driving. In this work, we combine the quantum transport study with Langevin dynamics and demonstrate that the nonvanishing antisymmetric friction tensor associated with Floquet driving results in a closed trajectory for the nuclei in the long-time limit. We show that Floquet driving strongly affects nuclear motion, resembling the Lorentz force. Our results indicate that Floquet driving can increase the temperature of the nuclei at low bias voltages, whereas Floquet driving can cool down the nuclei at high bias voltages. In addition, we show that Floquet driving can affect electron transport strenuously. Finally, we find out that there is an optimal frequency that maximizes electron current. We expect that the Floquet electronic friction model will provide a powerful tool for further research in nonadiabatic molecular dynamics near metal surfaces under Floquet driving.

Efficiently separating sulfur hexafluoride/nitrogen (SF6/N2) poses an urgent challenge. Four covalent organic frameworks (COFs) (Re % > 80%) with greater performance in SF6/N2separation experiment were selected from the CURATED database by high-throughput screening in this paper. XGB was selected among four machine learning models (SVM, RF, GBRT, and XGB) and this model had good fitting effects in terms of both regeneration (Re %, R2= 0.809) and ln(Sads). Relative importance analyses of XGB described that porosity and infinite dilution heat are the most key features for Re % and ln(Sads). The binding energy, charge density difference, Bader charge, and independent gradient model based on Hirshfeld partition (IGMH) analysis were all calculated to investigate the adsorption mechanisms. GCMC simulations combined with density functional theory calculations revealed that COF-638 exhibited an excellent SF6/N2separation performance. The probability distribution diagram of the center of mass illustrates the adsorption sites of SF6in coadsorption.

The composite support strategy is of great significance in regulating the reaction performance of catalysts. In this paper, the water–gas shift reaction catalyzed by copper clusters supported on the TiO2and CeOx–TiO2mixed support was studied comparatively. The introduction of a Ce2Oxoverlayer increases the adsorption energy of oxygen-containing species due to the conversion of adsorption sites from metals to the Cu8–CeOxinterface. It is more advantageous to react on copper clusters on the Cu/TiO2surface, mainly through the redox mechanism. The reaction on the Cu/CeOx–TiO2surface is more advantageous at the Cu8–CeOxinterface, also through the redox mechanism. Microkinetic analysis shows that the addition of the CeOxsupport significantly enhances the performance of the water–gas shift reaction. The reason for the high activity of the Cu/CeOx–TiO2catalyst is that the rate-determining step changes from H2O dissociation to OH dissociation. Fundamentally, the Ce site on the Cu8/CeOxinterface activates H2O and promotes the decomposition of H2O. As CeOxcan promote H2O dissociation largely, the excessive OH* results in surface poisoning and reduced C–O (or H2) formation, and the appropriate concentration of OH* is better for WGSR due to the balance of O–H bond activation and C–O (or H–H) bond formation, so the Cu–Ce–Ti model with the OH* ligand maybe the candidate of the active site for Cu/CeOx/TiO2. OH self-promoting reaction mechanism offers new insights into the fundamental role of surface adsorbed OH intermediate in WGSR. This article reveals the essence of the composite oxide support strategy in improving reaction performance, pointing out a new direction for regulating reaction performance.

Covalent organic framework (COF) materials are characterized by periodic π arrays and orderly open channels, but poor electrical conductivity limits their applications in opt-electric fields. In this paper, 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) were used to synthesize TPT-COF with a redox unit of triazine by Schiff base reaction. In order to improve the electrical conductivity of TPT-COF, we prepared Nickel Nanowires (NiNWs) by a chemical reduction method and then prepared TPT-COF/NiNWs composites with different loading amounts of NiNWs. With the addition of NiNWs, the two materials are assembled to obtain a nanorod structure by using the π–π packing effect of the COF and the bridging of function conductive NiNWs. The electrochemical properties of composite electrode materials with different contents of NiNWs were tested, and TPT-COF/NiNWs-15% exhibited better electrochemical performance in sulfuric acid electrolytes. The specific capacitance of TPT-COF/NiNWs-15% is 343 F/g, and the high power density is 10945 W/kg. The addition of NiNWs provides a good strategy to improve the electrical performance of the COF-based electrode materials.

Proton exchange membrane water electrolysis (PEMWE) is one of the potential strategies to generate green hydrogen energy, and anticorrosive coatings are mandatory to protect the bipolar plates, an important component of PEMWE. However, it is still challenging to explore the high-corrosion-resistance coatings by trial and error. In this paper, the corrosion properties of Ta and its alloys as examples are studied theoretically; in particular, the influences of crystal planes and alloying elements on the corrosion resistance have been studied systematically. Four descriptors, surface energy density ξ, work function τ, electronic descriptor ψ, and d band center ς, are proposed to screen the high-corrosion-resistance coatings. It is found that the electronic descriptor ψ can well predict the atomic escape energy and thus the corrosion resistance of Ta-based binary alloys with the coefficient of determination R2of 0.804 and 0.949, respectively. Among them, TaW and TaCr alloys exhibit the most excellent corrosion resistance with the lowest Icorr(<1.59 × 10–7A cm–2) and the highest Ucorr(> −0.011 V vs SHE) because of the largest −IpCOHP values and thus the strongest binding strength. The screening method is also applicable to the other alloys.

In this paper, we adopt a novel approach to investigate the ionic conduction near the percolation transition in a porous nanomaterial. We make use of a recently discovered humidity sensing property of aerosol-printed MoS2ink films, where the conductance, originated from ionic transport through water nanochannels within the films, is dependent on the ambient humidity. The experiments, performed for a set of four devices inside a chamber with controlled humidity, allow the experimental fine-tuning of the ionic conduction percolation within each nanoporous device by changing the ambient relative humidity, without the need of different samples for different stoichiometries as in usual percolation experiments. Our results indicate the existence, in our devices, of a common phenomenology consisting of two sequential modifications of the conductance as a function of humidity near percolation. The first is the true percolation transition with a universal critical exponent very close to unity. This is followed by an apparent increase in the critical exponent above the true transition. We also perform molecular dynamics simulations that allow the identification of a possible mechanism for dimensionality changes in the water nanochannels inside the material as a function of either humidity or material geometry as a possible scenario for the observed conductance modification in the conductive phase.

In this paper, the thermal transport characteristics of penta-CN2and -BCN, which can be seen as the analogues of penta-graphene, are systematically studied by first-principles calculation and solving the phonon Boltzmann transport equation. The results reveal that, in contrast to the traditional two-dimensional materials, the three-phonon scattering process is insufficient to adequately characterize the thermal transport mechanisms of the above two materials, and the four-phonon scattering process has an enormous impact on their thermal transport processes. The thermal conductivity of penta-CN2at room temperature is reduced by 44.1% after considering four-phonon scattering, and that of penta-BCN is dropped by 60.0% in the same case. Combining with phonon analysis, it can be found that four-phonon scattering mainly affects the phonons in the ZA branch, which is mainly due to the extremely isolated distribution of the ZA branch. Further, it can also be noticed that the number of the phonon scattering channel involved in the redistribution process is significantly higher than those of the other two four-phonon scattering processes, i.e., splitting and recombination processes, and even reaches the level of the three-phonon scattering processes. Under the influence of the above factors, the four-phonon scattering process plays an extremely important role in the thermal transport properties of penta-CN2and -BCN. Considering that the dispersion curves of the two structures do not have an obvious phonon bandgap, we can notice that the impact mechanism of four-phonon scattering in penta-CN2and -BCN is significantly different from those of other structures, which are also greatly affected by four-phonon scattering, e.g., BAs. The results in this work provide strong theoretical support for expanding the application of penta-structures and four-phonon scattering processes in the field of nanoscale heat transfer.

Hydrogen is a potential alternative reducing agent, which can greatly reduce CO2emission in the ironmaking process of vanadium titanomagnetite. This paper investigated the reaction process and kinetic characteristics of the hydrogen reduction of both untreated and preoxidized vanadium titanomagnetite using a thermogravimetric analyzer (TG). The effects of different preoxidation temperatures (Toxi= 500 °C, Toxi= 700 °C, and Toxi= 900 °C) on the reduction characteristics of vanadium titanomagnetite were compared at a reduction temperature of 1000 °C. It was found that the reduction degree and reduction rate of low-temperature (Toxi= 500 °C and Toxi= 700 °C) preoxidized vanadium titanomagnetite are higher than those of high-temperature (Toxi= 900 °C) preoxidized vanadium titanomagnetite. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses show that the low-temperature preoxidation process separates the Fe/Ti in vanadium titanomagnetite and forms micropores on the surface of the vanadium titanomagnetite, while the high-temperature preoxidation process allows the separated hematite and ilmenite to recombine and form pseudobrookite. The isothermal reduction experiments on untreated and preoxidized vanadium titanomagnetite were carried out, with reduction temperatures ranging from 600 to 1000 °C. The obtained results were subjected to kinetic analysis using conventional model-fitting and iso-conversional methods. The fitting results of different kinetic models show that the activation energies of the preoxidized vanadium titanomagnetite reduction reaction are lower than those of untreated vanadium titanomagnetite. In the entire range of the reduction reaction, the contracting area model (R2) can best describe the reaction between hydrogen and untreated and preoxidized vanadium titanomagnetite. After the preoxidized treatment, the reduction energy barrier of vanadium titanomagnetite decreases by about 38.0%.

Structure-sensitive chiroptical properties favor applications such as polarization detection and nonlinearity; however, large-scale tuning of circular dichroism (CD), for instance, flipped signal, is typically realized in two enantiomers with distinct handedness and rarely in a single planar chiral nanostructure. This paper numerically studies a trident-shaped nanostructure array that allows magnetic-field enhancement by forming semiclosed loop currents in quadrupolar localized plasmon (QL) to generate substantial chiroptical responses with a maximum CD magnitude of 33.1%. Locally changing the rotation of the building block at a small angle of 15° can efficiently modify the structural chirality of the unit cells and thus dramatically inverse the chiroptical responses from negative to positive. We arranged two trident-shaped nanostructures with slightly different configurations but opposite optical chirality into a unit to achieve a high-contrast CD signal with a narrowed line width. Calculations show that the new metamaterial with large electromagnetic-field enhancement in sharp corners enables the detection of low-concentration bovine serum albumin protein with the largest sensitivity of SCD= 795 RIU–1.

Optical matter (OM) arrays are self-organizing, ordered arrangements of nanometer- to micrometer-size particles, where interparticle forces are mediated by incident and scattered coherent light. The structures that form and their dynamics depend on the properties (e.g., material, size) of the constituent particles, as well as the incident and scattered light. While significant progress has been made toward understanding how the OM arrays are affected by the phase, polarization, and intensity profile of the incident light, the polarization induced in the particles and the light scattered by OM arrays have received less attention. In this paper, we establish the roles of electrodynamic interference, many-body coupling, and induced-polarization concomitant with the coherent light scattered by OM arrays. Experiments and simulations together demonstrate that the spatial profile and directionality of coherent light scattered by OM arrays in the far field are primarily influenced by interference, while electrodynamic coupling (interactions) and the associated polarization induced in the nanoparticle constituents have a quantitative wavelength-dependent effect on the total amount of light scattered by the arrays. Furthermore, the electrodynamic coupling in silver nanoparticle OM arrays is significantly enhanced by constructive interference and increases superextensively with the number of particles in the array. Particle size, and hence polarizability, also has a significant effect on the strength of the coupling. Finally, we simulate larger hexagonal OM arrays of Ag nanoparticles to demonstrate that the electrodynamic coupling and scattering enhancement observed in small OM arrays develop into surface lattice resonances observed in the infinite array limit. Our work provides insights for designing OM arrays to tune many-body forces and the coherent light that they scatter.

In this paper, the effects of crystallization advance on the material structure and electrical properties of lithium-ion Na+super ionic conductor (NASICON) glass ceramics were investigated. Glasses with Li1.5Al0.5Ge1.5(PO4)3and Li1.5Sc0.17Al0.33Ge1.5(PO4)3compositions were crystallized in controlled conditions to obtain gradual increment of the volume crystallized fraction. The glass-to-crystal transformation was then monitored by differential scanning calorimetry analysis (DSC), X-ray diffractometry (XRD), Raman spectroscopy, solid-state nuclear magnetic resonance spectroscopy (MAS NMR), and electron microscopy, along with chemical analyses. Finally, the electrical properties of the specimens were evaluated by impedance spectroscopy to observe the changes in electrical properties according to the crystallization advance. Results revealed that glasses containing scandium are more stable against crystallization than their neat counterparts. Crystallization led to the formation of single-phase NASICON glass ceramics. Scandium induced a lattice expansion of the NASICON structure. Furthermore, crystallization induces remarkable structural changes in the materials as a whole, either in local order or in medium to long order. No important increase in conductivity was observed in earlier stages of crystallization. After the percolation of crystals, conductivity increases sharply and the remaining glassy phase has little impact on the total conductivity of the material. Scandium expands the rhombohedral structure but increases the glass stability and reduces the sizes of crystals for the fully crystallized glass ceramics. Glass ceramics with larger grains are more propitious for conductivity than the more refined ones. Therefore, this paper offers key information about the understanding of NASICON crystallization and its structural evolution, providing important insights into the crystallization of these electrolytes.

The formation of 1:1 and 2:1 inclusion complexes between the hosts cyclodextrins (α-, β-, and γ-CD) and the guest 1-(4-carboxybenzyl)-4-[2-(4-pyridyl)vinyl]pyridinium chloride (guest CPP+·Cl–) was demonstrated by NMR spectroscopy. The inclusion complexes CPP+@α-CD, CPP+@β-CD and CPP+@γ-CD2display photochromic properties from pale yellow to red in the solid state. The electron-spin resonance (ESR) spectroscopic data of the CPP+@γ-CD2suggest that the photochromic behavior arises from the generation of the free radicals. The CPP+@γ-CD2can be easily coated on the filter paper and used in erasable inkless printing and anticounterfeiting. Most importantly, the mixture of CPP+@γ-CD2and 1+@β-CD (an inclusion complex previously reported, whose color after irradiation was blue) also can be coated on the filter paper, and the color of printing on the filter paper is tunable by controlling the mass proportions of CPP+@γ-CD2and 1+@β-CD.

This paper examines the reactive surface dynamics of energy- and angle-selected N2dissociation on a clean Ru(0001) surface. Presented herein are the first STM images of highly energetic N2dissociation on terrace sites utilizing a novel UHV instrument that combines a supersonic molecular beam with an in situSTM that is in-line with the molecular beam. Atomically resolved visualization of individual N2dissociation events elucidates the fundamental reactive dynamics of the N2/Ru(0001) system by providing a detailed understanding of the on-surface dissociation dynamics: the distance and angle between nitrogen atoms from the same dissociated N2molecule, site specificity and coordination of binding on terrace sites, and the local evolution of surrounding nanoscopic areas. These properties are precisely measured over a range of impinging N2kinetic energies and angles, revealing previously unattainable information about the energy dissipation channels that govern the reactivity of the system. The experimental results presented in this paper provide insight into the fundamental N2dissociation mechanism that, in conjunction with ongoing theoretical modeling, will help determine the role of dynamical processes such as energy transfer to surface phonons and nonadiabatic excitation of electron–hole pairs (ehps). These results will not only help uncover the underlying chemistry and physics that give rise to the unique behavior of this activated dissociative chemisorption system but also represent an exciting approach to studying reaction dynamics by pairing the angstrom-level spatiotemporal resolution of an in situSTM with nonequilibrium fluxes of reactive gases generated in a supersonic molecular beam to access highly activated chemical dynamics and observe the results of individual reaction events.

Pyrite FeS2has been investigated for a wide range of applications, including thermoelectrics, due to previous observations of large thermopower at room temperature. However, the values of thermopower reported in the literature are extremely sensitive to the nature of the sample─whether they are natural or lab-grown, bulk crystals or thin films─and an ambiguity in the magnitude and sign of the thermopower of pure FeS2exists. Variation in the magnitude of room-temperature thermopower has also been observed in Co-doped samples. Therefore, it is of interest to clarify the intrinsic thermopower of this system that could be measured in more pure samples. In this paper, we investigate the thermoelectric properties of Co-doped FeS2using first-principles calculations. We apply three different doping schemes to understand the effect of electron doping in FeS2, namely, explicit Co substitution, jellium doping, and electron addition within a rigid band approximation (RBA) picture. The calculated thermopower is less than −50 μV/K for all values of Co doping that we studied, suggesting that this system may not be useful in thermoelectric applications. Interestingly, we find that RBA substantially overestimates the magnitude of calculated thermopower compared to the explicit Co substitution and jellium doping schemes. The overestimation occurs because the changes in the electronic structure due to doping-induced structural modification and charge screening are not taken into account by the rigid shift of the Fermi level within RBA. RBA is frequently used in first-principles investigations of the thermopower of doped semiconductors, and Co-substituted FeS2illustrates a case where it fails.

A D–A conjugated polymer was used in fabrication of memory devices. However, devices using polymers as active layers alone do not lead to satisfactory results. In this paper, we have synthesized a donor–acceptor conjugated polymer by the Suzuki coupling reaction. The memory devices prepared by the polymer exhibit a ternary memory behavior. MoO3nanoparticles have a large number of oxygen vacancies on their surface that can act as charge traps. MoO3nanoparticles (NPs) are mixed with polymers to prepare memory devices for improved memory performance. The relationship between the mass percentage of MoO3NPs and the storage performance and mechanism of the storage device is studied. The first and second threshold voltages of the memory device are −0.5 and −0.75 V, respectively. A current ratio of 1:102.14:104.75for the “0″, “1”, and “2” resistance states of the device indicates a low probability of read/write errors. This work shows that polymer-embedded nanoparticle materials have practical application value in the field of next-generation nonvolatile memories.

Flexible metal–organic framework (MOF) compounds can exhibit very pronounced structural changes, which may be favorable for gas storage and gas separation applications. The noble gases xenon and krypton are increasingly important for both research and applications. Therefore, separation approaches with lower energy consumption are of great interest. In the present paper, the adsorption of pure xenon and krypton as well as their mixture by the flexible gate pressure MOFs is investigated using in situ high-pressure 129Xe NMR spectroscopy and volumetric gas adsorption in combination with density-functional theory (DFT) calculations. The chosen model MOF compound DUT-8(Ni) can be synthesized as a flexible or rigid structure by tuning the crystallite size. This allows us to discriminate possible effects exerted by the framework flexibility from influences of structure and composition.

Conjugated polymers composed of alternating electron donor and acceptor segments have come to dominate the materials being considered for organic photoelectrodes and solar cells, in large part because of their favorable near-infrared absorption. The prototypical electron-transporting push–pull polymer poly(NDI2OD-T2) (N2200) is one such material. While reasonably efficient organic solar cells can be fabricated with N2200 as the acceptor, it generally fails to contribute as much photocurrent from its absorption bands as the donor with which it is paired. Moreover, transient absorption studies have shown N2200 to have a consistently short excited-state lifetime (∼100 ps) that is dominated by a ground-state recovery. In this paper, we investigate whether these characteristics are intrinsic to the backbone structure of this polymer or if these are extrinsic effects from ubiquitous solution-phase and thin-film aggregates. We compare the solution-phase photophysics of N2200 with those of a pair of model compounds composed of alternating bithiophene (T2) donor and naphthalene diimide (NDI) acceptor units, NDI-T2-NDI and T2-NDI-T2, in a dilute solution. We find that the model compounds have even faster ground-state recovery dynamics (τ = 45, 27 ps) than the polymer (τ = 133 ps), despite remaining molecularly isolated in solution. In these molecules, as in the case of the N2200 polymer, the lowest excited state has a T2 to NDI charge-transfer (CT) character. Electronic-structure calculations indicate that the short lifetime of this state is due to fast nonradiative decay to the ground state (GS) promoted by strong CT–GS electronic coupling and strong electron-vibrational coupling with high-frequency (quantum) normal modes.

When density functional theory (DFT) is used for modeling polaron defects, the delocalized electronic states often appear due to self-interaction errors. Conventionally, the DFT + Umethod may possibly correct the self-interaction error and thus promote electron localization, but this does not always work. In this paper, based on the GGA + Uapproach, we have modeled small electron polarons by using bond distortion method (BDM) and occupation matrix control (OMC) method in TiO2. Both of these methods can control the position of the polaron at will. We evaluate the appropriate parameters for constructing stable polarons using the BDM. Meanwhile, the occupation of all orbitals of rutile and only low-energy orbitals of anatase was successfully realized using the OMC method. Calculation results show that the polarons constructed by the BDM are more stable irrespective of the crystal structure for TiO2. Furthermore, whichever method is used, the polarons formed in rutile are more stable. Electronic structure calculations demonstrate that rutile has a larger band gap after successful localization through BDM and OMC methods. On the contrary, the band gap of anatase decreases after localization because of the emergence of a new flat energy level at the Fermi level, generated mainly by localized Ti atoms. In order to better understand the polaron formation, we have studied charge transfer, bonding states, and electrostatic potential distributions around the polaron. In the localized solution, the Ti–O bonds around the polaron are all lengthened, while the stability and covalency of these bonds are reduced. The charge is strongly trapped in a potential well caused by lattice distortion, which leads to a lower electrostatic potential energy at the polaron position. In this work, polaron modeling methods and localized structure in TiO2contribute to a better understanding of the polaron structure and its related properties.

In this work, temperature dependent transient absorption spectroscopy measurements are presented on gallium-alloyed CdSe/ZnS core–shell nanoparticles between 30 and 130 °C. To our knowledge, temperature dependent measurements in these systems have been reported only in a few papers, although all processes related to carrier recombination are affected by temperature. For these experiments, gallium-alloyed CdSe/ZnS QD samples were used with nominal doping percentages of 2.5%, 7.5%, 15%. The experimental results show that the transient absorption decay is faster for the pristine CdSe/ZnS samples than in the gallium-alloyed samples at all temperatures. It is assumed that Ga-alloying promotes the formation of trions in the samples by introducing occupied impurity levels within the bandgap of CdSe. The resulting Coulomb blockade will, in turn, prolong the hot-electron relaxation process. By variation of the temperature, the distribution of charge carriers in the different recombination channels can be altered to accelerate recombination in the Ga-alloyed samples at higher temperatures. These measurements demonstrated their usefulness for observing the redistribution of charge carriers among different relaxation pathways.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most popular hole transport materials for replacing traditional high-temperature boron diffusion technology due to its low cost and easy preparation. However, pristine PEDOT:PSS has drawbacks, such as poor work function (WF) and poor film quality, which inhibit the improvement of cell efficiency. According to current research reports, a single dopant can improve only one of these two drawbacks. In this paper, we used Nafion to simultaneously improve the WF and wettability of PEDOT:PSS for preparing novel PEDOT:PSS/n-Si hybrid heterojunction solar cells with a tunnel-oxide passivated contact (TOPCon) back surface field structure, which we call PEDOT:PSS-Nafion (PPN)/n-Si hybrid heterojunction TOPCon solar cell. A cell efficiency of 11.08% was achieved after optimizing the ratio of PEDOT:PSS and Nafion. The three easily improved parameters, namely, series resistance (RS), reflectivity, and WF, were studied and optimized through simulation, achieving a cell efficiency of 20.66%. To reduce RSin the experiment, the Triton X-100-doped PEDOT:PSS film (PPTX) was introduced between the n-Si and PPN films to form highly conductive PPN/PPTX double hole transport layers, and the cell efficiency was increased from 11.08 to 13.7%. The experimental and simulated work presented a new thought and practical guidance for realizing low-cost, easy preparation, and high-efficiency silicon-based solar cells.

A proper understanding of the physical properties at the interface between a nonmagnetic topological insulator and a magnetic film is an indispensable input to develop high-functional spintronics devices using topological insulators. In this paper, we show the physical properties of manganese(II) phthalocyanine (MnPc)-adsorbed Bi2Se3and TlBiSe2, two topological insulators with similar electronic states but different surface compositions. The adsorption of MnPc induces significant electron doping on Bi2Se3, while only a small hole doping was induced on TlBiSe2. This difference in doping is due to the different molecular orientations on the two topological insulators: the flat-lying configuration on Bi2Se3that leads to a large overlap between the d-orbital of Mn and orbitals of surface Se, and the upright configuration on TlBiSe2that results from the presence of Tl atoms on the surface and leads to a negligible orbital overlap. These results pave the way for applications in spintronics devices combining magnetic organic molecules and topological insulators.

Graphene functionalization has been widely used in improving the thermal transport of graphene/epoxy composites owing to its performance in enhancing thermal conductivity and facilitating the formation of graphene networks. However, the heat transfer law and mechanism between functionalized graphene remain unclear. In this paper, the effects of distribution, type, and coverage of functional groups on the graphene–graphene interfacial thermal resistance (ITR) are analyzed by nonequilibrium molecular dynamics simulations. The results demonstrate that the graphene–graphene ITR depends on the synthetic effect of the graphene–graphene interaction, graphene–functional group interaction, and interaction between functional groups. The heat transfer contributions of those three interactions vary with the relative positions between functional groups. Then, the potential distribution of graphene is evaluated to compare the effects of different types of functional groups. It indicates that the potential difference is mainly attributed to functional groups. Compared with methyl, amino, and fluorine groups, hydroxyl groups have the largest potential difference and interaction. As the coverage of functional groups increases, the ITR of methylated graphene, aminated graphene, and hydroxylated graphene decreases inversely, whereas that of fluorinated graphene increases first and then decreases inversely. This work provides practical importance for the design and application of functionalized graphene in composite materials.

Biosensors have been used for a remarkable array of applications, including infectious diseases, environmental monitoring, cancer diagnosis, food safety, and numerous others. In particular, the global COVID-19 pandemic has exposed a need for rapid tests, so the type of biosensor that has gained considerable interest recently is immunoassays, which are used for rapid diagnostics. The performance of paper-based lateral flow and dipstick immunoassays is influenced by the physical properties of the nanoparticles (NPs), NP–antibody conjugates, and paper substrate. Many materials innovations have enhanced diagnostics by increasing the sensitivity or enabling unique readouts. However, negative side effects can arise at the interface between the biological sample and biomolecules and the NP or paper substrate, such as nonspecific adsorption and protein denaturation. In this Perspective, we discuss the immunoassay components and highlight chemistry and materials innovations that can improve sensitivity. We also explore the range of biointerface issues that can present challenges for immunoassays.

This paper presents an electrochemical SERS (EC-SERS) and computational study of the common herbicide atrazine. Herein, we highlight that the atrazine molecule shows a clear potential-dependent SERS signal that manifests as two different adsorption orientations at the nanostructured silver surface. This finding is supported by computational work and indicates that the initial adsorption orientation is perpendicular to the surface with the C–Cl moiety pointed away from the surface, and upon stepping to negative applied voltages, the atrazine molecule rotates such that the C–Cl and isopropyl moieties are orientated more planar to the surface, while the molecule remains oriented perpendicular to the surface. To the best of our knowledge, this paper represents the first EC-SERS study of atrazine and paves the way for a rapid point-of-need detection tool for atrazine monitoring in the environment wherein an enhanced signal can be detected at negative applied voltages.

Surface-enhanced Raman spectroscopy (SERS) is a perspective nondestructive analytic technique enabling the detection of individual nanoobjects, even single molecules. In this paper, we have studied the morphology of Ga islands deposited on chemical vapor deposition graphene by ultrahigh vacuum evaporation and local optical response of this system by the correlative Raman imaging and scanning electron microscopy (RISE). Contrary to the previous papers, where only an integral Raman response from the whole ununiformed Ga nanoparticles (NPs) ensembles on graphene was investigated, the RISE technique has enabled us to detect graphene Raman peaks enhanced by single Ga islands and particularly to correlate the Raman signal with the shape and size of these single particles. In this way and by a support of numerical simulations, we have proved a plasmonic nature of the Raman signal enhancement related to localized surface plasmon resonances. It has been found that this enhancement is island-size-dependent and shows a maximum for medium-sized Ga islands. A reasonable agreement between the simulations of the plasmon enhancement of electric fields in the vicinity of Ga islands and the experimental intensities of corresponding Raman peaks proved the plasmonic origin of the observed effect known as SERS.

In this paper, conductivity and magnetism in alternant hydrocarbons are discussed based on the topology of π-conjugated networks. In a molecular system with two spin centers, when the spins are separated by an odd-length walk, they interact antiferromagnetically with each other, but when they are separated by an even-length walk, they interact ferromagnetically. The conduction through the pathway connecting the two spins is expected to be effective for the former case, while ineffective for the latter case, but both show almost the same conductance in a magnetic system. This is because in the latter case, a feature in the electron transmission spectrum that causes destructive quantum interference is localized away from the Fermi level of the electrode and in a very narrow energy range, not affecting the zero-bias conductance. This tendency is further accentuated by generating weak coupling between the electrode surfaces and the spins to preserve the radical character of the molecule sandwiched between two electrodes. Although there is a challenge on how to stabilize radical molecules in a confined environment between electrodes, what is presented in this paper would give a clue on how to construct a system where magnetism and conductivity coexist.

This paper presents the synthesis and characterization of cobalt bismuth oxide (CBO) nanosheets with high surface area through a one-step low-temperature solvothermal method. The nanosheets were investigated for their photocatalytic ability for organic pollutant removal. High-resolution transmission electron microscopy and N2adsorption–desorption showed that the interconnected nanosheet morphology of CBO has a high surface area of 177 m2g–1. CBO-4 exhibited excellent photocatalytic performance for the degradation of the model organic pollutant tetracycline, with a degradation efficiency of 66.28% in the presence of H2O2. The proposed tetracycline degradation mechanism involved hydroxylation, demethylation, and ring-opening reactions. Furthermore, the CBO-4 catalyst showed good stability over five consecutive cycles. This study presents CBO-4 as a promising catalyst for photocatalytic organic pollutant removal, offering potential applications in environmental remediation.

The addition of a lateral alkyl chain is a well-known strategy to reduce π-stacked ensembles of molecules in solution, with the intention to minimize the interactions between the molecules’ backbones. In this paper, we study whether this concept generalizes to single-molecule junctions by using a combination of mechanically controllable break junction (MCBJ) measurements and clustering-based data analysis with two small series of model compounds decorated with various bulky groups. The systematic study suggests that introducing alkyl side chains also favors the formation of electrode-molecule configurations that are not observed in their absence, thereby inducing broadening of the conductance peak in the one-dimensional histograms. Thus, the introduction of alkyl chains in aromatic compounds for molecular electronics must be carefully designed and optimized for the specific purpose, balancing between increased solubility and the possibility of additional junction configurations.

Atom-substituting doping by atmospheric-pressure chemical vapor deposition (AP-CVD) is an effective and promising strategy for changing the properties of two-dimensional transition-metal dichalcogenides (2D TMDs). In this paper, we successfully grew V-doped MoSe2films. The photoluminescence (PL) spectra gradually red-shifted with the increase of the doping concentration, the X-ray photoelectron spectroscopy (XPS) after doping shifted toward a lower binding energy, and the change of polarity before and after doping can be seen in the transfer characteristic curves of back-gated field-effect transistors (FETs) based on V-doped and undoped MoSe2films and proves that the V atom successfully replaces the Mo atom and acts as a p-type dopant, which greatly improves the properties of back-gated FETs based on 2D V-doped MoSe2. The hole mobility of the doped samples can reach 111.34 cm2V–1s–1, the Ion/Ioffratio of the hole branch can reach 107, and the detector has a fast response time of 2.3 ms. The results show that the band gap, polarity, optical properties, and electrical properties of 2D MoSe2can be effectively adjusted by changing the V concentration, which provide a feasible way for 2D materials to realize high-performance scalable microelectronic devices and also provide new opportunities for 2D materials in electronic or optoelectronic applications.

There is a significant lack of literature addressing changes in the microstructure of different interfacial metal layer combinations employed in fabricating electrochemical sensors based on carbon nanomaterials. This research gap extends to analyzing their influence on the electrochemical performance, which, in turn, impacts the understanding of the properties of materials incorporating these layers. In this study, microstructural variations and electrochemical activity of chromium and titanium adhesion layers, in combination with nickel catalyst layers (designated as TiNi and CrNi), on silicon wafers were analyzed post annealing. Interestingly, during a brief annealing period of 5 min, TiNi developed a surface layer comprising graphitic carbon, alongside the formation of TiO2, TiC, and NiSi, and exhibited electrochemical activity toward both dopamine (DA) and ascorbic acid (AA). Conversely, CrNi annealed for 5 min did not show the presence of such a carbon layer and displayed no discernible electrochemical activity toward the target molecules. Only after an extended annealing time of 20 min, signs of a carbon layer appear on CrNi, displaying a moderate electrochemical activity toward DA and AA. The formation of a carbon layer on CrNi is delayed due to the presence of Ni near the surface, which disrupts the local equilibrium. Consequently, the formation of the Cr2O3barrier layer is delayed, which in turn permits carbon diffusion into the underlying Cr layer. Conversely, Ni stabilizes the β-Ti form and markedly decreases the solubility of carbon and oxygen within the TiNi system. By providing a comprehensive analysis of microstructural changes and their impact on the surface chemistry and electrochemical responses of commonly used interfacial metal layers, this paper offers invaluable insights in selecting suitable adhesion and catalyst layer combinations for carbon nanomaterial fabrication.

In this study, we explore the impact of halogen functionalization on the photophysical properties of the commonly used organic light-emitting diode (OLED) host material, 1,3-bis(N-carbazolyl)benzene (mCP). Derivatives with different numbers and types of halogen substituents on mCP were synthesized. By measuring steady-state and transient photoluminescence at 6 K, we study the impact of the type, number, and position of the halogens on the intersystem crossing and phosphorescence rates of the compounds. In particular, the functionalization of mCP with 5 bromine atoms results in a significant increase of the intersystem crossing rate by a factor of 300 to a value of (1.5 ± 0.1) × 1010s–1, and the phosphorescence rate increases by 2 orders of magnitude. We find that the singlet radiative decay rate is not significantly modified in any of the studied compounds. In the second part of the paper, we describe the influence of these compounds on the reverse intersystem crossing of the 7,10-bis(4-(diphenylamino)phenyl)-2,3-dicyanopyrazino-phenanthrene (TPA-DCPP), a TADF guest, via the external heavy atom effect. Their use results in an increase of the reverse intersystem crossing (RISC) rate from (8.1 ± 0.8) × 103s–1for mCP to (2.7 ± 0.1) × 104s–1for mCP with 5 bromine atoms. The effect is even more pronounced for the mCP analogue containing a single iodine atom, which gives a RISC rate of (3.3 ± 0.1) × 104s–1. Time-dependent DFT calculations reveal the importance of the use of long-range corrected functionals to predict the effect of halogenation on the optical properties of the mCP, and the relativistic approximation (ZORA) is used to provide insight into the strength of the spin–orbit coupling matrix element between the lowest-lying excited singlet and triplet states in the different mCP compounds.