Local Charge Research Articles

Quantum Defect Sensitization via Phase-Changing Supercharged Antibody Fragments.

Quantum defects in single-walled carbon nanotubes promote exciton localization, which enables potential applications in biodevices and quantum light sources. However, the effects of local electric fields on the emissive energy states of quantum defects and how they can be controlled are unexplored. Here, we investigate quantum defect sensitization by engineering an intrinsically disordered protein to undergo a phase change at a quantum defect site. We designed a supercharged single-chain antibody fragment (scFv) to enable a full ligand-induced folding transition from an intrinsically disordered state to a compact folded state in the presence of a cytokine. The supercharged scFv was conjugated to a quantum defect to induce a substantial local electric change upon ligand binding. Employing the detection of a proinflammatory biomarker, interleukin-6, as a representative model system, supercharged scFv-coupled quantum defects exhibited robust fluorescence wavelength shifts concomitant with the protein folding transition. Quantum chemical simulations suggest that the quantum defects amplify the optical response to the localization of charges produced upon the antigen-induced folding of the proteins, which is difficult to achieve in unmodified nanotubes. These findings portend new approaches to modulate quantum defect emission for biomarker sensing and protein biophysics and to engineer proteins to modulate binding signal transduction.

Oxygen-Deficient FeNbO4-x In-Situ Growth in Honey-Derived N-Doping Porous Carbon for Overall Water Splitting.

It is still a great challenge to reasonably design green, low cost, high activity and good stability catalysts for overall water splitting (OWS). Here, we introduce a novel catalyst with ferric niobate (FeNbO4) in-situ growing in honey-derived porous carbon of high specific surface area, and its catalytic activity is further enhanced by micro-regulation (oxygen vacancy and N-doping). From the experimental results and density functional theory (DFT) calculations, the oxygen vacancy in catalyst FeNbO4-x@NC regulates the local charge density of active site, thus increasing conductivity and optimizing hydrogen/oxygen species adsorption energy. FeNbO4 in-situ grows within N-doping honey-derived porous carbon, which can enhance active specific surface area exposure, strengthen gaseous substances escape rate, and accelerate electrons/ions transfer and electrolytes diffusion. Moreover, in-situ Raman also confirms O-species generation in oxygen evolution reaction (OER). As a result, the catalyst FeNbO4-x@NC shows good electrochemical performance in OER, HER and OWS.

Symmetry-breaking charge separation in a null-excitonic 3-dimensional rigid nonconjugated trimer.

Photoinduced symmetry-breaking charge separation (SB-CS) has been extensively observed in various oligomers and aggregates, which holds great potential for robust artificial solar energy conversion systems. It attaches great importance to the precise manipulation of interchromophore electronic coupling in realizing efficient SB-CS. The emerging studies on SB-CS suggested that it could be realized in null-excitonic aggregates, and a long-lived SB-CS state was observed, which offers an advanced platform and has gathered immense attention in the SB-CS field. Here, we unveiled the null-exciton coupling induced ultrafast SB-CS in a rigid polycyclic aromatic hydrocarbon framework, triperyleno[3,3,3]propellane triimides (TPPTI), in which three chromophores were attached through a nonconjugated bridge. Through a combination of theoretical calculations and steady-state absorption results, we demonstrated that this nonconjugated TPPTI possesses negligible exciton coupling. Increased solvent polarity was found to significantly enhance state mixing between local excited and charge transfer states. Using transient absorption spectroscopy, ultrafast SB-CS was observed in highly polar dimethylformamide, facilitated by a selective hole-transfer coupling and a favorable charge separation free energy (ΔGCS). Additionally, the rate ratio between SB-CS and charge recombination was at least high to 1800 in dimethylformamide. This investigation provides profound insights into the role of null-exciton coupling in dominating ultrafast SB-CS in multichromophoric systems.

From nanoscale heterogeneities to nanolites: cation clustering in glasses

The structural behavior of cations in multicomponent oxide glasses cannot be described within a random network model, due to the presence of cation clusters that provide original properties. These clustering processes are even observed for cations that may occur at a percent level concentration, which makes it all the more spectacular. In particular, the structural and chemical characteristics of Zr 4+ - and Fe 2+ /Fe 3+ -based clusters in (alumino)silicate glasses illustrate the link between the short-range order around cations and the formation of nanoscale heterogeneities. The structural characteristics of these Zr- or Fe-rich clusters are similar, as both are based on edge-sharing cation polyhedra. Cations may also occur in a network-forming position. In that case, cation sites are corner-linked with the silicate network. In such positioning, Pauling rules and local charge balance requirements will favor cations be diluted at a nanoscale. The topological constraints of these two types of local structure are stronger for the former than for the latter, as disorder effects are smaller for edge-sharing than for corner-sharing polyhedra. This may explain crystal nucleation during the growth of such ordered heterogeneities, giving rise to original properties that are illustrated in a large diversity of glassy materials encompassing high-tech glass-ceramics and volcanic glasses.

Synthesis of Double Trivalent Perovskite Quantum Dots Cs3BiSbX9 (X=Cl, Br, I) for Efficient CO2 Photoreduction Performance.

Non-toxic Bi halides have great potential in the field of CO2 photoreduction, but strong charge localization limits their charge separation and transfer. In this study, a series of Cs3BiSbX9 (X=Cl, Br, I) perovskite quantum dots (PQDs) are synthesized by antisolvent recrystallization at room temperature, in which Cs3BiSbBr9 PQDs has high selectivity (94.51%) and yield (15.32µmolg-1h-1) of CO2 to CO. In situ DRIFTS and theoretical calculations suggest that the surface charge can be tailored by halogen modulation, allowing for the customization of intermediate species. The Bi─Br─Sb symmetric charge distribution induced by the halogen Br promotes the formation of b─HCOO and reduces the reaction energy barrier of the rate-limiting step, while the weak electronegativity of Cl and the high electronegativity of I leads to m─HCOO and ─COOH production, which are detrimental to CO generation. This work provides new insights into the design of halide alloy perovskites for CO2 photoreduction.

Fragmentation and charge transfer in cyclic dipeptides with an aromatic side chain induced by VUV radiation

The fragmentation of three cyclic dipeptides (c-Glycil-Phenylalanine, c-Tryptophan-Tyrosine and c-Tryptophan-Tryptophan), characterized by an aromatic side chain, has been investigated by synchrotron radiation and photoelectron-photoion coincidence (PEPICO) experiments, assisted by atomistic simulations. The PEPICO experiments show that the charged moiety containing the aromatic side chain is the main fragment in the three samples. The theoretical exploration of the potential energy surfaces has allowed to identify the possible fragmentation paths leading to the formation of these fragments. Then, the analysis of the differences in the electronic density distributions of the neutral molecule and the cation and a molecular dynamics simulation provided an understanding of the preferred localization of the positive charge on the aromatic side chain of the cyclic dipeptide.

Multifunctional applications of organic light-emitting diodes and room temperature phosphorescence based on benzoyl-fluorene hybrid molecules

Organic light-emitting diodes (OLEDs) and room temperature phosphorescence (RTP) materials have attracted great interests for their wide application in lighting and other fields. How to efficiently utilize triplet excitons to achieve the multifunctionality of OLED and RTP simultaneously is a major challenge. Herein, two blue molecules, 3PCZFB and 3PCZBF were reported. Theoretical calculations indicate that both molecules possess hybrid localized charge transfer (HLCT) characteristic. More importantly, both can simultaneously obtain electro-fluorescence and RTP properties by multiple harvesting of triplet excitons with high spin-orbit coupling matrix element (SOCME). The introduction of benzoyl fluorene increased the contribution of the n-orbital, resulting in a high SOCME, which is beneficial to both high exciton utilization efficiency (EUE) and RTP. The non-doped OLED of 3PCZFB achieved maximum external quantum efficiency (EQEmax) of 4.9 % and EUE of 58.6 % at 459 nm. Besides, 0.1 % 3PCZFB and 3PCZBF doped in PMMA sheets achieve RTP efficiencies of 6.6 % at 524 nm and 25.9 % at 506 nm, as well as lifetimes of 379.8 ms and 204.8 ms. This is the first time Benzoyl fluorene-based molecules achieved dual-function applications in OLED and RTP by utilizing and recycling triplet excitons of T1.

In Situ Formed Li3N Networks by Soft Carbon‐Si3N4 for Superior All‐Solid‐State Lithium‐Metal Batteries

AbstractThe rapid growth of lithium (Li) dendrites has long hindered the development of all‐solid‐state lithium‐metal batteries (ASSLMB). Here, a composite soft carbon (SC)‐nano Si3N4 (SiN) interlayer (SC‐SiN) is designed for in situ formation of Li3N network (with high ionic conductivity/diffusivity) after lithium embedding in nano‐Si3N4, promoting the rapid migration of Li+ and guiding the metal Li to be deposited uniformly in a 3D manner within the interlayer. It can solve the problem of rapid consumption of Li+ and local charge accumulation at the interface of solid electrolyte and Li metal anode, thus avoiding the growth of Li‐dendrites. The resulting LCO/LPSCl/SC‐SiN‐Li ASSLMB achieves ultra‐high current density (12.5 mA cm−2) and ultra‐long cycle life (22 000 cycles with no degradation), as well as ultra‐high area capacity area capacity (15 mAh cm−2) and energy density (402.5 Wh kg−1), all of which break existing ASSLMB records. In addition, it is capable of 600 cycles at an areal capacity of 2.7 mAh cm−2 and 2 C (85.7% capacity retention). A pouch cell is also assembled to delivers high energy density (>320 Wh kg−1). These confirm the application potential of this configuration and are one of the most critical breakthroughs toward the commercialization of the ASSLMB.

Local charge rectification and electronic interactions in ZnIn2S4-x-Bi2MoO6-x heterojunction for enhancing synergistic piezo-photocatalytic hydrogen evolution and benzylamine oxidation

The synergistic utilization of vacancies and heterojunctions in piezo-photocatalysis holds great promise for mitigating the issue of charge recombination. However, the charge aggregation effect in vacancies and the disordered positive and negative charge centers in piezoelectric materials may potentially compromise the performance of synergistic piezo-photocatalysis. Here, the well-designed dual vacancies of ZnIn2S4-x and Bi2MoO6-x S-scheme heterojunction (BZ) was prepared for synergistic piezo-photocatalytic amines coupling to generate imines integrated with H2 production. Impressively, BZ-2 demonstrated an efficient N-benzylidenebenzylamine production rate of 4680 µmol g−1 h−1 and H2 formation rate of 4480 µmol g−1 h−1 without using any solvent or cocatalyst, where the formation rate of H2 is 10.25 times greater than that of ZnIn2S4-x. Experimental data and DFT calculations demonstrated that the presence of dual vacancies induces the formation of an interfacial Bi-S bond, which effectively regulates electronic interactions and rectifies charge disorder at the surface of the S-scheme heterojunction. Furthermore, this interfacial Bi-S bond acts as a strain center for providing a substantial electric field to drive charge transfer. Additionally, the electronic structural coupling contributes to lowering the activation energy and enhancing the reaction kinetics. This study offers profound insights into the relationship between atomic defects and S-scheme heterojunctions in piezo-photocatalysis, facilitating the design of high-efficiency materials.

Cocatalyst activity mapping for photocatalytic materials revealed by the pattern-illumination time-resolved phase microscopy.

Photocatalytic water-splitting represents a promising avenue for clean hydrogen production, necessitating an in-depth understanding of the photocatalytic reaction mechanism. The majority of the photocatalytic materials need cocatalysts to enhance the photo-oxidation or reduction reactions. However, the working mechanism, such as collecting charge carriers or reducing the reaction barrier, is not clear because they disperse inhomogeneously on a surface, and it is difficult to follow the local charge carrier behavior. This study employs the pattern-illumination time-resolved phase microscopy (PI-PM) method to unravel the spatial charge carrier behavior in photocatalytic systems, utilizing time-resolved microscopic image (refractive index change) sequences and their clustering analyses. This approach is robust for studying the change in local charge carrier behavior. We studied two major cocatalyst effects on photocatalysts: TiO2 with/without Pt and hematite with/without CoPi. The PI-PM method, supported by charge type clustering and the effects of scavengers, allowed for the analysis of local activity influenced by cocatalysts. This approach revealed that the introduction of cocatalysts alters the local distribution of charge carrier behavior and significantly impacts their decay rates. In TiO2 systems, the presence of Pt cocatalysts led to a local electron site on the micron scale, extending the lifetime to a few tens of microseconds from a few microseconds. Similarly, in hematite films with CoPi, we observed a notable accumulation of holes at cocatalyst sites, emphasizing the role of cocatalysts in enhancing photocatalytic efficiency. The study's findings highlight the complexity of charge carrier dynamics in photocatalytic processes and the significant influence of cocatalysts.

Regulating local charge distribution of single Ni sites in covalent organic frameworks for enhanced photocatalytic CO2 reduction

Covalent organic frameworks (COFs) engineered by single-atom sites have attracted significant attention for CO2 photoreduction. However, precisely manipulating the chemical environment of active sites on the COFs is a grand challenge. Herein, we synthesized a series of isostructural COFs for photocatalytic CO2 reduction, where the strong coordination conformation guides atomically dispersed metal sites to chelate spontaneously in the predesigned imine-pyridine position of COFs. Experimental and theoretical results revealed the crucial influence of the single-Ni site engineering and electronic structures of COF configuration on improving extended π-conjugation, exciton dissociation, charge separation efficiency, and charge carrier migration. Benefiting from the synergistic effect, the optimal Ni-TAPT-COF exhibited a record-high CO production rate of 25.5 mmol g-1h-1 and a selectivity of 98.8%, even natural-sunlight-driven diluted CO2 (10%). This work paves the way for the rational design of high-performance COF-based photocatalysts at the molecular level, highlighting their practical potential for CO2 photoreduction.

Rapid Surface Charge Mapping Based on a Liquid Crystal Microchip.

Rapid surface charge mapping of a solid surface remains a challenge. In this study, we present a novel microchip based on liquid crystals for assessing the surface charge distribution of a planar or soft surface. This chip enables rapid measurements of the local surface charge distribution of a charged surface. The chip consists of a micropillar array fabricated on a transparent indium tin oxide substrate, while the liquid crystal is used to fill in the gaps between the micropillar structures. When an object is placed on top of the chip, the local surface charge (or zeta potential) influences the orientation of the liquid crystal molecules, resulting in changes in the magnitude of transmitted light. By measuring the intensity of the transmitted light, the distribution of the surface charge can be accurately quantified. We calibrated the chip in a three-electrode configuration and demonstrated the validity of the chip for rapid surface charge mapping using a borosilicate glass slide. This chip offers noninvasive, rapid mapping of surface charges on charged surfaces, with no need for physical or chemical modifications, and has broad potential applications in biomedical research and advanced material design.

Broadband Green Luminescence and Phase Transition in Low-Dimensional Organic-Inorganic Hybrid Iodate.

Organic-inorganic hybrid iodide systems, which can form highly ordered chromophores and uniformly oriented transition dipole moments, serve as optimal host-guest systems for the fabrication of micrometer-scale optical devices. In particular, those with low-dimensional structures can exhibit strong quantum-limited and highly localized charges, enabling the generation of high exciton energies and stable excitation emission. In this study, we report a novel instance of an organic-inorganic hybrid iodate, (C13H11N2)(IO3), which was synthesized by incorporating the optically active organic compound, 9-aminoacridine. Upon crystallization in the monoclinic space group P21/c, this compound exhibits a direct optical band gap of 2.66 eV. The incorporation of discrete organic units within the low-dimensional structures induces pronounced local charges, culminating in broadband green luminescence with a peak at 540 nm under UV excitation. This corresponds to the CIE coordinates (0.37, 0.56). A potential phase transition was inferred through a comprehensive analysis of the variable temperature structure and emission spectra. Furthermore, first-principles calculations revealed the pivotal role of organic cations in facilitating broadband luminescence.

Plasmonic Imaging of Single DNA with Charge Sensitive Monolayer WS2.

Imaging the surface charge of biomolecules such as proteins and DNA, is crucial for comprehending their structure and function. Unfortunately, current methods for label-free, sensitive, and rapid imaging of the surface charge of single DNA molecules are limited. Here, we propose a plasmonic microscopy strategy that utilizes charge-sensitive single-crystal monolayer WS2 materials to image the local charge density of a single λ-DNA molecule. Our study reveals that WS2 is a highly sensitive charge-sensitive material that can accurately measure the local charge density of λ-DNA with high spatial resolution and sensitivity. The consistency of the surface charge density values obtained from the single-crystal monolayer WS2 materials with theoretical simulations demonstrates the reliability of our approach. Our findings suggest that this class of materials has significant implications for the development of label-free, scanning-free, and rapid optical detection and charge imaging of biomolecules.

Forecasting urban electric vehicle charging power demand based on travel trajectory simulation in the realistic urban street network

This paper presents a spatial-temporal urban charging power demand forecasting method based on EV travel trajectory simulation in the integrated urban street network and functional zones. Each EV trip is simulated via a travel trajectory based on the EV user’s travel behavior, which refers to the user’s decision-making processes regarding the choices of trip purpose, departure time, destination, trip route, parking time, and the time, location, and mode of EV charging. EV’s daily travel trajectory is built by merging the travel trajectories of the EV’s daily trips. The spatial-temporal slow and fast urban charging power demands are predicted using the simulated daily travel trajectories of available EVs in the urban area. The proposed simulation method is applied in the urban area of Campinas, Brazil. The results indicate that EVs’ daily travel trajectories are realistically produced to predict the daily charging load profiles at urban activity locations and functional zones.

Local spatial polarization induced efficient electron transfer in fluorinated borocarbonitride for boosting CO2 photoreduction

CO2 photoreduction into highly value-added chemicals over metal-free h-BCN has emerged as a promising strategy to address the issue of global warming. However, the serious carrier recombination caused by disordered charger transfer has limited its practical application. To circumvent this issue, fluorine modified h-BCN were synthesized using a facile heat treatment method. The surface halogenation created local spatial polarized electric field, which facilitated the local charge separation and transmission efficiency. Among them, BCN-F-4 exhibited the best photocatalytic CO2 reduction activitiy with CO and CH4 yield of 25.38 and 14.11 µmol g−1h−1, respectively. The turnover number (TON) of BCN-F-4 reached up to 163.6 μmol g−1h−1, 4.4 times that of BCN. Both theoretical simulation and experimental analysis demonstrated a strong covalent interaction between the F atoms and the h-BCN matrix, which gain deep understanding of the mechanism of prominent photocatalytic CO2 reduction activity boosted by surface halogenation.

Assessment of uniform charge assumption by investigating electrostatic charge distribution and potential during container filling: A numerical study

Using simulations, this study aims to investigate the actual charge distribution and resulting electrostatic potential during the filling process of a grounded metal barrel with low-conductivity diesel fuel. The flow rates used for loading were proposed based on the assumption of uniform charge distribution. Deviating from the uniform charge assumption, we observed local charge concentrations, including on the surface of the liquid. Despite the excessive surface charge, the maximum surface potential closely aligns with the prediction of the uniform charge assumption. This supports the practical viability of the proposed flow rates. Yet, considering a higher safety factor is advisable.

High‐Entropy Phase Stabilization Engineering Enables High‐Performance Layered Cathode for Sodium‐Ion Batteries

AbstractO3‐type layered oxides are considered as one of the most promising cathode materials for rechargeable sodium‐ion batteries (SIBs) due to their appealing energy density and feasible synthesis. Nevertheless, it undergoes complicated phase transitions and pronounced structural degradation during the cycling of charge/discharge process, rendering severe volumetric strain and poor cycling performance. Herein, a zero‐strain high‐entropy NaNi0.2Fe0.2Mn0.35Cu0.05Zn0.1Sn0.1O2 cathode for SIBs is presented by high‐entropy phase stabilization engineering. It is verified that this low‐nickel cobalt‐free high‐entropy cathode can deliver a highly reversible phase evolution, zero volumetric strain, and a significantly improved cycling performance in full cells (87% capacity retention after 500 cycles at 3.0 C). Combining X‐ray absorption spectra and first‐principles calculations, the varied elemental functions in the high‐entropy framework are clearly elucidated, namely, Ni/Fe/Cu acts as charge compensators, while Mn/Zn/Sn serve as interlayer slipping inhibitors through enhanced charge localization besides their stable valence states. By addressing the volumetric strain and cycling instability concerns for O3‐type cathode materials, this work presents a promising strategy for inhibiting irreversible phase transitions and structural degradation in intercalation electrodes, which significantly boosts the development of commercially feasible cathodes for high‐performance SIBs.

Ultrafast Photoinduced Phase Change in SnSe.

Time-resolved multiterahertz (THz) spectroscopy is used to observe an ultrafast, nonthermal electronic phase change in SnSe driven by interband photoexcitation with 1.55eV pump photons. The transient THz photoconductivity spectrum is found to be Lorentzian-like, indicating charge localization and phase segregation. The rise of photoconductivity is bimodal in nature, with both a fast and slow component due to excitation into multiple bands and subsequent intervalley scattering. The THz conductivity magnitude, dynamics, and spectra show a drastic change in character at a critical excitation fluence of approximately 6 mJ/cm^{2} due to a photoinduced phase segregation and a macroscopic collapse of the band gap.

1: Local energy band and charge carrier modulation by ferro‐/piezo‐phototronic effect in optoelectronic devices

1: Local energy band and charge carrier modulation by ferro‐/piezo‐phototronic effect in optoelectronic devices