Electrostatic Repulsive Forces Research Articles

An integrated modeling approach to predict critical flow rate for fines migration initiation in sandstone reservoirs and water-bearing formations

Fines migration causes formation damage in sandstone reservoirs and water-bearing subsurface formations. Several factors affect fines migration such as composition and salinity of permeating brine, flow rate, and system pH. Electrostatic forces of van der Waals attraction and electric double layer repulsion, gravitational force and hydrodynamic force all contribute to fines detachment and migration under certain conditions. The current research presents a new integrated model of electrostatic, gravitational, and hydrodynamic forces to estimate the critical injection rate of NaCl brine for fines migration initiation in subsurface formations.The DLVO modeling approach was modified by considering electrostatic, hydrodynamic, and gravitational forces. Parameters such as injection brine salinity, average fine particle size, and zeta potential of sand-brine systems were used, and effective forces were quantified. A microscopic force and torque balance approach was applied to model hydrodynamic forces to modify the DLVO model. The developed models were validated with experimental results.The profiles of injection velocity versus fine particle radius were generated and the models predicted critical flow rates of 0.9, 2.6, and 3.8 cc/min for 0.15 M, 0.2 M, and 0.25 M NaCl, respectively. For model validation, the coreflood experiments were performed on Berea sandstone core samples under given salinities and critical flow rates were determined. Comparable experimental results were obtained with critical flow rates of 1, 3, and 4 cc/min for 0.15 M, 0.2 M, and 0.25 M NaCl, respectively. In addition, sensitivity analysis assesses the impact of different forces on the fines migration phenomenon.Formation damage caused by fines migration is a well-documented problem in sandstone reservoirs and water-bearing formations. Regulating the injection/ permeating fluid rate and salinity can avoid fines migration and associated permeability impairment. Our study presents a novel approach incorporating electrostatic, gravitational, and hydrodynamic forces to accurately predict fines mobilization in fine-containing subsurface formations.

Enhancement of emulsification properties by modulation of egg white protein fibril structure with different heating times

Egg white protein (EWP) has poor emulsification ability due to the hydrophobic groups buried in the molecular structure. In contrast, the protein fibrils produced by acidic heat treatment are able to expose the hydrophobic groups and firmly adsorb to the surface of oil droplets. Therefore, the preparation of egg white protein fibrils (EWPF) can broaden the range of applications of EWP, such as low-fat emulsion-based foods. Since the heating time affects the growth condition of the fibrils and thereby the properties of their stabilized emulsions. The effect of treatment time on the structure properties and emulsification properties of EWP during fibrillation, also the effect of different environments on the stability of EWPF emulsion were investigated. The EWPF content increased with heating time. During the heating of EWP under acidic condition, proteins were hydrolyzed into peptides, subsequently peptides aggregated unidirectionally to form fibrils due to electrostatic repulsive forces at low pH. Compared with EWP, EWPF had larger particle size, higher ζ-potential, higher β-sheet content and greater surface hydrophobicity. In addition, the emulsifying activity and emulsification stability of the EWPF emulsion increased nearly two-fold compared with that of the EWP emulsion. Furthermore, it had smaller droplets, higher ζ-potential, and better thermal and ionic stability. This study could provide insights into the improvement of EWP emulsifying properties and fibril-modified EWP as stabilizing ingredients for emulsion-based foods. • EWP rich in acidic amino acids is an excellent material for fibrils preparation. • EWPF morphology gradually prolonged and aggregated with heating time. • The fine curled structure of EWPF can better encapsulate the oil droplets. • EWPF had the best emulsification properties when heated for 8 h. • Thermal stability and ionic stability of emulsion with EWPF were increased.

Comparative study on effects of pH, electrolytes, and humic acid on the stability of acetic and polyacrylic acid coated magnetite nanoparticles

The poor colloidal stability of magnetite nanoparticles (MNPs) limits their mobility and application, so various organic coatings (OCs) were applied to MNPs. Here, a comparative study on the colloidal stability of MNPs coated with acetic (HAc) and polyacrylic acids (PAA) was conducted under varied pH (5.0–9.0) in the presence of different concentrations of cations and anions, as well as humic acid (HA). Comparing the effects of various cations and anions, the stability of both HAc/PAA-MNPs followed the order: Na+ > Ca2+and PO43− > SO42− > Cl−, which could be explained by their adsorption behaviors onto HAc/PAA-MNPs and the resulting surface charge changes. Under all conditions even with more anion adsorption onto HAc-MNPs (0.14–22.56 mg/g) than onto PAA-MNPs (0.04–18.34 mg/g), PAA-MNPs were more negatively charged than HAc-MNPs, as PAA has a lower pHIEP (2.6 ± 0.1) than that of HAc (3.7 ± 0.1). Neither the HAc nor PAA coatings were displaced by phosphate even at considerably high phosphate concentration. Compared with HAc-MNPs, the stability of PAA-MNPs was greatly improved under all studied conditions, which could be due to both stronger electrostatic and additional steric repulsion forces among PAA-MNPs. Besides, under all conditions, Derjaguin-Landau-Verwey-Overbeek (DLVO) explained well the aggregation kinetic of HAc-MNPs; while extended DLVO (EDLVO) successfully predict that of PAA-MNPs, indicating steric forces among PAA-MNPs. The aggregation of HAc/PAA-MNPs was all inhibited in varied electrolyte solutions by HA (2 mg C/L) addition. This study suggested that carboxyl coatings with higher molecular weights and pKa values could stabilize MNPs better due to stronger electrostatic and additional steric repulsion. However, in the presence of HA, these two forces were mainly controlled by adsorbed HA instead of the organic pre-coatings on MNPs.

Kinetic and mechanistic analysis of membrane fouling in microplastics removal from water by dead-end microfiltration

This study explores and analyses the kinetic and mechanistic aspects of microfiltration cellulose acetate membrane fouling by polyamide (PA) and polystyrene (PS) particles in dead-end configuration and the main interactions between the microplastics and the membrane during the filtration process. First, PA and PS particles were characterised to define the differences in shape (regular and irregular), particle size distribution (10–105 µm and 20–320 µm), and surface charge (neutral and negative). The results showed that the prevailing mechanisms during microplastic filtrations were complete pore blocking followed by cake layer formation in both cases. The mechanisms’ kinetics were positively correlated to MPs load through a power-law relationship which was stronger for PS than for PA particles because of higher steric hindrance effects. On the other hand, increasing the working transmembrane pressure led to an optimum working condition, between 0.3 and 0.5 bar for PA and 0.3 bar for PS filtration. Overall, higher fouling was induced by the PA particles due to the higher PA hydrophobicity and their smaller size, which caused a denser cake layer. Instead, PS particles with higher irregularities and repulsive electrostatic forces formed a more porous layer but induced a high degree of abrasion on the membrane surface. Finally, membrane fouling led to an increase in hydrophobicity and roughness, probably causing further fouling. To conclude, modelling membrane fouling can help predict the best working conditions and the membrane replacement cycles to increase the MPs removal efficiency and reduce secondary MP-based pollution.

Методический подход к изучению седиментационной устойчивости тонкодисперсных отходов переработки минерального сырья по спутниковым данным загрязнения природных водоемов

The paper presents the results of the study of sedimentation stability of suspended finely-dispersed mineral particles based on satellite observations of their aggregation and sedimentation. The authors studied satellite data on self-purification of subarctic lakes polluted by apatite-nepheline, iron, and copper-nickel ore processing wastes. The multispectral images of lakes taken by Sentinel-2 spacecraft have allowed determining the average size of suspended finely-dispersed mineral processing wastes and the density of particle size distribution. To account for aggregation, the authors have designed a computer model of the dynamics of suspended particles and have set parameters of the forces of electrostatic and dispersion interactions of mineral particles from the Kola deposits. It is shown that the balance of repulsive electrostatic and dispersion attractive forces appears in the generation of aggregates of finely-dispersed mineral particles with characteristic fractal dimension, using Nepheline, Hematite, Quartz, and Pyrite as examples. The authors have developed an algorithm for matching the computer simulation results of the dynamics of suspended particles with the results of satellite images processing of lakes. The developed methodological approach makes it possible to determine the sedimentation stability of lakes’ pollution by finedispersed mineral processing wastes without surface observations. The research results allow calculating the sedimentation velocity of mineral particles and their aggregates of a given size. The good correspondence between the calculated parameters of particles aggregation and sedimentation and satellite observations data can be used to monitor the pollution of water bodies when adapting mineral processing technologies to modern production ecologization requirements, as well as to assess the waterenvironmental potential of the territory for rational management of natural resources.

Modulation of Structural, Electronic, and Optical Properties of Titanium Nitride Thin Films by Regulated In Situ Oxidation

Epitaxial titanium nitride (TiN) and titanium oxynitride (TiON) thin films have been grown on sapphire substrates using a pulsed laser deposition (PLD) method in high-vacuum conditions (base pressure <3 × 10-6 T). This vacuum contains enough residual oxygen to allow a time-independent gas phase oxidation of the ablated species as well as a time-dependent regulated surface oxidation of TiN to TiON films. The time-dependent surface oxidation is controlled by means of film deposition time that, in turn, is controlled by changing the number of laser pulses impinging on the polycrystalline TiN target at a constant repetition rate. By changing the number of laser pulses from 150 to 5000, unoxidized (or negligibly oxidized) and oxidized TiN films have been obtained with the thickness in the range of four unit cells to 70 unit cells of TiN/TiON. X-ray photoelectron spectroscopy (XPS) investigations reveal higher oxygen content in TiON films prepared with a larger number of laser pulses. The oxidation of TiN films is achieved by precisely controlling the time of deposition, which affects the surface diffusion of oxygen to the TiN film lattice. The lattice constants of the TiON films obtained by x-ray diffraction (XRD) increase with the oxygen content in the film, as predicted by molecular dynamics (MD) simulations. The lattice constant increase is explained based on a larger electrostatic repulsive force due to unbalanced local charges in the vicinity of Ti vacancies and substitutional O. The bandgap of TiN and TiON films, measured using UV-visible spectroscopy, has an asymmetric V-shaped variation as a function of the number of pulses. The bandgap variation following the lower number of laser pulses (150-750) of the V-shaped curve is explained using the quantum confinement effect, while the bandgap variation following the higher number of laser pulses (1000-5000) is associated with the modification in the band structure due to hybridization of O2p and N2p energy levels.

Stability Assessment of Polyvinyl-Ether-Based TiO2, SiO2, and Their Hybrid Nanolubricants

Poor characterisation of nanoparticle suspensions impedes the development of nanolubricants for use in refrigeration and air-conditioning systems. Chemical treatment techniques, such as surfactants, are inappropriate for enhancing the stability of nanolubricants intended for use in vapour-compression refrigeration (VCR) systems. Prior to incorporating nanolubricants into the system, the stability of TiO2 and SiO2 nanoparticles dispersed in PVE was therefore investigated. The nanolubricants were prepared by a two-step method with the aid of an ultrasonication bath homogeniser. Visual observation and ultraviolet–visible (UV–Vis) spectrophotometric analysis were used, and zeta potential analysis was then performed to confirm the nanolubricants’ stability condition. The TiO2/PVE nanolubricant was observed to be maintained at a 95% concentration ratio for up to 30 days of evaluation. The TiO2/PVE, SiO2/PVE, and SiO2-TiO2/PVE exhibited zeta potential values of 203.1 mV, 224.2 mV, and 105.3 mV, respectively, after 7 h of sonication. A high absolute value of zeta potential indicates that the electrostatic repulsive forces between nanoparticles are exceptionally strong, indicating an excellent stable suspension. The high values of zeta potentials validated the excellent stability conditions determined by UV–Vis analysis and visual observation. It can be concluded that ultrasonication times of 7 h produced the most stable state for mono- and hybrid nanolubricants.

Breakthrough in controlling membrane fouling and complete demulsification via electro-fenton pathway: Principle and mechanisms

The emulsified oil wastewater would cause profound damage to the environment if not appropriately treated. The difficulty in deforming the interfacial film of emulsions is still a key challenge for the emerging bio-inspired superhydrophilic membrane, resulting in membrane concentrates that need post-processing. Furthermore, the membrane fouling deeply inside membrane pores via complicated physicochemical interactions is hardly real-time mitigated by the conventional self-cleaning strategies, and remains another challenge for long-term operation. To break through these limitations, a novel electro-Fenton assisted superhydrophilic membrane was first designed, and the underlying self-cleaning and demulsification mechanisms were thoroughly unveiled. Extremely high permeation flux (2258.5 L ·m−2h−1) and flux recovery ratio (98.1%) were achieved. Both reversible and irreversible fouling could be well controlled through the real-time degradation of foulants and electrostatic repulsive forces between the negatively charged membrane and foulants. Strikingly, the surfactant could be decomposed by the in situ generated •OH, leading to the destruction of thermodynamic stability of oil-in-water emulsions. Consequently, the emulsions were transformed to large-sized floating oil and dispersed oil, achieving highly effective oil/water separation. These features manifest the attractive potential application in emulsion treatment, leading to a new era of radical-assisted super-anti-foluing and demulsification driven by electro-Fenton process.

Unveiling the Nanoscale Dynamics of the Exocytic Machinery in Chromaffin Cells with Single-Molecule Imaging.

Neuronal and hormonal communication relies on the exocytic fusion of vesicles containing neurotransmitters and hormones with the plasma membrane. This process is tightly regulated by key protein-protein and protein-lipid interactions and culminates in the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex formation and zippering that promotes vesicular fusion. Located on both sides of the vesicle and the plasma membrane, the zippering of the SNARE complex acts to overcome the energy barrier afforded by the repulsive electrostatic force stemming from apposing two negatively charged phospholipid membranes. Another component opposing the timely organization of the fusion machinery is thermal Brownian energy that tends to homogenize all cellular molecules by constantly switching their motions and directions through short-lived molecular interactions. Much less is known of the mechanisms counteracting these chaotic forces, allowing seamless cellular functions such as exocytic fusion. Super-resolution microscopy techniques such as single-molecule imaging have proven useful to start uncovering these nanoscale mechanisms. Here, we used single-particle tracking photoactivatable localization microscopy (sptPALM) to track syntaxin-1-mEos, a SNARE protein located on the plasma membrane of cultured bovine chromaffin cells. We demonstrate that syntaxin-1-mEos undergoes dramatic change in its mobility in response to secretagogue stimulation leading to increased nanoclustering. These nanoclusters are transient in nature and likely to provide docked vesicles with a molecular environment conducive to exocytic fusion.

Single Solution-Phase Synthesis of Charged Covalent Organic Framework Nanosheets with High Volume Yield.

Covalent organic framework nanosheets (COF-NSs) are emerging building blocks for functional materials, and their scalable fabrication is highly desirable. Current synthetic methods suffer from low volume yields resulting from confined on-surface/at-interface growth space and complex multiple-phase synthesis systems. Herein, we report the synthesis of charged COF-NSs in open space using a single-phase organic solution system, achieving magnitudes higher volume yields of up to 18.7 mg mL-1 . Charge-induced electrostatic repulsion forces enable in-plane anisotropic secondary growth from initial discrete and disordered polymers into large and crystalline COF-NSs. The charged COF-NS colloidal suspensions are cast into thin and compact proton exchange membranes (PEMs) with lamellar morphology and oriented crystallinity, displaying outstanding proton conductivity, negligible dimensional swelling, and good H2 /O2 fuel cell performance.

Nanomechanical probing of bacterial adhesion to biodegradable Zn alloys

Bacterial infections on implants cause an inflammatory response and even implant failure. Bacterial adhesion is an initial and critical step during implant infection. The prevention of bacterial adhesion to implant materials has attracted much attention, especially for biodegradable metals. A deep understanding of the mechanisms of bacterial adhesion to biodegradable metals is urgently needed. In this work, a bacterial probe based on atomic force spectroscopy was employed to determine the bacterial adhesion to Zn alloy, which depended on surface charge, roughness, and wettability. Negative surface charges of Zn, Zn-0.5Li, and 316L generated electrostatic repulsion force towards bacteria. The surface roughness of Zn-0.5Li was significantly increased by localized corrosion. Bacterial adhesion forces on Zn, Zn-0.5Li, and 316L were 325.2 pN, 519.1 pN, and 727.7 pN, respectively. The density of attached bacteria (early-stage bacterial adhesion) on these samples exhibited a positive correlation with the bacterial adhesion force. The bacterial adhesion force and adhesion work provide a quantitative determination of the interactions between bacteria and biodegradable alloys. These results provide a deeper understanding of early bacterial adhesion on Zn alloys, which can further guide the antibacterial surface design of biodegradable materials for clinical application.

Single Solution‐Phase Synthesis of Charged Covalent Organic Framework Nanosheets with High Volume Yield

AbstractCovalent organic framework nanosheets (COF‐NSs) are emerging building blocks for functional materials, and their scalable fabrication is highly desirable. Current synthetic methods suffer from low volume yields resulting from confined on‐surface/at‐interface growth space and complex multiple‐phase synthesis systems. Herein, we report the synthesis of charged COF‐NSs in open space using a single‐phase organic solution system, achieving magnitudes higher volume yields of up to 18.7 mg mL−1. Charge‐induced electrostatic repulsion forces enable in‐plane anisotropic secondary growth from initial discrete and disordered polymers into large and crystalline COF‐NSs. The charged COF‐NS colloidal suspensions are cast into thin and compact proton exchange membranes (PEMs) with lamellar morphology and oriented crystallinity, displaying outstanding proton conductivity, negligible dimensional swelling, and good H2/O2 fuel cell performance.

Superchaotropic Nano‐ion Binding as a Gelation Motif in Cellulose Ether Solutions

AbstractNanometer‐sized anions (nano‐ions) like polyoxometalates and boron clusters exhibit so‐called superchaotropic behavior, which describes their strong binding to hydrated non‐ionic matter in water. We show here that nano‐ions, at millimolar concentrations, dramatically enhance the viscosity and induce gelation of aqueous solutions of non‐ionic cellulose ethers (CEs), a class of widely utilized polymers known for their thickening and gel‐forming ability. These phenomena arise from an interplay of attractive forces and repulsive electrostatic forces between CE‐chains upon nano‐ion binding. The attractive forces manifest themselves as aggregation of CE‐chains into a physically crosslinked polymer network (gel). In turn, the electrostatic repulsions hamper the viscosity increase and gelation. Superchaotropic nano‐ion binding emerges as a novel and general physical crosslinking motif for CE‐solutions and exceeds by far the conventional thickening effects of classical salts and ionic surfactants.

Superchaotropic Nano-ion Binding as a Gelation Motif in Cellulose Ether Solutions.

Nanometer-sized anions (nano-ions) like polyoxometalates and boron clusters exhibit so-called superchaotropic behavior, which describes their strong binding to hydrated non-ionic matter in water. We show here that nano-ions, at millimolar concentrations, dramatically enhance the viscosity and induce gelation of aqueous solutions of non-ionic cellulose ethers (CEs), a class of widely utilized polymers known for their thickening and gel-forming ability. These phenomena arise from an interplay of attractive forces and repulsive electrostatic forces between CE-chains upon nano-ion binding. The attractive forces manifest themselves as aggregation of CE-chains into a physically crosslinked polymer network (gel). In turn, the electrostatic repulsions hamper the viscosity increase and gelation. Superchaotropic nano-ion binding emerges as a novel and general physical crosslinking motif for CE-solutions and exceeds by far the conventional thickening effects of classical salts and ionic surfactants.

Nanoengineering the Redispersibility of Cellulose Nanocrystals.

Enhancing the redispersibility of dried colloidal particles to yield stable dispersions after rehydration is a persistent challenge in the sustainable processing of nanocelluloses due to hydrogen bonding-induced irreversible aggregation. Programming nanocelluloses, such as cellulose nanocrystals (CNC), with moieties that enable colloidal repulsion after rehydration may address this challenge and contribute to the United Nation (UN)'s sustainable development goals (SDGs) of urban development and sustainable living (SDGs 9 and 11) and cradle-to-cradle processing (SDG 12). We hypothesize that imparting electrosteric repulsion to CNC via polyanionic disordered cellulose chains (hairs) protruding from each end may render the dried nanocrystals highly redispersible in aqueous media. Anionic hairy CNC (AHCNC), that is, CNC decorated with dicarboxylated cellulose (DCC) chains, were synthesized by the preferential, successive periodate/chlorite oxidation of the disordered regions of cellulose fibrils, bearing >5 mmol of carboxylate groups per gram. The colloidal properties of AHCNC were compared with those of sulfate half-ester group-functionalized CNC and TEMPO-oxidized CNC (TOCNC) after redispersion in aqueous media, followed by comparing the redispersibility of AHCNC and CNC in aqueous solutions containing monovalent or divalent cations and at varying pH. The AHCNC had remarkable aqueous redispersibility even at high ionic strengths and extreme pH. The unique redispersibility mechanism of dried AHCNC relies on the synergistic steric and electrostatic repulsion forces, recuperated upon the rehydration of DCC. This work may open new opportunities for more sustainable and cost-effective handling and processing of nanocelluloses.

MXene-PANI/PES composite ultrafiltration membranes with conductive properties for anti-fouling and dye removal

The appearance of the composite membrane provides a new research direction for reducing membrane fouling. In this study, polyaniline (PANI) and Ti3C2Tx (MXene) were combined by the electrostatic assembly method where PANI was used to adjust the distance between MXene layers and construct the conductive network. The conducting mixed ultrafiltration membranes were prepared by the non-solvent induced phase separation method, in which MXene and PANI were mixed into a polyethersulfone (PES) matrix. The permeation flux of pure water of the MXene-PANI/PES membrane was increased by 200.9%, the retention rate of bovine serum albumin (BSA) was kept above 99%, and the retention rate of Congo Red and Methyl blue dyes was 99.1% and 98.4%, respectively, this goes well beyond the PES membrane. In addition, through a series of conductivity tests, it has been proved that the conductive properties of composite membranes were greatly improved, and the conductivity of the MXene-PANI/PES composite membrane can reach 0.5 S m−1. After applying a negative voltage to the membrane, the negative charge around the surface of the membrane repels the negatively charged contaminant under the action of an electrostatic repulsion force, thereby the enrichment of pollutants on the membrane surface can be effectively reduced, and the FRR reached 93.7%. On the basis of ensuring membrane conductivity, we improved the permeability, selective separation, and anti-fouling ability of the membrane. This research shows great potential for the efficient development of an anti-fouling conductive separation membrane based on MXene.

Soil particle aggregation and aggregate stability associated with ion specificity and organic matter content

Soil aggregate formation and stability are profoundly influenced by soil organic matter (SOM) content and electrolyte conditions by altering particle interactions during soil particle aggregation and aggregate breakdown. However, the effect of the ion-interface reaction, especially the newly discovered asymmetric hybridization of counterions, and its coupling with SOM on particle interactions and accordingly the particle aggregation and aggregate breakdown remain unclear. In this study, four black soils with different SOM contents were adopted to examine the particle aggregation kinetics using dynamic laser scattering method and aggregate stability using aggregate breakdown intensity in Li+, Na+, and K+ solutions with different concentrations. Combining experimental results with theoretical calculation of particle interactions, it found that different patterns of asymmetric hybridization between the three counterions produce ion specificity and lead to an ion sequence of Li+ < Na+ < K+ in promoting soil particle aggregation and reducing soil aggregate breakdown by decreasing the electrostatic repulsive force between soil particles. An increase in SOM, particularly its dissolvable fraction, increases the electrostatic repulsive force and steric repulsion and then inhibits soil particle aggregation, which is contrary to the effect of the ion sequence. The effects of ion specificity and SOM on particle aggregation could cancel each other in some specific cases of ion species and SOM contents. Moreover, similar to the above ion sequence, the increase in SOM also reduces soil aggregate breakdown and improves soil aggregate stability, because SOM greatly increases the van der Waals attractive force and short-range bonding interactions but rarely changes the electrostatic repulsive force between particles in soil aggregates.

Revisiting the Role of Hydrogen in Lithium‐Rich Antiperovskite Solid Electrolytes: New Insight in Lithium Ion and Hydrogen Dynamics

AbstractLi2OHX(X= Cl or Br) with an antiperovskite structure possess the advantages of low melting point, low cost, and ease of scaling‐up, which show great promise for applications in all‐solid‐state Li metal batteries (ASSLMBs). However, Li‐ion transport mechanisms in Li2OHXare still debated and the influence of H on the electrochemical performance of Li2OHXis yet to be explored. Herein, combining the theoretical calculations and experimental measurements, it is found that H affects Li‐ion transport, crystal stability, electrochemical stability, and electronic conductivity of Li2OHX. Compared with H‐free Li3OCl, although H helps to generate vacancy‐like defects, the electrostatic repulsive force between H and Li‐ion leads to an increase in both the activation energy and the diffusion length (space compensation effect), resulting in special Li ion transport trajectories along the Li‐O plane. Decreasing H content reduces the electronic conductivity and enhances the reduction‐resistant ability of Li2OHX, promoting the cycling stability and rate performance of Li∣Li2OHX∣Li symmetric cells and the ASSLMBs. This work delivers a new insight into the role of H in antiperovskite Li2OHXand can serve as guidance for solid electrolyte design.

Effect of complexing agent on ceria particle removal in post-STI CMP cleaning process

Ceria (CeO2) abrasive is extensively used in the chemical mechanical polishing process (CMP) for shallow trench isolation (STI) owing to its capability to form Ce-O-Si bonds with the silicon dioxide (SiO2) dielectric layer. However, although this interaction substantially improves its CMP performance, it increases the difficulty of removing ceria particles and exacerbates the challenge of post-CMP cleaning. In this study, the cleaning effect of three complexing agents on ceria particles on the polished silicon dioxide surface at pH 11 was investigated: glycine (Gly), ethylenediamine tetraacetic acid (EDTA), and 1.2-bis-(3-aminopropylamino) ethylenediamine (TAD). The cleaning efficacy of the complexing agents on ceria particles was evaluated using zeta potential, contact angle, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Then the desorption mechanism of ceria particles was then explored by UV–visible spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS) and molecular dynamics simulation. The results of multiple measurement results indicate that the three complexing agents have obvious removal effects on ceria particles, and 0.15 wt% EDTA at pH 11 can remove 99% of ceria particles from the SiO2 substrate. The cleaning efficacy of carboxyl functional groups is superior and increases with the growth of the number of functional groups. The removal mechanism of ceria abrasives by complexing agent was proposed. Through the undercutting effect of carboxyl functional groups, EDTA can break the Ce-O-Si chemical connection formed during the CMP process and complex Ce3+ ions to prevent particle redeposition. Additionally, it accelerates particle desorption by enhancing the electrostatic repulsion force between the CeO2 and SiO2 substrate.

Indirect Control of Donor/Acceptor Interactions for Highly Efficient Space‐Confined Thermally Activated Delayed Fluorescence Emitters

AbstractConformational engineering is essential to further reinforce the luminescent properties of thermally activated delayed fluorescence (TADF) materials featuring through‐space charge transfer (TSCT) characteristics. Herein, two TSCT‐TADF emitters (8MeDM‐B and 8FDM‐B) with the methyl and fluorine moieties substituted at the C8 site of the rigid spiro‐fluorene bridge is reported. Derivation of the C8 site is first proposed to control the molecular configuration with the ability to indirectly tune the intramolecular interaction between donor and acceptor groups. As a result, 8MeDM‐B and 8FDM‐B both present small singlet‐triplet energy gaps, fast reverse intersystem crossing rates, and high photoluminescence quantum yields. Interestingly, the smaller fluorine atom not the bigger methyl group exhibits more evident electrostatic repulsive force onto the central donor and thus rectifies the central spiro structure. Consequently, the high external quantum efficiency values of 28.8% and 31.7% for 8MeDM‐B and 8FDM‐B‐based electroluminescence devices are achieved, respectively. This study offers a measure for enhancing TSCT‐TADF emitters without directly modifying the donor or acceptor.