Ion Size Research Articles

Influence of ionic size on the optical and thermodynamical properties of chitosan based polymer composites with different ammonium halides

The biopolymer chitosan has been dissolved with 1% of acetic acid and the same has been embedded with different salts of ammonium halides like NH4F, NH4Cl, NH4Br, and NH4I with different concentrations to make the composites. The density, refractive index, and ultrasonic velocity of the said composite materials were measured and the space-filling factor along with polarizability and dielectric constant is obtained from refractive index data. From the refractive index data, the parameters like dielectric constant(ε), polarizability(α), and space-filling factor are calculated and from the ultrasonic velocity, the thermodynamical properties like relaxation strength (r s), acoustic impedance (Z), adiabatic compressibility (βs), intermolecular free length (Lf) and surface tension (σ) were calculated. The ultrasonic velocity of chitosan solution is 1515 ms− 1. The addition of ammonium halides leads to increase in ultrasonic velocity. The intermolecular free length (Lf), adiabatic compressibility (βs), and relaxation strength (r s) are decreasing and all other parameters are increasing with respect to ionic size and concentration of ammonium halides. All the results are analyzed and discussed with respect to the ionic size of the ammonium salts and concentrations.

A novel LaAl1-xNbxO3 NTC ceramic with excellent stability for high-temperature thermistor

A series of LaAl1-xNbxO3 (0 ≤ x ≤ 0.100) samples were synthesized via the solid phase method. Characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) confirmed the formation of a solid solution in LaAl1-xNbxO3 (0 ≤ x ≤ 0.100) materials without the emergence of additional phases following Nb doping. Transmission electron microscopy (TEM) revealed distinct lattice fringes with a d value of 0.274 nm, corresponding to the (110) plane of LaAlO3 (PDF #82–0478). The introduction of Nb dopant caused distortions in the cell parameters of LaAlO3 due to ionic radius size effects, changes in Nb valence, fluctuations in oxygen vacancy concentration and Coulomb forces. Specifically, the lattice exhibited a shrinkage for 0 ≤ x ≤ 0.025, expansion for 0.025 <x ≤ 0.075, and subsequent shrinkage for 0.075 <x ≤ 0.100. Resistance measurements indicated that LaAl1-xNbxO3 (0 ≤ x ≤ 0.100) materials exhibited favorable negative temperature coefficient (NTC) characteristics in the temperature range of 600 °C–1400 °C. Hall measurements revealed that the materials functioned as P-type semiconductors with hole carriers, and Nb doping enhanced carrier concentration. Aging tests demonstrated that the aging drift rate of LaAl0.9Nb0.1O3 could be as low as 0.906% after aging it at 1000 °C for 500 h, a crucial parameter for practical applications of LaAl1-xNbxO3 (0 ≤ x ≤ 0.100) materials in high-temperature NTC applications.

Integrating Internal Fragments in the Interpretation of Top-Down Sequencing Data of Larger Oligonucleotides.

In the context of direct top-down analysis or concerted bottom-up characterization of nucleic acid samples, the waning yield of terminal fragments as a function of precursor ion size poses a significant challenge to the gas-phase sequencing of progressively larger oligonucleotides. In this report, we examined the behavior of oligoribonucleotide samples ranging from 20 to 364 nt upon collision-induced dissociation (CID). The experimental data showed a progressive shift from terminal to internal fragments as a function of size. The systematic evaluation of experimental factors, such as collision energy, precursor charge, sample temperature, and the presence of chaotropic agents, showed that this trend could be modestly alleviated but not suppressed. This inexorable effect, which has been reported also for other activation techniques, prompted a re-examination of the features that have traditionally discouraged the utilization of internal fragments as a source of sequence information in data interpretation procedures. Our simulations highlighted the ability of internal fragments to produce self-consistent ladders with either end corresponding to each nucleotide in the sequence, which enables both proper alignment and correct recognition of intervening nucleotides. In turn, contiguous ladders display extensive overlaps with one another and with the ladders formed by terminal fragments, which unambiguously constrain their mutual placement within the analyte sequence. The experimental data borne out the predictions by showing ladders with extensive overlaps, which translated into uninterrupted "walks" covering the entire sequence with no gaps from end to end. More significantly, the results showed that combining the information afforded by internal and terminal ladders resulted in much a greater sequence coverage and nucleotide coverage depth than those achievable when either type of information was considered separately. The examination of a series of 58-mer oligonucleotides with high sequence homology showed that the assignment ambiguities engendered by internal fragments did not significantly exceed those afforded by the terminal ones. Therefore, the balance between potential benefits and perils of including the former makes a compelling argument for the development of integrated data interpretation strategies, which are better equipped for dealing with the changing fragmentation patterns obtained from progressively larger oligonucleotides.

Development of Hydroxyapatite Coatings for Orthopaedic Implants from Colloidal Solutions: Part 1-Effect of Solution Concentration and Deposition Kinetics.

This study introduces and explores the use of supersaturated solutions of calcium and phosphate ions to generate well-defined hydroxyapatite coatings for orthopaedic implants. The deposition of hydroxyapatite is conducted via several solutions of metastable precursors that precipitate insoluble hydroxyapatite minerals at a substrate-solution interface. Solutions of this nature are intrinsically unstable, but this paper outlines process windows in terms of time, temperature, concentration and pH in which coating deposition is controlled via the stop/go reaction. To understand the kinetics of the deposition process, comparisons based on ionic strength, particle size, electron imaging, elemental analyses and mass of the formed coating for various deposition solutions are carried out. This comprehensive dataset enables the measurement of deposition kinetics and identification of an optimum solution and its reaction mechanism. This study has established stable and reproducible process windows, which are precisely controlled, leading to the successful formation of desired hydroxyapatite films. The data demonstrate that this process is a promising and highly repeatable method for forming hydroxyapatites with desirable thickness, morphology and chemical composition at low temperatures and low capital cost compared to the existing techniques.

Matrix-Enhanced SIMS: The Influence of Primary Ion Species and Cluster Size on Ion Yield and Ion Yield Enhancement of Lipids.

Time-of-flight secondary ion mass spectrometry is one of the most promising techniques for label-free analysis of biomolecules with nanoscale spatial resolution. However, high-resolution imaging of larger biomolecules such as phospholipids and peptides is often hampered by low yields of molecular ions. Matrix-enhanced SIMS (ME-SIMS), in which an organic matrix is added to the sample, is one promising approach to enhancing the ion yield for biomolecules. Optimizing this approach has, however, been challenging because the processes involved in increasing the ion yield in ME-SIMS are not yet fully understood. In this work, the matrix α-cyano-4-hydroxycinnamic acid (HCCA) has been combined with cluster primary ion analysis to better understand the roles of proton donation and reduced fragmentation on lipid molecule ion yield. A model system consisting of 1:100 mol ratio dipalmitoylphosphatidylcholine (DPPC) in HCCA as well as an HCCA-coated mouse brain cryosection have been studied using a range of Bi and Ar cluster ions. Although the molecular ion yield increased with an increase in cluster ion size, the enhancement of the signals from intact lipid molecules decreased with an increase in cluster ion size for both the model system and the mouse brain. Additionally, in both systems, protonated molecular ions were significantly more enhanced than sodium and potassium cationized molecules for all of the primary ions utilized. For the model system, the DPPC molecular ion yield was increased by more than an order of magnitude for all of the primary ions studied, and fragmentation of DPPC was dramatically reduced. However, on the brain sample, even though the HCCA matrix reduced DPPC fragmentation for all of the primary ions studied, the matrix coating suppressed the ion yield for some lipids when the larger cluster primary ions were employed. This indicated insufficient migration of the lipids into the matrix coating, so that dilution by the matrix overpowered the enhancement effect. This study provides strong evidence that the HCCA matrix both enhances protonation and reduces fragmentation. For imaging applications, the ability of the analytes to migrate to the surface of the matrix coating is also a critical factor for useful signal enhancement. This work demonstrates that the HCCA matrix provides a softer desorption environment when using Bi cluster ions than that obtained using the large gas cluster ions studied alone, indicating the potential for improved high spatial resolution imaging with ME-SIMS.

Enhancement in the alkaline stability of poly(arylene ether ketone)-typed anion-exchange membranes via phenylene piperidinium blocks

In alkaline environments, the cationic groups and polymeric backbones of conventional poly(arylene ether ketone)-typed anion-exchange membranes (AEMs) tend to degrade. Herein, we report poly(phenylene piperidinium-co-arylene ether ketone)s (QPPPiAEK-x) with enhanced alkaline stability as potential AEM candidates. Specifically, a diphenyl piperidine precursor was synthesized and subjected to Ni(0)-catalyzed coupling polymerization with poly(arylene ether ketone) oligomers and followed by classic Menshutkin reaction. Membranes with an ion exchange capacity ranging from 1.85 to 2.24 meq g-1 showed high water uptakes (97.7%–159.2%) and high OH- conductivities at 80 °C (73.4–82.2 mS cm-1) but moderate swelling behaviors (i.e., in-plane swelling ratios of 28.0%–35.8%, and through-plane swelling ratios of 28.4%–56.2%). Morphological studies confirmed the presence of hydrophilic–hydrophobic microphase separation (ionic domain sizes of 17.9–22.3 nm) in all membranes, which was ascribed to the high feed content of phenylene piperidinium blocks. The H2/O2 single-cell test revealed the highest power output (187.7 mW cm-2) for the QPPPiAEK-2.0 membrane at 60 °C and 100% relative humidity. During the stability test, all membranes exhibited adequate ion conduction abilities. The most durable membrane retained 69.6% of its initial conductivity after 936 h in a 1 M NaOH solution at 80 °C. Results of ex-situ nuclear magnetic resonance spectroscopy revealed that approximately 9.7%–20.6% of cationic decomposition was the main degradation pathway for the QPPPiAEK-x ionomers, whereas 2.6%–4.4% accounted for the cleavage of backbones. Our study provides a promising methodology for fabricating alkali-stable AEMs for fuel cell applications.

Ternary-Metal Sn-Pb-Zn Perovskite to Reconstruct Top Surface for Efficient and Stable Less-Pb Perovskite Solar Cells.

Though Sn-Pb alloyed perovskite solar cells (PSCs) achieved great progress, there is a dilemma to further increase Sn for less-Pb requirement. High Sn ratio (>70%) perovskite exhibits nonstoichiometric Sn:Pb:I at film surface to aggravate Sn2+ oxidation and interface energy mismatch. Here, ternary metal alloyed (FASnI3 )0.7 (MAPb1- x Znx I3 )0.3 (x = 0-3%) is constructed for Pb% < 30% perovskite. Zn with smaller ionic size and stronger ionic interaction than Sn/Pb assists forming high-quality perovskite film with ZnI6 4- enriched at surface to balance Sn:Pb:I ratio. Differing from uniform bulk doping, surface-rich Zn with lower lying orbits pushes down the energy band of perovskite and adjusts the interface energy for efficient charge transfer. The alloyed PSC realizes efficiency of 19.4% at AM1.5 (one of the highest values reported for Pb% < 30% PSCs). Moreover, stronger bonding of Zn─I and Sn─I contributes to better durability of ternary perovskite than binary perovskite. This work highlights a novel alloy method for efficient and stable less-Pb PSCs.

Mineral and crystal chemical study of pseudo-C2/mnon-metamict chevkinite-(Ce): An investigation into the intracrystalline distribution of LREE, HREE, and octahedral cations in samples from the Azores and Pakistan

AbstractThe cation distribution among the A, B, C, and D sites of 13 crystals of chevkinite-(Ce) by X-ray single-crystal diffraction and electron microprobe analyses is reported in this article. The general formula of chevkinite-(Ce) is A4BC2D2O8(Si2O7)2, where A = REE, Ca, Th, Sr; B = Fe, Mn, Mg; C = Fe, Ti, Nb, Zr, Mg, Al; and D = Ti. Ten crystals come from quartz-bearing syenite samples of Agua de Pau (Azores Islands), and three are euhedral chevkinite crystals of a quartz-bearing pegmatite from Tangir Valley, northwestern Pakistan. The real space group for these samples is P21/a, but the average structure in space group C2/m was used for structural refinement and further interpretation. Cation distribution was determined by minimization of the function fΣNσ2 that represents the sum of the squared numbers of standard deviation by which each expected quantity differs from the calculated one. Both X-ray diffraction and electron microprobe data were considered in minimization. Our results show that the two non-equivalent A sites are occupied dominantly by REE and Ca, distributed mainly as a function of their ionic size. Lanthanum enters only the 10-coordinated A2 site, whereas heavier and smaller REE enter only the 8-coordinated A1. Furthermore, comparison between bond valence sum and formal charge revealed highly stretched bonds for the A1 polyhedron, suggesting that bond lengths are too long for HREE. These findings can help better characterize the well-known ability of chevkinite to fractionate LREE from HREE. The Azores chevkinite is particularly enriched in Nb relative to its host rock. Our results show that Ti occupancy in the D sites can be as low as ca. 50% due to the presence of significant amounts of Nb, besides Fe and Zr. For two Azores crystals showing patchy zoning, a complex history of late-stage crystallization is inferred, with multiple events of Ca and REE enrichments. One of these crystals showed the best structure refinement, implying that late-magmatic to deuteric alteration stages did not affect its crystallinity. The CaO content of Azores chevkinites practically spans the entire chevkinite field in the chevkinite/perrierite CaO vs. FeO discrimination diagram. In addition, we identified possible structural stability limits that can be linked to the occupancy of the B site at high CaO, and of the C sites at high-FeO contents. The Pakistan chevkinites were also analyzed by Mössbauer spectroscopy. Only one Fe3+ component was identified, which occupies the C sites. Among the two ferrous doublets, the component with the highest isomeric shift value is Fe2+ entering the most distorted crystallographic site B, while the other, representative of a less distorted octahedral site, corresponds to Fe2+ entering the D sites.

Size-dependent polymeric arrays of heterometallic Cs+–Ln3+ β-diketonates

A series of alkali–lanthanide heterometallic systems such as Cs+–Ln3+ β-diketonate complexes [Ln(TFPB)4Cs]n (Ln = La (1), Pr (2), Eu (3), Y (4), Yb (5), Lu (6) and TFPB = 4,4,4-trifluoro-1-phenyl-1,3-butanedione) were prepared and structurally explored. The complexes exist only in polymeric forms while both monomeric and polymeric structures are found in the previously reported Na+–Ln3+ congeners. Tuning the sizes of the central rare earth ions from La3+ to Lu3+ results in three types of infinite Cs+–Ln3+ chains which are helical, two-step zigzag and single zigzag patterns. Nonetheless, the Na+–La3+ and Na+–Eu3+ complexes (1-Na and 3-Na) are isomorphous polymers. The size variation of the Ln3+ ions can also alter the degree of π interactions of the Cs+ ions with β-diketonate fragments and phenyl rings. Interestingly, multiple interactions are detected in the complexes with small rare earth ions (5 and 6). Photoluminescence measurements reveal much brighter red emission of 3 than that of 3-Na. It is assumed that the Cs+ ions have more appropriate size than the Na+ ions toward the binding with [Eu(TFPB)4]– anions via oxygen and fluorine atoms, alleviating the energy dissipation of the excited states.

Tailoring Tensile Strain in Pb–Sn Perovskite Film for Efficient and Stable Narrow‐Bandgap Perovskite Solar Cells

Pb–Sn perovskites (PSPs) with narrow bandgap and low toxicity show great promise in next‐generation perovskite‐based photovoltaics, especially in constructing all‐perovskite tandem solar cells as the rare subcell. However, partially replacing Pb by Sn with smaller ionic size in PSPs is shown to reduce their crystal lattice symmetry, which leads to intrinsic compressed lattice strain and reduced structural stability, resulting in the poor device performance of PSPs‐based solar cells. Herein, the effect of lattice tensile strain on the optoelectronic properties of FA0.7MA0.3Pb0.5Sn0.5I3 film is investigated and the tensile strain is finely adjusted by introducing monovalent‐cation chlorides with different cation sizes as additive. It is found that a moderate tensile strain in the film is beneficial for stabilizing the crystal structure, promoting oriented crystal growth and reducing the defect density. After optimization, FA0.7MA0.3Pb0.5Sn0.5I3‐based perovskite solar cells using FACl as additive can produce the device with champion power conversion efficiency (PCE) of 19.30% together with improved device reproducibility. Importantly, the FACl‐based device shows robust stability that exhibits no PCE loss after being stored in N2 for 1000‐h. This work provides new insight into the key role of tensile strain in PSPs, which can facilitate the development of PSP‐based optoelectronic devices.

(Invited) Structure and Dynamics of Interfacial Species in Electrical Double Layer

Understanding electrochemical processes is of importance for many industrial and scientific fields. Especially, interfacial species, such as electrolyte ions and solvent significantly affect electrochemical reaction activity. Surface oxide species also promote or inhibit various electrode reactions; therefore, the oxidation processes of metal electrode have been investigated using in situ vibrational spectroscopy. Infrared (IR) spectroscopy is an important tool because it can detect the complementary vibrational modes of surface oxide species. However, observation of the low-frequency mode is restricted by infusible IR windows such as CaF2, that are generally used in the IR reflection absorption spectroscopy (IRAS). We developed a complementary IR method that can be used to avoid contamination by dissolved ions from window material. The fusible low-pass IR window can be applied to in-situ IRAS measurements [1,2]. The adsorbed hydroxide was observed on the single crystal Pt electrodes depending on the surface orientation, its coverage was correlated with the decrease in oxygen reduction reaction activity [3]. Recent time resolved X-ray diffraction measurements revealed that there is a delay in the approach of alkali metal cations to surface because the interfacial water causes a blocking effect [4]. Therefore, the kinetics of approaching step in the EDL is significantly different from that of migration in the bulk phase, and the adsorption rate depends on the hydration structure, ionic valence, and ionic size. Although X-ray diffraction provides a distribution of interfacial species, it does not provide sufficient information about species identification and molecular orientation. We investigated the coadsorption dynamics of metal cation and (bi)sulfate anion using time resolved IR measurement [5]. Boron doped diamond (BDD) is a promising material of which properties are significantly different from those of metals and other carbon materials. However, the complex atomic arrangement and oxidation state of the polycrystalline BDD surface inhibit an atomic level study on the relationship between the electrochemical response and surface structure. More detailed surface analyses are necessary for the investigation of the electrode surface of BDD. We applied in situ ATR−IR spectroscopy to reveal the oxidative species and dopamine oxidation on the BDD electrode [6,7].[1] M. Nakamura, Y. Nakajima, N. Hoshi, H. Tajiri, O. Sakata, ChemPhysChem, 14, 2426 (2013).[2] M. Nakamura, Y. Nakajima, K. Kato, O. Sakata, N. Hoshi, J. Phys. Chem. C, 119, 23586 (2015).[3] T. Kumeda, H. Tajiri, O. Sakata, N. Hoshi, M. Nakamura, Nat. Commun., 9, 4378 (2018).[4] M. Nakamura, H. Kaminaga, O. Endo, H. Tajiri, O. Sakata, N. Hoshi, J. Phys. Chem. C, 118, 22136 (2014).[5] M. Nakamura, T. Banzai, Y. Maehata, O. Endo, H. Tajiri. O. Sakata, N. Hoshi, Sci. Rep., 7, 914 (2017).[6] T. Ogose, S. Kasahara, N. Ikemiya, N. Hoshi, Y. Einaga, M. Nakamura, J. Phys. Chem. C, 122, 27456 (2018).[7] R. Hosoda, N. Kamoshida, N. Hoshi, Y. Einaga, M. Nakamura, Carbon, 171, 814 (2021).

Pressure-Dependent Crystal Radii

This article reports the pressure-dependent crystal radii of Mg, Si, Ge, Be, Fe, Ca, Sr, Ba, Al, Ti, Li, Na, K, Cs, and of some rare earths, that is: the major Earth mantle elements, important minor, and some trace elements. Pressure dependencies of O2−, Cl−, and Br− are also reported. It is shown that all examined cation radii vary linearly with pressure. Cation radii obey strict correlations between ionic compressibilities and reference 0 GPa radii, thus reducing previous empirical rules of the influence of valence, ion size, and coordination to a simple formula. Both cation and anion radii are functions of nuclear charge number and a screening function which for anions varies with pressure, and for cations is pressure-independent. The pressure derivative of cation radii and of the anion radii at high pressure depends on electronegativity with power −1.76.

Layered Monoclinic Perrierite Oxo-Silicate La4Mn5Si4O22+Δ: A New Interstitial Oxide Ion Conductor for Low Temperature Applications

Oxide-ion conductors are important for various energy applications such as solid oxide fuel cells, solid oxide electrolyser cells, oxygen separation membranes, oxygen sensors, etc. State-of-the-art stable oxygen active materials often have adequate oxygen ion diffusion and chemical surface exchange only at high temperatures (> 700 oC). A promising strategy to improve the oxygen ion transport is to use the interstitial oxygen ion conductors as the interstitial diffusion barriers are often lower than vacancy-mediated diffusion barrier, potentially enabling reduced operation temperatures. However, due to the large size of the oxide ion, the formation of an adequate concentration of interstitials is difficult and hence the number of interstitial oxygen conductors is currently limited to just a handful of compounds, e.g., Ruddlesden-Popper, apatite, melilite, scheelite, fluorite and disordered hexagonal perovskites.We screened a large number of oxide materials using high-throughput ab initio methods (Please see separate poster from Jun Meng on this screening) and predicted stable formation and fast diffusion of interstitial oxygen in a new class of material La4Mn5Si4O22+δ (LMS), motivating us to synthesize this material and experimentally study its oxide ion transport properties. The room temperature X-ray diffraction study followed by Rietveld refinement confirmed its layered monoclinic perrierite structure. Electron probe micro-analysis (EPMA) and iodometric titration revealed the presence of the hyper stoichiometric oxygen anion (δ ~ + 0.5) confirming the interstitial oxygen ions within LMS lattice. Thermogravimetric analysis showed a small mass increment in LMS when heated at high temperatures suggesting the high temperature stability of interstitial oxygen ions. The measured ionic conductivity of LMS is higher than the yttria stabilized ZrO2, perovskite oxide La1-xSrxCo1-yFeyO3 and Ruddlesden-Popper oxide materials. Electrical conductivity relaxation studies demonstrated that self-diffusion and surface exchange coefficients of oxygen ion are comparable to or higher than many state-of-the-art oxide ion conductors. Finally, the high temperature stability of the synthesised material was confirmed using X-ray diffraction after each measurement.Overall, this experimental study confirms computational predictions that layered perrierite LMS is a new class of interstitial oxide ion conductors and suggests our overall approach may help the rational design of interstitial mediated oxide ion conductors-based devices suitable for efficient and stable applications at low temperature.

In Situ Analysis of the Effect of Tetraakylammonium Salts on the Selectivity and Efficiency of Acrylonitrile Electrohydrodimerization

Traditional chemical manufacturing processes are primarily powered by fossil-fuel combustion, and often require operation at elevated temperatures and pressures. Introducing electrosynthesis as an alternative to thermal processes at industrial scale can allow direct integration of renewable electricity with chemical manufacturing, accelerating the decarbonization of large-scale chemical processes. However, there are major challenges that must be addressed before implementing organic electrosynthesis on an industrial level, such as the low solubility of organic reactants in aqueous electrolytes and the existence of multiple reaction pathways that lead to undesired byproducts. In this presentation, we will discuss our work on electrolyte design strategies to enhance the performance of adiponitrile (ADN) electrosynthesis. ADN is a large volume precursor of hexamethylenediamine, which is a monomer used in Nylon 6,6 manufacturing. The most commonly used method for ADN production, the thermochemical hydrocyanation of 1,3-butadiene, is energy intensive and uses hydrogen cyanide, a highly toxic reactant. Alternatively, ADN can be produced electrochemically via the hydrodimerization of acrylonitrile (AN), which is the largest and most successful industrial organic electrochemical process. In this reaction, the addition of tetraalkylammonium (TAA) salts as supporting electrolytes in large concentrations has been widely accepted to enhance the solubility of organic reactants. It has been hypothesized that TAA ions boost the selectivity towards ADN by increasing the AN concentration in the electrical double layer (EDL). Recent studies by our group explored the effect of the molecular size and concentration of TAA ions on the selectivity and efficiency of ADN production. Resulting trends suggest that the reaction is strongly limited by mass transport of organic reactants to the EDL at high current densities. Despite these advances, the local effects of TAA ions on the concentration of reactants and intermediates in the EDL remain unclear. Inspired by prior demonstrations, we developed a spectroelectrochemical method for quantitatively assessing the concentration of species at the electrode/electrolyte interface. This method relies on an electrochemical flow cell integrated with an attenuated total reflection (ATR) Fourier-transform infrared (FTIR) spectrometer to quantify concentrations of reactive species in the near-electrode region. Our results demonstrate that the presence of TAA ions increases the local concentration of AN at the electrode, and that applied potential increases TAA ion concentration. These results provide insights into the effects of supporting ions and potential in organic electrosynthesis selectivity.Figure caption: Schematic view of the enhancement of acrylonitrile (AN) concentration in the electrical double layer (EDL) by the addition of Tetrabutylammonium (TBA) ions to the aqueous electrolyte. Figure 1

New insights into the molecular structure and dynamics of a recyclable and ionically crosslinked carboxylated nitrile rubber (XNBR)

Ionic crosslinking offers a route to rubber reprocessability due to ion pairs’ dynamism, with recent studies focusing on tensile properties recovery. However, this research aims to provide, for the first time, a comprehensive overview of the recyclability of carboxylated nitrile rubber (XNBR), spotlighting changes in molecular dynamics through multiple recycling cycles beyond tensile tests. A uniquely recyclable XNBR, incorporating ZnO as a multifunctional additive, was designed alongside a simple, scalable, two-step recycling process. Evidence of the delicate balance between crosslink density and molecular entanglements that affects the dynamics of the recycled material was found. Recycling also restricts the molecular dynamics near ionic domains; attributed to a higher crosslink density (from 3.69×10-5molcm−3 in the pristine sample to 6.00×10-5molcm−3 after the third cycle), caused by a decreased ionic clusters size (aggregation number drops from 12.2 to 6.9). Remarkably, negligible differences (<10%) in compressive fatigue behavior and an enhanced chemical resistance in different solvents (up to 350% increase in motor oil) were also observed, ensuring suitable performance in conditions closer to service. Overall, this study demonstrates the feasibility of XNBR recycling and provides a broad understanding of this material at the molecular level.

Stabilizing α-FAPbI3 at FAPbI3/SnO2-X Interface By Reducing Oxygen Vacancies in SnO2-X

CH3NH3PbI3 (CH3NH3 + is denoted MA hereinafter) was selected as the photoactive material in the early stage of perovskite solar cell (PSC) research. However, MAPbI3 shows poor thermal stability due to high volatility of the MA organic cation. Replacing the MA organic cation with a CH(NH2)2 + (CH(NH2)2 + is denoted FA hereinafter) organic cation was suggested to resolve the thermal stability issue. Additionally, FAPbI3 holds higher potential for high-efficiency solar cells with a broader photoresponse range in the solar spectrum than MAPbI3. However, fabricating FAPbI3 thin films is more challenging than MAPbI3. FA exhibits a larger ionic size (2.56 Å) than MA (2.17 Å), making incorporation of FA into PbI6 octahedra difficult. Incorporating FA induces tilting of PbI6 octahedra, which causes reversible deformation of perovskite-phase FAPbI3 (α-phase) into unfavorable phases (δ-phase and PbI2) at room temperature. Several reports on stabilizing the α-phase of FAPbI3, such as through heterogeneous cation or anion mixing, have been presented. For example, mixing smaller ions such as MA, Cs, and Br reduces the unit cell volume of FAPbI3, enhancing hydrogen bonding between FA and the PbI6 octahedron. This hydrogen bonding prevents reversible deformation of and stabilizes the α-phase of FAPbI3 in ambient atmosphere. In conventional PSCs, the perovskite layer usually forms an interface with an electron or hole transport layer (ETL or HTL). The compatibility of materials forming the interface is significant for separating charges from the perovskite with minimal loss. Nevertheless, although stabilizing FAPbI3 in a bulk manner is widely studied, stabilizing FAPbI3 at the interface is relatively overlooked. Stabilizing FAPbI3 at the interface is more important since the interface contains a high portion of structural defects compared to the bulk, almost 100-fold. Unfavorable phases, such as δ-phase FAPbI3 and PbI2, formed at the interface will hinder the charge extraction process from FAPbI3 to the transport layer, similar to defects. Especially, in the n-i-p structure, the perovskite is epitaxially deposited over the ETL, and tuning the interface after deposition is nearly impossible, which stresses the importance of the surface structure of the ETL. In the case of FAPbI3/SnO2-x, Sn and O are the key atoms for stabilizing the PbI6 octahedron and organic cation, respectively, which affects the growth of the perovskite at the interface. Oxygen vacancies in the surface of SnO2-x can cause distortion of the perovskite structure at the interface, inducing unfavorable phases, such as the δ-phase, PbI2, or other unknown phases. Furthermore, oxygen vacancies are more prevalent issue in SnO2-x than TiO2-x due to the stronger multivalency of Sn, which further emphasizes control of oxygen vacancies in SnO2-x. Since the open-circuit voltage (Voc) and fill factor (FF) show greater potential for improvement than the short-circuit current density (Jsc), stabilizing α-FAPbI3 at the interface may be a necessary step for researchers to further increase the power conversion efficiency (PCE) and stability of PSCs. In this work, we systematically studied the formation of δ-phase FAPbI3 and PbI2 induced by oxygen vacancies of the SnO2-x surface at the FAPbI3/SnO2-x interface. Using X-ray diffraction (XRD) and transmission electron microscopy (TEM), we observed PbI2 segregation and δ-phase FAPbI3 formation adjacent to SnO2-x. The generation of iodine interstitials at the interface was revealed as the driving force of the unfavorable phase transition. The absence of oxygen atoms interacting with tin atoms lowered the energy barrier for iodine interstitial generation almost by half, and the iodine interstitials accelerated the unfavorable phase transition of FAPbI3. For the first time, organic cation loss at the FAPbI3/SnO2-x interface was also observed as a severe drawback to forming an ideal heterojunction. Oxygen vacancies in the SnO2-x surface, which act as hydrogen bonding sites for FA cations, induced withdrawal of FA cations, which was revealed by X-ray photoelectron spectroscopy (XPS) measurements. Inspired by this phenomenon, we fabricated a SnO2-x layer with reduced oxygen vacancies by using oxidized black phosphorus quantum dots (O-BPs). The multiple P=O bonds of O-BPs effectively assisted the formation of a SnO2-x layer with minimal oxygen vacancies. After P=O passivation, most of the detrimental effects were mitigated, showing highly stable α-FAPbI3 crystal structures. Consequently, we achieved a maximum PCE of 23.43% with enhanced thermal and operational stability.

Bimetallic Ru1−xVxO2 and trimetallic Ru1−x−yVxCryO2 alloy nanofibers for efficient, stable and pH-independent oxygen evolution reaction catalysis

We present ruthenium-vanadium mixed alloy metal oxide (Ru1−xVxO2) nanofibers as well as chromium (Cr) doped Ru1−x−yVxCryO2 nanofibers using electrospinning and subsequent thermal annealing procedures as cost-effective, highly active and stable electrocatalyst for oxygen evolution reaction (OER). Both Ru1−xVxO2 and Ru1−x−yVxCryO2 nanofibers exhibited tetragonal crystalline structure, confirming that Ru, V, and Cr ions randomly occupied the tetragonal lattice sites due to the similar ionic sizes. Both Ru1−xVxO2 and Ru1−x−yVxCryO2 nanofibers showed excellent OER electrocatalytic activity, characterized by low overpotentials and small Tafel slopes, in both acidic and alkaline conditions. Ru1−xVxO2 (x = 0.52) nanofibers demonstrated an enhanced elemental substitution effect, leading to an enlarged active surface area that contributed to their exceptional OER activity. Ru1−x−yVxCryO2 nanofibers, achieved through optimal doping with Cr4+ ions, not only displayed significantly improved stability but also exhibited high OER activity. Interestingly, both Ru1−xVxO2 and Ru1−x−yVxCryO2 nanofibers consistently catalyzed alkaline OER, even under conditions of reactant depletion. These nanofibers, containing noble Ru with less than half of the total metal content, are proposed as efficient and cost-effective OER catalysts for use in both acidic and alkaline media.

Co-Intercalation Batteries (CoIBs): The Use of TiS2 As Electrode for Solvent Co-Intercalation in Sodium-Ion Batteries

With the rising demand for lithium-ion batteries (LIBs), sodium-ion batteries (SIBs) have become an attractive alternative with the promise of improved safety, reduced cost, and lower environmental impact.1 However, the larger ion size of sodium cation has major consequence on the battery chemistry, which provides several challenges and opportunities for designing electrode materials and electrolyte solutions.2 Graphite is the currently most used anode material in LIBs. However, its use in SIBs, with traditional carbonate-based electrolytes, results in very poor specific capacities due to unfavorable thermodynamic processes.3 A strategy around this problem is to choose different solvents: Ethers and in particular glymes can exhibit a co-intercalation behavior into the graphite structure by forming ternary graphite intercalation compounds.4, 5 Although the co-intercalation of solvent molecules with sodium cation leads to a large increase in the graphite framework, the cycle life and rate capability of the reaction are excellent.Regardless of this, there is a lack of evidence for a comparable reaction with other electrode materials. Hence, it would be of interest to identify a cathode material that operates via this same mechanism. A battery based on solvent co-intercalation at both electrodes can have minimized charge-transfer resistances due to the absence of desolvation steps, and great cycle life. Thus, such a system can show high power density over many cycles. It has also been shown that stripping of the solvation shell can be the rate limiting step for battery operation, especially at subzero temperatures.6 Such a solvent co-intercalation battery (CoIB) could therefore be more energy efficient compared to other batteries or could enable a better low-temperature performance.Transition metal dichalcogenides (TMDs) have emerged as promising anode materials owing to their low cost, high electric conductivity, good thermal stability and environmental friendliness. Among them, titanium sulphide (TiS2), with a two-dimensional framework, exhibits several advantages such as a high conductivity (compare to other metal oxides), a larger interlayer distance (0.569 nm) compared to graphite (0.335 nm) and high stability. 7 Several papers have reported on the use of TiS2 as an anode material for SIBs, and observed that the voltage profiles and electrochemical behaviour of the system is highly dependent on the choice of electrolyte. However, this has seldomly been explicitly stated and the cause of the electrolyte dependence has never been investigated. By using operando and in-situ techniques such as Operando XRD and dilatometry, Na-diglyme complexes were showed to co-intercalate, similar as graphite, into TiS2. In contrast, no signs of solvent co-intercalation are observed in cyclic ethers and conventional carbonate-based electrolytes – where instead the redox reaction with TiS2 results in the formation of different NaxTiS2 compounds.As we identified TiS2 as “co-intercalation electrode” in glyme-based electrolytes it served to create the first ever solvent co-intercalation battery (CoIB – pronounced Co-IB) which was done by pairing TiS2 (positive electrode) with graphite (negative electrode).8 This work could enable the development of highly energy efficient batteries with minimum charge transfer resistances and References I. Hasa, S. Mariyappan, D. Saurel, P. Adelhelm, A. Y. Koposov, C. Masquelier, L. Croguennec and M. Casas-Cabanas, J. Power Sources, 2021, 482, 228872. P. Adelhelm, P. Hartmann, C. L. Bender, M. Busche, C. Eufinger and J. Janek, Beilstein Journal of Nanotechnology, 2015, 6, 1016-1055. B. Jache and P. Adelhelm, Angew. Chem., 2014, 126, 10333-10337. B. Jache, J. O. Binder, T. Abe and P. Adelhelm, Physical Chemistry Chemical Physics, 2016, 18, 14299-14316. M. Goktas, C. Bolli, J. Buchheim, E. J. Berg, P. Novák, F. Bonilla, T. f. Rojo, S. Komaba, K. Kubota and P. Adelhelm, ACS applied materials & interfaces, 2019, 11, 32844-32855. S. S. Zhang, K. Xu and T. R. Jow, Journal of Power Sources, 2003, 115, 137-140. Q. Yun, L. Li, Z. Hu, Q. Lu, B. Chen and H. Zhang, Adv. Mater., 2020, 32, 1903826. G. A. Ferrero, G. Avall, K. A. Mazzio, Y. Son, K. Janssen, S. Risse and P. Adelhelm, Adv. Energy Mater., 2022, 2202377. an improved low temperature performance, where the charge transfer can become rate limiting. Figure 1

(Invited) Advanced Organic Electrode Materials for High-Performance and Sustainable Na-Ion Batteries

Na-ion batteries (NIBs) are promising alternatives to Li-ion batteries (LIBs) due to the low cost, abundance, and high sustainability of sodium resources. However, the high performance of inorganic electrode materials in LIBs does not extend to NIBs because of larger ion size of Na+ than Li+ and more complicated electrochemistry. Therefore, it is vital to search for high-performance electrode materials for NIBs. To this end, organic electrode materials (OEMs) with the advantages of high structural tunability and abundant structural diversity show great promise in developing high-performance NIBs. To achieve advanced OEMs for NIBs, a fundamental understanding of the structure–performance correlation is desired for rational structure design and performance optimization. Tailoring molecular structures of OEMs can enhance their performance in Na-ion batteries, however, the substitution rules and the consequent effect on the specific capacity and working potential remain elusive. Herein, we explored the electrochemical performances and reaction mechanisms of various carboxylate-based anode materials, including halogenated sodium carboxylates, N-doped sodium carboxylates, etc. By examining sodium carboxylates with different functional groups, selective N substitution, and extended conjugation structure, we exploited the correlation between structure and performance to establish substitution rules for high-capacity OEMs. Our results show that substitution position and types of functional groups are essential to create active centers for uptake/removal of Na+ and thermodynamically stabilize organic structures. Furthermore, rational host design and electrolytes modulation were performed to extend the cycle life. In addition to sodium carboxylate-based anode materials, we also designed and synthesized novel organic cathode materials based on azo and carbonyl groups for NIBs. The electrochemical performance of the organic cathode materials with an extended conjugated structure such as a naphthalene backbone structure is better than that with benzene and biphenyl structures due to faster kinetics and lower solubility in the electrolyte. It unravels the rational design principle of extending π-conjugation aromatic structures in redox-active polymers to enhance the electrochemical performance. To further optimize the organic cathodes, nitrogen-doped or single layer graphene is employed to increase the conductivity and mitigate the dissolution of organic materials in the electrolytes. The resulting organic cathodes deliver high specific capacity, long cycle life, and fast-charging capability. Post-cycling characterizations were employed to study the chemical structure and morphology evolution upon cycling, demonstrating that the active centers (azo and carbonyl groups) in the organic cathode materials can undergo reversible redox reactions with Na+ for sustainable NIBs. Our work provides a valuable guideline for the design principle of high-capacity and stable OEMs for sustainable energy storage.

(Digital Presentation) Self-Discharge Study of Carbon-Based Supercapacitors with Tunable Pore Size

Electrochemical double-layer capacitors (EDLCs), as a major type of energy storage devices besides rechargeable batteries such as lithium-ion batteries, holds excellent properties such as high power density and ultra-long cycling stability[1-3]; however, its fast self-discharge process has become the major issue that impedes its development and application. Even though research on EDLCs’ self-discharge has demonstrated that the fast self-discharge rate can be tuned even repressed through modifying certain structural properties of electrodes or electrolytes[4-9], to the end of realizing full control over the self-discharge process requires unveiling the fundamental relation between structural parameters (i.e., the pore structure, the surface functionalities, the electrolytic ion size and shape, and etc.) and the self-discharge performance.Carbon, due to its superior chemical stability, high surface area, natural abundance, etc.[4,10], has become one of the main types of electrode materials under extensive research interest for developing advanced EDLCs. Herein, we focus on tuning the pore size, one of the major structural properties of carbon materials relating to its electrochemical performance, to study its effects on self-discharge process and to learn how to construct the optimal pore structure with respect to certain application requirements.In this work, porous carbon materials with designed pore structure are prepared via soft-template method to analyse the self-discharge performance. Through investigating the effects of pore size, as the single variable, on the self-discharge process, as well as on the micro-electrochemical process on the electrode/electrolyte interface, underlying mechanism between pore size and the self-discharge performance has been constructed. These findings should provide guidance on how to locate the optimal pore size for a chosen electrolyte and to realize control over self-discharge, which will serve as solid references for designing the next-generation EDLCs with high performance and controllable self-discharge rates. Reference [1] X. Chen, R. Paul, L. Dai, Natl. Sci. Rev., 2017, 4(3), 453-489.[2] G. Wang, L. Zhang, J. Zhang, Chem. Soc. Rev ., 2012, 41, 797-828.[3] Y. Liu, Y. Shen, L. Sun, J. Li, C. Liu, W. Ren, F. Li, L. Gao, J. Chen, F. Liu, Y. Sun, N. Tang, H. Cheng, Y. Du, Nat. Commun., 2016, 7, 10921.[4] Q. Zhang, C. Cai, J.W. Qin, B.Q. Wei, Nano Energy., 2014, 4, 14-22.[5] T. Tevi, H. Yaghoubi, J. Wang, A. Takshi, J. Power Sources., 2013, 241, 589-596.[6] L. Chen, H. Bai, Z. Huang, L. Li, Energy Environ. Sci., 2014, 7, 1750-1759.[7] G. Shul, D. Bélanger, Phys. Chem. Chem. Phys., 2016, 18, 19137-19145.[8] M. Xia, J. Nie, Z. Zhang, X. Lu, Z.L. Wang, Nano Energy., 2018, 47, 43-50.[9] J. Menzel, E. Frackowiak, K. Fic, Electrochimica Acta, 2020, 332, 135435.[10] D.P. Dubal, O. Ayyad, V. Ruiz, P. Gomez-Romero, Chem. Soc. Rev., 2015, 44, 1777–1790. Figure 1