Ion Size Research Articles

Electrode-dependent thermoelectric effect in ionic hydrogel fiber for self-powered sensing and low-grade heat harvesting

Ionic thermoelectric materials show great significance for wearable energy devices, owing to the capability of the conversion between thermal and electrical energy. The two-dimensional massive structure which is difficult to integrate with fabrics of ionic thermoelectric materials, however, prevent them from realizing their full potential when employed in wearable electronics. In this work, ionic thermoelectric 1D PAM/LiTFSI4 hydrogel fibers with high aspect ratio, inherent flexibility, conductivity, anti-freezing, self-adhesion and self-healing properties are constructed by free radical polymerization technology based on a template strategy, which contains a PAM polymer matrix and an LiTFSI conductive material. Based on thermal diffusion, owing to the ion size difference, the covalent cross-linked polymer network and the electrode-dependent effect promote rapid transport of the cations and boost ion concentration difference, resulting in a huge ionic Seebeck coefficient of 19.02 mV K−1. Meanwhile, embedding hydrogel fibers into the woven textile demonstrates a promising thermoelectric wristband with desirable human heat collection and electrical output capabilities. What’s more, thanks to the introduction of LiTFSI, the microstructure and molecular network system of hydrogel fibers are reshaped, which significantly improved the ionic conductivity of hydrogel fiber, and endowed them with anti-freezing, self-adhesion and self-healing properties. The PAM/LiTFSI4 hydrogel fiber also has excellent strain and temperature sensing properties, which enable a variety of human signal monitoring. Besides, the hydrogel fiber-based sensor can realize self-powered sensing by generating a thermovoltage. Thus, combining the merits of one-dimensional structure, superior thermoelectric performances, sensing at low temperature, excellent adhesion, self-healing and anti-freezing properties together, believing that the PAM/LiTFSI4 hydrogel fiber will render new numerous in human signal monitoring and low-grade heat harvesting applications like wearable electronics and wearable energy supply devices.

Liquid state theory of the structure of model polymerized ionic liquids.

We employ polymer integral equation theory to study a simplified model of semiflexible polymerized ionic liquids (PolyILs) that interact via hard core repulsions and short range screened Coulomb interactions. The multi-scale structure in real and Fourier space of PolyILs (ions chosen to mimic Li, Na, K, Br, PF6, and TFSI) are determined as a function of melt density, Coulomb interaction strength, and ion size. Comparisons with a homopolymer melt, a neutral polymer-solvent-like athermal mixture, and an atomic ionic liquid are carried out to elucidate the distinct manner that ions mediate changes of polymer packing, the role of excluded volume effects, and the influence of chain connectivity, respectively. The effect of Coulomb strength depends in a rich manner on ion size and density, reflecting the interplay of steric packing, ion adsorption, and charge layering. Ion-mediated bridging of monomers is found, which intensifies for larger ions. Intermediate range charge layering correlations are characterized by a many-body screening length that grows with PolyIL density, cooling, and Coulomb strength, in disagreement with Debye-Hückel theory, but in accord with experiments. Qualitative differences in the collective structure, including an ion-size-dependent bifurcation of the polymer structure factor peak and pair correlation function, are predicted. The monomer cage order parameter increases significantly, but its collective ion counterpart decreases, as ions become smaller. Such behaviors allow one to categorize PolyILs into two broad classes of small and large ions. Dynamical implications of the predicted structural results are qualitatively discussed.

Sr and Fe-Substituted LaMnO3 Perovskite for High-Rate Asymmetric Hybrid Supercapacitors

Perovskite has been getting significant attention in solar cells, photocatalysts, and hybrid supercapacitors. The symmetry or structural stability of ABO3-type perovskite oxides depends mainly on the size of ‘A’ and ‘B’ cations, which determines the material properties. The partial substitution of these cations may be used to tune these properties. The ionic sizes and valence states of the cations play an important role in improving the properties of perovskite. In this study, the substitution of La3+ with Sr2+ with a larger ionic radius and Mn3+ with Fe3+ with a similar ionic radius favored both the crystal symmetry and the mixed ionic-electronic conductivity of the perovskite. Electrodes based on La0.7Sr0.3Mn0.5Fe0.5O3 (LSMFO55) exhibited a faradaic behavior with a specific capacity of 330 C g-1 (92 mAh g-1) at a 12C rate, while this electrode maintained a capacity of 259 C g-1 at 240C (charge or discharge in 15s). Additionally, exohedral carbon nano-onions (CNO) were introduced as a negative electrode to design an asymmetric hybrid supercapacitor (AHS) with a widened cell voltage. The use of CNO as a negative electrode in the AHS improved the rate capability drastically compared to rGO. This device maintained a good energy density even at an extra-high charging rate (600C), owing to its outstanding rate capability. The high-rate performance of the LSMFO55//CNO AHS can be elucidated by successful fabrication with a mixed ionic-electronic conductive positive electrode and a CNO negative electrode. Tuning the electronic and ionic conductivities by cationic substitution and introducing CNO negative electrodes can provide a practical high-rate hybrid device using various perovskites.

Steric Effects of Tetraalkylammonium Hydroxides on Nafion in Adiponitrile Production

Over the last two decades, the chemical industry has witnessed a 43% increase in greenhouse gas emissions, with organic chemicals contributing to 75% of the total chemical production [1]. While organic electrosynthesis is a promising method for reducing the environmental impact of chemical manufacturing, advancing this technology faces significant challenges due to the limited viability of membranes used in divided electrochemical reactors. Despite the need for suitable membranes for electrosynthesis, only a few studies have explored the use of ion-conducting membranes for electro-organic reactions [2-7]. In this study, we aim to provide additional insights into the role of membranes in electrosynthesis and their behavior when exposed to electrolytes containing organic components.We selected adiponitrile electrosynthesis, one of the largest industrial electro-organic processes, as a model reaction [2,3]. We used Nafion as a model membrane material. Electrolytes used in adiponitrile electrosynthesis contain tetraalkylammonium (TAA) ions to enhance the selectivity of electro-organic reactions. Here, we present a systematic study exploring how TAA ions impact Nafion's structure and transport properties. We exposed Nafion membranes to solutions with varying concentrations and sizes of TAA ions, including tetramethyl (TMA), tetraethyl (TEA), tetrapropyl (TPA), and tetrabutyl (TBA). We quantified TAA ion sorption in the membranes using ATR-FTIR. The results reveal that TAA ion sorption saturates when the solution concentration exceeds 0.02 M. Compared to the conductivity of Nafion equilibrated in pure water (9.8 x 10-2 S/cm), the membrane conductivity after exposure to TAA solutions exhibits a substantial decline, decreasing by up to 4 orders of magnitude. We performed small-angle X-ray scattering experiments to correlate the conductivity results with structural changes in Nafion. The measurements revealed that the spacing between Nafion's ion-conducting domains decreases as the TAA ion concentration increases. For example, when membranes are exposed to 1.0 M TBA solutions, the domain spacing drops from 4.9 nm to 3.76 nm compared to membranes equilibrated in pure water. Consequently, we infer those organic ions reduce the size of ion-conducting domains due to the diffusion of water from the membranes into the surrounding electrolyte, resulting in decreased conductivity. These results represent an important step in elucidating structure-property relationships in ion-conducting membranes used for organic electrosynthesis.Reference[1] 2022. Our Risks for Infectious Diseases Is Increasing Because of Climate Change. CDC:NCEZID [updated 2022 August 02]. https://www.cdc.gov/ncezid/what-we-do/climate-change-and-infectious-diseases/index.html.[2] N. Tanbouza. 2020 J. iScience. 23 101720[3] Suryanto, B. H. R.; Kristianto, H. A.; Yi, Z. "Electrosynthesis: An overview of green chemistry.” Current Opinion in Green and Sustainable Chemistry 16 (2019): 28-34.[4] Baizer, M.; Lust, E.; Williamson, S.E.; Connor, R.F. "Electrochemical Synthesis of Adiponitrile." Industrial & Engineering Chemistry Process Design and Development, 1966, 5 (1), 56–62.[5] D. E. Danly 1984 J. Electrochem. Soc. 131 435C[6] Blanco, D.; Prasad, P.; Dunningan, K.; Modestino, M. React. Chem. Eng., 2020, 5, 136[7] Katzenberg, A.; Angulo, A.; Kusoglu, A.; Modestino, M. Macromolecules 2021, 54, 5187−5195 Figure 1

Correlation of structural and magnetic properties of RFeO3 ( R=Dy,Lu )

In orthoferrites the rare-earth (R) ion has a big impact on structural and magnetic properties; in particular, the ionic size influences the octahedral tilt and the R3+−Fe3+ interaction modifies properties like the spin reorientation. Growth-induced strain in thin films is another means to modify materials properties since the sign of strain affects the bond length and therefore directly the orbital interaction. Our study focuses on epitaxially grown (010)-oriented DyFeO3 and LuFeO3 thin films, thereby investigating the impact of compressive lattice strain on the magnetically active Dy3+ and magnetically inactive Lu3+ compared to uniaxially strained single-crystal DyFeO3. The DyFeO3 films exhibits a shift of more than 20 K in spin-reorientation temperatures, maintain the antiferromagnetic Γ4 phase of the Fe lattice below the spin reorientation, and show double-step hysteresis loops for both in-plane directions between 5 and 390 K. This is the signature of an Fe-spin-induced ferromagnetic Dy3+ lattice above the Néel temperature of the Dy. The observed shift in the film spin reorientation temperatures vs lattice strain is in good agreement with isostatic single-crystal neutron diffraction experiments with a rate of 2 K/kbar. Published by the American Physical Society 2024

Ion-Exchange Doping of Semiconducting Single-Walled Carbon Nanotubes.

Semiconducting single-walled carbon nanotubes (SWCNTs) are a promising thermoelectric material with high power factors after chemical p- or n-doping. Understanding the impact of dopant counterions on charge transport and thermoelectric properties of nanotube networks is essential to further optimize doping methods and to develop better dopants. This work utilizes ion-exchange doping to systematically vary the size of counterions in thin films of small and large diameter, polymer-sorted semiconducting SWCNTs with AuCl3 as the initial p-dopant and investigates the impact of ion size on conductivity, Seebeck coefficients, and power factors. Larger anions are found to correlate with higher electrical conductivities and improved doping stability, while no significant effect on the power factors is found. Importantly, the effect of counterion size on the thermoelectric properties of dense SWCNT networks is not obscured by morphological changes upon doping. The observed trends of carrier mobilities and Seebeck coefficients can be explained by a random resistor model for the nanotube network that accounts for overlapping Coulomb potentials leading to the formation of an impurity band whose depth depends on the carrier density and counterion size. These insights can be applied more broadly to understand the thermoelectric properties of doped percolating disordered systems, including semiconducting polymers.

Self-Propagating Fabrication of a 3D Graphite@rGO Film Anode for High-performance Potassium-Ion Batteries.

Graphite, with abundant resources and low cost, is regarded as a promising anode material for potassium-ion batteries (PIBs). However, because of the large size of potassium ions, the intercalation/deintercalation of potassium between the interlayers of graphite results in its huge volume expansion, leading to poor cycling stability and rate performance. Herein, a self-propagating reduction strategy is adopted to fabricate a flexible, self-supporting 3D porous graphite@reduced graphene oxide (3D-G@rGO) composite film for PIBs. The 3D porous network can not only effectively mitigate the volume expansion in graphite but also provide numerous active sites for potassium storage as well as allow for electrolyte penetration and rapid ion migration. Therefore, compared to the pristine graphite anode, the flexible 3D-G@rGO film electrode exhibits greatly improved K-storage performance with a reversible capacity of 452.8 mAh g-1 at 0.1 C and a capacity retention rate of 80.4% after 100 cycles. It also presents excellent rate capability with a high specific capacity of 139.1 and 94.2 mAh g-1 maintained at 2 and 5 C, respectively. The proposed self-propagating reduction strategy to construct a three-dimensional self-supporting structure is a viable route to improve the structural stability and potassium storage performance of graphite anodes.

Influence of Rare-Earth Doping Content and Type on Phase Transformation and Transport Properties in Highly Doped CeO2.

Rare-earth doped CeO2 materials find extensive application in high-temperature energy conversion devices such as solid oxide fuel cells and electrolyzers. However, understanding the complex relationship between structural and electrical properties, particularly concerning rare-earth ionic size and content, remains a subject of ongoing debate, with conflicting published results. In this study, we have conducted comprehensive long-range and local order structural characterization of Ce1-xLnxO2-x/2 samples (x ≤ 0.6; Ln = La, Nd, Sm, Gd, and Yb) using X-ray and neutron powder diffraction, Raman spectroscopy, and electron diffraction. The increase in the rare-earth dopant content leads to a progressive phase transformation from a disordered fluorite structure to a C-type ordered superstructure, accompanied by reduced ionic conductivity. Samples with low dopant content (x = 0.2) exhibit higher ionic conductivity in Gd3+ and Sm3+ series due to lower lattice cell distortion. Conversely, highly doped samples (x = 0.6) exhibit superior conductivity for larger rare-earth dopant cations. Thermogravimetric analysis confirms increased water uptake and proton conductivity with increasing dopant concentration, while the electronic conductivity remains relatively unaffected, resulting in reduced ionic transport numbers. These findings offer insights into the relationship between transport properties and defect-induced local distortions in rare-earth doped CeO2, suggesting the potential for developing new functional materials with mixed ionic oxide, proton, and electronic conductivity for high-temperature energy systems.

Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7: A novel candidate thermal insulation oxide for high-temperature coatings

A novel high-entropy oxide, Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7, was synthesized via Sol-Gel and high-temperature calcining method. The powder and bulk specimen for Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7 were characterized, and its thermophysical performances were measured. The researching conclusions indicate that the synthesized nano-powder is very pure, and the block specimen has a sole pyrochlore structure, densified microstructure, and uniform distribution of elements. The low thermal conductivity is ascribed to phonon scattering stemmed from the ionic size and atomic mass disorders derived from multi-component addition. The high lattice-energy leads to a relatively low thermal expansion coefficient, which satisfies the demand of thermal barrier coating. The Sm2Gd0.25Dy0.25Er0.25Yb0.25TaO7 oxide also maintains outstanding phase steadiness up to 1200 °C.

Mechanism of overscreening breakdown by molecular-scale electrode surface morphology in asymmetric ionic liquids

The interfacial nature of the electric double layer (EDL) assumes that electrode surface morphology significantly impacts the EDL properties. Since molecular-scale roughness modifies the structure of EDL, it is expected to disturb the overscreening effect and alter differential capacitance (DC). In this paper, we present a model that describes EDL near atomically rough electrodes with account for short-range electrostatic correlations. We provide numerical and analytical solutions for the analysis of conditions for the overscreening breakdown and DC shift estimation. Our findings reveal that electrode surface structure leads to DC decrease and can both break or enhance overscreening depending on the relation of surface roughness to electrostatic correlation length and ion size asymmetry.

Dielectric Boundary Force for the Minimization of the Mean-Field Electrostatic Free-Energy Functional Including the Ionic Size Effect

The generalized Poisson–Boltzmann equation with the uniform ionic size is investigated. In mean-field theory, the ionic size effect is added by modifying the entropy effect of solvent molecules in the electrostatic free-energy functional of ion concentrations. Taking minimization of the mean-field electrostatic free-energy functional including the ionic size effect with respect to the ion concentrations, the minimum free-energy is obtained (see (4.6) in Li [(2009a) “Continuum electrostatics for ionic solutions with non-uniform ionic sizes,” Nonlinearity 22(4), 811–833]. Maximizing the minimum free-energy with respect to the electrostatic potential determines the generalized Poisson–Boltzmann equation. By the definition of shape derivative, the first variation of this minimum free-energy with respect to variation of the dielectric boundary is derived. Thus, the dielectric boundary force of an ionic solution with multiple ionic species with the uniform ionic size is obtained.

Elastic-acoustic, optical and thermoelectric investigation of Cu6AsS5X (X= Br, I) for renewable energy applications

First-principles computations examine the structure, optoelectronic, elastic-acoustic, and thermoelectric characteristics of Cu6AsS5X (X = Br, I). The renowned Perdew – Burke – Ernzerhoff generalized gradient approximation (PBEsol–GGA) was employed to compute the physical and elastic parameters; however, the energy band structure of Cu6AsS5Br and Cu6AsS5I has been more precisely determined by employing the Trans and Blaha technique of the modified Becke-Johnson (TB–mBJ) potential. The lattice constants of Cu6AsS5Br and Cu6AsS5I in the cubic structure increase from 10.24 Å to 10.27 Å as a consequence of an increase in atomic number (ionic size). Several properties are extracted from the computed density of state (DOS) and band structure (BS). The computed values for the gap between the valence and conduction bands indicate that the compounds are semiconducting. These compounds' prominent absorption peaks in the UV energy range suggest that argyrodites can be utilized for optoelectronic (OE) devices operating in this spectral region. The cubic compounds (C11, C12, and C44) elastics constants, as well as different parameters like Kleinman's parameters ζ, Hardness (H), melting temperature (Tm), Lame's constant, Zener anisotropy (A), acoustic behavior and its isotropy, and Poisson ratios (ʋ) are calculated. Furthermore, the thermoelectric properties have been calculated using the BoltzTrap package integrated into WIEN2K. The positive Seebeck coefficient (S), increased electrical conductivity (σ) and low thermal conductivity (k) indicates p-type semiconductors. These compounds' greater Figure of merit (ZT) shows their potential candidacy for thermoelectric applications

Reverse-Selective Anion Separation Relies on Charged "Hourglass" Gate.

According to the hydration size and charge property of separated ions, the transport channel can be constructed to achieve precision ion separation, but the ion geometry as a separation parameter to design the channel structure is rarely reported. Herein, a reverse-selective anion separation membrane composed of a metal-organic frameworks (MOFs) layer with a charged "hourglass" channel as an ion-selective switch to manipulate oxoanion transport is developed. The gate in "hourglass" with tetrahedral geometry similar to the oxoanion (such as SO2- 4, Cr 2O2- 7, and MnO- 4) boosts the transmission effect oxoanion much larger than Cl- through geometric matching and Coulomb interaction. Specific channel structure exhibits an abnormal selectivity for SO2- 4/Cl- of 20, Cr 2O2- 7/Cl- of 6.6, and MnO- 4/Cl- of 4.0 in a binary-ion system. The transfer behavior of SO2- 4 in the channel revealed by molecular dynamics simulation and density functional theory calculation further indicates the mechanism of the abnormal separation performance. The universality of the membrane structure is validated by the formation of different nitrogen-containing modified layers, which also achieves in situ growth of the MOFs layer, and exhibits similar reversal separation performance. The geometric configuration control of ion transport channels presents a novel effective strategy to realize the precise separation of target ions.

Can Aqueous Na2SO4-Based Neutral Electrolyte Increase Energy Density of Monolithic Wood Biochar Electrode Supercapacitor?

The performance of supercapacitors is significantly influenced by both the nature and the concentration of the electrolyte employed. This study investigates the impact of a neutral electrolyte on the electrochemical properties of the maple-derived monolithic wood biochar (MWB)–sodium sulfate (Na2SO4) supercapacitor. The goal is to determine if a neutral electrolyte, in this case Na2SO4, can increase the supercapacitor energy density compared to a previous study employing a KOH electrolyte. Starting from examining the ion sizes and conductivities of salt species in KOH and Na2SO4 electrolytes, the difference in voltage window, measured specific capacitance, and resistance are discussed. By switching the electrolyte from 4 M KOH to 0.5/1 M Na2SO4, the voltage stability window was extended from 0.8 V to 1.4 V. For 1 M Na2SO4, the supercapacitor attains a specific capacitance of 46 F/g at 5 mA/g, accompanied by an energy density of 12.5 Wh/kg and a maximum power density of 300 W/kg. The MWB electrode, derived from naturally abundant wood, when combined with the non-toxic Na2SO4 electrolyte, offers an environmentally friendly and cost-effective energy storage solution. With a prolonged lifetime and minimal maintenance requirements, MWB-Na2SO4 supercapacitors emerge as a promising choice for diverse applications.

Multifaceted anchoring ligands for uniform orientation and enhanced cubic-phase stability of perovskite quantum dots

All-inorganic CsPbI3 perovskite quantum dots (PQDs) hold significant potential for next-generation photovoltaics due to their unique optoelectronic properties, and the surface-bound ligand playing a key role in the stability and functionality of CsPbI3 PQDs. Initially used long-chain ligands in PQDs synthesis stabilize the black phase but hinder charge transport when employed to solar cells, necessitating their replacement with shorter ones. However, this leads to the formation of surface defects and loss of tensile strain, resulting in the transition to the undesired orthorhombic phase (δ-phase) and compromising PQD solar cell performance. Therefore, developing a ligand exchange process that achieves the optimal balance between conductivity and stability in PQD solid films continues to be a significant challenge. To address these issues, we developed an efficient ligand-exchange process utilizing a multifaceted anchoring ligand, 2-thiophenemethylammonium iodide (ThMAI). The larger ionic size of ThMA+ compared to Cs+ facilitates the restoration of surface tensile strain in PQDs, while its thiophene and ammonium groups enable effective passivation of surface defects. Owing to these advantages, ThMAI-treated CsPbI3 PQD thin films exhibit improved carrier lifetime, uniform PQD orientation, and increased ambient stability. As a result, the ThMAI-treated CsPbI3 PQD solar cells demonstrate an improved power conversion efficiency (PCE) of 15.3 % and an enhanced device stability.

Structure Directing Effects of the Tetraphenylphosphonium Cation upon the Formation of Lanthanoid Anilate Coordination Polymers

AbstractFour lanthanoid anilate coordination polymers (CPs) were synthesised using fluoranilate and chloranilate ligands with La(III), Eu(III) and Dy(III), and PPh4+ as the countercation. The presence of the PPh4+ countercation had a structure directing effect on the CP topology, with a 3D diamondoid (dia) network obtained with La(III) whilst 2D square grid (sql) networks were obtained with Eu(III) and Dy(III). This work represents the first use of fluoranilate in lanthanoid anilate CPs. The additional hydrogen bonding sites afforded by the fluorine substituent influences the packing of the crystal structure whilst the variation in lanthanoid ion size helps determine the topology of the CP.

Adsorption–desorption and leaching behavior of benzovindiflupyr in different soil types

Benzovindiflupyr is a succinate dehydrogenase inhibitor fungicide that targets mitochondrial function for disease control. In this study, we investigated the adsorption–desorption and leaching behavior of benzovindiflupyr in eight soil types using the batch equilibrium method and the soil column leaching method. A Freundlich model (r2 > 0.9959) was used to better characterize the adsorption-desorption process in eight soil types, with adsorption coefficients (KF-ads) ranging from 2.303 to 17.886. KF-ads was significantly and positively correlated (p < 0.05) with the organic carbon content. High temperatures and increased initial pH of aqueous solutions led to a decrease in benzovindiflupyr adsorption in the soil. The adsorption was also influenced by factors such as ionic strength, humic acid, surfactant type, microplastic type, and particle size and concentration. Moreover, benzovindiflupyr exhibited low leachability in all four soils selected, but different leaching solutions affected the risk of benzovindiflupyr migration to groundwater. Overall, this study provides insights into the adsorption characteristics of benzovindiflupyr in different soils and provides key information for environmental risk assessment.

Standard partial molar volumes of single aqueous ions composing ionic liquids. Measurement and evaluation of temperature dependent values. Parsing and LSER correlation with molecular descriptors based on DFT/COSMO approach

The densities of highly dilute aqueous solutions (m < 0.2 mol·kg−1) of 50 common ionic liquids (ILs) or related salts were accurately measured at seven equidistant temperatures in the range of (288.15 to 318.15) K and ambient pressure. The examined set of ILs/salts composed of 31 ions was judiciously selected to cover wide ranges of ion sizes and chemical structures and allow reliable evaluation of ionic contributions. The data were duly analyzed to infer related thermodynamic properties and information on the behavior of these systems on a molecular level. Appropriate means of mathematical statistics were used to estimate data uncertainties, assign weights to data correlations, and judge the significance of the results obtained. The standard partial molar volumes V¯∞ of the ILs/salts at infinite dilution were evaluated through fitting the concentration dependence of respective apparent molar volumes to Redlich-Meyer equation and their temperature dependence was correlated to quadratic polynomial. The data presented were compared whenever possible with those available in the literature; good agreement was often found, although some data from the literature were also considerably dispersed or in error. Standard partial molar volumes of ILs/salts obeying ionic additivity were split by least-squares optimization into temperature-dependent single-ion values based on the Conway-Millero extrathermodynamic assumption. The ionic additivity of BV parameter was also identified. Its magnitude for anions is typically greater than that for cations, supporting the fact that an anion dominates the volumetric behavior of aqueous ILs. As the BV,anion and the second temperature derivative ∂2V¯anion∞/∂T2 were found to correlate, the two solute’s water structure making/breaking ability indicators appear to speak consistently. Enhanced values of standard partial molar expansion were observed for both strongly kosmotropic and chaotropic anions and a plausible explanation of this phenomenon was suggested. To correlate and analyze the effect of ionic structure on V¯ion,298∞, Linear Solvation Energy Relationship (LSER) methodology with the recently proposed four quantum chemistry computed descriptors based on DFT/COSMO approach was employed providing excellent fit (SD = 2.48 cm3·mol−1, R2 = 0.9996).

Study on the adsorption mechanism of fluorescent nano-tracer in sandstone core

Chemical tracer testing technology has increasingly become the preferred method for reservoir monitoring in oil fields due to its low cost and high efficiency. Understanding the migration behavior and adsorption mechanisms of chemical tracers in porous media is crucial for designing tracer injection processes and enhancing the accuracy of tracer test interpretation. This study employs an enhanced Stöber sol-gel method to synthesize fluorescent silica nanoparticles. After surface modification with the silane coupling agent γ-(methacryloyloxy) propyltrimethoxysilane (KH570) and doping with two fluorescent dyes, a multicolor fluorescent nano-tracer (PMFN) was synthesized. This study conducted dynamic and equilibrium adsorption experiments to investigate the adsorption behavior of PMFN on sandstone surfaces. To elucidate the adsorption mechanism of PMFN, we fitted the adsorption equilibrium experimental data using the Langmuir, Freundlich, and Temkin isothermal adsorption models. The adsorption kinetics were studied using the Lagergren, Elovich, and pseudo-first-order kinetic models. Additionally, we assessed the influence of ionic strength and particle size on the adsorption of PMFN by calculating the DLVO interaction forces between PMFN and the sandstone surface. The results showed that PMFN adsorption on sandstone primarily occurs in the pre-contact stage and is characterized by monolayer adsorption. When the ionic strength of the solution is 0.001 mol/L, the maximum repulsive energy barrier between PMFN and the sandstone surface hinders adsorption.

Enhanced Hydrogen Production in Microwave‐Driven Water‐Splitting Redox Cycles by Engineering Ceria Properties

AbstractSustainable hydrogen, produced from renewable sources such as solar or wind, plays a decisive role in driving industrial decarbonization. Among hydrogen production technologies, steam electrolysis, and solar‐driven thermochemical cycles using reducible solid oxides show promise but face challenges due to high operation temperatures. Microwave‐driven redox chemical looping enables the direct, contactless electrification of the process, reducing the operation temperature and complexity. Previous works showed that microwaves can efficiently drive reduction/water‐splitting cycles using Gd‐doped ceria at low temperatures (&lt;250 °C), but adjustment of material properties is needed. Here, the key properties of materials are explored that affect the redox mechanism by screening a series of doped ceria materials to enhance microwave‐driven hydrogen production. Evaluation of trivalent dopants (La3+, Gd3+, Y3+, Yb3+, Er3+, and Nd3+) reveals that reduction correlates with lattice and electronic properties. The composition Ce0.9La0.1O2‐δ achieves 1.41 mL g−1, the highest hydrogen production among the studied series. Its narrower bandgap allows for reaching higher conductivity upon microwave‐driven reduction at lower temperatures, while a larger ionic lattice size boosts solid‐state oxygen diffusion. Overall, this research remarks on the critical properties of ceria‐based materials that enhance hydrogen production in microwave‐driven water‐splitting cycles, supporting the design of more efficient materials for sustainable chemical production technology.