Abstract Traditional microemulsions are ubiquitous nanostructured liquids stabilized by high surfactant concentrations that can be a significant drawback. Here, we show that surfactant-free microemulsions can be formulated when amphiphilicity is incorporated directly into a protic ionic liquid solvent. Using combined high-resolution X-ray and neutron scattering with isotopic labeling, we show that an amphiphilic ionic liquid, propylammonium nitrate, functions both as a polar solvent and hydrotrope, generating polar–apolar nanostructured domains without a conventional surfactant monolayer. In contrast, a non-amphiphilic ionic liquid, ethanolammonium nitrate, simply acts as a polar solvent, driving solvophobic segregation in purely non-aqueous mixtures. The balance between Coulomb interactions, hydrogen bonding, and amphiphilicity determines domain structure and phase coexistence. These results show that cation amphiphilicity is the molecular parameter that controls the nanostructure and phase behavior in surfactant-free microemulsions. This behavior is expected to apply to systems in which amphiphilicity is embedded within the solvent.

Bulk measurements obscure critical microscopic variations, limiting the mechanistic understanding of complex electrocatalyst interfaces central to sustainability technologies. Although emerging single-particle techniques address ensemble averaging, they focus on catalyst structure, reactant adsorption or special model reactions, and cannot quantify turnover rates of practical electrocatalytic reactions. Here we report domino-reaction-enabled label-free imaging for nanoscopic electrocatalysis (DELINE), enabling subparticle, single-turnover imaging of surface water dissociation under operando conditions. DELINE decouples size–structure effects in electrocatalysts, reveals unexpected heterogeneity in Volmer transition states and uncovers strong coupling between charge-transfer coefficient and exchange velocity. Using DELINE imaging, we provide evidence of a compensation rule in electrocatalysis, akin to Meyer–Neldel behaviour. Cost-effective and high-throughput, DELINE quantifies key activity descriptors at single-particle/subparticle levels under realistic conditions, bridging the theory–experiment gap and accelerating catalyst screening. Understanding nanoscale heterogeneity in electrocatalytic reactions is critical for advancing catalyst design and performance. Now, a single-turnover imaging technique with subparticle resolution, DELINE, is introduced, which enables the mapping of electrocatalytic reactions and is used to probe surface water dissociation.

This study examines three choline-based ionic liquids-choline glycinate, choline phosphate, and choline acetate-as catalysts for poly(ethylene terephthalate) (PET) depolymerization under conventional and microwave heating. Choline glycinate maintained 88-90% PET conversion across both heating methods through its dual-functionality hydrogen bonding network. Choline phosphate and acetate showed method-dependent performance: 90% conversion under conventional heating versus 45-60% under microwave conditions due to viscosity and bonding limitations. All three ionic liquids tolerated up to 30 wt % water under conventional heating and 10 wt % under microwave heating, eliminating dehydration requirements. The heating method controlled product selectivity: conventional heating produced terephthalic acid exclusively, while microwave conditions yielded mixed terephthalic acid and bis(2-hydroxyethyl) terephthalate potentially through water nanodroplets creating localized hotspots. Ionic liquid basicity controls conversion efficiency while heating rate determines product distribution. These results provide a framework for designing rapid, predictable PET recycling processes using biocompatible catalysts.

Salt-in-ionic liquids (SiILs) are promising electrolytes for batteries. This study reveals how water affects the nanostructure, surface forces, and electrochemical properties of sodium-SiILs with bis(trifluoromethanesulfonyl)imide ([TFSI]-) using experiments and molecular dynamics simulations. Dry sodium-SiILs exhibit long-range repulsive forces that deviate from classical electrostatics and are influenced by surface-induced aggregation of nanoscale ionic clusters. Addition of water reduces cluster size and order, yielding force profiles more similar to neat ILs. Atomic force microscopy shows water-induced cluster reorganization near negatively charged surfaces. Water-in-SiILs exhibit increased capacitance and a shift from camel- to bell-shaped profiles, indicating a fundamental change in the double layer, while enhancing conductivity and maintaining a wide electrochemical stability window. These findings underscore the sensitivity of the SiIL nanostructure to hydration from bulk to interface and its critical role in electrochemical properties. Advances in the understanding of the interplay between the nanostructure and screening are essential for the rational design of the solid electrolyte interphase, a crucial component dictating battery performance and safety.

Polyoxometalate-ionic liquids (POM-ILs) show promise for catalysis and energy storage, but how molecular structure controls nanostructure remains unclear. This study uses small-angle X-ray scattering to examine how POM geometry and cation chain length affect self-assembly in four systems combining Keggin ([SiW11O39]8-) or Dawson ([P2W18O62]6-) polyoxometalates with tetraoctylammonium (Q8+) or hexadecyltributylphosphonium (Q16+) cations. Keggin-Q8 remained solid because the high POM charge density (-8) overwhelms the limited disorder imparted by the octyl chains. Dawson-Q8 formed a liquid with a 22.1 Å spacing, matching simple volume-fraction packing. Both Q16 systems produced liquids with an amphiphilic nanostructure. The repeat spacings of Dawson-Q16 (34.5 Å) and Keggin-Q16 (28.5 Å) exceed volume-fraction predictions by 75% and 45%, respectively, due to solvophobic self-assembly into polar/apolar domains. These results demonstrate that the POM charge density and cation chain length control liquid formation and the nanostructure.

Advancements in aluminium-ion batteries require new non-corrosive electrolytes with high oxidation stability. Recently, haloaluminate-free electrolytes based on Al(OTF) 3 and Al(TFSI) 3 salts have attracted interest for aluminum electrochemistry; nevertheless, reversible Al 0/3+ cycling in these systems remains debated. This work reveals that Al 0 electrodeposition universally fails in Al(OTF) 3 and Al(TFSI) 3 based ionic liquid electrolytes because Al 3+ spontaneously extracts F - from anion and OH - from residual water, forming tightly bound tetrahedral complexes. Energy calculations show that deprotonation of coordinated water requires far less energy than Al 3+ desolvation, explaining why hydrogen evolution dominates. Even rigorous vacuum drying and LiAlH 4 addition cannot eliminate residual water from these hygroscopic salts. These findings provide a fresh perspective on aluminium electrolyte design, emphasizing ligand stability as a prerequisite for diversifying reaction towards Al 3+ desolvation and electroplating over parasitic processes.

Small-angle X-ray scattering is used to investigate how cation and diluent control nanostructure and swelling in bis-2,2 '-ethylhexylsulfosuccinate (AOT) surface-active ionic liquids (SAILs). Alkylammonium and alkylmethylimidazolium AOT salts form sponge-like liquids with curved amphiphilic bilayers whose periodicity and order depend on cation chain length and branching, and on cation head group. Increasing chain length is consistent with a transition from cations segregated in polar domains towards intercalation within the bilayer. Water dilution enhances intercalation, yielding highly swellable sponge and bilayer-based lyotropic mesophases. In contrast, dilution with the ionic liquid ethylammonium nitrate favours cation partitioning into the polar domains, which alters swelling and favours long-range composition fluctuations. These results establish the molecular parameters for designing nanostructured SAILs.

Hypothesis: The addition of water to a non-ionic N-oxide deep eutectic solvent (DES) composed of phenylacetic acid (PhAA) and N-dodecylmorpholine-N-oxide (MO-12) in a 1:1 M ratio (PhAA/MO-12) will promote interfacial nanostructure formation due to increased proton transfer and solvophobic interactions, leading to reduced friction. Experiments: The interfacial structure and friction of PhAA/MO-12 with water content up to 41.9 wt% were investigated at mica surfaces. Atomic force microscopy (AFM) was used to measure normal force-separation profiles, lateral images, and nanoscale friction. Findings: Conductivity increases over twentyfold with the addition of 23.6 wt% water. AFM force curves reveal that increasing water content in PhAA/MO-12 leads to a more pronounced interfacial structure with steps extending further into the bulk. High-resolution near-surface images show a well-defined sponge-like nanostructure at 23.6 wt% water, which is absent in the neat DES. The enhanced nanostructure is attributed to increased proton transfer from PhAA to MO-12 and segregation of polar and apolar domains driven by water strengthened solvophobic interactions. Friction reduces up to 72 % for >= 7.0 wt% water compared to the neat DES, due to a more robust boundary layer facilitated by water.

Hypothesis The friction and interfacial nanostructure of a water-in-surface-active ionic liquid mixture, 1.6 M 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate ([BMIm][AOT]), can be tuned by applying potential on Au(1 1 1) and stainless steel. Experimental Atomic force microscopy (AFM) was used to examine the friction and interfacial nanostructure of 1.6 M [BMIm][AOT] on Au(1 1 1) and stainless steel at different potentials. Findings Superlubricity (vanishing friction) is observed for both surfaces at OCP+1.0 V up to a surface-dependent critical normal force due to [AOT](-) bilayers adsorbing strongly to the positively charged surface thus allowing AFM tip to slide over solution-facing hydrated anion charged groups. High-resolution AFM imaging reveals ripple-like features within near-surface layers, with the smallest amplitudes at OCP+1 V, indicating the highest structural stability and resistance to thermal fluctuations due to highly ordered boundary [AOT](-) bilayers templating robust near-surface layers. Exceeding the critical normal force at OCP+1.0 V causes the AFM tip to penetrate the hydrated [AOT](-) layer and slide over alkyl chains, increasing friction. At OCP and OCP-1.0 V, higher friction correlates with more pronounced ripples, attributed to the rougher templating [BMIm](+) boundary layer. Kinetic experiments show that switching from OCP-1.0 V to OCP+1.0 V achieves superlubricity within 15 s, enabling real-time friction control.

High-resolution atomic force microscopy (AFM) images reveal that anion size systematically controls the dimensions of cation Wigner crystal-like structures (WCLS) at silica-electrolyte interfaces. Calcium halide solutions (CaCl2, CaBr2, CaI2) at pH 10.5 form hexagonally close-packed Ca2+ structures with spacings of 3.6-3.8 Å (CaCl2), 4.8 Å (CaBr2), and 5.0-5.1 Å (CaI2). The CaCl2 spacing matches the Cl- diameter, suggesting direct Ca2+-Cl- contact, whereas Br- and I- systems show consistent 0.7-0.9 Å offsets above their ionic diameters, indicating partially hydrated states. This behavior reflects the balance between ionic charge density and hydration effects. The high charge density of Cl- enables strong Ca2+ interactions sufficient to displace hydration waters, while the lower charge densities of Br- and I- lead to less strong attractions with Ca2+ and partial hydration layers are preserved. These findings demonstrate how ion size and hydration control Stern layer ion organization, providing new insights into the electrical double layer structure.

HYPOTHESIS:Diluting the surface-active ionic liquid 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (BMIM AOT) with the non-solvating diluent 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE) will reduce viscosity while preserving essential nanostructures and electrochemical properties, creating locally concentrated ionic liquids (LCILs) suitable for energy storage applications. EXPERIMENTS:BMIM AOT:TFTFE mixtures at 2:1, 1:1, and 1:2 weight ratios were investigated using rheological measurements, conductivity analysis, cyclic voltammetry, electrochemical impedance spectroscopy, small- and wide-angle X-ray scattering (S/WAXS), and atomic force microscopy (AFM). FINDINGS:TFTFE addition at 1:1 weight ratio reduced BMIM AOT viscosity by 99 % and increased conductivity by over one order of magnitude while maintaining electrochemical stability (>4 V). S/WAXS revealed preservation of characteristic sponge-like nanostructures in the bulk for all BMIM AOT:TFTFE mixtures investigated. Differential capacitance measurements showed enhanced charge storage capabilities, with maximum performance at 1:1 ratio due to improved ion mobility. AFM showed that TFTFE enhances solvophobic segregation at neutral interfaces but reduces interfacial nanostructures at charged surfaces. These findings reveal that SAIL-based LCILs achieve optimal balance between low viscosity and stable nanostructures, making them promising electrolytes for energy storage devices requiring fast charge-discharge rates and electrochemical stability.

Ionic liquid (IL) dynamics at solid interfaces dictate their electrochemical performance. Experimental and computational advances reveal that interfacial IL diffusion is orders of magnitude slower than in bulk, varies with surface potential, geometry and chemistry, and exhibits exceptionally slow structural relaxation. Most recently, experimental breakthroughs have enabled direct visualization of interfacial nanostructure dynamics through video-rate AFM. Parallel advances in computational methods provide molecular-level insights into potential-dependent ion redistribution and charging dynamics. We propose that coupling real-time in situ visualization with methods offering dynamic compositional information will reveal the interplay between nanostructure and chemical processes at IL/solid interfaces. Understanding this behavior holds the key to designing high-performance electrochemical systems.

IL-doped alkali-metal salts, commonly known as salt-in-ionic liquids (SiILs), have drawn attention over recent years as electrolytes in batteries. SiILs are a class of highly concentrated, strongly correlated, and asymmetric electrolytes, with low volatility, low flammability, and extraordinary thermal and chemical stability. It has been reported that the transference numbers of alkali metals are negative in Li-based SiILs when the mole fraction of Li+ is low. This behavior can be explained by the formation of negatively charged ionic clusters composed of alkali metal cations and anions. On the other hand, MD simulations have also suggested a different ionic arrangement under high concentrations of salts, where a percolated ionic network can form, leading to positive transference numbers of metal cations. In this work, we have focused on the interfacial structure and behavior of Na-based SiILs on charged surfaces. Sodium trifluoromethanesulfonimide (NaTFSI) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) have been selected as the alkali-metal salt and the IL, respectively, and systematically mixed at different molar ratios. An extended Surface Forces Apparatus (eSFA) and Atomic Force Microscopy (AFM) were employed for probing structural features such as the arrangement and layering of ions at charged surfaces, while Wide Angle X-ray Scattering (WAXS) was used to explore the bulk structure of the SiILs. The effect of water as an additive to SiILs, so called water-in-salt-in-ionic liquids (WiSILs) has also been investigated, as an additional component to tune nanostructure ionic mobility, and interfacial interactions. By understanding the properties of electric double layer (EDL) and the formation of solid electrolyte interface (SEI), we aim to provide insights to design materials for the next-generation batteries beyond Li-based chemistries to improve energy resilience.

HYPOTHESIS:We postulate that the amphiphilic nanostructure of ionic liquids, consisting of interpenetrating networks of polar and apolar domains, may enable them to support distinct self-assembled organogel-like and hydrogel-like structures. EXPERIMENTS:The structures of gels formed by the low molecular weight gelator 12-hydroxystearic acid (12HSA) and its ammonium salts have been investigated from the molecular to the microscale by a combination of powder X-ray diffraction, SAXS/WAXS, FTIR, CD, and optical microscopy, together with rheological characterisation of the gels formed. FINDINGS:12HSA is shown to form long-lived ionogels in ethylammonium and propylammonium nitrate ionic liquids at low concentrations via two distinct mechanisms; supramolecular, hydrogen-bond driven aggregation of the acid and amphiphilic assembly of the conjugate base. 12HSA gel structures were shown to consist of high aspect-ratio twisted crystalline fibrils assembled from H-bonded dimers, similar to organogels, while 12HS salts form an elongated rectangular ribbon of solvophobically-associated lamellar stacks with an opposite twist to the acid form. Partial neutralisation of 12HSA gels with base can generate coexisting mixtures of both types of gel in these ILs.

HYPOTHESIS:Water-in-salt electrolytes (WiSEs) are safer alternatives to organic electrolytes in lithium-ion batteries. While surfactants have been proposed as performance enhancing additives, their self-assembly behaviour in these concentrated systems is completely unknown. We hypothesise that ionic surfactants can form micelles in WiSEs with their structure dependent on salt type, salt-to-surfactant ratio, and temperature. EXPERIMENTS:The self-assembly of dodecyltrimethylammonium bromide (DTAB) in various WiSEs was investigated using small-angle neutron scattering. We examined systems containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium nitrate (LiNO3), or sodium nitrate (NaNO3) across various salt-to-surfactant ratios and temperatures (25-80 °C). FINDINGS:The surfactant DTAB forms micelles in all WiSEs studied, persisting at salt concentrations far beyond those in conventional aqueous solutions. In LiTFSI WiSEs, salt concentration determines micelle structure. Hydrophobic TFSI- counterions screen the micelle surface at 5 mol/kg, forming elongated micelles, while at ≥8 mol/kg they intercalate between headgroups, producing globular micelles. At certain high salt/low surfactant compositions, traditional micelles do not form. Instead, small, disordered clusters are formed that are further enhanced at elevated temperatures. In contrast, hydrophilic NO3- counterions (LiNO3 and NaNO3 systems) maintain near identical morphologies regardless of salt concentration, though co-ion type strongly affects morphology. Na+ produces well-defined wormlike micelles while Li+ causes instability, resulting in highly polydisperse assemblies. These findings provide a platform for enhancing WiSEs through protective electrode interfaces that further reduce water activity, inhibit lithium dendrite formation, and control ion transport. This work also advances fundamental understanding of surfactant self-assembly in concentrated electrolytes and in nanostructured fluids.

Mixed-cation ILs containing P1444+ significantly improve sodium cycling stability, revealed through in situ techniques studying interfacial nano-structuring.

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an RNA-binding protein containing low-complexity domains (LCDs), which are known to regulate protein behavior under stress conditions. This study demonstrates the ability to control hnRNPK’s transitions into four distinct material states—monomer, soluble aggregate, liquid droplet, and fibrillar hydrogel—by modulating environmental factors such as temperature and protein concentration. Importantly, the phase-separated and hydrogel states are newly identified for eGFP-hnRNPK, marking a significant advancement in understanding its material properties. A combination of biophysical techniques, including DLS and SEC-LS, were used to further characterize hnRNPK in monomeric and soluble aggregate states. Structural methods, such as SANS, SAXS, and TEM, revealed the elongated morphology of the hnRNPK monomer. Environmental perturbations, such as decreased temperature or crowding agents, drove hnRNPK into phase-separated or gel-like states, each with distinct biophysical characteristics. These novel states were further analyzed using SEM, X-ray diffraction, and fluorescence microscopy. Collectively, these results demonstrate the complex behaviors of hnRNPK under different conditions and illustrate the properties of the protein in each material state. Transitions of hnRNPK upon condition changes could potentially affect functions of hnRNPK, playing a significant role in regulation of hnRNPK-involved processes in the cell.