Efficient and long-lasting electrocatalysts are one of the key factors in determining their large-scale commercial viability. Although the fundamentals of deactivation and regeneration of electrocatalysts are crucial for understanding and sustaining durable activity, little has been conducted on metalloids compared to metal-derived ones. Herein, by virtue of in situ seconds-resolved X-ray absorption spectroscopy, we discovered the chemical evolution during the deactivation-regeneration cycles of tellurium clusters supported by nitrogen-doped carbon (termed Te-ACs@NC) as a high-performance electrocatalyst in the hydrogen evolution reaction (HER). Through in situ electrochemical reduction, Te-ACs@NC, which had been deactivated due to surface phase transitions in a previous HER process, was reactivated and regenerated for the next run, where partially oxidized Te was found, surprisingly, to perform better than its nonoxidized state. After 10 consecutive deactivation-regeneration cycles over 480 h, the Te-ACs@NC retained 85% of its initial catalytic activity. Theoretical studies suggest that local oxidation modulates the electronic distribution within individual Te clusters to optimize the adsorption energy of water molecules and reduce dissociation energy. This study provides fundamental insights into the rarely explored metalloid cluster catalysts during deactivation and regeneration and will assist in the future design and development of supported catalysts with high activity and long durability.

Polyelectrolyte porous membranes (PPMs) have numerous applications in modern science and technology. Here, we describe a new platform for creating multifunctional supramolecular PPMs (SPPMs) by cross-linking of single-component homopoly(ionic liquid)s (PILs) containing hydrophilic anions (Br^–, MBr_y^–, M = Sn, Pb, Sb, Bi) with H₂O molecules. With a range of experimental evidence and support from theoretical calculations, we show that the porous architecture is formed by H₂O molecules-induced phase separation of the polycationic moieties of the homo-PILs between their polar and apolar domains, which are cross-linked together by multiple hydrogen (H)-bonding interactions. Furthermore, we discover these SPPMs show reversible, dynamic, wide-range color tuning, depending on the excitation wavelength, as well as ultrasensitive color change toward humidity and temperature stimuli, endowing them with great promise in color-on-demand applications. These findings, together with the scalable and green synthetic approach, bode well for advanced membrane materials and color-on-demand applications based upon such SPPM systems.

Understanding the reconstruction of surface sites is crucial for gaining insights into the true active sites and catalytic mechanisms. While extensive research has been conducted on reconstruction behaviors of atomically dispersed metallic catalytic sites, limited attention has been paid to non-metallic ones despite their potential catalytic activity comparable or even superior to their noble-metal counterpart. Herein, we report a carbonaceous, atomically dispersed non-metallic selenium catalyst that displayed exceptional catalytic activity in the hydrazine oxidation reaction (HzOR) in alkaline media, outperforming the noble-metal Pt catalysts. In situ X-ray absorption spectroscopy (XAS) and Fourier transform infrared spectroscopy revealed that the pristine SeC₄ site pre-adsorbs an ∗OH ligand, followed by HzOR occurring on the other side of the OH–SeC₄. Theoretical calculations proposed that the pre-adsorbed ∗OH group pulls electrons from the Se site, resulting in a more positively charged Se and a higher polarity of Se–C bonds, thereby enhancing surface reactivity toward HzO/R.

Solvent free ionic liquid (IL) electrolytes facilitate high-voltage supercapacitors with enhanced energy density, but their complex ion arrangement and through that the electrochemical properties, are limited by strong Coulombic ordering in the bulk state and like-charged ion repulsion at electrified interfaces. Herein, a unique interfacial phenomenon resulting from the presence of carbon dioxide loaded in 1-Ethyl-3-methylimidazoliumtetrafluorborate electrolyte that simultaneously couples to IL ions and nitrogen-doped carbonaceous electrode is reported. The adsorbed CO₂ molecule polarizes and mitigates the electrostatic repulsion among like-charged ions near the electrified interface, leading to an ion “bridge effect” with increased interfacial ionic density and significantly enhanced charge storage capability. The unpolarized CO₂ possessing a large quadrupole moment further reduces ion coupling, resulting in higher conductivity of the bulk IL and improved rate capability of the supercapacitor. This work demonstrates polarization-controlled like-charge attraction at IL–electrode–gas three-phase boundaries, providing insights into manipulating complex interfacial ion ordering with small polar molecule mediators. 

Tremendous efforts have been devoted to exploiting synthetic wet adhesives for real-life applications. However, developing low-cost, robust, and multifunctional wet adhesive materials remains a considerable challenge. Herein, a wet adhesive composed of a single-component poly(ionic liquid) (PIL) that enables fast and robust underwater adhesion is reported. The PIL adhesive film possesses excellent stretchability and flexibility, enabling its anchoring on target substrates regardless of deformation and water scouring. Surface force measurements show the PIL can achieve a maximum adhesion of 56.7 mN·m^–1 on diverse substrates (both hydrophilic and hydrophobic substrates) in aqueous media, within ∼30 s after being applied. The adhesion mechanisms of the PIL were revealed via the force measurements, and its robust wet adhesive capacity was ascribed to the synergy of different non-covalent interactions, such as of hydrogen bonding, cation−π, electrostatic, and van der Waals interactions. Surprisingly, this PIL adhesive film exhibited impressive underwater sound absorption capacity. The absorption coefficient of a 0.7 mm-thick PIL film to 4–30 kHz sound waves could be as high as 0.80–0.92. This work reports a multifunctional PIL wet adhesive that has promising applications in many areas and provides deep insights into interfacial interaction mechanisms underlying the wet adhesion capability of PILs. 

The role of N-heterocyclic carbene, a well-known reactive site, in chemical catalysis has long been studied. However, its unique binding and electron-donating properties have barely been explored in other research areas, such as metal capture. Herein, we report the design and preparation of a poly(ionic liquid)-derived porous organic polycarbene adsorbent with superior gold-capturing capability. With carbene sites in the porous network as the “nanotrap”, it exhibits an ultrahigh gold recovery capacity of 2.09 g/g. In-depth exploration of a complex metal ion environment in an electronic waste-extraction solution indicates that the polycarbene adsorbent possesses a significant gold recovery efficiency of 99.8%. X-ray photoelectron spectroscopy along with nuclear magnetic resonance spectroscopy reveals that the high performance of the polycarbene adsorbent results from the formation of robust metal-carbene bonds plus the ability to reduce nearby gold ions into nanoparticles. Density functional theory calculations indicate that energetically favourable multinuclear Au binding enhances adsorption as clusters. Life cycle assessment and cost analysis indicate that the synthesis of polycarbene adsorbents has potential for application in industrial-scale productions. These results reveal the potential to apply carbene chemistry to materials science and highlight porous organic polycarbene as a promising new material for precious metal recovery.

Ionic liquid (IL) materials are promising electrolytes with striking physicochemical properties for energy and environmental applications. Heterogeneous structures and transport quantities of ILs are intrinsically intercorrelated and span multiple spatiotemporal scales. Multiscale modeling methodology unifying theoretical calculations, atomistic, and coarse-grained simulations based on successive coarse-graining schemes is an efficient approach to explore complex phase behaviors of these ion-containing materials at extended spatiotemporal scales with a modest computational cost. In this chapter, we will provide several examples concentrated on tetraalkylphosphonium and imidazolium ILs showing how to sketch an effective modeling protocol to obtain force field parameters derived at high-resolution scales being transferred to low-resolution levels in a self-consistent computational scheme using a bottom-up approach bridging different length and time scales. Concluding remarks and an outlook on multiscale strategies in understanding and predictive capabilities of ILs and their mixtures are addressed in the final section to highlight future challenges and opportunities associated with IL materials in multiscale modeling community.

There is a growing interest in sustainable and high performance supercapacitors (SCs) operating at elevated temperatures as they are highly demanded in heat-durable electronics. Here, we present a biomass-derived nonfluorinated ionic liquid (IL) [P₄₄₄₄][HFuA] and its structural analogue [P₄₄₄₄][TpA] as electrolytes for supercapacitors comprising multiwall carbon nanotubes and activated charcoal (MWCNTs/AC) mixed carbon composite electrodes. A detailed investigation of the effect of scan rate, temperature, potential window and orientation of ions on the electrodes surfaces is performed. The supercapacitors exhibited relatively lower specific capacitance for both [P₄₄₄₄][HFuA] and [P₄₄₄₄][TpA] ILs at room temperature. However, the specific capacitance has significantly increased with an increase in temperature and potential window. The equivalent serie resistances of the SCs is deceased with increasing temperatures, which is a result of improved ionic conductivities of the IL electrolytes. In CV cycling at 60 °C, the capacitor with [P₄₄₄₄][HFuA] IL-based electrolyte retained about 90% of its initial capacitance, while the capacitor with [P₄₄₄₄][TpA] IL-based electrolyte retained about 83% of its initial capacitance. Atomistic computations revealed that the aromatic [FuA]⁻ and [TpA]⁻ anions displayed perpendicular distribution that can effectively neutralize charges on the carbon surfaces. However, the [HFuA]⁻ anion exhibited somewhat tilted configurations on the carbon electrode surfaces, contributing to their outstanding capacitive performance in electrochemical devices.

Liquid solutions and mixtures are part of our everyday lives and also important for their chemical and industrial applications. While considered fairly unattractive substances when kept in bottles and containers, their behavior as molecules can be completely the opposite, continuously attracting scientists to explain it better. Very strong repulsive and attractive interactions between the molecules can create most intriguing local structures, aggregates and complexes, whose spatial organization is often difficult to rationalize. Also, the same mixture can behave completely differently depending on the composition ratio, affecting strongly its macroscopic properties. To gain insight into the complex world of binary liquid mixtures, deep eutectic solvents and ionic liquid systems, combined theoretical and experimental studies are necessary. In this chapter we introduce the methodology of computer simulations and illustrate with several examples of the often-unexpected behavior of many liquid mixtures. 

Nanofiltration (NF) membranes are playing increasingly crucial roles in addressing emerging environmental challenges by precise separation, yet understanding of the selective transport mechanism is still limited. In this work, the underlying mechanisms governing precise selectivity of the polyamide NF membrane were elucidated using a series of monovalent cations with minor hydrated radius difference. The observed selectivity of a single cation was neither correlated with the hydrated radius nor hydration energy, which could not be explained by the widely accepted NF model or ion dehydration theory. Herein, we employed an Arrhenius approach combined with Monte Carlo simulation to unravel that the transmembrane process of the cation would be dominated by its pairing anion, if the anion has a greater transmembrane energy barrier, due to the constraint of anion–cation coupling transport. Molecular dynamics simulations further revealed that the distinct hydration structure was the primary origin of the energy barrier difference of cations. The cation having a larger incompressible structure after partial dehydration through subnanopores would induce a more significant ion–membrane interaction and consequently a higher energy barrier. Moreover, to validate our proposed mechanisms, a membrane grafting modification toward enlarging the energy barrier difference of dominant ions achieved a 3-fold enhancement in ion separation efficiency. Our work provides insights into the precise separation of ionic species by NF membranes.