Multinuclear (1H, 31P, and 7Li) NMR was applied to understand the ion dynamics in silica-based iongels with a fluorine-free ionic liquid (IL), tetrabutylphosphonium 2-2-(2-methoxyethoxy)ethoxy acetate, [P4,4,4,4][MEEA], doped with 10 and 30 mol % of LiMEEA. The results were compared with bulk [P4,4,4,4][MEEA]/LiMEEA electrolytes and those confined in the “hard” silica matrix of a porous glass. It was found that lithium ion (Li+) local dynamics and Li+ diffusion coefficients are strongly affected by confinements in an iongel and in the porous glass, as was revealed from the analysis of NMR parameters, such as diffusion decays (DDs) in 7Li PFG NMR spectra, broadening of the 7Li NMR resonance lines and variations in the 31P and 7Li chemical shifts. However, NMR diffusometry data does suggest that the studied electrolytes in the iongel confinement yet have properties like bulk electrolytes: (i) high ion diffusivities, (ii) weak alterations of Vogel-Fulcher-Tammann (VFT) parameters for diffusion; and (iii) high transport numbers of ions. The diffusion coefficients of the [MEEA]- anion and the [P4,4,4,4]+ cation are comparable in the bulk, while they are significantly different in the iongels: The specific interactions of the [P4,4,4,4]+ cations with the negatively charged silica matrix slowed down diffusivities of the cations, while almost no effect of the matrix on diffusivities of the [MEEA]- anions was noticed. It was also found that the tortuosity of the iongel channels has a negligible effect on diffusivities of ions. The lithium complexation or/and solvation shells of Li+ ions remained unaffected. Thus, the ionic liquid-based iongel electrolyte acquired the advantages of a semi-solid phase and offered transport properties of a liquid electrolyte. 

Driven by the potential applications of ionic liquid (IL) flow for charging graphene-based surfaces in many emerging technologies, recent research efforts have focused on understanding ion dynamics and structuring at IL–graphene interfaces. Here, graphene colloid probe (GrP) atomic force microscopy (AFM) was used to probe the dynamics and ion structuring of 1-butyl-3-methylimidazolium tetrafluoroborate at graphene surfaces under various bias voltages. In particular, the AFM-measured nanofriction provides a good measure of the dynamic properties of the ILs at graphene surfaces. Compared with the IL at the unbiased graphene surface (0 V), the charged graphene surfaces with either negative (–1, –2 V) or positive (+1, +2 V) voltages favor a reduction in the friction coefficient by the IL. A higher magnitude of the bias voltage applied on the graphene surface with either sign (–2 or +2 V) results in a smaller friction coefficient than that at –1 and +1 V. In combination with the AFM-probed contact stiffness, adhesion forces, and ion structuring force curves with an ion orientational distribution according to molecular dynamics (MD) simulations, we discovered that the unbiased graphene surface (0 V) possesses randomly structured IL ions and that the graphene colloid probe is more likely to become stuck, resulting in more energy dissipation to contribute to a larger friction coefficient. Biasing of the graphene surface under either negative or positive voltages resulted in uniformly arranged ions, which produced a more ordered ion structure and, thus, a smoother sliding plane to reduce the friction coefficient. Electrochemical impedance spectroscopy (EIS) for the IL with graphene as an electrode demonstrated a greater ionic conductivity in the IL paired with the biased graphene than in the unbiased one, implying faster ion movement at the charged graphene, which is beneficial for reducing the friction coefficient.

Titanium dioxide (TiO2) nanostructures exhibit exceptional flexibility for integration into surface-enhanced Raman spectroscopy (SERS) sensing platforms enabling nanoscale trace detection of biomolecules with high sensitivity. However, fabricating TiO2 nanomaterials for large-scale SERS applications remains challenging due to the high cost and complexity of synthesis methods. In this study, we demonstrate a cost-effective and scalable approach using commercial TiO2 P25 nanoparticles as the SERS substrates, functionalized with a phosphonium-based fluorine-free ionic liquid (IL) comprising the trihexyl(tetradecyl)phosphonium cation ([P6,6,6,14]+) with four long alkyl chains and the 2–2-(2-methoxyethoxy)ethoxy anion ([MEEA]−). This IL serves as a nanoscale “linker”, effectively bridging Cytochrome c (Cyt c) molecules with TiO2 nanoparticles, significantly enhancing the Cyt c–TiO2 interactions and SERS signal intensity. The optimized system achieves remarkable sensitivity, enabling the detection of Cyt c concentrations as low as 5 × 10–4 M, with an enhancement factor increased by 1 order of magnitude compared to the control system. This work stresses the importance of nanoscale interactions and offers an alternative straightforward strategy for trace protein detection using commercially available TiO2 P25 nanoparticles, thus circumventing the need for complex nanomaterial fabrication methods.

The electrochemical and charge storage performance of a fluorine-free structurally flexible hybrid pyrrolidinium-based ionic liquid electrolyte (HILE) in a symmetric graphite-based supercapacitor is thoroughly investigated. The HILE revealed thermal decomposition at above 230°C, a glass transition (Tg) temperature of below −70°C, and ionic conductivity of 0.16 mS cm−1 at 30°C. The chemical and electrochemical properties are investigated using a systematic variable temperature 1H and 31P NMR spectroscopy and diffusometry, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). The supercapacitor demonstrated a notable specific capacitance of 186 F g−1 at a scan rate of 1 mV s−1 and a specific capacitance of 122 F g−1 at a current density of 0.5 A g−1. The maximum energy density of 48.8 Wh kg−1, a power density of 450 W kg−1 at a current density of 0.5 A g−1, and a potential window of 4 V were obtained. Altogether, this study demonstrates that the new HILE can be used in symmetric graphite-based supercapacitors over a wide potential window of 4 V and a temperature range from −20°C to 90°C. 

The reaction of wood with maleic anhydride (MA) and sodium hypophosphite (SHP) has been identified as a viable modification method, with macroscopical properties indicating formation of cross-linking to explain the results. However, the chemical reaction between wood and the modification reagents has not been studied yet. To resolve this, the reaction was studied with solid-state 13C cross-polarization magic-angle-spinning (CP-MAS) and 31P MAS nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) to reveal the formation of bonds between wood components, MA and SHP during the treatments to explain the formation of cross-linking and the possible fixation of phosphorus in wood. XPS, solid state 13C and 31P MAS NMR revealed the maleation of wood in the absence of SHP, whilst its presence led to forming a succinic adduct observed through the C-P bond formation, as evidenced by the loss of the maleate C=C bonds at around 130 ppm and the upfield shift of the peak at 165–175 ppm, which was also significantly smoothed, as well as the increase in a peak at 26 ppm due to the reaction between the maleate group and SHP; however, the C-P-C bond could not be unambiguously rationalized from the obtained data. On the other hand, a resonance line at 16 ppm in 31P MAS NMR and the peaks in the XPS P 2p spectrum suggested the formation of a cross-linked structure at low concentrations of SHP, which was more likely to be phosphonate (C-P-O) than organophosphinic acid (C-P-C). The results herein provide a greater fundamental understanding of the mechanisms involved in the reaction of wood, MA and SHP, providing further scope for improved treatment systems in the future.

The purpose of this study was to enhance students’ understanding of surface wetting by exploring the relationship between contact angles and nanopatterned surface structures as part of the required course, “Chemistry in Nanoscience.” We developed a comprehensive three-part activity, combining theory, experiments, and modeling of surface wetting, for 30 sophomore students of the Department of Materials Science and Engineering who had finished gateway courses related to materials science and physical chemistry. In the first exercise, students dug into the theoretical foundations of surface wetting by deriving and interpreting Young’s, Wenzel’s, and Cassie–Baxter’s equations. The second exercise involved digital experiments wherein students observed changes in wetting properties on different nanopatterned surface structures via an online app. Finally, the third exercise presented a nanoscale model using a wetting parameter to enhance students’ understanding of surface wetting at the molecular level. Student learning outcome evaluations revealed that this hands-on integrative approach substantially improved students’ understanding of surface wetting concepts. Students obtained a comprehensive understanding of surface wetting by deriving wetting models, visualizing contact angle variations in digital experiments, and linking these to a nanoscale wetting parameter. Moreover, students expressed greater confidence and enthusiasm for tackling complex topics in surface science and research.

The utilization of metal–organic frameworks (MOFs) in energy storage applications is constrained by their limited electrical conductivity and insufficient chemical robustness, posing various challenges and limitations. Nevertheless, research has demonstrated that MOF structures with exceptional porosity and adaptable architectures yield a wide range of composites, presenting promising prospects for improving their electrochemical performance in energy storage devices. When combined with other advanced materials, MOFs form composite structures overcoming these constraints by exhibiting superior electrical conductivity, electrochemical activity, and stability in comparison to pure MOFs. This article comprehensively overviews the designed chemistry of MOF-composites for metal-ion batteries (MIBs) and metal-ion capacitors (MICs). The synthesis and properties of various composites involving MOFs, including MOF-MXene, MOF-carbon nanomaterials (CNM)/graphene/carbon, MOF-transition metal oxide (TMO), MOF/polymers, MOF-derived layered double hydroxide (LDH), as well as the challenges and mitigation strategies have been discussed. A brief overview of MOF-composites as electrode materials for MIBs, including lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (KIBs) is presented. The recent developments in MICs, such as lithium-ion capacitors (LICs), magnesium-ion capacitors (MGICs), zinc-ion capacitors (ZICs), sodium-ion capacitors (SICs), and potassium-ion capacitors (KICs) have also been included. Furthermore, the electrochemical performance of the MOF composites has been assessed using a range of metrics, including output voltage, capacity, cycle stability, energy density (ED), and power density (PD). A comprehensive analysis has also been conducted to identify potential obstacles and possible mitigations to explore future possibilities. Overall, a comprehension of MOF-based materials and potential approaches for enhancing the futuristic progression of MOF-composite materials for MIBs and MICs have been elucidated.

The energy demand cannot be fully accomplished as the rate of increasing worldwide population is larger than the production of energy. The increasing population also leads to the development of more electrical components, which need a lot of energy to store, so energy storing devices are the need of the hour. Batteries and supercapacitors are the main class of such energy storage devices. Graphene is a 2D nanomaterial suitable for energy storage devices as electrode material due to its remarkable properties like high theoretical specific surface area and high electrical conductivity. Still, scientific works are underway to optimize the synthesis and applicability of graphene and its derivative materials in energy storage systems. This chapter discusses graphene and its derivatives for supercapacitor applications. Further, the electrochemistry behind storing energy in storage devices is discussed. This in-depth examination of graphene-based materials for energy storage may help researchers better comprehend the advantages and the most promising outcomes of such materials.