Ultrathin Films of MXene Nanosheets Decorated by Ionic Branched Nanoparticles with Enhanced Energy Storage Stability

Two-dimensional (2D) materials such as MXenes have shown great potential for energy storage applications due to their high surface area and high conductivity. However, their practical implementation is limited by their tendency to restack, similar to other 2D materials, leading to a decreased long-term performance. Here, we present a novel approach to addressing this issue by combining MXene (Ti3C2Tx) nanosheets with branched ionic nanoparticles from polyhedral oligomeric silsesquioxanes (POSS) using an amphiphilicity-driven assembly for the formation of composite monolayers of nanoparticle-decorated MXene nanosheets at the air-water interface. The amphiphilic hybrid MXene/POSS monolayers allow for the fabrication of organized multilayered films with ionic nanoparticles supporting the nanoscale gap between MXene nanosheets. For these composite multilayers, we observed a 400% enhancement in specific capacitance compared to pure drop-cast MXene films. Furthermore, dramatically enhanced electrochemical cycling stability for ultrathin-film electrodes (<400 nm in thickness) with a 91% capacitance retention over 10,000 cycles has been achieved. Our results suggest that this insertion of 0D ionic nanoparticles with complementary interactions in between 2D MXene nanosheets could be extended to other hybrid 0D-2D nanomaterials, providing a promising pathway for the development of hybrid electrode architectures with enhanced ionic transport for long-term energy cycling and storage, capacitive deionization, and ionic filtration.

Recent Advancements in Novel Sensing Systems through Nanoarchitectonics

The fabrication of various sensing devices and the ability to harmonize materials for a higher degree of organization is essential for effective sensing systems. Materials with hierarchically micro- and mesopore structures can enhance the sensitivity of sensors. Nanoarchitectonics allows for atomic/molecular level manipulations that create a higher area-to-volume ratio in nanoscale hierarchical structures for use in ideal sensing applications. Nanoarchitectonics also provides ample opportunities to fabricate materials by tuning pore size, increasing surface area, trapping molecules via host-guest interactions, and other mechanisms. Material characteristics and shape significantly enhance sensing capabilities via intramolecular interactions, molecular recognition, and localized surface plasmon resonance (LSPR). This review highlights the latest advancements in nanoarchitectonics approaches to tailor materials for various sensing applications, including biological micro/macro molecules, volatile organic compounds (VOC), microscopic recognition, and the selective discrimination of microparticles. Furthermore, different sensing devices that utilize the nanoarchitectonics concept to achieve atomic-molecular level discrimination are also discussed.

GUANIDINIIUM-CONTAINING OLIGOMER CATIONIC PROTONIC IONIC LIQUIDS

By reacting a dian epoxy oligomer with guanidinium hydrochloride, a synthesis method of guanidinium-containing cationic proton oligomeric ionic liquids (OIL) capable of condensation reactions was developed. These compounds are characterized by an amphiphilic structure combining a flexible oligoether or hydroxyl-containing guanidinium oligoether block with terminal hydroxyl-containing guanidinium fragments. These compounds are capable of supramolecular organization due to the self-association of flexible oligoether blocks with terminal hydroxyl-containing guanidinium fragments from the outside of the formed cluster. They are characterized by two glass transition temperatures, which differ significantly in magnitude. The structure formed by the flexible oligoether component is determined by its segmental mobility with the glass transition temperature in the range (70–85 °C), and the terminal guanidinium fragments are responsible for the manifestation of the cohesive nature of the glass transition of the oligomer as a whole with the glass transition temperature in the range (-70)–(-60 °C), which characteristic of classical ionic liquids. The proton conductivity of the synthesized compounds in anhydrous conditions reaches a value of 1,94·10-3 S/cm at 120 °C and is determined not by the absolute value of the introduced protons, but by their specific number in relation to the MW oligomers. The synthesized OIL are of interest as electrolytes with an anhydrous conduction mechanism and starting reagents for the synthesis of ion-containing block copolymers of various functional purposes.