7 research outputs found
Nonclassical Crystal Growth of Supramolecular Polymers in Aqueous Medium
International audienceAbstract A mechanistic understanding of the principles governing the hierarchical organization of supramolecular polymers offers a paradigm for tailoring synthetic molecular architectures at the nano to micrometric scales. Herein, the unconventional crystal growth mechanism of a supramolecular polymer of superbenzene(coronene)âdiphenylalanine conjugate (CrâFF OEt ) is demonstrated. 3D electron diffraction (3D ED), a technique underexplored in supramolecular chemistry, is effectively utilized to gain a molecularâlevel understanding of the gradual growth of the initially formed poorly crystalline hairy, fibrilâlike supramolecular polymers into the ribbonâlike crystallites. The further evolution of these nanosized flat ribbons into microcrystals by oriented attachment and lateral fusion is probed by timeâresolved microscopy and electron diffraction. The gradual morphological and structural changes reveal the nonclassical crystal growth pathway, where the balance of strong and weak intermolecular interactions led to a structure beyond the nanoscale. The role of distinct Ï âstacking and Hâbonding interactions that drive the nonclassical crystallization process of CrâFF OEt supramolecular polymers is analyzed in comparison to analogous molecules, PyâFF OEt and CrâFF forming helical and twisted fibers, respectively. Furthermore, the CrâFF OEt crystals formed through nonclassical crystallization are found to improve the functional properties
Urea-Based Deep Eutectic Solvent with Magnesium/Lithium Dual Ions as an Aqueous Electrolyte for High-Performance Battery-Supercapacitor Hybrid Devices
A new deep eutectic solvent (DES) made from urea, magnesium chloride, lithium perchlorate and water has been developed as the electrolyte for battery-supercapacitor hybrid devices. The physicochemical characteristics of DES electrolytes and potential interactions between electrolyte components are well analyzed through electrochemical and spectroscopic techniques. It has been discovered that the properties of DES electrolytes are highly dependent on the component ratio, which allows us to engineer the electrolyte to meet the requirement of the battery application. Perylene tetracarboxylic di-imide and reduced graphene oxide ha ve been combined to produce a composite (PTCDI/rGO) that has been tested as the anode in DES electrolyte. This composite shows that the capacitive contribution is greater than 90% in a low scan rate, resulting in the high rate capability. The PTCDI/rGO electrode exhibits no sign of capacity degradation and its coulombic efficiency is close to 99% after 200 cycles, which suggests excellent reversibility and stability. On the other hand, the electrochemical performance of lithium manganese oxide as the cathode material is studied in DES electrolyte, which exhibits the maximum capacity of 76.5 mAh/g at 0.03 A/g current density. After being successfully examined in terms of electrode kinetics, capacity performance, and rate capability, the anode and cathode materials are combined to construct a two-electrode system with DES electrolyte. At a current density of 0.03 A/g, this system offers 43.5 mAh/g specific capacity and displays 55.5% retention of the maximum capacity at 1 A/g. Furthermore, an energy density of 53 Wh/kg is delivered at a power density of 35 W/kg
Exfoliation of Reduced Graphene Oxide with Self-Assembled ÏâGelators for Improved Electrochemical Performance
Among
several methodologies to improve the solution processing of graphene-based
materials, noncovalent functionalization has been considered as the
simplest and nondestructive method. Herein, we show that molecular
self-assembly process can be used as a useful tool to exfoliate reduced
graphene oxide (RGO), resulting in hybrid materials with improved
physical properties. Upon interacting with a Ï-gelator, the
dispersing ability of the RGO increased significantly in most of nonpolar
and polar aprotic solvents when compared to the bare one. The amount
of RGO dispersed was 1.7â1.8 mg mL<sup>â1</sup> in solvents
such as toluene, <i>o</i>-dichlorobenzene (ODCB) and tetrahydrofuran
(THF). Morphological studies revealed that aggregation of Ï-gelator
over RGO helps to exfoliate graphene layers to remain as individual
sheets with higher surface area. Experimental studies revealed enhanced
surface area (250 m<sup>2</sup> g<sup>â1</sup>) and better
conductivity (3.7 S m<sup>â1</sup>) of the hybrid materials
with 30% of RGO content resulting in excellent electrochemical performance
(specific capacitance of 181 F g<sup>â1</sup>) as electrodes
for supercapacitors
Recent Progress of 2D Layered Materials in Water-in-Salt/Deep Eutectic Solvent-Based Liquid Electrolytes for Supercapacitors
Supercapacitors are candidates with the greatest potential for use in sustainable energy resources. Extensive research is being carried out to improve the performances of state-of-art supercapacitors to meet our increased energy demands because of huge technological innovations in various fields. The development of high-performing materials for supercapacitor components such as electrodes, electrolytes, current collectors, and separators is inevitable. To boost research in materials design and production toward supercapacitors, the up-to-date collection of recent advancements is necessary for the benefit of active researchers. This review summarizes the most recent developments of water-in-salt (WIS) and deep eutectic solvents (DES), which are considered significant electrolyte systems to advance the energy density of supercapacitors, with a focus on two-dimensional layered nanomaterials. It provides a comprehensive survey of 2D materials (graphene, MXenes, and transition-metal oxides/dichalcogenides/sulfides) employed in supercapacitors using WIS/DES electrolytes. The synthesis and characterization of various 2D materials along with their electrochemical performances in WIS and DES electrolyte systems are described. In addition, the challenges and opportunities for the next-generation supercapacitor devices are summarily discussed