Storing Energy in Biodegradable Electrochemical Supercapacitors

Polypyrrole-Stabilized Polypeptide for Eco-Friendly Supercapacitors

As an energy storage technology, supercapacitors (SCs) have become an important part of many electronic systems because of their high-power density, long cycle life, and maintenance-free characteristics. However, the widespread development and use of electronics, including SCs, have led to the generation of a large amount of e-waste. In addition, achieving compatibility between stability and biodegradability has been a prominent challenge for implantable electronics. Therefore, environmentally friendly SCs based on polypyrrole (PPy)-stabilized polypeptide (FF) are demonstrated in this study. The fully degradable SC has a layer-by-layer structure, including polylactic acid/chitosan (PLA-C) support layers, current collectors (Mg), FF/PPy composite layers, and a polyvinyl alcohol/phosphate buffer solution (PVA/PBS) hydrogel. It has the advantages of being light, thin, flexible, and biocompatible. After 5000 cycles in air, the capacitance retention remains at up to 94.7%. The device could stably operate for 7 days in a liquid environment and completely degrade in vitro within 90 days without any adverse effect on the environment. This work has important implications for eco-friendly electronics and will have a significant impact on the implantable biomedical electronics.

N-Aminoacyl-3-amino-nido-carboranes as a Group of Boron-Containing Derivatives of Natural Amino Acids

A new group of nido-carboranyl derivatives of natural (S)-amino acids containing from 9 to 18 boron atoms was obtained in good yields as a result of acylation of 3-amino-1,2-dicarba-closo-dodecaborane followed by deboronation. The proposed approach is convenient and based on the use of readily available reagents and is suitable for the synthesis of enantiopure nido-carboranyl derivatives of amino acids with various side chains, including water-soluble boron-containing amino acids (17 examples).

Chirality in peptide-based materials: From chirality effects to potential applications

Chirality is ubiquitous in nature with primary cellular functions that include construction of right-/left-handed helix and selective communications among diverse biomolecules. Of particularly intriguing are the chiral peptide-based materials that can be deliberately designed to change physicochemistry properties via tuning peptide sequences. Critically, understanding their chiral effects are fundamental for the development of novel materials in chemistry and biomedicine fields. Here, we review recent researches on chirality in peptide-based materials, summarizing relevant typical chiral effects towards recognition, amplification, and induction. Driven forces for the chiral discrimination in affinity interaction as well as the handedness preferences in supramolecular structure formation at both the macroscale and microscale are illustrated. The implementation of such chirality effects of artificial copolymers, assembled aggregates and their composites in the fields of bioseparation and bioenrichment, cell incubation, protein aggregation inhibitors, chiral smart gels, and bionic electro devices are also presented. At last, the challenges in these areas and possible directions are pointed out. The diversity of chiral roles in the origin of life and chirality design in different organic or composite systems as well as their applications in drug development and chirality detection in environmental protection are discussed.

Updating atomic charge parameters of aliphatic amino acids: a quest to improve the performance of molecular modeling via sequential molecular dynamics and DFT-GIAO-NMR calculations

In this work, we observe the behavior of the dipole moment, atomic charges, solute-solvent interactions and NMR spectroscopy of aliphatic amino acids in a water solution via the computational simulations of classical molecular dynamics and DFT quantum calculations. Our results indicate that the convergence of the atomic charge of the solute, from an iterative process, together with the dipole moment of the amino acid, alters the lifetime of hydrogen bonds present in the first solvation shell, resulting in the modification of its structure and dynamics. Using GIAO-DFT-NMR calculations, we assessed the impact of these structural solute-solvent modifications on the magnetic shielding constants of the solute carbon atoms. In this sense, we evaluate the importance of an update in parameters that describe atomic charges present in the CHARMM36 force field.

Molecular dynamic simulations, GIAO-NMR and TD-DFT spectroscopy analyze for zwitterionic isoleucine (ILE)N , 1 ≤ N ≤ 6, in water solution

In this article, we investigate the effects of the isoleucine (ILE)_N amino acid chain growth, N = 1.0.6, the ILE conformational effect as well as the solvent presence on the electrical and magnetic spectroscopic properties when these compounds are in aqueous solution. Computational molecular dynamics simulations were performed to include the solvent medium and generate uncorrelated configurations involving solute-solvent structures. The charge point model for solvent was used to obtain the results for quantum mechanical calculation, in special DFT calculations, for (ILE)_N structures. Our results for the magnetic shielding constant obtained via GIAO-DFT-NMR calculations show that there is evidence of a magnetic behavior that characterizes the number of peptide bonds and, therefore, how the N isoleucine polypeptide chain is composed. TD-DFT results also show an absorption band shift to larger wavelengths indicating a dependence on N growth.

Controlled synthesis of a hierarchical CuNi2O4@SnS nanocauliflower-like structure on rGO as a positive electrode material for an asymmetric supercapacitor

Hierarchical CuNi2O4@SnS@rGO/NF is a promising electrode material for building up an impressive supercapacitor.

A semi-GCMC simulation study of electrolytic capacitors with adsorbed titrating peptides

We use semi-grand canonical Monte Carlo simulations to study an electrolytic capacitor with an adsorbed peptide on the electrode surfaces. Only homogeneous peptides are considered, consisting of only a single residue type. We find that the classical double-hump camel-shaped differential capacitance in such systems is augmented by the addition of a third peak, due to the capacitance contribution of the peptide, essentially superimposed on the salt contribution. This mechanistic picture is justified using a simple mean-field analysis. We find that the position of this third peak can be tuned to various surface potential values by adjusting the ambient pH of the electrolyte solution. We investigate the effect of changing the residue type and the concentration of the adsorbed peptide and of the supporting electrolyte. Varying the residue species and pH allows one to modify the capacitance profile as a function of surface potential, facilitating the design of varying discharging patterns for the capacitor.

The Evolution of Flexible Electronics: From Nature, Beyond Nature, and To Nature

The flourishing development of multifunctional flexible electronics cannot leave the beneficial role of nature, which provides continuous inspiration in their material, structural, and functional designs. During the evolution of flexible electronics, some originated from nature, some were even beyond nature, and others were implantable or biodegradable eventually to nature. Therefore, the relationship between flexible electronics and nature is undoubtedly vital since harmony between nature and technology evolution would promote the sustainable development. Herein, materials selection and functionality design for flexible electronics that are mostly inspired from nature are first introduced with certain functionality even beyond nature. Then, frontier advances on flexible electronics including the main individual components (i.e., energy (the power source) and the sensor (the electric load)) are presented from nature, beyond nature, and to nature with the aim of enlightening the harmonious relationship between the modern electronics technology and nature. Finally, critical issues in next-generation flexible electronics are discussed to provide possible solutions and new insights in prospective exploration directions.

Promising High-Performance Supercapacitor Electrode Materials from MnO2 Nanosheets@Bamboo Leaf Carbon

MnO₂@bamboo leaf (BL) carbon composites have been prepared by a hydrothermal method, wherein, the BL porous carbon structure was based on BLs. The MnO₂@BL composites were characterized by SEM, TEM, XRD, Raman, XPS, and TGA. The electrochemical properties of the composites were investigated in a three-electrode system using 1 M Na₂SO₄ aqueous solution as an asymmetric supercapacitor electrolyte. Electrochemical measurements showed that the MnO₂@BL composites can be applied in asymmetric supercapacitors and exhibited a good cycling stability with a capacitance retention ratio of 85.3% after 5000 cycles (at 0.5 A g^-1). The MnO₂@BL composites were promising materials for application in supercapacitors.

First principle approach to elucidate transport properties through L-glutamic acid-based molecular devices using symmetrical electrodes

Protein-based electronics is one of the emerging technology in which inventive electronic devices are being adduced and developed based on the selective actions of specific proteins. The explicit actions can be predicted if the building blocks of proteins (i.e., amino acids) are studied decorously. We emphasize our work on electronic transport properties of L-glutamic acid (i.e., L-amino acid) stringed to gold, silver, and copper electrodes, respectively, to form three distinct devices. For our calculations, we employ NEGF-DFT approach using self-consistent function. Electronic coupling and tunneling barriers between the molecule and the electrodes have been emphasized with an inception of delocalization of molecular orbitals within the device. We observe strong correlation between tunneling barrier and Mulliken charge transfer between molecule and electrodes. The asymmetrical carbon chain (-CH₂) within the molecule exhibits negative differential resistance (NDR) and rectification ratio. The device using molecule with copper electrodes exhibits the highest peak to valley current ratio of 1.84. The rectification ratio of the device with gold, silver, and copper electrodes is 2.35, 2.25, and 15.62, respectively, at finite bias. These results yield fresh insight on the potential of L-glutamic acid like bio-molecule in the emerging field of proteotronics.

Exploring doped or vacancy-modified graphene-based electrodes for applications in asymmetric supercapacitors

We report here density functional theory calculations and molecular dynamics atomistic simulations to determine the total capacitance of graphene-modified supercapacitors.

High Specific Capacitance Electrode Material for Supercapacitors Based on Resin-Derived Nitrogen-Doped Porous Carbons

Carbon-based materials, as electrodes for supercapacitors, have attracted tremendous attention. Therefore, nitrogen-doped porous carbons (NPCs) were prepared through a facile carbonization/activation strategy by treating different mass ratios of melamine-urea-formaldehyde resin and KOH. It is clearly demonstrated that because of the introduction of KOH, the resulting NPCs were shown to have increased specific surface area and a rich pore structure, and the best sample possessed a large specific surface area of 2248 m² g^-1 and high N content, which contributed to the good electrochemical performance for supercapacitors. Accordingly, a three-electrode system assembles NPCs as an electrode using aqueous KOH solution; the specific capacitance was 341 F g^-1 under the current density of 1 A g^-1 and retained a specific capacitance of almost 92% after 5000 cycles. The maximum energy output for a symmetrical solid-state supercapacitor with NPCs as the electrode material was 9.60 W h kg^-1 at 1 A g^-1. NPCs have promising applications on high-performance supercapacitors and other energy-storage devices.

Understanding the stability of polypeptide membranes in ionic liquids: a theoretical molecular dynamics study

Stability analysis of polypeptide membranes in ionic liquids can make possible new applications of these membranes in energy storage and ionic solution separation.

Investigating the asymmetry in the EDL response of C60/graphene supercapacitors

Molecular dynamics simulations were employed to model C₆₀/graphene composite electrodes that can expand the effective area and performance of supercapacitors.