Moumita Kotal

Sulfur and Nitrogen Co‐Doped Graphene Electrodes for High‐Performance Ionic Artificial Muscles

UNLABELLED Sulfur and nitrogen co-doped graphene electrodes for bioinspired ionic artificial muscles, which exhibit outstanding actuation performances (bending strain of 0.36%, 4.5 times higher than PEDOT PSS electrodes, and 96% of initial strain after demonstration over 18 000 cycles), provide remarkable electro-chemo-mech anical properties: specific capacitance, electrical conductivity, and large surface area with mesoporosity.

Soft but Powerful Artificial Muscles Based on 3D Graphene–CNT–Ni Heteronanostructures

Bioinspired soft ionic actuators, which exhibit large strain and high durability under low input voltages, are regarded as prospective candidates for future soft electronics. However, due to the intrinsic drawback of weak blocking force, the feasible applications of soft ionic actuators are limited until now. An electroactive artificial muscle electro-chemomechanically reinforced with 3D graphene-carbon nanotube-nickel heteronanostructures (G-CNT-Ni) to improve blocking force and bending deformation of the ionic actuators is demonstrated. The G-CNT-Ni heteronanostructure, which provides an electrically conductive 3D network and sufficient contact area with mobile ions in the polymer electrolyte, is embedded as a nanofiller in both ionic polymer and conductive electrodes of the ionic actuators. An ionic exchangeable composite membrane consisting of Nafion, G-CNT-Ni and ionic liquid (IL) shows improved tensile modulus and strength of up to 166% and 98%, respectively, and increased ionic conductivity of 0.254 S m-1 . The ionic actuator exhibits enhanced actuation performances including three times larger bending deformation, 2.37 times higher blocking force, and 4 h durability. The electroactive artificial muscle electro-chemomechanically reinforced with 3D G-CNT-Ni heteronanostructures offers improvements over current soft ionic actuator technologies and can advance the practical engineering applications.

Sulfur and nitrogen co-doped holey graphene aerogel for structurally resilient solid-state supercapacitors under high compressions

Structural energy storage devices having load-bearing or stress-tolerant functionalities are crucial for designing wearable and soft electronics. In order to supply power to next-generation electronic systems, structurally resilient solid-state supercapacitors (SRSSs) with sustainable conductivities and electrochemical performances under large compressions are a promising candidate. Here, we report a synthetic porous framework of a nitrogen and sulfur co-doped holey graphene aerogel (NS-HGA) for SRSSs under high compression loadings. Such a covalently interconnected holey graphene nano-architecture co-doped with nitrogen (3.11%) and sulfur (1.87%) has a greatly improved resilient structural integrity, with repeatable elasticity along with high compressive strength. Therefore, the NS-HGA featuring high electrolyte ion storage, unhindered ion channels, excellent conductivity (21.66 S m−1), and promising electrochemical performances exhibits significantly high volumetric capacitance (203 mF cm−3) in a SRSS with good rate capability and almost unaltered capacitance even at 50% compression, with good durability for 200 cycles. Interestingly, when four NS-HGA:SRSSs were integrated into series, a bright green LED was illuminated even after charging for very few seconds. The proposed dual heteroatom-doped holey graphene aerogel, devoid of any pseudocapacitive materials, can be successfully used for high compression-permissive SRSSs in the modern era of wearable and soft elastic electronics.

Recent Progress in Multifunctional Graphene Aerogels

Two dimensional (2D) graphene has become one of the most intensively explored carbon allotropes in materials science owing to attractive features like its outstanding physicochemical properties. In order to further realize practical applications, the fabrication of self-assembled 2D individual graphene sheets into 3D graphene aerogels (GAs) with special structures and novel functions, is now becoming essential. Moreover, GAs are ideal as supports for the introduction of nanoparticles, polymers, and functional materials to further enhance their applications in broad areas. GAs have light weight, large surface area, good compressibility, extensibility, and high electrical conductivity. They have been used as efficient electrodes for batteries, in supercapacitors, and in sensors and actuators. This critical review mainly addresses recent progress in the methods used for their syntheses, their properties, and applications for energy storage, and in sensors and actuators. Furthermore, to assist advanced research for practical applications of these emerging materials, the technical challenges are discussed, and future research directions are proposed.

Defect engineering route to boron nitride quantum dots and edge-hydroxylated functionalization for bio-imaging

Hexagonal boron nitride (h-BN) has considerable potential for applications owing to its attractive features including good thermal conductivity, chemical stability, and unique optical properties. However, because h-BN is chemically inert and thermally stable, it is hard to synthesize boron nitride quantum dots (BNQDs) using chemical methods such as oxidation, hetero-atom doping or functionalization. Here, we report a defect engineering method to synthesize BNQDs from h-BN using physical energy sources including an impinging process of heated iron nanoparticles, microwave irradiation and sonication. Furthermore, edge-hydroxylated functionalization was employed to enhance the intracellular uptake of the BNQDs in cells for bioimaging. The edge-hydroxylated BNQDs (EH-BNQDs) showed blue colored photoluminescence with 325 nm laser excitation, good cytotoxicity performance with approximately 100% cell viability, and a good attachment to cell surfaces. The successful endocytosis of EH-BNQDs using a cancer cell line was also demonstrated.

Electroionic Antagonistic Muscles Based on Nitrogen-Doped Carbons Derived from Poly(Triazine-Triptycene)

Abstract Electroactive soft actuators and bioinspired artificial muscles have received burgeoning interest as essential components in future electronic devices such as soft haptic‐feedback systems, human‐friendly wearable electronics, and active biomedical devices. However, important challenging issues including fast response time, ultralow input power, robust operation in harsh environments, high‐resolution controllability, and cost‐effectiveness remain to be resolved for more practical applications. Here, an electroionic antagonistic artificial muscle is reported based on hierarchically porous nitrogen‐doped carbon (HPNC) electrodes derived from a microporous poly(triazine‐triptycene) organic framework (PtztpOF). The HPNC, which exhibits hierarchically micro‐ and mesoporous structures, high specific capacitance of 330 F g−1 in aqueous solution, large specific surface area of 830.46 m2 g−1, and graphitic nitrogen doping, offers high electrical conductivity of 0.073 MS m−1 and outstanding volumetric capacitance of 10.4 MF m−3. Furthermore, it is demonstrated that a novel electroionic antagonistic muscle based on HPNC electrodes successfully displays extremely reliable and large bending deformations and long‐term durability under ultralow input voltages. Therefore, microporous polymer or covalent organic frameworks can be applied to provide significant improvements in electroactive artificial muscles, which can play key roles as technological advances toward bioinspired actuating devices required for next‐generation soft and wearable electronics.