Effects of a dual functional filler, polyethersulfone-g-carboxymethyl chitosan@MWCNT, for enhanced antifouling and penetration performance of PES composite membranes

Ultrafiltration technology, separating water from impurities by the core membrane, is an effective strategy for treating wastewater to meet the ever-growing requirement of clean and drinking water. However, the similar nature of hydrophobic organic pollutants and the membrane surface leads to severe adsorption and aggregation, resulting unavoidable membrane degradation of penetration and rejection. The present study presents a novel block amphiphilic polymer, polyethersulfone-g-carboxymethyl chitosan@MWCNT (PES-g-CMC@MWCNT), which is synthesized by grafting hydrophobic polyethersulfone to hydrophilic carboxymethyl chitosan in order to suspend CMC in organic solution. A mixture of hydrophilic carboxymethyl chitosan and hydrophobic polymers (polyethersulfone), in which hydrophilic segments are bonded to hydrophobic segments, could provide hydrophilic groups, as well as gather and remain stable on membrane surfaces by their hydrophobic interaction for improved compatibility and durability. The resultant ultrafiltration membranes exhibit high water flux (198.10 L m-2·h-1), suitable hydrophilicity (64.77°), enhanced antifouling property (82.96%), while still maintains excellent rejection of bovine serum albumin (91.75%). There has also been an improvement in membrane cross-sectional morphology, resulting in more regular pores size (47.64 nm) and higher porosity (84.60%). These results indicate that amphiphilic polymer may be able to significantly promote antifouling and permeability of ultrafiltration membranes.

Recent Progress in Polyaniline and its Composites for Supercapacitors

Polyaniline (PANI) has piqued the interest of nanotechnology researchers due to its potential as an electrode material for supercapacitors. Despite its ease of synthesis and ability to be doped with a wide range of materials, PANI's poor mechanical properties have limited its use in practical applications. To address this issue, researchers investigated using PANI composites with materials with highly specific surface areas, active sites, porous architectures, and high conductivity. The resulting composite materials have improved energy storage performance, making them promising electrode materials for supercapacitors. Here, we provide an overview of recent developments in PANI-based supercapacitors, focusing on using electrochemically active carbon and redox-active materials as composites. We discuss challenges and opportunities of synthesizing PANI-based composites for supercapacitor applications. Furthermore, we provide theoretical insights into the electrical properties of PANI composites and their potential as active electrode materials. The need for this review stems from the growing interest in PANI-based composites to improve supercapacitor performance. By examining recent progress in this field, we provide a comprehensive overview of the current state-of-the-art and potential of PANI-based composites for supercapacitor applications. This review adds value by highlighting challenges and opportunities associated with synthesizing and utilizing PANI-based composites, thereby guiding future research directions.

Electrochemical Synthesis of Functionalized Graphene/Polyaniline Composite Using Two Electrode Configuration for Supercapacitors

An effective approach for the large-scale fabrication of conducting polyaniline (PANI) using in situ anodic electrochemical polymerization on nickel foam which had been coated in aryl diazonium salt (ADS)-modified graphene (ADS-G). In the present work, ADS-G was used as a high surface-area support material for the electrochemical polymerization of PANI. The electrochemical performances of the ADS-G/PANI composites exhibited better suitability as supercapacitor electrode materials than those of the PANI. The ADS-G/PANI composites achieved a specific capacitance of 528 F g-1, which was higher than that of PANI (266 F g-1) due to excellent electrode-electrolyte interaction and the synergistic effect of electrical conductivity between ADS-G and PANI in the composites. These findings suggest that the ADS-G/PANI composites are a suitable composite for potential supercapacitor applications.

The Use of Layer-by-Layer Self-Assembly and Nanocellulose to Prepare Advanced Functional Materials

The current knowledge about the formation of layer-by-layer (LbL) self-assemblies using combinations of nanocelluloses (NCs) and polyelectrolytes is reviewed. Herein, the fundamentals behind the LbL formation, with a major focus on NCs, are considered. Following this, a special description of the limiting factors for the formation of LbLs of only NCs, both anionic and cationic, and the combination of NCs and polyelectrolytes/nanoparticles is provided. The ability of the NCs and polyelectrolytes to form dense films with excellent mechanical properties and with tailored optical properties is then reviewed. How low-density, wet stable networks of cellulose nanofibrils can be used as substrates for the preparation of antibacterial, electrically interactive, and fire-retardant materials by forming well-defined LbLs inside these networks is then considered. A short outlook of the possible uses of LbLs containing NCs is given to conclude.

Lignin Cellulose Nanofibrils as an Electrochemically Functional Component for High-Performance and Flexible Supercapacitor Electrodes

The increasing demand for wearable electronics has driven the development of supercapacitor electrode materials toward enhanced energy density, while being mechanically strong, flexible, as well as environmentally friendly and low-cost. Taking advantage of faradaic reaction of quinone groups in natural lignin that is covalently bound to the high-strength cellulose nanofibrils, the fabrication of a novel class of mechanically strong and flexible thin film electrodes with high energy storage performance is reported. The electrodes were made by growing polyaniline (PANI) on flexible films composed of lignin-containing cellulose nanofibrils (LCNF) and reduced graphene oxide (rGO) nanosheets at various loading levels. The highest specific capacitance was observed for the LCNF/rGO/PANI electrode with 20 wt% rGO nanosheets (475 F g^-1 at 10 mV s^-1 and 733 F g^-1 at 1 mV s^-1 ), which represented a 68 % improvement as compared to a similar electrode made without lignin. In addition, the LCNF/rGO(20)/PANI electrode demonstrated high rate performance and cycle life (87 % after 5000 cycles). These results indicated that LCNF functioned as an electrochemically active multifunctional component to impart the composite electrode with mechanical strength and flexibility and enhanced overall energy storage performance. LCNF/rGO(20)/PANI electrode was further integrated in a flexible supercapacitor device, revealing the excellent promise of LCNF for fabrication of advanced flexible electrodes with reduced cost and environmental footprint and enhanced mechanical and energy storage performances.

Active Basal Plane Catalytic Activity via Interfacial Engineering for a Finely Tunable Conducting Polymer/MoS2 Hydrogen Evolution Reaction Multilayer Structure

The fixation of the catalyst interface is an important consideration for the design of practical applications. However, the electronic structure of MoS₂ is sensitive to its embedding environment, and the catalytic performance of MoS₂ catalysts may be altered significantly by the type of binding agents and interfacial structure. Interfacial engineering is an effective method for designing efficient catalysts, arising from the close contact between different components, which facilitates charge transfer and strong electronic interactions. Here, we have developed a layer-by-layer (LbL) strategy for the preparation of interfacial MoS₂-based catalyst structures with two types of conducting polymers on various substrates. We demonstrate how the assembled partners in the LbL structure can significantly impact the electronic structures in MoS₂. As the number of bilayers grows, using polypyrrole as a binder remarkably increases the catalytic efficacy as compared to using polyaniline. On the one hand, the ratio of S₂^2- (or S^2-), which is related to the remaining active hydrogen evolution reaction (HER) species, is further increased. On the other hand, density functional theory calculations indicate that the interfacial charge transport from the conducting polymers to MoS₂ may boost the HER activity of the interfacial structure of the conducting polymer/MoS₂ by decreasing the adsorption free energy of the intermediate H* at the S sites in the basal plane of MoS₂. The optimized catalytic efficacy of the (conducting polymer/MoS₂)_n assembly peaks is obtained with 16 assembly cycles. In preparing interfacial catalytic structures, the LbL-based strategy exhibits several key advantages, including the flexibility of choosing assembly partners, the ability to fine-tune the structures with precision at the nanometer scale, and planar homogeneity at the centimeter scale. We expect that this LbL-based catalyst immobilization strategy will contribute to the fundamental understanding of the scalability and control of highly efficient electrocatalysts at the interface for practical applications.

Electrochemistry of Multilayer Electrodes: From the Basics to Energy Applications

Growing environmental concern has increased the demand for clean energy, and various technologies have been developed to utilize renewable energy sources. With the development of highly efficient energy conversion and storage systems, fundamental studies on the electrochemistry of electrodes are critical because the functionality of most of these systems relies on interfacial electrochemical reactions that occur on the surfaces of the electrodes. In this context, efficient electrode design methods are required to study specific electrochemical principles and the mechanisms of interfacial reactions on the surface of electrodes.Compared with other electrode fabrication methods, layer-by-layer (LbL) assembly is a simple, inexpensive, and versatile process for producing highly ordered multilayer thin-film electrodes from a diverse array of materials. LbL-assembled multilayer electrodes exhibit distinct electrochemical properties compared with electrodes created via other fabrication methods because of the nanoscale control of the composition and structures of electrodes afforded by LbL assembly. LbL assembly can generate unique nanoarchitectures from a multiplicity of electroactive components to investigate the detailed electrochemical mechanisms within the electrode, allowing for investigations of the internal-architecture-dependent electrochemical properties within the electrodes. As electrochemical LbL research has progressed over the last 10 years, our group has performed pioneering studies on the fundamental electrochemical properties of multilayer electrodes fabricated via LbL assembly for diverse energy applications. In this Account, we aim to outline the fundamental electrochemistry occurring at the nanoscale level on multilayer thin-film LbL electrodes using our work to illustrate these concepts, including the dependence of the electrochemistry on the thickness and architecture of multilayer electrodes, competition between mass and charge transfer, and control over the ion-permeation selectivity and interfacial dipole moments in multilayer electrodes. We anticipate that our approach to LbL-assembled electrodes will be of great interest and provide an attractive platform for the investigation of fundamental multilayer thin-film electrochemistry. We also believe that it will provide guidelines for research efforts toward future electrode engineering.

Fabrication and Electrochemical Performance of PVA/CNT/PANI Flexible Films as Electrodes for Supercapacitors

The flexible and rechargeable energy storage device with excellent performance is highly desired due to the demands of portable and wearable devices. Herein, by integrating the bendability and stretchability of Polyvinyl alcohol (PVA), pseudocapacitance of Polyaniline (PANI), and the charge transport ability of carbon nanotubes (CNTs), PVA/CNT/PANI flexible film was fabricated as supercapacitor electrodes with excellent electrochemical performance and flexibility. Full-solid supercapacitor is prepared based on PVA/H₂SO₄ gel electrolyte and as-prepared film electrodes. The device achieves an areal capacitance of 196.5 mF cm^-2 with high cycling stability. The flexible properties of PVA, the conductivity of CNT, and the pseudo-capacitance of PANI contribute to the superior performance. Present work develops a facile and effective way for preparing flexible electrode materials. In present work, we fabricated PVA/CNT/PANI flexible film as supercapacitor electrodes with excellent electrochemical performance and flexibility.

Oxidative Spin-Spray-Assembled Coordinative Multilayers as Platforms for Capacitive Films

The spin-spray-assisted layer-by-layer (LbL) assembly technique was used to prepare coordinative oxidative multilayers from Ce(IV), inorganic polyphosphate (PP), and graphene oxide (GO). The films consist of successive tetralayers and have a general structure (PP/Ce/GO/Ce)n. Such oxidative multilayers have been shown to be a general platform for the electrodeless generation of conducting polymer and melanin-type films. Although the incorporation of GO enhances the film growth, the conventional dip LbL method is very time consuming. We show that the spin-spray method reduces the time required to grow thick multilayers by the order of magnitude and the film growth is linear from the beginning, which implies a stratified structure. We have deposited poly(3,4-ethylenedioxothiophene), PEDOT, on the oxidative multilayers and studied these redox-active films as models for melanin-type capacitive layers for supercapacitors to be used in biodegradable electronics, both before and after the electrochemical reduction of GO to rGO. The amount of oxidant and PEDOT scales linearly with the film thickness, and the charge transfer kinetics is not mass transfer-limited, especially after the reduction of GO. The areal capacitance of the films grows linearly with the film thickness, reaching a value of ca. 1.6 mF cm-2 with 20 tetralayers, and the specific volumetric (per film volume) and mass (per mass of PEDOT) capacitances are ca. 130 F cm-3 and 65 F g-1, respectively. 5,6-Dihydroxyindole can also be polymerized to a redox-active melanin-type film on these oxidative multilayers, with even higher areal capacitance values.

Recent Advances in Layer-by-Layer Assembled Conducting Polymer Based Composites for Supercapacitors

Development of well-designed electrodes is the key to achieve high performance supercapacitors. Therefore, as one of the effective methods, a layer-by-layer (LBL) approach is often fruitfully employed for the fabrication of electrode material. Benefiting from a tunable parameter of the LBL approach, this approach has paved a way to design a highly ordered nanostructured electrode material with excellent performance. Conducting polymers (CPs) are the frontrunners in supercapacitors and notably, the LBL assembly of CPs is attracting extensive attention. Therefore, this critical review covers a comprehensive discussion on the research progress of CP-based composites with special importance on the LBL approach predominately for supercapacitors. Following a brief discussion on supercapacitors and CPs, the most up-to-date techniques used in LBL are highlighted.

Unveiling high specific energy supercapacitor from layer-by-layer assembled polypyrrole/graphene oxide|polypyrrole/manganese oxide electrode material

A novel layer-by-layer (LBL) based electrode material for supercapacitor consists of polypyrrole/graphene oxide and polypyrrole/manganese oxide (PPy/GO|PPy/MnO₂) has prepared by electrochemical deposition. The formation of LBL assembled nanocomposite is confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The field emission scanning electron microscopy images clearly showed that PPy/MnO₂ was uniformly coated on PPy/GO. The PPy/GO|PPy/MnO₂ symmetrical supercapacitor has revealed outstanding supercapacitive performance with a high specific capacitance of 786.6 F/g, an exceptionally high specific energy of 52.3 Wh/kg at a specific power of 1392.9 W/kg and preserve a good cycling stability over 1000 cycles. It is certain that PPy/GO|PPy/MnO₂ has an extraordinary perspective as an electrode for future supercapacitor developments. This finding contributes to a significant impact on the evolution of electrochemical supercapacitor.

Nanocellulose supported hierarchical structured polyaniline/nanocarbon nanocomposite electrode via layer-by-layer assembly for green flexible supercapacitors

The development of a hierarchical structured multicomponent nanocomposite electrode is a promising strategy for utilizing the high efficiency of an electroactive material and improving the electrochemical performance. We propose cellulose nanofibril (CNF) aerogels with a nanoscale fiber-entangled network as the skeleton (via layer-by-layer (LbL) assembly) of electroactive materials polyaniline (PANi), carboxylic multiwalled carbon nanotubes (CMWCNTs), and graphene oxide (GO) to obtain structurally ordered polymer–inorganic hybrid nanocomposite electrodes for high-capacity flexible supercapacitors. The uniformly distributed multilayer nanoarchitecture, interconnected network, and hydrophilicity of the electrode provide a high specific surface area, excellent ion diffusion channels, and large effective contact area, thereby improving the electrochemical performance of the supercapacitor electrode. The specific capacitance of the CNF-[PANi/CMWCNT]₁₀ (CPC₁₀) and CNF-[PANi/RGO]₁₀ (CPR₁₀) electrodes reaches 965.80 and 780.64 F g⁻¹ in 1 M aqueous H₂SO₄ electrolyte, respectively; the corresponding values in PVA/H₃PO₄ electrolyte are 1.59 and 1.46 F cm⁻². In addition, the assembled symmetric supercapacitors show good energy densities of 147.23 and 112.32 mW h cm⁻², as well as excellent durability and flexibility. Our approach offers a simple and effective method for fabricating an ideal well-structured nanocomposite electrode for green and flexible energy storage devices via LbL assembly.

Cellulose nanofibril aerogel was used as a nanofibrous scaffold for layer-by-layer assembly of polyaniline and nano-carbons for flexible and high capacitance supercapacitor applications.

Nanoforest: Polyaniline Nanotubes Modified with Carbon Nano-Onions as a Nanocomposite Material for Easy-to-Miniaturize High-Performance Solid-State Supercapacitors

This article describes a facile low-cost synthesis of polyaniline nanotube (PANI_NT)–carbon nano-onion (CNO) composites for solid-state supercapacitors. Scanning electron microscopic (SEM) analyses indicate a uniform and ordered composition for the conducting polymer nanotubes immobilized on a thin gold film. The obtained nanocomposites exhibit a brush-like architecture with a specific capacitance of 946 F g⁻¹ at a scan rate of 1 mV s⁻¹. In addition, the nanocomposites offer high conductivity and a porous and well-developed surface area. The PANI_NT–CNO nanocomposites were tested as electrodes with high potential and long-term stability for use in easy-to-miniaturize high-performance supercapacitor devices.

Diffusion controlled multilayer electrocatalysts via graphene oxide nanosheets of varying sizes

Controlling the architecture of hybrid nanomaterial electrodes is critical for understanding their fundamental electrochemical mechanisms and applying these materials in future energy conversion and storage systems. Herein, we report highly tunable electrocatalytic multilayer electrodes, composed of palladium nanoparticles (Pd NPs) supported by graphene sheets of varying lateral sizes, employing a versatile layer-by-layer (LbL) assembly method. We demonstrate that the electrocatalytic activity is highly tunable through the control of the diffusion and electron pathways within the 3-dimensional multilayer electrodes. A larger-sized-graphene-supported electrode exhibited its maximum performance with a thinner film, due to facile charge transfer by the mass transfer limited in the early stage, while a smaller-sized-graphene-supported electrode exhibited its highest current density with higher mass loading in the thicker films by enabling facile mass transfer through increased diffusion pathways. These findings of the tortuous-path effect on the electrocatalytic electrode supported by varying sized graphene provide new insights and a novel design principle into electrode engineering that will be beneficial for the development of effective electrocatalysts.

Layer-by-layer assembled polyaniline/carbon nanomaterial-coated cellulosic aerogel electrodes for high-capacitance supercapacitor applications

Cellulosic aerogel was used as a porous lightweight substrate to layer-by-layer assembly polyaniline and carbon nanomaterials for high capacitance supercapacitor applications.

A composite thin film of simultaneously formed carbon and SnO2 QDs for supercapacitor application

A simple, one-step, low-cost combustion method for the simultaneous formation of two/more component QD thin films

Electrical and Electrochemical Properties of Conducting Polymers

Conducting polymers (CPs) have received much attention in both fundamental and practical studies because they have electrical and electrochemical properties similar to those of both traditional semiconductors and metals. CPs possess excellent characteristics such as mild synthesis and processing conditions, chemical and structural diversity, tunable conductivity, and structural flexibility. Advances in nanotechnology have allowed the fabrication of versatile CP nanomaterials with improved performance for various applications including electronics, optoelectronics, sensors, and energy devices. The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties. The size and morphology of the materials are also discussed as key parameters that affect their major properties. Finally, the latest trends in research on electrochemical capacitors and sensors are introduced through an in-depth discussion of the most remarkable studies reported since 2003.

Carbon-based supercapacitors for efficient energy storage

The advancement of modern electronic devices depends strongly on the highly efficient energy sources possessing high energy density and power density. In this regard, supercapacitors show great promise. Due to the unique hierarchical structure, excellent electrical and mechanical properties, and high specific surface area, carbon nanomaterials (particularly, carbon nanotubes, graphene, mesoporous carbon and their hybrids) have been widely investigated as efficient electrode materials in supercapacitors. This review article summarizes progress in high-performance supercapacitors based on carbon nanomaterials with an emphasis on the design and fabrication of electrode structures and elucidation of charge-storage mechanisms. Recent developments on carbon-based flexible and stretchable supercapacitors for various potential applications, including integrated energy sources, self-powered sensors and wearable electronics, are also discussed.

Graphene/polyaniline@carbon cloth composite as a high-performance flexible supercapacitor electrode prepared by a one-step electrochemical co-deposition method

A one-step electrochemical co-deposition method was used to prepare a graphene/polyaniline composite on carbon cloth for high-performance flexible supercapacitors.

Octadecyl-viologen Photooxidation in Surface Films: Macroscopic Contraction of Langmuir Monolayer by UV Irradiation

The effects of UV radiation on a viologen derivative, octadecylviologen (OV), in Langmuir monolayers at the air-aqueous solution interface and in Langmuir-Blodgett (LB) films have been investigated. Langmuir monolayers suffer a sharp contraction after UV irradiation, clearly visible by the drop in surface pressure or the loss of surface area observed in the surface pressure-area isotherms. The UV-vis reflection measurements reveal a deep change in the OV monolayer caused by a photochemical reaction, which suggests the pyridones formation as photoreaction products. LB films (Z type), before and after being irradiated with UV light, have been studied by using UV-vis absorption and infrared and X-ray photoelectron spectroscopy. The results confirm that after the photodegradation of the viologen films, the presence of oxygen results in the appearance of pyridones as reaction products. This article demonstrates that, in the absence of catalysts, the photooxidation of viologen surface films occurs only under a particular molecular organization imposed by the air-water interface.

Vanadium Pentoxide Nanobelt-Reduced Graphene Oxide Nanosheet Composites as High-Performance Pseudocapacitive Electrodes: ac Impedance Spectroscopy Data Modeling and Theoretical Calculations

Graphene nanosheets and graphene nanoribbons, G combined with vanadium pentoxide (VO) nanobelts (VNBs) and VNBs forming GVNB composites with varying compositions were synthesized via a one-step low temperature facile hydrothermal decomposition method as high-performance electrochemical pseudocapacitive electrodes. VNBs from vanadium pentoxides (VO) are formed in the presence of graphene oxide (GO), a mild oxidant, which transforms into reduced GO (rGO_HT), assisting in enhancing the electronic conductivity coupled with the mechanical robustness of VNBs. From electron microscopy, surface sensitive spectroscopy and other complementary structural characterization, hydrothermally-produced rGO nanosheets/nanoribbons are decorated with and inserted within the VNBs’ layered crystal structure, which further confirmed the enhanced electronic conductivity of VNBs. Following the electrochemical properties of GVNBs being investigated, the specific capacitance C_sp is determined from cyclic voltammetry (CV) with a varying scan rate and galvanostatic charging-discharging (V–t) profiles with varying current density. The rGO-rich composite V₁G₃ (i.e., VO/GO = 1:3) showed superior specific capacitance followed by VO-rich composite V₃G₁ (VO/GO = 3:1), as compared to V₁G₁ (VO/GO = 1:1) composite, besides the constituents, i.e., rGO, rGO_HT and VNBs. Composites V₁G₃ and V₃G₁ also showed excellent cyclic stability and a capacitance retention of >80% after 500 cycles at the highest specific current density. Furthermore, by performing extensive simulations and modeling of electrochemical impedance spectroscopy data, we determined various circuit parameters, including charge transfer and solution resistance, double layer and low frequency capacitance, Warburg impedance and the constant phase element. The detailed analyses provided greater insights into physical-chemical processes occurring at the electrode-electrolyte interface and highlighted the comparative performance of thin heterogeneous composite electrodes. We attribute the superior performance to the open graphene topological network being beneficial to available ion diffusion sites and the faster transport kinetics having a larger accessible geometric surface area and synergistic integration with optimal nanostructured VO loading. Computational simulations via periodic density functional theory (DFT) with and without V₂O₅ adatoms on graphene sheets are also performed. These calculations determine the total and partial electronic density of state (DOS) in the vicinity of the Fermi level (i.e., higher electroactive sites), in turn complementing the experimental results toward surface/interfacial charge transfer on heterogeneous electrodes.

Recent developments in the layer-by-layer assembly of polyaniline and carbon nanomaterials for energy storage and sensing applications. From synthetic aspects to structural and functional characterization

The construction of hybrid polymer-inorganic nanoarchitectures for electrochemical purposes based on the layer-by-layer assembly of conducting polymers and carbon nanomaterials has become increasingly popular over the last decade. This explosion of interest is primarily related to the increasing mastery in the design of supramolecular constructs using simple wet chemical approaches. Concomitantly, this continuous research activity paved the way to the rapid development of nanocomposites or "nanoblends" readily integrable into energy storage and sensing devices. In this sense, the layer-by-layer (LbL) assembly technique has allowed us to access three-dimensional (3D) multicomponent carbon-based network nanoarchitectures displaying addressable electrical, electrochemical and transport properties in which conducting polymers, such as polyaniline, and carbon nanomaterials, such as carbon nanotubes or nanographene, play unique roles without disrupting their inherent functions - complementary entities coexisting in harmony. Over the last few years the level of functional sophistication reached by LbL-assembled carbon-based 3D network nanoarchitectures, and the level of knowledge related to how to design, fabricate and optimize the properties of these 3D nanoconstructs have advanced enormously. This feature article presents and discusses not only the recent advances but also the emerging challenges in complex hybrid nanoarchitectures that result from the layer-by-layer assembly of polyaniline, a quintessential conducting polymer, and diverse carbon nanomaterials. This is a rapidly developing research area, and this work attempts to provide an overview of the diverse 3D network nanoarchitectures prepared up to now. The importance of materials processing and LbL integration is explored within each section and while the overall emphasis is on energy storage and sensing applications, the most widely-used synthetic strategies and characterization methods for "nanoblend" formation and performance evaluation are also presented.

Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: an excellent structure for high-performance flexible solid-state supercapacitors

Thin, robust, lightweight, and flexible supercapacitors (SCs) have aroused growing attentions nowadays due to the rapid development of flexible electronics. Graphene-polyaniline (PANI) hybrids are attractive candidates for high performance SCs. In order to utilize them in real devices, it is necessary to improve the capacitance and the structure stability of PANI. Here we report a hierarchical three-dimensional structure, in which all of PANI nanofibers (NFs) are tightly wrapped inside reduced graphene oxide (rGO) nanosheet skeletons, for high-performance flexible SCs. The as-fabricated film electrodes with this unique structure showed a highest gravimetric specific capacitance of 921 F/g and volumetric capacitance of 391 F/cm³. The assembled solid-state SCs gave a high specific capacitance of 211 F/g (1 A/g), a high area capacitance of 0.9 F/cm², and a competitive volumetric capacitance of 25.6 F/cm³. The SCs also exhibited outstanding rate capability (~75% retention at 20 A/g) as well as excellent cycling stability (100% retention at 10 A/g for 2000 cycles). Additionally, no structural failure and loss of performance were observed under the bending state. This structure design paves a new avenue for engineering rGO/PANI or other similar hybrids for high performance flexible energy storage devices.

Unconventional supercapacitors from nanocarbon-based electrode materials to device configurations

We review here recent developments in unconventional supercapacitors from nanocarbon-based electrode materials to device configurations.

Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes

We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm(-2), and exhibit excellent cycling stability with ∼ 100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.