Conductive metal–organic frameworks (c-MOFs) show great potential in electrochemical energy storage thanks to their high electrical conductivity and highly accessible surface areas. However, there ...are significant challenges in processing c-MOFs for practical applications. Here, we report on the fabrication of c-MOF nanolayers on cellulose nanofibers (CNFs) with formation of nanofibrillar CNF@c-MOF by interfacial synthesis, in which CNFs serve as substrates for growth of c-MOF nanolayers. The obtained hybrid nanofibers of CNF@c-MOF can be easily assembled into freestanding nanopapers, demonstrating high electrical conductivity of up to 100 S cm–1, hierarchical micromesoporosity, and excellent mechanical properties. Given these advantages, the nanopapers are tested as electrodes in a flexible and foldable supercapacitor. The high conductivity and hierarchical porous structure of the electrodes endow fast charge transfer and efficient electrolyte transport, respectively. Furthermore, the assembled supercapacitor shows extremely high cycle stability with capacitance retentions of >99% after 10000 continuous charge–discharge cycles. This work provides a pathway to develop flexible energy storage devices based on sustainable cellulose and MOFs.
One of the biggest challenges we will face over the next few decades is finding a way to power the future while maintaining strong socioeconomic growth and a clean environment. A transition from the ...use of fossil fuels to renewable energy sources is expected. Cellulose, the most abundant natural biopolymer on earth, is a unique, sustainable, functional material with exciting properties: it is low‐cost and has hierarchical fibrous structures, a high surface area, thermal stability, hydrophilicity, biocompatibility, and mechanical flexibility, which makes it ideal for use in sustainable, flexible energy storage devices. This review focuses on energy storage applications involving different forms of cellulose (i.e., cellulose microfibers, nanocellulose fibers, and cellulose nanocrystals) in supercapacitors, with particular emphasis on new trends and performance considerations relevant to these fields. Recent advances and approaches to obtaining high capacity devices are evaluated and the limitations of cellulose‐based systems are discussed. For the first time, a combination of device‐specific factors such as electrode structures, mass loadings, areal capacities, and volumetric properties are taken into account, so as to evaluate and compare the energy storage performance and to better assess the merits of cellulose‐based materials with respect to real applications.
The most exciting recent advances in the supercapacitor application of cellulose composites based on different types of cellulose are summarized. In particular, this work focuses on parameters of cellulose‐based electrodes which affect the overall capacity performance metrics of supercapacitors. Approaches toward the realisation of high active masses and high volumetric capacitances for cellulose based electrodes are discussed.
Solar energy fits well with the increasing demand for clean sustainable energy. This paper describes a freestanding hybrid film composed of a conductive metal–organic framework layered on cellulose ...nanofibres which enables efficient solar power generation. The working principle, which is different from the mechanisms of traditional photovoltaic or solid-state thermoelectric generation systems, is based on ionic thermophoresis and electrokinetic effects. Given the strong light absorption and low thermal conductivity of the film, a large thermal gradient can be produced on the surface under light illumination to induce fast water evaporation in an aqueous electrolyte. The thermal gradient and the water evaporation drive selective ion transport through the charged nanochannels, which generates ionic thermoelectric and streaming potentials, respectively. The assembled device can produce a sustained voltage output of ∼1.1 V, with a high power density of up to 15 W m −2 under one sun illumination. This study provides a new route for solar power generation.
Freestanding nanopapers were fabricated by the assembly of metal–organic frameworks (MOFs) onto cellulose nanofibers (CNFs). The CNFs are wrapped by continuously nucleated MOF layers (CNF@MOF) by ...interfacial synthesis, with the charge density on the surface of the CNFs and the dosage of the surfactant polyvinylpyrrolidone (PVP) being carefully adjusted. The obtained CNF@MOF nanofibers with long‐range, continuous, hybrid nanostructures were very different to the composites formed by aggregation of MOF nanoparticles on the substrates. Four typical MOFs (HKUST‐1, Al‐MIL‐53, Zn‐MOF‐74, ZIF‐CO3‐1) were successfully grown onto CNFs in aqueous solutions and further fabricated into freestanding nanopapers. Because of their unique nanostructures and morphologies, the corresponding flexible nanopapers exhibit hierarchical meso‐micropores, high optical transparency, high thermal stability, and high mechanical strength. A proof‐of‐concept study shows that the CNF@MOF nanopapers can be used as efficient filters to separate volatile organic compounds (VOCs) from the air. This work provides a new path for structuring MOF materials that may boost their practical application.
Freestanding nanopapers are herein fabricated for the first time by the assembly of metal–organic frameworks wrapping on cellulose nanofibers (see figure). The nanopapers exhibit hierarchical meso‐ and micropores, high optical transparency, excellent mechanical strength, flexibility, and high thermal stability. They may find use as efficient filters for separating volatile organic compounds.
An All-Organic Proton Battery Emanuelsson, Rikard; Sterby, Mia; Strømme, Maria ...
Journal of the American Chemical Society,
04/2017, Letnik:
139, Številka:
13
Journal Article
Recenzirano
Rechargeable batteries that use organic matter as the capacity-carrying material have previously been considered a technology for the future. Earlier batteries in which both the anode and cathode ...consisted of organic material required significant amounts of conductive additives and were often based on metal-ion electrolytes containing Li+ or Na+. However, we have used conducting poly(3,4-ethylenedioxythiophene) (PEDOT), functionalized with anthraquinone (PEDOT-AQ) or benzonquinone (PEDOT-BQ) pendant groups as the negative and positive electrode materials, respectively, to make an all-organic proton battery devoid of metals. The electrolyte consists of a proton donor and acceptor slurry containing substituted pyridinium triflates and the corresponding pyridine base. This slurry allows the 2e–/2H+ quinone/hydroquinone redox reactions while suppressing proton reduction in the battery cell. By using strong (acidic) proton donors, the formal potential of the quinone redox reactions is tuned into the potential region in which the PEDOT backbone is conductive, thus eliminating the need for conducting additives. In this all-organic proton battery cell, PEDOT-AQ and PEDOT-BQ deliver 103 and 120 mAh g–1, which correspond to 78% and 75%, respectively, of the theoretical specific capacity of the materials at an average cell potential of 0.5 V. We show that PEDOT-BQ determines the cycling stability of the device while PEDOT-AQ provides excellent reversibility for at least 1000 cycles. This proof-of-concept shows the feasibility of assembling all-organic proton batteries which require no conductive additives and also reveals where the challenges and opportunities lie on the path to producing plastic batteries.
All‐polymer and paper‐based energy storage devices have significant inherent advantages in comparison with many currently employed batteries and supercapacitors regarding environmental friendliness, ...flexibility, cost and versatility. The research within this field is currently undergoing an exciting development as new polymers, composites and paper‐based devices are being developed. In this report, we review recent progress concerning the development of flexible energy storage devices based on electronically conducting polymers and cellulose containing composites with particular emphasis on paper‐based batteries and supercapacitors. We discuss recent progress in the development of the most commonly used electronically conducting polymers used in flexible device prototypes, the advantages and disadvantages of this type of energy storage devices, as well as the two main approaches used in the manufacturing of paper‐based charge storage devices.
Recent progress within the field of conducting polymer and cellulose‐based charge storage is reviewed with particular emphasis on the development of environmentally friendly, versatile and flexible paper‐based batteries and supercapacitors. The latter devices, which can be constructed from a few paper sheets, enable the realization of a range of new types of charge storage devices.
Covalent organic frameworks (COFs) constitute a family of crystalline porous polymers that are being studied for electrochemical energy storage. However, their low electrical conductivity and poor ...processability have largely limited their electrochemical performances and practical applications. Here, we develop an interfacial synthesis method to grow few-layered 2D redox-active COFs (DAAQ-TFP COF) on the surface of carboxylated carbon nanotubes (c-CNTs) in order to fabricate core-shell c-CNT@COF nanofibers, for which the thickness and the morphology of the COF nanolayers can be finely controlled. When using the c-CNT@COFs as electrode material, the tailored nanostructure with high electrical conductivity allows efficient electron transfer, while the few-layered structure of the COF promotes fast electrolyte ion diffusion in the near-surface region, which results in an efficient utilization of the redox active sites in COF. More significantly, c-CNT@COFs with nanofibrous structure show good processability and can be assembled into freestanding and flexible nanopapers with the assistance of Cladophora cellulose. Given the good electrochemical performance and excellent flexibility, the nanopaper electrodes are assembled into flexible hybrid capacitors, showing high areal capacitance and extremely long lifetime. This study provides a new pathway for the development of next generation sustainable and flexible energy storage devices based on COFs and cellulose materials.
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•Redox-active COF nanolayers with controlled morphology and thickness were fabricated on the surface of CNT.•The obtained c-CNT@COF nanofibers showed high electrical conductivity and good processability.•Interweaving the c-CNT@COF nanofibers with Cladophora cellulose and CNTs formed freestanding and flexible nanopapers.•The nanopaper electrodes were assembled into flexible and foldable hybrid capacitors.
•Efficient method for crosslinking DAC beads with chitosan.•Highly porous beads with high specific surface area produced.•Beads stable at highly alkaline conditions.•High adsorption capacity for ...Congo red dye.
Micrometer sized 2,3-dialdehyde cellulose (DAC) beads were produced via a recently developed method relying on periodate oxidation of Cladophora nanocellulose. The produced dialdehyde groups and pristine hydroxyl groups provided the DAC beads with a vast potential for further functionalization. The sensitivity of the DAC beads to alkaline conditions, however, limits their possible functionalization and applications. Hence, alkaline-stable and porous cellulose beads were prepared via a reductive amination crosslinking reaction between 2,3-dialdehyde cellulose beads and chitosan. The produced materials were thoroughly characterized with different methods. The reaction conditions, including the amount of chitosan used, conditions for reductive amination, reaction temperature and time, were investigated and the maintained morphology of the beads after exposure to 1M NaOH (aq.) was verified with SEM. Different washing and drying procedures were used and the results were studied by SEM and BET analysis. Furthermore, FTIR, TGA, EDX, XPS, DLS and elemental analysis were performed to characterize the properties of the prepared beads. Finally, the alkaline-stable porous chitosan cross-linked 2,3-dialdehyde cellulose beads were applied as adsorbent for the dye Congo red. The crosslinked beads displayed fast and high adsorption capacity at pH 2 and good desorption properties at pH 12, providing a promising sorption material.
Electrodes based on organic matter operating in aqueous electrolytes enable new approaches and technologies for assembling and utilizing batteries that are difficult to achieve with traditional ...electrode materials. Here, we report how thiophene‐based trimeric structures with naphthoquinone or hydroquinone redox‐active pendent groups can be processed in solution, deposited, dried and subsequently polymerized in solid state to form conductive (redox) polymer layers without any additives. Such post‐deposition polymerization offers efficient use of material, high mass loading (up to 10 mg cm−2) and good flexibility in the choice of substrate and coating method. By employing these materials as anode and cathode in an acidic aqueous electrolyte a rocking‐chair proton battery is built. The battery shows good cycling stability (85 % after 500 cycles), withstands rapid charging, with full capacity (60 mAh g−1) reached within 100 seconds, allows for direct integration with photovoltaics, and retains its favorable characteristics even at −24 °C.
Combining naphthoquinone or hydroquinone redox‐active pendent groups, an all‐organic battery was designed to operate in aqueous electrolyte. This battery does not only show good capacity retention over 500 cycles but can also be charged ultra‐rapidly using a potential step, enabling easy integration with an organic solar cell.
•Ca2+-crosslinked nanocellulose self-standing hydrogels are proposed for wound healing applications.•The hydrogels could maintain a suitable moist environment for different types of wounds according ...to water retention tests.•The hydrogels present excellent biocompatibility towards dermal fibroblasts and blood-derived monocytes/macrophages.•The hydrogels are non pro-inflammatory in terms of cytokine secretion and reactive oxygen species production.•The potential of nanofibrillated cellulose hydrogels for the development of advanced wound healing dressings is highlighted.
Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented biocompatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the material´s potential to maintain a suitable moist environment for different type of wounds. The hydrogels did not affect dermal fibroblasts monolayer cultures upon direct contact, as cell monolayers remained intact after application, incubation and removal of the materials. Inflammatory response studies with blood-derived mononuclear cells revealed the inert nature of the hydrogels in terms of cytokine secretion and reactive oxygen species production. Results highlight the great potential of ion-crosslinked NFC hydrogels for the development of advanced wound dressings, where further functionalization of the material could lead to improved properties towards the healing of specific wound types.
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