Porous nanoplatelets wrapped carbon aerogels by pyrolysis of regenerated bamboo cellulose aerogels as supercapacitor electrodes

Cellulose-based aerogel derived N, B-co-doped porous biochar for high-performance CO2 capture and supercapacitor

The remarkable characteristics of porous biochar have generated significant interest in various fields, such as CO2 capture and supercapacitors. The modification of aerogel-derived porous biochar through activation and heteroatomic doping can effectively enhance CO2 adsorption and improve supercapacitor performance. In this study, a novel N, B-co-doped porous biochar (NBCPB) was synthesized by carbonating and activating the N, B dual-doped cellulose aerogel. N and B atoms were doped in-situ using a modified alkali-urea method. The potassium citrate was served as both an activator and a salt template to facilitate the formation of a well-developed nanostructure. The optimized NBCPB-650-1 (where 650 corresponded to activation temperature and 1 represented mass ratio of potassium citrate activator to carbonized NBCPB-400 precursor) displayed the largest micropore volume of 0.40 cm3·g-1 and a high specific surface area of 891 m2·g-1, which contributed to an excellent CO2 adsorption capacity of 4.19 mmol·g-1 at 100 kPa and 25 °C, a high CO2/N2 selectivity, and exceptional reusability (retained >97.5 % after 10 adsorption-desorption cycles). Additionally, the NBCPB-650-1 electrode also delivered a high capacitance of 220.9 F·g-1 at 1 A·g-1. Notably, the symmetrical NBCPB-650-1 supercapacitor exhibited a high energy density of 9 Wh·kg-1 at the power density of 100 W·kg-1. This study not only presents the potential application of NBCPB-650-1 material in CO2 capture and electrochemical energy storage, but also offers a new insight into easy-to-scale production of heteroatomic-modified porous biochar.

Incorporation of Cellulose-Based Aerogels into Textile Structures

Given their exceptional attributes, aerogels are viewed as a material with immense potential. Being a natural polymer, cellulose offers the advantage of being both replenishable and capable of breaking down naturally. Cellulose-derived aerogels encompass the replenish ability, biocompatible nature, and ability to degrade naturally inherent in cellulose, along with additional benefits like minimal weight, extensive porosity, and expansive specific surface area. Even with increasing appreciation and acceptance, the undiscovered possibilities of aerogels within the textiles sphere continue to be predominantly uninvestigated. In this context, we outline the latest advancements in the study of cellulose aerogels' formulation and their diverse impacts on textile formations. Drawing from the latest studies, we reviewed the materials used for the creation of various kinds of cellulose-focused aerogels and their properties, analytical techniques, and multiple functionalities in relation to textiles. This comprehensive analysis extensively covers the diverse strategies employed to enhance the multifunctionality of cellulose-based aerogels in the textiles industry. Additionally, we focused on the global market size of bio-derivative aerogels, companies in the industry producing goods, and prospects moving forward.

The effect of synthesis conditions and process parameters on aerogel properties

Aerogels are remarkable nanoporous materials with unique properties such as low density, high porosity, high specific surface area, and interconnected pore networks. In addition, their ability to be synthesized from various precursors such as inorganics, organics, or hybrid, and the tunability of their properties make them very attractive for many applications such as adsorption, thermal insulation, catalysts, tissue engineering, and drug delivery. The physical and chemical properties and pore structure of aerogels are crucial in determining their application areas. Moreover, it is possible to tailor the aerogel properties to meet the specific requirements of each application. This review presents a comprehensive review of synthesis conditions and process parameters in tailoring aerogel properties. The effective parameters from the dissolution of the precursor step to the supercritical drying step, including the carbonization process for carbon aerogels, are investigated from the studies reported in the literature.

Graphene Nanocomposites as Innovative Materials for Energy Storage and Conversion-Design and Headways

This review mainly addresses applications of polymer/graphene nanocomposites in certain significant energy storage and conversion devices such as supercapacitors, Li-ion batteries, and fuel cells. Graphene has achieved an indispensable position among carbon nanomaterials owing to its inimitable structure and features. Graphene and its nanocomposites have been recognized for providing a high surface area, electron conductivity, capacitance, energy density, charge-discharge, cyclic stability, power conversion efficiency, and other advanced features in efficient energy devices. Furthermore, graphene-containing nanocomposites have superior microstructure, mechanical robustness, and heat constancy characteristics. Thus, this state-of-the-art article offers comprehensive coverage on designing, processing, and applying graphene-based nanoarchitectures in high-performance energy storage and conversion devices. Despite the essential features of graphene-derived nanocomposites, several challenges need to be overcome to attain advanced device performance.

Natural microfibrils/regenerated cellulose-based carbon aerogel for highly efficient oil/water separation

Cellulose-based carbon aerogels as biodegradable and renewable biomass materials have presented potential applications in oil/water separation. Herein, a novel carbon aerogel composed of natural microfibrils/regenerated cellulose (NM/RCA) was directly prepared by economical hardwood pulp as raw material using a novel co-solvent composed of deep eutectic solvent (DES) and N-methyl morpholine-N-oxide monohydrate (NMMO·H₂O). In addition, the morphology and structure of the filiform natural microfibers could be remained after carbonized at 400 ℃, which resulted in a low density (8-10 mg cm^-3), high specific surface area (768.89 m² g^-1) and high sorption capability. In addition, the aerogel exhibited high compressibility, outstanding elasticity, excellent fatigue resistance, and recyclability (80.5% height recovery after repeating 100 cycles at the strain of 80%). Due to the morphology and composition of the carbonized microfiber surface, the superhydrophobic materials with a water contact angle of 151.5°, could sorb various oils and organic solvents with 65-133 times its own weight and maintain 91.9% sorption capacity after 25 cycles. In addition, the aerogels could achieve the continuous separation of carbon tetrachloride (CCl₄) from water with a high flux rate of 11,718.8 L m^-2 h^-1. Therefore, our prepared NM/RCA aerogels are anticipated to have broad potential applications in oil purification and contaminant remediation.

Three‐dimensional nanoporous activated carbon electrode derived from acacia wood for high‐performance supercapacitor

Herein, the novel acacia wood based hierarchical porous activated carbons (AWCs) are easily prepared, low cost and have excellent characterization, such as special biomass nanopores via structural stability and large specific surface areas. Activating agents such as KOH, ZnCl2, and H3PO4 have been used to convert acacia wood carbon into active carbons such as AWC-K, AWC-Z, and AWC-P, respectively, which are named after the activating agent. As a supercapacitor electrode, the AWC-K sample has a high yield was 69.8%, significant specific surface area of 1563.43 m2g−1 and layer thickness of 4.6 mm. Besides that, it showed specific capacitance of 224.92 F g−1 at 0.5 A g−1 in 2 M KOH as electrolyte. In addition, the AWC-K//AWC-K symmetrical supercapacitor device displays high energy density of 23.98 Wh kg−1 at 450 W kg−1 power density with excellent cycling number stability was 93.2% long lifetime of 10,000 cycles using 0.5 M Na2SO4 as electrolyte. The high electrochemistry performance mainly contributed the special biomass pores structure. Therefore, the presented approach opens new avenues in supercapacitor applications to meet energy storage.

Biopolymers-Derived Materials for Supercapacitors: Recent Trends, Challenges, and Future Prospects

Supercapacitors may be able to store more energy while maintaining fast charging times; however, they need low-cost and sophisticated electrode materials. Developing innovative and effective carbon-based electrode materials from naturally occurring chemical components is thus critical for supercapacitor development. In this context, biopolymer-derived porous carbon electrode materials for energy storage applications have gained considerable momentum due to their wide accessibility, high porosity, cost-effectiveness, low weight, biodegradability, and environmental friendliness. Moreover, the carbon structures derived from biopolymeric materials possess unique compositional, morphological, and electrochemical properties. This review aims to emphasize (i) the comprehensive concepts of biopolymers and supercapacitors to approach smart carbon-based materials for supercapacitors, (ii) synthesis strategies for biopolymer derived nanostructured carbons, (iii) recent advancements in biopolymer derived nanostructured carbons for supercapacitors, and (iv) challenges and future prospects from the viewpoint of green chemistry-based energy storage. This study is likely to be useful to the scientific community interested in the design of low-cost, efficient, and green electrode materials for supercapacitors as well as various types of electrocatalysis for energy production.

Green Nanocomposites for Energy Storage

The green nanocomposites have elite features of sustainable polymers and eco-friendly nanofillers. The green or eco-friendly nanomaterials are low cost, lightweight, eco-friendly, and highly competent for the range of energy applications. This article initially expresses the notions of eco-polymers, eco-nanofillers, and green nanocomposites. Afterward, the energy-related applications of the green nanocomposites have been specified. The green nanocomposites have been used in various energy devices such as solar cells, batteries, light-emitting diodes, etc. The main focus of this artifact is the energy storage application of green nanocomposites. The capacitors have been recognized as corporate devices for energy storage, particularly electrical energy. In this regard, high-performance supercapacitors have been proposed based on sustainable nanocomposites. Consequently, this article presents various approaches providing key knowledge for the design and development of multi-functional energy storage materials. In addition, the future prospects of the green nanocomposites towards energy storage have been discussed.

Nitrogen-doped carbon composite derived from ZIF-8/polyaniline@cellulose-derived carbon aerogel for high-performance symmetric supercapacitors

Cellulose derived carbon aerogel (CA) with unique three-dimensional network coated with polyaniline (PANI) on its surface is used as a scaffolding framework to anchor ZIF-8. The designed ZIF-8 derived porous carbon (ZC)/PANI@CA (ZPCA) hybrid carbon composite through a facile solution immersion chemical route and subsequent carbonization process is employed as electrode for supercapacitor, which has contributed a large specific surface area, a hierarchical porous structure and reasonable N content (up to 6.27 at.%). The synthesized ZPCA electrode achieves an outstanding capacitance of 388 F g^-1 at 0.5 A g^-1 as well as an excellent cycling performance. More inspiringly, the symmetric supercapacitor based ZPCA achieves a high energy density of 13.4 Wh kg^-1 at a power density of 250 W kg^-1 using 2 M KOH aqueous solution, and an ultrahigh energy density of 81.8 Wh kg^-1 at a power density of 950 W kg^-1 is realized using Et₄NBF₄/AN electrolyte.

Biorefinery Approach for Aerogels

According to the International Energy Agency, biorefinery is "the sustainable processing of biomass into a spectrum of marketable bio-based products (chemicals, materials) and bioenergy (fuels, power, heat)". In this review, we survey how the biorefinery approach can be applied to highly porous and nanostructured materials, namely aerogels. Historically, aerogels were first developed using inorganic matter. Subsequently, synthetic polymers were also employed. At the beginning of the 21st century, new aerogels were created based on biomass. Which sources of biomass can be used to make aerogels and how? This review answers these questions, paying special attention to bio-aerogels' environmental and biomedical applications. The article is a result of fruitful exchanges in the frame of the European project COST Action "CA 18125 AERoGELS: Advanced Engineering and Research of aeroGels for Environment and Life Sciences".

Cellulose Aerogel Derived Hierarchical Porous Carbon for Enhancing Flavin-Based Interfacial Electron Transfer in Microbial Fuel Cells

The flavin-based indirect electron transfer process between electroactive bacteria and solid electrode is crucial for microbial fuel cells (MFCs). Here, a cellulose-NaOH-urea mixture aerogel derived hierarchical porous carbon (CPC) is developed to promote the flavin based interfacial electron transfer. The porous structure of the CPC can be tailored via adjusting the ratio of urea in the cellulose aerogel precursor to obtain CPCs with different type of dominant pores. According to the electrocatalytic performance of different CPC electrodes, the CPCs with higher meso- and macropore area exhibit greatly improved flavin redox reaction. While, the CPC-9 with appropriate porous structure achieves highest power density in Shewanella putrefaciens CN32 MFC due to larger active surface for flavin mediated interfacial electron transfer and higher biofilm loading. Considering that the CPC is just obtained from the pyrolysis of the cellulose-NaOH-urea aerogel, this work also provides a facile approach for porous carbon preparation.

Scalable Top-to-Bottom Design on Low Tortuosity of Anisotropic Carbon Aerogels for Fast and Reusable Passive Capillary Absorption and Separation of Organic Leakages

Creation of sustainable, cost-effective, and scalable absorbents with ideal absorption properties is a worldwide challenge because many high-performance absorbents are still restricted in laboratory scope due to several critical defects (like complex and eco-unfriendly synthesis process, high cost, and difficulty in large-scale production). Herein, a facile and scalable top-to-bottom design is proposed to create a kind of novel anisotropic carbon aerogels with low tortuosity of stacked laminated structure, derived from the hierarchical cellular channels of balsa wood. By virtue of this unique structure and favorable oleophilicity, fast passive capillary absorption with low flow resistance is achieved (as demonstrated by the theoretical modeling). As a result, the anisotropic carbon aerogels have quite sensitive selectivity to separate organic pollutants from water, broad-spectrum and high absorption capacity for different organic liquids (13 277-31 597 mg g^-1), and superior recyclability (98.7% absorption capacity retention after five cycles). Combining these outstanding performances with a cheap preparation strategy as well as good environmental friendliness, this work provides a kind of potential scalable materials for efficient reusable absorption and separation of organic leakages.

An l-glutaminase enzyme reactor based on porous bamboo sticks and its application in enzyme inhibitors screening

Inspired by the porous and fibrous structure of commercially available bamboo, herein we created an l-glutaminase enzyme reactor based on bamboo sticks. The enzyme was immobilized onto the bamboo sticks through a glutaraldehyde modification to achieve covalent bonding. The enzymatic hydrolysis efficiency of the prepared l-glutaminase@bamboo sticks based porous enzyme reactor was evaluated by chiral ligand exchange capillary electrochromatography using l-glutamine as the substrate. l-glutaminase@bamboo exhibited improved enzymatic hydrolysis performances, including high hydrolysis efficiency (maximum rate V_max: two fold higher than the free enzyme), prolonged stability (14 days) and good reusability. l-Glutaminase@bamboo sticks also expanded application capability in pharmaceutical industry in enzyme inhibitor screening. These excellent properties could be attributed to the micropores of bamboo sticks, which led to the fast enzymatic kinetics. The results suggest that the pores of bamboo sticks played an important role in the proposed enzyme reactor during the hydrolysis of l-glutamine and l-glutaminase inhibitor screening.

Bioinspired aerogel based on konjac glucomannan and functionalized carbon nanotube for controlled drug release

In this study, a facile marine bioinspired surface modification approach for carboxyl-functionalized multiwalled carbon nanotube (CCNT) and enhanced interfacial adhesion with the konjac glucomannan (KGM) matrix were illustrated to develop aerogels. Combined with FT-IR, XRD, Raman, TGA, XPS and SEM results, it was indicated that functionalized CCNT (PCCNT) is a reinforcer through hydrogen bond interactions in the aerogel formation process, which could be the main reason for the enhancement. The swelling and vitro release behavior of KGM/PCCNT aerogels were studied under two conditions using the drug 5-fluorouracil (5-FU). The release amount of 5-FU incorporated into KGM/PCCNT4 aerogel was about 48% at pH 1.2 and 62% at pH 6.8 after11 h, respectively. The results showed that the release rate of 5-FU from the KGM/PCCNT4 aerogel using PCCNT could be effectively controlled, suggesting potential applications for it as a drug carrier in targeted delivery in the biomedical filed.

Nanomaterials in Advanced, High-Performance Aerogel Composites: A Review

Aerogels are one of the most interesting materials of the 21st century owing to their high porosity, low density, and large available surface area. Historically, aerogels have been used for highly efficient insulation and niche applications, such as interstellar particle capture. Recently, aerogels have made their way into the composite universe. By coupling nanomaterial with a variety of matrix materials, lightweight, high-performance composite aerogels have been developed for applications ranging from lithium-ion batteries to tissue engineering materials. In this paper, the current status of aerogel composites based on nanomaterials is reviewed and their application in environmental remediation, energy storage, controlled drug delivery, tissue engineering, and biosensing are discussed.

Sustainable Utilization of Biomass Refinery Wastes for Accessing Activated Carbons and Supercapacitor Electrode Materials

Biomass processing wastes (humins) are anticipated to become a large-tonnage solid waste in the near future, owing to the accelerated development of renewable technologies based on utilization of carbohydrates. In this work, the utility of humins as a feedstock for the production of activated carbon by various methods (pyrolysis, physical and chemical activation, or combined approaches) was evaluated. The obtained activated carbons were tested as potential electrode materials for supercapacitor applications and demonstrated combined micro- and mesoporous structures with a good capacitance of 370 F g^-1 (at a current density of 0.5 A g^-1 ) and good cycling stability with a capacitance retention of 92 % after 10 000 charge/discharge cycles (at 10 A g^-1 in 6 m aqueous KOH electrolyte). The applicability of the developed activated carbon for practical usage as a supercapacitor electrode material was demonstrated by its successful utilization in symmetric two-electrode cells and by powering electric devices. These findings provide a new approach to deal with the problem of sustainable wastes utilization and to advance challenging energy storage applications.

Cellulose Aerogels: Synthesis, Applications, and Prospects

Due to its excellent performance, aerogel is considered to be an especially promising new material. Cellulose is a renewable and biodegradable natural polymer. Aerogel prepared using cellulose has the renewability, biocompatibility, and biodegradability of cellulose, while also having other advantages, such as low density, high porosity, and a large specific surface area. Thus, it can be applied for many purposes in the areas of adsorption and oil/water separation, thermal insulation, and biomedical applications, as well as many other fields. There are three types of cellulose aerogels: natural cellulose aerogels (nanocellulose aerogels and bacterial cellulose aerogels), regenerated cellulose aerogels, and aerogels made from cellulose derivatives. In this paper, more than 200 articles were reviewed to summarize the properties of these three types of cellulose aerogels, as well as the technologies used in their preparation, such as the sol⁻gel process and gel drying. In addition, the applications of different types of cellulose aerogels were also introduced.