3D Carbon Aerogel Research Articles

Three dimensional carbon aerogel for microwave absorption from chitosan

3D carbon aerogel is widely used for the fabrication of microwave absorption materials as it is characterized by tunable dielectric properties, ultra-low density, high porosity, and ultra-large specific surface area. We synthesize phenolic aerogels using chitosan as a soft template, phenol and formaldehyde as carbon sources, and acetic acid as a catalyst. We explore the influence of the carbonization temperature on the materials' microstructure, chemical composition, and absorption performance. We also study the mechanism of microwave absorption. The results revealed that carbonized carbon aerogel is characterized by a typical porous structure and a large specific surface area. It was also observed that the degree of carbonization improved with an increase in the carbonization temperature. The minimum reflection loss for the carbon aerogel (carbonized at 700 °C) with a filler loading of 15 wt % is recorded to be −41 dB at 12.24 GHz. The effective absorption bandwidth can reach 5.24 GH at 2.5 mm. The minimum reflection loss for the carbon aerogel (carbonized at 750 °C) with a filler loading of 8 wt % was −36 dB at 13.12 GHz. Under these conditions, the effective absorption bandwidth can reach 4.88 GH. When the thickness is only 1.5 mm, the minimum reflection loss is −14 dB, and the effective bandwidth can reach 4.2 GHz. The fine absorption performance can be attributed to the excellent dielectric constant of the material and the property of impedance matching. The results indicate that the synthesized lightweight and efficient carbon can promote the development and application of microwave-absorbing materials.

Bimetallic Bi–Sn micro-/nanospheres@cellulose nanocrystal derived carbon aerogel composite anode for high-performance Mg-ion batteries

Magnesium-ion batteries (MIBs) have recently received widespread attention for energy storage. Nevertheless, the development of suitable anode materials remains significant challenges. Herein, a novel bimetallic Bi–Sn micro-/nanospheres homogenously embedded in cellulose nanocrystal derived carbon aerogel (CNC-CA@Bi–Sn) composite was constructed through a facile ion-induced gelation and in-situ thermal reduction processes. As an anode for MIBs, the CNC-CA@Bi–Sn electrode delivered high reversible specific capacity of 334 mAh g−1 after 100 cycles at 100 mA g−1, superior rate performance and long cycling lifespan with a reversible capacity of 187 mAh g−1 (ultralow capacity fade rate of 0.099% per cycle) at high current density of 1000 mA g−1 for 500 cycles. The excellent electrochemical performance should be attributed to the synergetic effects of unique three-dimensional (3D) nanoporous structure, dual phase microstructure and rich phase boundaries, biphase-based and carbon buffering matrices, which could effectively accommodate the large volume changes during the demagnesiation/magnesiation processes, significantly shorten diffusion lengths and improve the diffusion kinetics of Mg2+. This work provided a promising strategy for the design and synthesis of Bi–Sn biphasic material coupling with 3D carbon aerogel, which could be extended to other novel electrodes for high-performance MIBs.

Biomass-derived photothermal carbon aerogel for efficient solar-driven seawater desalination

Solar-driven interface evaporation is an effective method to produce fresh water to alleviate the shortage of water resources. However, there are still challenges in preparing photothermal conversion materials with high evaporation rate, high photothermal conversion efficiency and low cost. Herein, a 3D carbon aerogel with excellent photothermal conversion performance was prepared by using environmental-friendly biomass materials as the matrix. The hydrophilic 3D photothermal carbon aerogel with low thermal conductivity was prepared by depositing polydopamine and loading Cu nanoparticles (CuNPs) on the surface of bacterial cellulose nanofibers. The deposition of PDA improved the mechanical properties and hydrophilicity of carbon aerogel, and the introduction of CuNPs further enhanced the photothermal conversion performance of carbon aerogel. Interestingly, the side temperature of 3D carbon aerogel was lower than the ambient temperature in the evaporation process, which could absorb energy from the environment and significantly improve the photothermal conversion efficiency, giving rise to the impressive water evaporation rate (2.07 kg·m−2·h−1) and photothermal conversion efficiency (115.36%) of 3D carbon aerogel under 1 sun. Moreover, the prepared 3D carbon aerogel had excellent purification effect on seawater, strong acid/alkali and dye solution, demonstrating its broad application prospect in the field of solar-driven seawater desalination.

Scalable fabrication of quantum-sized CoS1.97 nanoparticles anchoring on biomass carbon aerogel for energy storage application

Exploiting earth-abundant and cost-efficient electrode materials is an effective strategy to fulfil the urgent demand for high-efficiency energy-storage. Carbon aerogels (CAs) with conductive skeleton and large specific area have attracted significant attention in electrode materials. However, how to achieve the large-scale production of CAs with both high energy storage capability and reasonable cost still remains a challenge. Herein, a scalable and cost-effective route toward constructing cobalt sulfide nanoparticles/carbon aerogel (CoS1.97/CA) hybrid electrode is described. Quantum-sized CoS1.97 nanoparticles are synthesized by in situ selective vulcanization of Co2+ absorbed on the carbonaceous watermelon tissues which acts as current collector for the fast electrons transfer. Quantum-sized CoS1.97 nanoparticles provide abundant active sites for the redox reaction with electrolyte ions in the hybrid electrode, thus leading to an excellent electrochemical capacity of 1715 C g−1. Furthermore, an asymmetric supercapacitor is assembled by employing CoS1.97/CA-500 as positive electrode and CA as negative electrode, which delivers the highest capacity of 51.5 mAh g−1 and energy density of 36.4 Wh kg−1. In addition, an impressive cycling span of 20000 cycles is obtained with capacity retention reaching up to 98.9%, demonstrating its high stability for real-world application. These findings demonstrate the bio-inspired and cost-effective development of 3D carbon aerogel electrode for incorporating with other novel materials for the applications in energy storage.

Integrating adsorption and in situ advanced oxidation for the treatment of organic wastewater by 3D carbon aerogel embedded with Fe-doped carbonitrides.

Wastewater containing organic pollutants with high toxicity and poor biodegradability poses a considerable threat to human health and the ecosystem. Although adsorption and advanced oxidation processes (AOPs) are currently the most widely used technologies for wastewater treatment, limitations of these two independent processes make the treatment effect unsatisfactory. Herein, a system of integrating adsorption and subsequent in situ AOPs is established by a 3D carbon aerogel embedded with Fe-doped carbonitrides (Fe-NC/CAG). The SEM and BET analysis demonstrate that Fe-NC/CAG possesses porous structures with a specific surface area of 518.7 m2/g. The XRD result indicates the formation of Fe0 and Fe3O4 in Fe-NC/CAG. The impacts of operational parameters such as Fe-NC/CAG dosage, pollutants concentration, temperature, initial pH, and inorganic ions on the adsorption efficiency are investigated. The adsorption kinetics is predominantly based on the pseudo-second-order model. After adsorbing organic pollutants, the Fe-NC/CAG is immersed in peroxymonosulfate (PMS) solution. The adsorbed pollutants are in situ degraded by PMS-based AOPs, leading to the regeneration of Fe-NC/CAG. At optimum conditions, the integrating process established by Fe-NC/CAG achieves over 90% removal of antibiotics, phenolics, and dyes as well as keeps stable performance even after 6 cycles. This integrating adsorption and AOPs system is expected to open up a rich field for wastewater treatment.

Sustainable regeneration of a honeycomb carbon aerogel used as a high-capacity adsorbent for Fluoxetine removal

Pharmaceuticals and personal care products (PPCPs) harm ecosystems and human health. The focus is now being put on regulating discharges at wastewater treatment plants (WWTPs). Stressful and lonely lifestyles, accentuated by the COVID-19 outbreak, have led to an increase in the consumption of antidepressants, particularly in the form of Fluoxetine (FLX). A highly effective process for the removal of PPCPs is of key importance for the economic feasibility of the process in the industry. Consequently, a high-capacity adsorption/regeneration system is crucial to solving this problem. In this study, the removal of FLX by an adsorption process and the subsequent in situ regeneration of the adsorbent was evaluated in successive cycles. NQ40 honeycomb 3D carbon aerogel was employed as a high-capacity adsorbent, obtaining uptakes of 125.24 mg/g. A detailed study of NQ40 and the mechanisms governing the adsorption process was conducted, with chemisorption and intra-particle diffusion playing the main role. A Fenton and a Fenton-like process with peroxymonosulfate (PMS) were evaluated for regeneration purposes, finding hydrogen peroxide to be more efficient in removing a high concentration of FLX. A regeneration capacity of 98.85% was achieved in the first NQ40 adsorption-regeneration cycle and 98.04% in the second one, without negatively affecting the structural characteristics of NQ40. Therefore, with a high porosity, low density, high biocompatibility, high chemical stability and 3D structural stability, this aerogel is at the forefront of novel high-capacity adsorbent materials for industrial-scale use in WWTPs.

3D carbon aerogel from waste corrugated cardboard as a photothermal reservoir for solar steam generation.

Three-dimensional carbon aerogel (CA800) was prepared from waste corrugated cardboard (WCC) by the procedure of slurrying, solvent replacement, drying, and carbonization in turn, and the product was explored as an all-in-one evaporator for solar steam generation without bulk water. Carbonization of the precursor was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer. Results showed that CO2, CO, furfural, and levoglucosan were released during pyrolysis of WCC within the range of 300 to 390 °C, while polymerization of newly formed char between 390 and 580 °C mainly resulted in the formation of CO2 and CO. Both pyrolysis and polymerization reactions can be described by diffusion-controlled mechanisms, and the activation energies were 155.62 and 11.17 kJ mol-1, respectively. CA800 possessed a BET surface area of 210 m2 g-1. Light can be effectively absorbed and converted into heat by CA800, and its surface temperature achieving 73 °C under 1 kW m-2 irradiation. CA800 had outstanding wettability due to the presence of hydrophilic minerals in carbon matrix, and it was able to store as much as 15 times its own weight in water due to its abundant interconnected channels and hierarchical nanopores. Solar-driven water evaporation rate over CA800 achieved 1.72 kg m-2 (normalized to projection area), which was nearly 6 times higher than the value achieved by the bare water system. The photothermal conversion efficiency was calculated to be 118 %, and the overestimated efficiency was caused by the environmental energy gained by the cold evaporation surface of CA800.

Multifunctional N and O co-doped 3D carbon aerogel as a monolithic electrode for either enzyme immobilization, oxygen reduction and showing supercapacitance

Herein, a novel N and O co-doped three dimensional (3D) hybrid carbon aerogel (CA) was prepared by a two-step carbonization technology, i.e. preoxidation process (240 °C, air atmosphere) and carbonization process (600∼1000 °C, nitrogen atmosphere). It was found that the peroxidation process could improve the thermostability and heteroatoms content during the carbonization. The obtained CA samples inherited their original morphology of “string-bead” network and had a higher heteroatoms content, while the control samples did not. We focused on the application of this CA in either lactate oxidase-modified, super-capacitive and oxygen reductive electrodes. The fabricated lactate-powered integrated electronic skin could produce a maximum power density of ca. 1.3 mW cm−2, which allowed powering a multiplexed metabolic electronic in situ. The sample of CF-PVA-PANI800 showed the highest specific capacitance of 427.2 F g−1 at a discharge specific current of 0.5 A g−1. The synergistic effect of the N functionalities endowed the sample of CF-PVA-PANI900 with similar electrocatalytic activity to a 20 wt% commercial Pt/C catalyst for ORR. This fabrication strategy of carbon aerogel may provide a new alternative for preparing more heteroatom-doped 3D carbon materials in future.

Biomass-Derived Carbon Materials: Controllable Preparation and Versatile Applications.

Biomass-derived carbon materials (BCMs) are encountering the most flourishing moment because of their versatile properties and wide potential applications. Numerous BCMs, including 0D carbon spheres and dots, 1D carbon fibers and tubes, 2D carbon sheets, 3D carbon aerogel, and hierarchical carbon materials have been prepared. At the same time, their structure-property relationship and applications have been widely studied. This paper aims to present a review on the recent advances in the controllable preparation and potential applications of BCMs, providing a reference for future work. First, the chemical compositions of typical biomass and their thermal degradation mechanisms are presented. Then, the typical preparation methods of BCMs are summarized and the relevant structural management rules are discussed. Besides, the strategies for improving the structural diversity of BCMs are also presented and discussed. Furthermore, the applications of BCMs in energy, sensing, environment, and other areas are reviewed. Finally, the remaining challenges and opportunities in the field of BCMs are discussed.

Additive Manufacturing Assisted Solvent Casting of 3D Free-Standing Carbonaceous Hydrogels and Aerogels As Electrodes for Supercapacitors

In a quest for renewable and highly efficient energy storage devices, carbonaceous hydrogels obtained from biopolymers have received much attention owing to their multifunctional properties [1]. The ability to fine-tune the structures of these hydrogels and the prospects of fabricating 3D hydrogels-based carbon electrodes with highly porous and interconnected nanostructure is believed to provide efficient migration of electrolyte ions and electrons. Even though additive manufacturing (AM) of hydrogels with 3D structures could simplify the fabrication, the printability of each material varies greatly. Furthermore, the mechanical properties of hydrogels are often too weak to withstand the printing of structures with a certain height [2].Herein, we demonstrate a facile and versatile method for the fabrication of novel and highly porous 3D carbon aerogel electrodes from bio-hydrogels based on additive manufacturing assisted solvent casting process followed by freeze drying and pyrolysis. Firstly, the negative templates with the required resolution and geometry were 3D printed using high-resolution stereolithography (SLA) based AM technology to be used as master molds and the pattern were transferred to the biopolymeric hydrogels during ionic crosslinking induced self-assembly, leading to gelation. After completion of the gelling process, the casted hydrogel was removed from the master mold, washed with deionized water, frozen using solid carbon dioxide (dry ice) and lyophilized (freeze-dried) to preserve the structure. The lyophilized free-standing aerogels were then converted to free-standing 3D pyrolytic carbon aerogels in a high-temperature tubular furnace at 900°C under a nitrogen environment. Different characterization techniques such as FTIR, BET, SEM, Raman, XRD and XPS were employed to access the influence of the process parameters on the final microstructure of the 3D carbon aerogels. The as-prepared 3D free-standing carbon aerogel when used as a binder-free electrode showed outstanding charge storage capability and kinetics arising from interconnected 3D porous channels. The versatility of this approach was further verified by the successful preparation of novel multifunctional 3D free-standing carbon aerogel hybrids using GO, CNT and/or metal oxides and its application as a structured binder-free supercapacitor electrode with improved electrochemical performance.With the advantageous features of synergistically regulating the structure and composition, the proposed method combining AM and casting could be used as a versatile tool to develop structured bio-hydrogels, to be used as precursor material for constructing novel architectured free-standing carbon electrode materials with well-defined geometry and controlled pore size distribution. The final shape of carbon electrode depends on the 3D geometry of the additive manufactured negative template used for the replication during solvent casting. This technique would broaden the library of hydrogels materials that could be constructed freely in three-dimensions for the fabrication of structured and free-standing porous bio-carbon based electrodes for high-performance supercapacitor application.

Biomass‐Derived 3D Carbon Aerogel with Carbon Shell‐Confined Binary Metallic Nanoparticles in CNTs as an Efficient Electrocatalyst for Microfluidic Direct Ethylene Glycol Fuel Cells

AbstractFlexible and 3D carbon aerogels (CAs) composed of carbon nanotubes (CNTs) with carbon shell‐confined binary palladium–nickel (Pdx–Niy) nanocatalysts on carbon fibers (Pdx–Niy/NSCNT/CA) have been developed through a facile chemical vapor deposition method. The 3D porous carbon network and the synergistic effect of carbon shell‐confined bimetal nanoparticles of rationally constructed aerogels facilitate enhanced electrocatalytic and antipoisoning activities toward ethylene glycol (EG) oxidation reaction compared to the commercial Pt/C catalyst. With the 3D morphological features and direct growth of Pd–Ni bimetallic nanoparticles encapsulated CNTs on carbon fibers, the Pd52–Ni48/NSCNT/CA delivers a maximum microfluidic direct ethylene glycol fuel cell (µDEGFC) power density and durability of, respectively, 62.8 mW cm−2 and 60 h. The superior performance observed, with Pd52–Ni48/NSCNT/CA amongst the catalysts reported in the literature, opens an exciting research avenue towards powering next‐generation, portable electronics.

N‐Doped 3D Carbon Aerogel with Trace Fe as an Efficient Catalyst for the Oxygen Reduction Reaction

AbstractThe development of highly efficient, stable, and low‐cost oxygen reduction reaction (ORR) electrocatalysts is urgently required. Herein, a three‐dimensional (3D) N‐doped carbon aerogel with trace Fe (ca. 0.60 wt%) was synthesized by using carbon aerogel as the main raw material with facile KOH activation and a solid‐state pyrolysis technique. The pyrolysis temperature and trace amount of Fe play crucial roles in the ORR activity. The optimal product (Fe−N‐CA‐800) displayed onset and half‐potentials of 0.918 and 0.798 V in alkaline solution and 0.801 and 0.592 V in acidic media, respectively. Besides, the methanol crossover effect and long‐term stability for Fe−N‐CA‐800 were better than those of Pt/C. Furthermore, the Fe‐Nx sites were proven to be the main ORR catalytic sites by using SCN−. The robust 3D structure with hierarchical pores, unique chemical composition, and uniform Fe‐Nx active sites contributed to the superior ORR performance. The low‐cost and efficient Fe−N‐CA‐800 catalyst presents potential in fuel cells and metal‐air batteries.

Synergistic effects of 2D graphene oxide nanosheets and 1D carbon nanotubes in the constructed 3D carbon aerogel for high performance pollutant removal

To create interspace-enlarged and sites-exposed graphene-based adsorbents for pollutant management, three-dimensional macrostructures (3D GTs) were facilely constructed via self-assembly of two-dimensional graphene oxide nanosheets (2D GO) and one-dimensional carbon nanotubes (1D CNTs). Since the existence of CNTs acting like frames may reinforce the mechanical strength of the GO nanosheets, the density of the stable and porous 3D GTs was reduced to 0.2mg/mL which was much lower than the minimum concentration required to form pure GO 3D macrostructures. The 3D GTs exhibited superior adsorption capabilities to emerging pollutants such as oxytetracycline (1729mg/g) and diethyl phthalate (680mg/g), and traditional pollutants such as methylene blue (685mg/g), Cd2+ (235mg/g) and diesel (421g/g). The adsorption capacity of 3D GTs is higher than the reported graphene/GO and CNTs-based adsorbents, which can be attributed to the synergistic effects of GO and CNTs in micro-environment, nano-substrate, and active sites. Firstly, the assembled GO sheets were highly separated and in monolayer form, which created large interspaces in 3D GTs. Secondly, GO and CNTs provided abundant adsorption sites. Thirdly, the micro environment of interspaces in stable 3D GTs could be tuned to achieve selective adsorption to particular pollutant. In short, we propose a super graphene-based adsorbent which is competitive and scalable for water purification.

Methanol Oxidation and Oxygen Reduction Activity of PtIrCo-Alloy Nanocatalysts Supercritically Deposited within 3D Carbon Aerogel Matrix

The comprehensive investigation of ternary PtIrCo-alloy nanoparticles supported on 3D carbon aerogel matrix toward Methanol Oxidation Reaction (MOR) and Oxygen Reduction Reaction (ORR) is focused on CO tolerance in MOR, methanol vs. oxygen selectivity in ORR, and the structural changes within the metal alloy nanoparticles caused by the heat treatment and the electrochemical conditioning. Amorphous tri-metallic Pt59Ir34Co7-nanoparticles with mean size of 1.47±0.21nm were formed within 3D CA matrix in supercritical CO2 (scCO2) from the Pt, Ir, and Co organometallic precursors. Depending on the heat-treatment temperature (600°C or 900°C), the amorphous organometallic phase of Pt, Ir and Co was transformed into a single-phase fcc PtIrCo-alloy nanoparticles with a mean particle size of 1.68±0.33nm and 2.68±0.61nm, respectively. The fcc lattice parameters of the PtIrCo-alloy (0.389nm at 600°C and 0.386nm at 900°C) were smaller than that of the Pt fcc lattice (0.392nm) and the lattice parameters reduced proportionally to the heat-treatment temperatures. After 50 electrochemical cycles, PtIrCo/CA catalysts display improved MOR specific activity (∼2.5 X Pt/C), mass activity (∼3 X Pt/C) at 0.7V vs. SHE, higher CO-tolerance, and better electrochemical stability than Pt/C, but less CO-tolerance and stability than PtRu/C. Regarding ORR, the PtIrCo/CA catalysts demonstrate enhanced ORR specific activity (∼5.5 X Pt/C) and mass activity (∼6.3 X Pt/C) at 0.7V vs. SHE along with superior methanol-tolerance in comparison to Pt/C. The structural changes associated with PtIrCo/CA fcc-lattice parameter with respect to Pt-lattice have contributed to better MOR and ORR activities. Faster surface diffusion associated with weak adsorption of hydroxide species and higher selective adsorption of oxygen in comparison to methanol onto PtIrCo-alloy surface could have contributed to their better CO-tolerant MOR and methanol-resistant ORR activity compared to Pt-catalyst.

3D Interconnected Porous Carbon Aerogels as Sulfur Immobilizers for Sulfur Impregnation for Lithium‐Sulfur Batteries with High Rate Capability and Cycling Stability

To eliminate capacity‐fading effects due to the loss of sulfur cathode materials as a result of polysulfide dissolution in lithium–sulfur (Li–S) cells, 3D carbon aerogel (CA) materials with abundant narrow micropores can be utilized as an immobilizer host for sulfur impregnation. The effects of S incorporation on microstructure, surface area, pore size distribution, and pore volume of the S/CA hybrids are studied. The electrochemical performance of the S/CA hybrids is investigated using electrochemical impedance spectroscopy, galvanostatical charge–discharge, and cyclic voltammetry techniques. The 3D porous S/CA hybrids exhibit significantly improved reversible capacity, high‐rate capability, and excellent cycling performance as a cathode electrode for Li–S batteries. The S/CA hybrid with an optimal incorporating content of 27% S shows an excellent reversible capacity of 820 mAhg−1 after 50 cycles at a current density of 100 mAg−1. Even at a current density of 3.2C (5280 mAg−1), the reversible capacity of 27%S/CA hybrid can still maintain at 521 mAhg−1 after 50 cycles. This strategy for the S/CA hybrids as cathode materials to utilize the abundant micropores for sulfur immobilizers for sulfur impregnation for Li–S battery offers a new way to solve the long‐term reversibility obstacle and provides guidelines for designing cathode electrode architectures.

3D-Graphitized and Iron Modified Carbon Aerogels for Sustainable Energy Applications

3D-carbon aerogel nanomatrix has been modified with iron nitrate in the amounts of 10 and 20 wt. % by wet incipient method. The crystal structure, morphology, and electrocatalytic activity of the formed nanocomposites have been studied in comparison to the unmodified carbon aerogels after their heat-treatment at 900oC, 1200oC and 1400oC in argon. The mass and specific surface area losses in these materials reduced with iron doping is clear from BET isotherms and BJH pore size analysis. The HRTEM analysis confirms the presence of uniformly distributed ~43.5nm iron nanoparticles surrounded by graphite layers. The XRD analysis show that the level of graphitization increases with the sintering temperature and the concentration of the iron-containing phase. The ORR electrocatalytic activity studies demonstrate the influence of the heat-treatment temperature of samples on the ORR activity. Temperature programed reduction is carried out to understand the reduction behavior of these catalysts to metallic iron, to use them as substrates for direct CNT growth.