Because of their unique characteristics, graphene aerogels are attractive materials for a wide range of applications. However, due to their micro-fibrous structure, strength and resilience, which are both desired properties, are generally considered to be mutually exclusive. By employing a bidirectional freeze-drying technique, researchers from the Zhejiang University (China) have successfully manufactured monolithic graphene aerogels uniting both properties.

Comparison of lamellar structure of thalia dealbata stem (left) and graphene aerogel (right)

In order to achieve those exceptional characteristics, the micro-scale architecture of the aerogels was based on the structure of a thalia dealbata stem, which is able to provide sufficient strength to support the plants leaves and blossoms while enduring powerful external forces (e.g. strong winds). The mimicking of this special three-dimensional lamellar structure consisting of bridged layers (see Figure above), yielded aerogel structures exhibiting strength and resilience simultaneously (see Figure below).

Images of fresh cubic graphene aerogel before compression (left), graphene monolith compressed by >6000 times its own weight (middle), recovered aerogel after compression (right).

When compared to a graphene aerogel exhibiting a random structure, the biomimetic aerogel showed a significant superiority in recovery behavior after being strained. Furthermore, the authors found that the aerogel architecture and hence the mechanical properties of the graphene structures can be further optimized by tuning the precursor composition.

The fabrication of such firm and robust structures could be play a pivotal role in establishing graphene aerogels in sensing applications. Additionally, the manufacturing technique reported by the authors can potentially be extended to other materials in order to obtain tailored micro-architectures.

More details: Miao Yang et al.; Biomimetic Architectured Graphene Aerogel with Exceptional Strength and Resilience, ACS Nano, 2017, 11 (7), pp 6817–6824. https://doi.org/10.1021/acsnano.7b01815

Read more at: https://www.forbes.com/sites/samlemonick/2017/07/31/plant-inspires-super-strong-aerogel/#2b9b35b96415

The Hamburg based startup Aerogelex has received the ETPN (European Technology Platform for Nanomedicine) Award 2017 for Best Nanomedicine Product/Deal at the Bio-Europe 2017. The awards committee was impressed by Aerogelex’s biopolymer aerogels for wound dressing, pharmaceutical, and life science applications.

Best Nanomedicine Product/Deal 2017 Awardee Aerogelex founder
Dr. Raman Subrahmanyam, Best Nanomedicine Early Clinical Stage Project
Awardee Dr. Su Metcalfe, and ETPN Chairman Patrick Boisseau

Aerogelex’s goal is to facilitate the implementation of aerogels in cosmetic, food, pharmaceutical, and thermal applications by transferring their wealth of knowledge about aerogels and aerogel manufacturing to partners who see value in the performance aerogels can offer.  Aerogelex will partner with companies and research groups to solve the materials and processing challenges associated with bringing aerogels and aerogel-based materials to market.

Aerogelex is currently open to partnership with individuals and companies who looking to establish a foothold in biopolymer aerogels, or who are interested in using supercritical drying in their manufacturing process. Businesses that partner with Aerogelex will get access to an aerogel production plant where aerogel prototypes can be manufactured and optimized. After a successful pilot phase, partnering companies will learn how to manufacture aerogels on a large scale in order to establish their own expertise.

To get a glimpse of the technological opportunities that supercritical drying and biopolymer aerogels offer, curious minds can purchase the first official product from Aerogelex on BuyAerogel.com. The ”AeroEggs” up for sale are unique aerogels made from hard-boiled eggs that reveal the endless possibilities that aerogels can offer.

Full video of Nanomedicine Award ceremony with presentation from Aerogelex founder Dr. Raman Subrahmanyam:  https://www.youtube.com/watch?v=P6JXJBrQVfY&list=PLjyB2R13BJCv4XVHoxm1TsZL_VkZiELDk

Increasing atmospheric CO₂ levels and dwindling fossil fuel resources have motivated the search for sustainable and renewable sources of energy. Hydrogen is considered to be an environmentally friendly alternative to common fossil fuels, as it does not emit environmentally harmful greenhouse gases upon combustion. Therefore, the quest for an efficient and sustainable way of generating hydrogen on a large scale is in full swing.

Supercritical water gasification (SCWG) of biomass is one such renewable hydrogen production technique that is currently being investigated. Due to the unique properties of supercritical water (e.g. high diffusivity, miscibility with gases) the process promises high energy conversion efficiencies. However, a suitable catalyst for the reaction, ensuring high H₂ yields while suppressing coke and tar formation, has remained elusive. Researchers from the University of Western Ontario (Canada) have recently synthesized a Ru-Ni-Al₂O₃ catalyst which has shown promise for the SCWG process.

Synthesis of the catalyst required the formation of a clear solution which was achieved by mixing the aluminum support in isopropanol at 75 °C followed by the addition of nitric acid. Thereafter, the metallic precursors (nickel nitrate and ruthenium acetylacetonate) were added to the sol to initiate the aging process. After completion of the gel formation, the liquids contained in the porous structure were extracted via low temperature supercritical drying with CO₂. In a last step the samples were calcined and reduced at 600 °C to obtain the ready-to-use aerogel catalysts (see Figure below).

Schematic of Ru-Ni-Al₂O₃ aerogel catalyst production technique

The Ru-Ni-Al₂O₃ aerogel, synthesized via this process, exhibited a higher specific surface area and pore volume when compared to impregnated or xerogel Ru-Ni-Al₂O₃ catalysts. These superior structural features significantly enhanced the hydrogen yields during SCWG, due to the increase in available active surface area. Furthermore, the porous aerogel morphology was also shown to decrease unwanted coke formation on the catalyst surface. A comparison of Ni-Al₂O₃ and Ru-Ni-Al₂O₃ aerogel catalysts revealed that the promoting nature of ruthenium (Ru) leads to superior catalytic activities for the bimetallic composite. Additionally, the utilization of Ru further decreased coke formation during the gasification reaction.

In order to assess the cyclic stability of the aerogel structures Ni-Al₂O₃ and Ru-Ni-Al₂O₃ catalysts were employed in three consecutive SCWG reactions. Both structures showed signs of deactivation (e.g. decrease in surface area), however, even during the third experimental run a decent catalytic activity was observed for both structures. For example, the recycled Ru-Ni-Al₂O₃ aerogel exhibited only slightly smaller hydrogen yields than the fresh Ru-Ni-Al₂O₃ xerogel and the fresh impregnated Ni-Al₂O₃ catalysts.

Although numerous projects aiming at the development of renewable energy generation processes are in progress, we are still a long way from a fully formed strategy to replace fossil fuels globally. Therefore, technical advancements paving the way to a more sustainable future are essential. This study has shown that aerogels could play an integral role in propelling alternative processes such as supercritical water gasification to market maturity.

More details: Md. Zakir Hossain, Muhammad B.I. Chowdhury, Anil Kumar Jhawar, Paul A. Charpentier; Supercritical water gasification of glucose using bimetallic aerogel Ru-Ni-Al₂O₃ catalyst for H₂ production, Biomass and Bioenergy Volume 107, December 2017, Pages 39-51. https://doi.org/10.1016/j.biombioe.2017.09.010

As demand for oil increases, so does its extraction and, consequently, the frequency of production-related accidents. This necessitated advancements in oil separation and absorption techniques to make sure that environmental disasters can be prevented.

An efficient way to remove oil and solvents from contaminated waters are absorbents, which directly remove the oil in the deployed surroundings. Additionally, they facilitate the possibility of recycling the absorbed oil after recollection. However, common absorbing materials utilized for the cleaning of oil spills are known to have a low environmental compatibility.

Died water droplets on top of hydrophobic cotton cellulose aerogel

In light of these facts, researchers from the National University of Singapore have synthesized novel environmentally benign cotton-cellulose aerogels which exhibit promising oil absorption characteristics. The monolithic pure cotton (PC) and cellulose-cotton (CC) aerogels were manufactured using a freeze-drying technique. In order to ensure hydrophobicity of the materials (see figure on the right), the aerogels were silanized using methyltrimethoxysilane. Thereafter, the absorption capacity of the aerogels was investigated for different solvents (e.g. dichloromethane, motor oil, ethanol).

The synthesized PC and CC aerogels were able to absorb all utilized solvents to large extents with loading capacities of up to 100 g/g being measured. Additionally it was discovered that absorption capacities increase with solvent density. In order to analyze the recyclability of the aerogels, two different recycling techniques were investigated. These experiments revealed that distillation cycling guarantees a superior sustaining of the absorbing performance when compared to squeeze cycling.

The intriguing findings of the authors once again highlight that aerogels can be applied in areas reaching beyond the field of insulation.

More details: Hanlin Cheng et. al; Cotton aerogels and cotton-cellulose aerogels from environmental waste for oil spillage cleanup, Materials & Design Volume 130, 15 September 2017, Pages 452-458. https://doi.org/10.1016/j.matdes.2017.05.082

Although monolithic aerogels of numerous types and forms have been produced using a broad palette of techniques, it remains a challenge to accurately tailor the micro- and macrostructure of the resulting three-dimensional structures. Recently, researchers from Kansas State University (USA) have presented a 3D-printing freeze drying technique promising just that.

Different aerogel geometries produced using the 3DFAP production technique

The so-called 3D freeze assembling printing (3DFAP) technique facilitates the fabrication of monolithic aerogels of various macrostructures (see figure on the right). Using this process, the team of researchers was able to produce silver nanowire aerogels (SNWA), that have ultra-low density (1.3 mg/cm³) and high electrical conductivity (0.24 S/cm), while also exhibiting outstanding mechanical features such as good compressive resistance and tunable Poisson ratios (even negative). Experiments investigating the effect of mechanical stress on material resistance revealed outstanding cyclic stability. Furthermore, the different structures were found to exhibit extremely high mechanical resilience, even under tensile stress.

In light of these promising results, the authors conclude that through facilitating the manipulation of the aerogel macrostructure, the novel production technique offers the possibility to manufacture three-dimensional aerogel structures for applications in the fields of sensing, energy storage or catalysis. They are also convinced that the 3DFAP technique can be applied to produce other 3D nanomaterial architectures.

More details: Pengli Yan et. al; 3D Printing Hierarchical Silver Nanowire Aerogel with Highly Compressive Resilience and Tensile Elongation through Tunable Poisson’s Ratio, Small Volume 13, Issue 38 October 11, 2017. http://onlinelibrary.wiley.com/doi/10.1002/smll.201701756/abstract

Read more at: http://www.advancedsciencenews.com/3d-printing-tunable-poisson-ratio-metallic-aerogels/

Owing to their unique characteristics, graphene aerogels are considered promising materials for a wide range of applications in fields such as energy storage, catalysis, and sensing. A research team from the Tsinghua University (China) has successfully demonstrated that another item can be added to this impressive list — adsorption and pre-concentration of air pollutants. Hierarchical porous graphene aerogels (HPGAs) synthesized via self-assembly, freeze drying and subsequent calcination have been shown to possess outstanding characteristics for extracting chemical warfare agents (CWAs) from ambient air.

Morphological structure images of hierarchical porous graphene aerogel (HPGA) at different magnifications.

The researchers found that the graphene aerogels, composed of a porous three-dimensional pore network (see Figure above), exhibited a good thermal and mechanical stability. Adsorption experiments with sarin, a highly toxic nerve agent, showed that the HPGAs display outstanding adsorption/desorption behavior in a wide range of operation conditions (e.g. desorption temperature, relative humidity). Furthermore, repeated cycling of the graphene aerogels did not result in a drop in adsorption efficiency or a change in material morphology, underlining the high resilience of HPGAs.

Given those intriguing results, the authors hypothesize that graphene aerogels could be efficient materials for the removal of other hazardous gases from air and hence might prove to be a promising alternative in cases of industrial accidents or terrorist attacks.

More details: Qiang Han, Liu Yang, Qionglin Liang and Mingyu Ding; Three-dimensional hierarchical porous graphene aerogel for efficient adsorption and preconcentration of chemical warfare agents, Carbon Volume122, October 2017, pages 556-563. https://doi.org/10.1016/j.carbon.2017.05.031

Aerogels, long familiar only to researchers and pioneers,  are now making their way into consumer products. One such example is the newly introduced Life-Pocket^TM  by the Norwegian company Helly Hansen.

Helly Hansen Life-Pocket

It is rumored that when the Canadian Skiing Team was asked which improvements they hoped for in skiing apparel, they explicitly demanded for an insulated smartphone chest pocket, which facilitates a longer battery lifetime. With the aim of making the pro-skiers innermost wish a reality, the team at Helly Hansen found a partner which had a solution at hand — PrimaLoft (USA), a company focused on insulation for outerwear, gloves and footwear.

Using “Primaloft Aerogel Gold” insulating material, the designers at Helly Hansen have created a pocket which protects the battery of cell phones even in the most extreme weather conditions (-28.0 °C / -18.4 ℉). This high performance insulation composite (CLO ratings: 1.29-2.00) is a pressure resistant material encapsulated in a waterproof membrane that can be used for insulating pockets, shoes and gloves.

Since the aerogel is only located on the outside of the jacket, body warmth is utilized to maintain a certain temperature inside the chest pocket and hence prevent temperature-related performance decrease of smartphone batteries. According to the company, jackets equipped with the Life-Pocket^TM  and the Life-Pocket+^TM keep phones two or three times warmer than regular ski jackets, respectively.  

Initial hands-on tests of the product showed a significant increase in battery life, demonstrating that the aerogel-insulated pocket delivers on its promise (more details).

It will be interesting to see whether the unique characteristics of aerogel materials begin to attract a broader interest from product designers.

Read more at: https://www.hellyhansen.com/news/the-life-pocket-saving-battery-life-in-cold-environments/

Read more at: https://www.airfreshing.com/news-helly-hansen-life-pocket

Read more at: https://gearjunkie.com/aerogel-helly-hansen-lifepocket-powder-suit

Read more at: https://gearjunkie.com/primaloft-gold-aerogel-insulation

Supercapacitors are generally viewed as promising energy storage alternatives for future mobile applications, due to their immense energy and power density. Researchers from the Jiangsu University (China) have now been able to greatly improve electrochemical characteristics of graphene/polyaniline aerogels, which are considered a promising material for super capacitor electrodes, by doping them with nitrogen.

The resulting 3D nitrogen-graphene/polyaniline (N-GE/PANI) foams exhibited a rough and wrinkled surface area on which the PANI spheres were incorporated (see Figure).

SEM images of (a, b) N-GE and (c, d) N-GE/PANI electrode composites. The insets in (c) and (d) are a photo of the 3D N-GE/PANI monolith and an SEM image of PANI nanospheres, respectively

Furthermore, it was found that the combination of N-GE and PANI resulted in superior specific capacitance, when compared to the individual materials. This finding was ascribed to the synergetic effect of combining a conductive polymer ensuring a large pseudocapacitance of the electrode and a highly porous nitrogen-doped carbon matrix which provides a high conductivity and rigidity. Another line of experiment, analyzing the cycling stability of the novel electrode material found that after 5000 cycles the specific capacitance of the electrode was largely retained  (95.9 %), indicating the suitability of the foam composite for long-term operation.

Given these promising results, the authors conclude that the extraordinary characteristics of the synthesized electrode make it an auspicious candidate for applications in supercapacitors.

More details: Jun Zhu, Lirong Kong, Xiaoping Shen, Quanrun Chen, Zhenyuan Ji, Jiheng Wang, Keqiang Xu, Guoxing Zhu; Three-dimensional N-doped graphene/polyaniline composite foam for high performance supercapacitors, Applied Surface Science Volume 428, 15 January 2018, Pages 348-355. https://doi.org/10.1016/j.apsusc.2017.09.148

Researchers from the Swiss Federal Laboratories for Materials Science and Technology (Empa) have discovered that the insulating properties of state-of-the-art insulating bricks can be significantly enhanced by replacing the filling material with silica aerogel granules.

Commercially available insulating bricks (shown in the figure below), which unite structural and insulating functions in one component, are composed of a rigid clay or concrete shell in which the cavities are filled with an insulating material (e.g. mineral wool, PU foam). While their simplicity makes these monoliths, in theory, an ideal building material, their inferior insulating performance compared to a layered approach (i.e. layering different materials for structural and insulating purposes on top of each other), has limited the application of insulating bricks in the building sector.

Image of “Aerobrick” — Insulating brick with silica aerogel granule filling.

However, simulations and measurements showed that by replacing the filling material with silica aerogel the thermal conductivity of the insulating brick can be significantly reduced (> 30 %), yielding a higher insulating performance for a given brick thickness. Accordingly, this facilitates the construction of thinner insulating walls, which is crucial in locations where space-saving architecture is required (e.g. dense urban locations).

Due to the cost of aerogels, the “Aerobrick” is not an economically viable solution today. Nonetheless, the authors conclude that the projected future drop in aerogel prices will potentially transform aerogel-filled insulating bricks into a strong alternative to layered insulating techniques in the near future.

More details: Jannis Wernery, Avner Ben-Ishai, Bruno Binder, Samuel Brunner; Aerobrick – An aerogel-filled insulating brick, Energy Procedia Volume 134, October 2017, Pages 490–498 https://doi.org/10.1016/j.egypro.2017.09.607

In an interdisciplinary study entitled “Spirited Skies Project” researchers of the School of Creative Arts and Humanities (Charles Darwin University, Australia), the AMC Metropolitan College (Greece) and the University of Science and Technology (China) have explored the idea of manufacturing aerogel-based dome structures for goedesic and lunar habitats.

After highlighting aerogel characteristics relevant for applications in architecture such as their insulating, optical and acoustic properties, the authors present examples of aerogel composites used in architecture like the glazed skylight of the Eli and Edythe Broad Art Museum (Lansing, USA).

Figure 1: Exterior view of Eli and Edythe Broad Art Museum (Lansing, USA).

Although the cost of aerogel materials currently limits their application to selected signature projects, the writers conclude that the rising demand for passive building design combined with dropping aerogel prices will soon facilitate the utilization of such composites in the building sector on a large scale.

Driven by these developments, the authors envisage the possibility of dome-like structures consisting of facades filled with translucent aerogels (see Figure 2 below). This design would allow structures that are naturally lit and highly insulated.

Figure 2: a) Exterior view of lunar glass domes “Spirited skies”. b) Lunar glass dome’s interior view.

More details: Michaloudis I, Skouloudi M, Bok C, Jingyan Q (2017) Spirited Skies Project: Silica Aerogel Domes for the Habitat of the Future. Adv Automob Eng 6: 166. doi: 10.4172/2167-7670.1000166 https://www.omicsonline.org/peer-reviewed/spirited-skies-project-silica-aerogel-domes-for-the-habitat-of-the-future-94152.html