#nanoporous

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Scientists at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), the CiQUS research study centre at the University of Santiago de Compostela (USC) and the Donostia International Physics Center (DIPC) have actually effectively synthesised a graphene membrane with pores whose size, shape and density can be tuned with atomic accuracy at the nanoscale. Led by ICREA Prof. Aitor Mugarza from the ICN2 and Prof. Diego Peña from CiQUS, their work brings us one action more detailed to opening the capacity of this much admired product in electronic devices, and in filtering and picking up applications. Released today in Science with ICN2 scientist Dr. César Moreno as very first author, an interview was held today at the Barcelona Institute of Science and Technology (BIST), with extra existence of Prof. Aran Garcia-Lekue representing the DIPC.

So why all the difficulty?

Engineering pores at the nanoscale in graphene can alter the basic homes of this product. For a start it ends up being permeable or sieve-like. This modification alone, integrated with graphene’s intrinsic strength and nano-slimness, indicate its future usage as the most resistant, energy-efficient and selective filter for exceptionally little compounds, from greenhouse gases to salt, to biomolecules.

However a 2nd, possibly less user-friendly modification likewise occurs when the spacing in between pores is likewise decreased to a couple of atoms. Doing so changes the graphene from semimetal to semiconductor, unlocking for its usage in electronic applications, where it might be utilized to change the bulkier, more stiff silicon elements utilized today.

Nevertheless, while all this holds true in theory, producing such a product needs an accuracy that existing fabrication approaches have yet to accomplish, and look not likely to ever do so. The issue is the technique: punching holes in or otherwise controling a product that is simply one atom thick is an extremely fiddly job. In the work explained here, the group takes a “bottom up” technique based upon the concepts of molecular self-assembly and 2D polymerisation, efficiently growing the graphene from scratch with the nanopores currently integrated.

How it works

For this technique to work, you initially require a really particular precursor particle to utilize as the preliminary foundation, developed such that they will act as meant when subjected to various stimuli. In this work these precursors were developed and produced by artificial chemistry professionals at CiQUS, prior to being required to the ICN2 for the abovementioned “bottom-up” assembly of nanoporous graphene. Here they were sent to a number of rounds of heating at heats while put on a gold surface area, which serves to catalyse the responses by which the particles are very first polymerised, to form long, lace-like “nanoribbons”, and after that bonded laterally, to develop the wanted 2D “nanomesh” structure total with uniformly spaced, uniformly sized pores.

When one plus one provides more than 2 …

Simulated at the DIPC and evaluated experimentally at the ICN2 in cooperation with ICREA Prof. Sergio O. Valenzuela, the outcome is a brand-new sort of graphene that shows electrical homes comparable to those of silicon which can likewise serve as a highly-selective molecular screen. Applied in combination, these 2 homes are anticipated to permit the advancement of combined filter and sensing unit gadgets which will not just sort for particular particles, however will additionally obstruct or monitor their passage though the nanopores utilizing an electrical field. Such electrical readings would supply extra info regarding specifically exactly what concentrations which particle are travelling through the pores when, something which likewise indicates possible applications in more effective DNA sequencing.

Undoubtedly, the real-world applications of such a tunable, evenly nanoporous graphene membrane are manifold. They vary from contamination tracking and mitigation, to water desalinisation, as well as applications in biomedicine, where such a slim, versatile, biocompatible membrane might be utilized to support stopping working organs like the kidney, among the body’s natural filters.

A patent for the resulting nanoporous graphene membrane has actually likewise been submitted, with the scientists presently trying to find chances to evaluate their product in various applications.

Source: Catalan Institute of Nanoscience and Nanotechnology (ICN2)

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Researchers at the Catalan Institute of Nanoscience and Nanotechnology (ICN2), the CiQUS research centre at the University of Santiago de Compostela (USC) and the Donostia International Physics Center (DIPC) have successfully synthesised a graphene membrane with pores whose size, shape and density can be tuned with atomic precision at the nanoscale. Led by ICREA Prof. Aitor Mugarza from the ICN2 and Prof. Diego Peña from CiQUS, their work brings us one step closer to unlocking the potential of this much lauded material in electronics, and in filtration and sensing applications. Published this week in Science with ICN2 researcher Dr. César Moreno as first author, a press conference was held this morning at the Barcelona Institute of Science and Technology (BIST), with additional presence of Prof. Aran Garcia-Lekue representing the DIPC.

So why all the fuss?

Engineering pores at the nanoscale in graphene can change the fundamental properties of this material. For a start it becomes permeable or sieve-like. This change alone, combined with graphene’s intrinsic strength and nano-slimness, points to its future use as the most resilient, energy-efficient and selective filter for extremely small substances, from greenhouse gases to salt, to biomolecules.

But a second, perhaps less intuitive change also takes place when the spacing between pores is similarly reduced to a few atoms. Doing so transforms the graphene from semimetal to semiconductor, opening the door for its use in electronic applications, where it could be used to replace the bulkier, more rigid silicon components used today.

However, while all of this is true in theory, producing such a material requires a precision that current fabrication methods have yet to achieve, and look unlikely to ever do so. The problem is the approach: punching holes in or otherwise manipulating a material that is just one atom thick is an incredibly fiddly task. In the work described here, the team takes a “bottom up” approach based on the principles of molecular self-assembly and 2D polymerisation, effectively growing the graphene from scratch with the nanopores already built-in.

How it works

For this approach to work, you first need a very specific precursor molecule to use as the initial building blocks, designed such that they will behave as intended when subjected to different stimuli. In this work these precursors were designed and produced by synthetic chemistry specialists at CiQUS, before being taken to the ICN2 for the abovementioned “bottom-up” assembly of nanoporous graphene. Here they were submitted to several rounds of heating at high temperatures while placed on a gold surface, which serves to catalyse the reactions by which the molecules are first polymerised, to form long, lace-like “nanoribbons”, and then bonded laterally, to create the desired 2D “nanomesh” structure complete with evenly spaced, evenly sized pores.

When one plus one gives more than two…

Simulated at the DIPC and tested experimentally at the ICN2 in collaboration with ICREA Prof. Sergio O. Valenzuela, the result is a new kind of graphene that exhibits electrical properties akin to those of silicon which can also act as a highly-selective molecular sieve. Applied in conjunction, these two properties are predicted to allow the development of combined filter and sensor devices which will not only sort for specific molecules, but will alternatively block or monitor their passage though the nanopores using an electric field. Such electrical readings would provide additional information as to precisely what concentrations of which molecule are passing through the pores and when, something which also points to possible applications in more efficient DNA sequencing.

Indeed, the real-world applications of such a tunable, uniformly nanoporous graphene membrane are manifold. They range from pollution monitoring and mitigation, to water desalinisation, and even applications in biomedicine, where such a slim, flexible, biocompatible membrane could be used to support failing organs like the kidney, one of the body’s natural filters.

A patent for the resulting nanoporous graphene membrane has also been filed, with the researchers currently looking for opportunities to test their material in different applications.

Source : Catalan Institute of Nanoscience and Nanotechnology (ICN2)

SME images revealing the formation of nanoporosity in free corrosion dealloying in gold samples. The lower left image shows the loss of colour. Credit to UNIST.

An ultra light, high-density nanoporous gold (np-Au) has been developed by a research team from the Ulsan National Institute of Science and Technology (UNIST), South Korea.

The team started with a ball milling technique to increase the flexural strength of gold-silver precursor alloys, before employing a corrosion dealloying process to separate the silver. Professor Iu-Young Kim said, ‘Ball-milled np-Au has a much greater density of two-dimensional defects than annealed and prestrained np-Au, where interangular fracture is preferred.

‘Therefore, the probable existance of grain boundary opening in the highest tensile region is attributed to the flexural strength of np-Au.’

A 3D reconstruction of a nanoporous gold sample from TXM tomography. Credit to Dunand Research Group.

The nanoporous gold surface loses its shine and eventually turns to black at sizes smaller than 100nm, evoking the name ‘black gold’.

University of Illinois researchers have uncovered a way to design batteries that are thousands of times more powerful, 30 times smaller and charge 1000 times faster than current offerings. If what the research team claims is true, the next generation of batteries may be just around the corner.

So -- what's the secret behind the team's amazing battery? "Nanoporous" electrodes.

In their simplest form, batteries generate power by exploiting chemical reactions between two electrodes (i.e. cathode and anode) and an electrolyte -- the substance which fills the space between both electrodes. Lithium-based materials have long been the chemistry of choice for high-powered electronics.

Although battery technology has undoubtedly improved over the years, we arguably haven't seen a truly major advancement in portable power since the first commercial lithium ion battery (pdf) hit the scene in 1991. Li-ion batteries have remained the best trade-off between high power density and high specific energy for consumer electronics.

While touted alternatives, like fuel cells, boast desirable attributes like high specific energy and super capacitors promise near-instant charge times, each technology suffers at least one major shortcoming. It's been effectively impossible to develop a battery that excels at everything, but Illinois researchers believe they have solved this conundrum.

"If you want high energy you can’t get high power; if you want high power it’s very difficult to get high energy." noted James Pikul, a graduate student involved in the project.

By carefully fabricating highly-porous electrodes, scientists greatly increased the amount of surface exposed to electrolytic molecules. This massive bump in exposed surface area vastly improved battery effectiveness, combining high power density with favorable energy storage.

Miniature batteries with shorter charge times and greater power output will likely encourage manufacturers to think outside the box. The future may hold wireless devices with greater range and more utility, better medical implants and even practical, wearable electronics.