Researchers from the Technical College of Munich have been utilizing GCS HPC sources to develop extra environment friendly strategies for producing graphene on the industrial scale.
Graphene could also be among the many most enjoyable scientific discoveries of the final century. Whereas it’s strikingly acquainted to us — graphene is taken into account an allotrope of carbon, that means that it primarily the identical substance as graphite however in a special atomic construction — graphene additionally opened up a brand new world of prospects for designing and constructing new applied sciences.
The fabric is two-dimensional, that means that every “sheet” of graphene is just one atom thick, however its bonds make it as sturdy as among the world’s hardest metallic alloys whereas remaining light-weight and versatile. This invaluable, distinctive mixture of properties have piqued the curiosity of scientists from a variety of fields, resulting in analysis in utilizing graphene for next-generation electronics, new coatings on industrial devices and instruments, and new biomedical applied sciences.
It’s maybe graphene’s immense potential that has consequently prompted considered one of its largest challenges — graphene is troublesome to provide in giant volumes, and demand for the fabric is regularly rising. Latest analysis signifies that utilizing a liquid copper catalyst could also be a quick, environment friendly means for producing graphene, however researchers solely have a restricted understanding of molecular interactions taking place throughout these transient, chaotic moments that result in graphene formation, that means they can’t but use the strategy to reliably produce flawless graphene sheets.
With a view to tackle these challenges and assist develop strategies for faster graphene manufacturing, a group of researchers on the Technical College of Munich (TUM) has been utilizing the JUWELS and SuperMUC-NG high-performance computing (HPC) programs on the Jülich Supercomputing Centre (JSC) and Leibniz Supercomputing Centre (LRZ) to run high-resolution simulations of graphene formation on liquid copper.
A window into experiment
Graphene’s enchantment primarily stems from the fabric’s completely uniform crystal construction, that means that producing graphene with impurities is wasted effort. For laboratory settings or circumstances the place solely a small quantity of graphene is required, researchers can place a bit of scotch tape onto a graphite crystal and “peel” away atomic layers of the graphite utilizing a way that resembles how one would use tape or one other adhesive to assist take away pet hair from clothes. Whereas this reliably produces flawless graphene layers, the method is sluggish and impractical for creating graphene for large-scale functions.
Trade requires strategies that might reliably produce high-quality graphene cheaper and sooner. One of many extra promising strategies being investigated entails utilizing a liquid metallic catalyst to facilitate the self-assembly of carbon atoms from molecular precursors right into a single graphene sheet rising on prime of the liquid metallic. Whereas the liquid affords the flexibility to scale up graphene manufacturing effectively, it additionally introduces a bunch of problems, such because the excessive temperatures required to soften the everyday metals used, corresponding to copper. When designing new supplies, researchers use experiments to see how atoms work together underneath quite a lot of circumstances. Whereas technological advances have opened up new methods for gaining perception into atomic-scale conduct even underneath excessive circumstances corresponding to very excessive temperatures, experimental strategies don’t at all times permit researchers to look at the ultra-fast reactions that facilitate the right adjustments to a cloth’s atomic construction (or what features of the response might have launched impurities). That is the place laptop simulations could be of assist, nevertheless, simulating the conduct of a dynamic system corresponding to a liquid isn’t with out its personal set of problems.
“The issue describing something like that is it’s essential apply molecular dynamics (MD) simulations to get the appropriate sampling,” Andersen stated. “Then, in fact, there may be the system dimension — it’s essential have a big sufficient system to precisely simulate the conduct of the liquid.” In contrast to experiments, molecular dynamics simulations supply researchers the flexibility to take a look at occasions taking place on the atomic scale from quite a lot of totally different angles or pause the simulation to deal with totally different features.
Whereas MD simulations supply researchers insights into the motion of particular person atoms and chemical reactions that might not be noticed throughout experiments, they do have their very own challenges. Chief amongst them is the compromise between accuracy and price — when counting on correct ab initio strategies to drive the MD simulations, this can be very computationally costly to get simulations which can be giant sufficient and final lengthy sufficient to precisely mannequin these reactions in a significant means.
Andersen and her colleagues used about 2,500 cores on JUWELS in intervals stretching over a couple of month for the latest simulations. Regardless of the huge computational effort, the group might nonetheless solely simulate round 1,500 atoms over picoseconds of time. Whereas these might sound like modest numbers, these simulations have been among the many largest carried out of ab initio MD simulations of graphene on liquid copper. The group makes use of these extremely correct simulations to assist develop cheaper strategies to drive the MD simulations in order that it turns into attainable to simulate bigger programs and longer timescales with out compromising the accuracy.
Strengthening hyperlinks within the chain
The group revealed its record-breaking simulation work within the Journal of Chemical Physics, then used these simulations to check with experimental knowledge obtained of their most up-to-date paper, which appeared in ACS Nano.
Andersen indicated that current-generation supercomputers, corresponding to JUWELS and SuperMUC-NG, enabled the group to run its simulation. Subsequent era machines, nevertheless, would open up much more prospects, as researchers might extra quickly simulate bigger numbers or programs over longer intervals of time.
Andersen obtained her PhD in 2014, and indicated that graphene analysis has exploded throughout the identical interval. “It’s fascinating that the fabric is such a latest analysis focus — it’s virtually encapsulated in my very own scientific profession that folks have seemed intently at it,” she stated. Regardless of the necessity for extra analysis into utilizing liquid catalysts to provide graphene, Andersen indicated that the two-pronged method of utilizing each HPC and experiment can be important to additional graphene’s improvement and, in flip, use in industrial and industrial functions. “On this analysis, there’s a nice interaction between idea and experiment, and I’ve been on either side of this analysis,” she stated.
Reference: “Actual-Time Multiscale Monitoring and Tailoring of Graphene Development on Liquid Copper” by Maciej Jankowski, Mehdi Saedi, Francesco La Porta, Anastasios C. Manikas, Christos Tsakonas, Juan S. Cingolani, Mie Andersen, Marc de Voogd, Gertjan J. C. van Baarle, Karsten Reuter, Costas Galiotis, Gilles Renaud, Oleg V. Konovalov and Irene M. N. Groot, 1 June 2021, ACS Nano.
Funding for JUWELS and SuperMUC-NG was supplied by the Bavarian State Ministry of Science and the Arts, the Ministry of Tradition and Analysis of the State of North Rhine-Westphalia, and the German Federal Ministry of Training and Analysis by means of the Gauss Heart for Supercomputing (GCS).