Project

Discipline

electronic structure; single-layer nanopores; osmotic transport; two dimensional materials; ab initio molecular dynamics; nanofluidics; osmotic energy conversion

Lead
Unser Ziel ist es, die Prinzipien der Osmose auf molekularer Ebene mittels atomistischer Simulationen zu verstehen, indem wir Modellsysteme mit empirischen Berechnungstechniken untersuchen und gleichzeitig realistischere Membranen mit ab initio (quantenmechanischen) Methoden erforschen. Um dieses Ziel zu erreichen, wird eine Prozedur geschaffen, um die hydrodynamische Theorie der Osmose und beschleunigte Probenahmetechniken zu koppeln, um Transporteigenschaften an nanofluidischen Grenzflächen mittels Ab-Initio-Simulationen zu berechnen. Wir werden diese Prozedur auf die Untersuchung des Ionen- und Wassertransports durch atomar dünne Membrane in verschiedenen Systemen anwenden. Im ersten Jahr des Projekts werden wir den Wassertransport an einer Vielzahl von Grenzflächen untersuchen, während wir uns im zweiten und dritten Jahr auf den ionischen Transport im linearen und nichtlinearen Bereich konzentrieren werden.
Lay summary
Durch die Mischung von Salz- und Süßwasser an den Flussmündungen kann eine große Menge an Energie, die so genannte blaue Energie, genutzt werden. Dennoch bleibt die blaue Energie eine unerforschte Quelle, da die Effizienz herkömmlicher Membrane begrenzt ist. Jüngste Experimente haben über eine extrem hohe Leistung berichtet, die durch den ionischen Transport entlang zweidimensionale Materialien und Nanoröhrenmembranen erzeugt wird. Obwohl die elektronische Struktur und die quantenmechanische Natur von Materialien als sehr relevant für die nanoskalige osmotische Energieumwandlung angesehen wird, ist ihre Rolle für den ionischen Transport nicht bekannt. Wir werden die Rolle der elektronischen Struktur von Materialien für den ionischen Transport untersuchen, indem wir beschleunigte ab initio Molekularen Dynamik-Simulationen durchführen und die Transporteigenschaften mit Hilfe der hydrodynamischen Theorie berechnen. Bis zum Ende des Projectes werden wir die Grundprinzipien für die Entwicklung von Nanomembranen zur osmotischen Stromerzeugung festgelegt haben. Weitere Bereiche, die von der vorgeschlagenen Forschung profitieren werden, sind Wasserentsalzung, Transport in Biomembranen und DNA-Sequenzierung durch Nanoporen.

Direct link to Lay Summary

Last update: 05.12.2018

Active participation

A vast amount of energy may be harnessed from the mixing between salty and fresh water at river estuaries. This, so-called blue energy, is induced by the osmotic pressure built between reservoirs at different solute concentrations. It is estimated that the overall power that can be generated by exploiting salinity concentration gradients is of the same order as that currently produced from hydroelectric power plants, globally. So far, however, osmotic energy remains a largely unexplored source, due to challenges in fabricating membranes that can effectively harvest the potential of seas and oceans.Recent progress in nano-fabrication and nano-characterization techniques, as well as the rise of graphene and other two-dimensional materials, have opened new venues for the development of osmotic membranes. For instance, recent experimental works have shown that boron nitride nanotubes and nanometer MoS2 single-layer nanopores can harvest osmotic energy with unprecedented efficiency. However, a number of fundamental questions have to be addressed in order to scale-up the production of nanomembranes for osmotic power generation. In particular, the atomistic mechanisms of ionic and water transport in real nanomembranes under different transport regimes are unclear. Pioneering experimental results suggest that the chemical nature and the electronic structure of different materials is key to understand osmotic and nanofluidic transport in real systems, but it is extremely challenging for experiments to provide atomic resolution into the structure and transport at the nanomembrane/fluid interface. Computer simulations instead, play an increasingly important role and it is now possible to use them to bring about major breakthroughs in understanding the fluid structure and dynamics at the interface with nanomembranes under operating aqueous conditions. However, so far there has been little to no attempt to investigate the role of the electronic structure on osmotic flow in nanofluidics. At the nanoscale specific electronic effects play a crucial role, and understanding the relation between the electronic structure and osmotic transport is therefore key to design efficient membranes for osmotic energy conversion. Given the importance to find and effectively harvest different types of renewable energy sources, this represents a fundamental question in the chemical and physical sciences, which has not been answered, yet.We aim to answer this question with atomistic simulations, by coupling systematic studies on model systems treated using empirical potentials with in depth explorations of more realistic membranes, treated using ab initio (i.e. quantum mechanical) methods, to account explicitly for the electronic structure of liquid/solid interfaces. To achieve this goal, the hydrodynamic theory of osmosis will be coupled to enhanced sampling techniques, in order to compute transport properties at nanofluidic interfaces using ab initio simulations. We will apply this framework to the study of ion and water transport across atomically thin membranes, both in the linear regime and in the nonlinear regime, with a particular focus on the recently observed ionic Coulomb blockade. This work will also take advantage of the exchange with experimental groups involved in the fabrication of nanomembranes to explore novel materials for osmotic energy applications. By accounting explicitly for the electronic structure of different materials, not only will we establish the key physical principles for the development of stable and efficient nanomembranes for osmotic power generation, but we may also improve our understanding of water purification and desalination, of ionic transport in biological pores, and of sequencing of DNA through nanopores.