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SUMMARY:Probing Realistic Water-2D Material Interfaces via Combined Quantu
 m and Classical Simulations - Ananth Govind Rajan\, Indian Institute of Sc
 ience Bangalore\, India
DTSTART:20230227T140000Z
DTEND:20230227T143000Z
UID:TALK197773@talks.cam.ac.uk
CONTACT:Dr Venkat Kapil
DESCRIPTION:Two-dimensional (2D) materials are gaining increasing attentio
 n for use in seawater desalination\, osmotic power harvesting\, and biolog
 ical sensing devices. Because water comes into close contact with 2D mater
 ial surfaces in these applications\, it is important to understand water-2
 D material interactions at the molecular level. At the same time\, 2D mate
 rials often have vacancies and roughness in them\, and thus understanding 
 their effect on interfacial properties is crucial to model such interfaces
  realistically. In this talk\, I will highlight our recent work on the com
 bined use of quantum-mechanical density functional theory (DFT) calculatio
 ns and classical molecular dynamics (MD) simulations to probe water-2D mat
 erial interfaces. While DFT calculations can be used to predict the distri
 bution of charge inside defective 2D materials\, MD simulations can be use
 d to simulate the thermodynamic and transport properties of interfacial wa
 ter.\n\nI will discuss the effect of vacancy defects and surface roughness
  on the wettability and slip length of water on hexagonal boron nitride (h
 BN)\, a prominent 2D material. At the molecular level\, the no-slip bounda
 ry condition is violated\, as quantified by the slip length of water on th
 e surface. I will show that vacancies at a lower concentration of 0.082 nm
 -2 do not affect the wettability of hBN\, although they still affect the w
 ater slip length. On the other hand\, vacancies at a larger concentration 
 of 0.32 nm-2 affect interfacial properties significantly. In fact\, nitrog
 en vacancies at such concentrations can increase the slip length of water 
 on hBN threefold to around 18 nm\, presenting defective hBN as an alternat
 ive high-slip surface to graphene. I will also demonstrate how surface rou
 ghness in hBN can explain the water contact angle of 66° and water slip l
 ength of 1 nm measured experimentally\, highlighting the prominent role pl
 ayed by electrostatic interactions in the interfacial properties of water 
 on realistic hBN surfaces. Overall\, these multi-scale investigations of t
 hermodynamic and transport properties offer new insights into the wettabil
 ity of defective 2D material surfaces and water flow on them.
LOCATION:Zoom link: https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHpt
 UXlRSkppQT09
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