By Josh Perry, Editor
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An undergraduate researcher at Virginia Tech University (Blacksburg, Va.) developed a computational model that describes the interaction between water and the surface of 2-D hexagonal boron nitride and will allow scientists to better predict the behavior of water at this interface, which could be a step towards boron-nitride-based electronics.

Chemical engineering junior Preeya Achari was first author on a new computational model for understanding the interaction between water and 2-D boron nitride. (Virginia Tech)

According to a report from the school, junior Preeya Achari, a chemical engineering student, was first author on a new paper describing the model.

“Achari arrived at Virginia Tech looking for a challenge and was drawn to working with the unfamiliar field of computational materials science — a field that utilizes computational methods and supercomputers to understand existing materials and accelerate materials discovery and development,” the report said. She has worked in the computational lab since her sophomore year.

Hexagonal boron nitride has several properties that make it a promising building block for electronic devices, including its resistance to oxidation, flexibility, and high strength-to-weight ratio, which the article explained make it a potential improvement over graphene.

“Prior to the development of the new model, understanding the molecular-level structure of water at the contact surface with hexagonal boron nitride proved very challenging, if not impossible,” the article said. “The development may provide more control in performance of devices made with hexagonal boron nitride and water.”

The research was recently published in Computational Materials Science. The abstract stated:

“Non-bonded force-field (FF) parameters between a two-dimensional hexagonal boron nitride (hBN) sheet and water molecules were developed. The hBN sheet was modelled using Tersoff potential. Three commonly used water models, namely SPC, SPC/E, and SPC/Fw were utilized to represent water. Particle swarm optimization (PSO) was employed to accelerate the development of accurate FF parameters to reproduce the experimental macroscopic contact angle of a water droplet (∼47°) on the hBN sheet.

“To the best of our knowledge, this study presents the first example of optimizing hBN-water interactions through reproduction of the macroscopic contact angle of water. A systematic two-step approach was utilized to develop these parameters by using a nanoscopic water droplet with 2000 molecules. In the first step, the hBN-water interactions were optimized to reproduce a macroscopic contact angle of water, ∼47° for a nanoscopic droplet with 2,000 molecules (FF Set-I).

“In the second step, the FF parameters were optimized such that the ∼47° angle was reproduced for the macroscopic water droplet (FF Set-II). The binding energies of an adsorbed water molecule in its prefered configuration on the hBN sheet were approximately −7.49 and −8.08?kJ/mol for Set-I and Set-II, respectively.

“These values were in good agreement with results from previous studies. Structural and dynamical properties of a water droplet such as the Z-density profile of oxygen atoms, angle made by OH-vector with Z-axis, and the average hydrogen bonds per molecule were also determined to validate the developed FF parameters.

“All three water models could predict these properties of water at the hBN-water interface with reasonable accuracy.”