Effect of Hydrophobic Silicon Substrate on the Ice Formation at Different Temperatures

Abstract

In this work, we investigate the effect of silicon substrate and temperature on the ice formation through molecular dynamics simulations. It was found that silicon substrate accelerates the ice formation rate. Depending on the temperatures of the systems, the formation rate can be accelerate or decelerated. The obtained results showed that, as the temperature increased from the lowest temperature 100K to the highest temperature 220K, the number of water molecules transformed into ice decreased. We found that the hydrophobic property of silicon is not a barrier for approaching ice formation. The high correlation between Si and the hydrogen atoms of water molecules stimulated the ice formation on the surface of silicon and allowed the formation of amorphous ice directly on the surface of silicon. The temperature effect on ice formation was in distinguishing two different behaviors one from 100K to 180K and the second above 180K. These behaviors were related to the temperature of which amorphous ice is stable. The results of the average number of hydrogen bonds and their lifetime are in parallel with the results of the number density profiles that can best explain how silicon affects the ice formation. The coordination number of water molecules increased with the decrease of the temperature for silicon substrate which means that bigger ice clusters were found. The ice molecules, which were formed near the silicon substrate, are more recognized than that of the bulk. To better understand these effects, bulk systems were used as comparative systems.