Molecular dynamics simulation of the graphene–water interface: comparing water models

Abstract

In this work, different water models (i.e. SPC/E, TIP3P, TIP4P/2005, TIP5P, SPC/Fw, TIP4P/2005f and SWM4_DP) are implemented to simulate water on neutral, negatively charged and positively charged graphene. In all cases ambient conditions are considered. Structural and dynamical properties for water are calculated to quantify the differences among various water models. The results show that SPC/E, TIP4P/2005, SPC/Fw, TIP4P/2005f and SWM4_DP water models yield a similar structure for interfacial water on graphene, whether it is neutral, negatively charged or positively charged. TIP5P is the model whose predictions for the structure of the interface deviate the most from those of the other models. Although qualitatively the results are for the most part similar, a large quantitative variation is observed among the dynamical properties predicted when various water models are implemented. Although experimental data are not available to discriminate the most/least accurate of the model predictions, our results could be useful for comparing results for interfacial water obtained implementing different models. Such critical comparison will benefit practical applications such as the development of energy-storage and water-desalination devices (e.g. electric double-layer capacitors), among others.

Keywords::

• water
• interfacial effects
• graphene

Acknowledgements

Financial support was provided, in part, by the US Department of Energy Contract DE-SC0001902. Generous allocations of computing time were provided by the University of Oklahoma Supercomputing Center for Education and Research (OSCER) and by the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory. NERSC is supported by the DoE Office of Science under Contract No. DE-AC02-05CH11231.