Wetting and Interfacial Properties of Water Nanodroplets in Contact with Graphene and Monolayer Boron-Nitride Sheets
Wetting and Interfacial Properties of Water Nanodroplets in Contact with Graphene and Monolayer Boron-Nitride Sheets
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DOI：
10.1021/nn204661d
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发表时间：
2012-03-01
期刊：
影响因子：
17.1
通讯作者：
Zeng, Xiao Cheng
中科院分区：
文献类型：
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作者：
Li, Hui;Zeng, Xiao Cheng
Bom-Oppenheim量子分子动力学（QMD）模拟进行调查润湿，扩散，和与石墨烯片或单层氮化硼（BN）片接触的水纳米滴的界面特性。第一次使用QMD模拟计算了两个片材上的水纳米滴的接触角。还研究了石墨烯或BN片附近的水滴的结构和动力学性质，以深入了解水滴与衬底之间的界面相互作用。QMD模拟结果与以前的经典MD模拟和实验测量进行了比较。QMD模拟表明，石墨烯片产生87度的接触角，而单层BN片产生86度的接触角。因此，与石墨烯一样，单层BN片也是弱疏水性的，即使BN键需要大的局部偶极矩。QMD模拟还表明，界面水可以在石墨烯和单层BN片的接触表面上诱导净正电荷，并且鉴于石墨烯是半金属，这种电荷诱导可能影响接触石墨烯的电子结构。还计算了石墨烯上过冷状态的纳米水滴的接触角。结果发现，在过冷条件下，水纳米液滴表现出明显大于在环境条件下的接触角。
Bom-Oppenheim quantum molecular dynamics (QMD) simulations are performed to investigate wetting, diffusive, and interfacial properties of water nanodroplets in contact with a graphene sheet or a monolayer boron-nitride (BN) sheet. Contact angles of the water nanodroplets on the two sheets are computed for the first time using QMD simulations. Structural and dynamic properties of the water droplets near the graphene or BN sheet are also studied to gain insights into the interfacial interaction between the water droplet and the substrate. QMD simulation results are compared with those from previous classic MD simulations and with the experimental measurements. The QMD simulations show that the graphene sheet yields a contact angle of 87 degrees, while the monolayer BN sheet gives rise to a contact angle of 86 degrees. Hence, like graphene, the monolayer BN sheet is also weakly hydrophobic, even though the BN bonds entail a large local dipole moment. QMD simulations also show that the interfacial water can induce net positive charges on the contacting surface of the graphene and monolayer BN sheets, and such charge induction may affect electronic structure of the contacting graphene in view that graphene is a semimetal. Contact angles of nanodroplets of water in a supercooled state on the graphene are also computed. It is found that under the supercooled condition, water nanodroplets exhibit an appreciably larger contact angle than under the ambient condition.