Ostrowski Joseph H J, Eaves Joel D
Department of Chemistry and Biochemistry, 215 UCB, University of Colorado at Boulder , Boulder, Colorado 80309, United States.
J Phys Chem B. 2014 Jan 16;118(2):530-6. doi: 10.1021/jp409342n. Epub 2014 Jan 3.
Using molecular dynamics simulations, we study the hydrophobic effect on electrically doped single layer graphene. With doping levels measured in volts, large changes in contact angle occur for modest voltages applied to the sheet. The effect can be understood as a renormalization of the surface tension between graphene and water in the presence of an electric field generated by the dopant charge, an entirely collective effect termed electrowetting. Because the electronic density of states scales linearly in the vicinity of the Fermi energy, the cosine of the contact angle scales quartically with the applied voltage rather than quadratically, as it would for a two-dimensional metal or in multiple layer graphene. While electrowetting explains the phenomenon, it does not account for the slight asymmetry observed in the hydrophobic response between n- and p-doping.
通过分子动力学模拟，我们研究了疏水作用对电掺杂单层石墨烯的影响。以伏特为单位测量掺杂水平时，对石墨烯片施加适度电压会导致接触角发生大幅变化。这种效应可以理解为在掺杂电荷产生的电场存在下，石墨烯与水之间表面张力的重整化，这是一种完全的集体效应，称为电润湿。由于费米能量附近的电子态密度呈线性缩放，接触角的余弦与施加电压的四次方成正比，而不是像二维金属或多层石墨烯那样与电压的平方成正比。虽然电润湿解释了这一现象，但它无法解释在n型和p型掺杂的疏水响应中观察到的轻微不对称性。
