Repulsive van der Waals forces due to hydrogen exposure on bilayer graphene
M. Boström and Bo E. Sernelius
The binding of two freestanding graphene sheets to each other and of a neutral sheet to a substrate is caused by van der Waals and Casimir interactions. We have studied these effects in a previous work [EPL 95 (2001) 57003] and found unexpected power laws for this interaction.
In the present work we have found theoretically that the attractive van der Waals forces between two graphene sheets on a SiO2 substrate can turn repulsive if hydrogen is entering the space between the sheets. Similar effects have been noticed experimentally [Surf. Sci. 605, 1662 (2011)] on a SiC substrate.
This is an example of quantum levitation. The origin is similar to the spectacular effect that Liquid Helium climbs the walls of a beaker.
Repulsive forces are very tractable. They may lead to the suppression of stiction, which is an overwhelming problem for micro- and nanoscale mechanical devices.
How can these findings be utilized?
They may helpful in the field of hydrogen storage.
They may lead to a method for peeling of single graphene sheets from multiple stacks.
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Last updated: 01/30/12