Abstract: The efect of contact electrifcation on adhesion has been debated in recent years for gecko and bio-inspired dry adhesion material. To understand the fundamentals of this issue for Carbon Nanotube (CNT) dry adhesives, contact electrifcation and its relationship with adhesion are systematically studied using the frst-principles calculation. Charge transfers from CNT or its special form, graphene, to the metal surface during the contact, and the transferred charge linearly correlates with the work function diference. Meanwhile, the adhesion energy is linearly related to the transferred charge for both CNT and graphene. More charge transfers from the fat graphene to metal surfaces than the curved CNT, leading to higher adhesion between graphene and metal surfaces. The curved structure of the CNT causes an irregular change of charge at the interface and hinders the charge transfer. Moreover, the curved structure induces electronic localization, which also decreases the interfacial charge transfer. The structure afects contact electrifcation, and hence adhesion is further demonstrated by the CNT with diferent deformation when contacting diferent surfaces. This study advances our understanding of contact electrifcation and its relationship with adhesion at the interface for bio-inspired carbon adhesive materials and sheds light on the control of them for engineering applications.

Key words: Contact electrifcation, Adhesion, Bio-inspired adhesive CNT, First-principles calculation, Interfacial interaction