First-Principles Study on Tuning of Contact Electrification and Adhesion of Bio-inspired Adhesive Carbon-Based Materials via an External Electric Field

Mimicking the adhesion ability of animals using bio-inspired materials and, consequently, the tuning of adhesion have aroused tremendous research interest. In this study, we focus on the tuning of interfacial adhesion of adhesive carbon nanotubes (CNTs) and their deformed state (graphene) via an external electric field using first-principles calculations. The results show that the adhesion energy of CNT or graphene almost decreases linearly as the electric field changes from -0.2 to 0.2 V/angstrom. The variation of adhesion under the electric field is further found to be closely related to contact electrification as the negative fields facilitate interfacial charge transfer, and the positive fields reduce charge transfer. Electronic behaviors are further investigated to uncover the working mechanism of an external electric field, which also explains the more sensitive responses of contact electrification and hence adhesion in CNT systems compared to graphene systems. It is further found that the external electric field essentially changes the local work function of surfaces and consequently modulates contact electrification and hence adhesion. This study advances our understanding of adhesion and contact electrification under an electric field and sheds light on the tuning of adhesion of bio-inspired adhesive materials in engineering applications.