title: On the Mechanism of Hydrophilicity of Graphene.
abstract: It is generally accepted that the hydrophilic property of graphene can be affected by the underlying substrate. However, the role of intrinsic vs substrate contributions and the related mechanisms are vividly debated. Here, we show that the intrinsic hydrophilicity of graphene can be intimately connected to the position of its Fermi level, which affects the interaction between graphene and water molecules. The underlying substrate, or dopants, can tune hydrophilicity by modulating the Fermi level of graphene. By shifting the Fermi level of graphene away from its Dirac point, via either chemical or electrical voltage doping, we show enhanced hydrophilicity with experiments and first principle simulations. Increased vapor condensation on graphene, induced by a simple shifting of its Fermi level, exemplifies applications in the area of interfacial transport phenomena.
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland.
authors.forename: Guo
authors.initials: G
authors.lastname: Hong
authors.affiliation: Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University , 52064 Aachen, Germany.
authors.forename: Yang
authors.initials: Y
authors.lastname: Han
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Schutzius
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland.
authors.forename: Ying
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University , 52064 Aachen, Germany.|Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University , 52062 Aachen, Germany.
authors.forename: Ming
authors.initials: M
authors.lastname: Hu
authors.affiliation: Institute of Functional Nano & Soft Materials (FUNSOM), Collaborative Innovation Center of Suzhou Nano Science and Technology, Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , Suzhou, Jiangsu 215123, P. R. China.
authors.forename: Jiansheng
authors.initials: J
authors.lastname: Jie
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland.
authors.forename: Chander S
authors.initials: CS
authors.lastname: Sharma
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology , Laboratory for Nanoscale Materials Science, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Müller
authors.affiliation: Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich , Sonneggstrasse 3, 8092 Zurich, Switzerland.
authors.forename: Dimos
authors.initials: D
authors.lastname: Poulikakos
keywords: Fermi-level engineering; condensation; graphene; hydrophilicity