Hierarchical, Dual-Scale Structures of Atomically Thin MoS2for Tunable Wetting.
Molybdenum disulfide (MoS2), a well-known solid lubricant for low friction surface coatings, has recently drawn attention as an analogue two-dimensional (2D) material beyond graphene. When patterned to produce vertically grown, nanoflower-structures, MoS2shows promise as a functional material for hydrogen evolution catalysis systems, electrodes for alkali metal-ion batteries, and field-emission arrays. Whereas the wettability of graphene has been substantially investigated, that of MoS2structures, especially nanoflowers, has remained relatively unexplored despite MoS2nanoflower's potential in future applications. Here, we demonstrate that the wettability of MoS2can be controlled by multiscale modulation of surface roughness through (1) tuning of the nanoflower structures by chemical vapor deposition synthesis and (2) tuning of microscale topography via mechanical strain. This multiscale modulation offers broadened tunability (80-155°) compared to single-scale tuning (90-130°). In addition, surface adhesion, determined from contact angle hysteresis (CAH), can also be tuned by multiscale surface roughness modulation, where the CAH is changed in range of 20-40°. Finally, the wettability of crumpled MoS2nanoflowers can be dynamically and reversibly controlled through applied strain (∼115-150° with 0-200% strain), and remains robust over 1000 strain cycles. These studies on the tunable wettability of MoS2will contribute to future MoS2-based applications, such as tunable wettability coatings for desalination and hydrogen evolution.
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
Jonghyun
J
Choi
Vacuum Center, Korea Research Institute of Standards and Science , Daejeon, 34113, Republic of Korea.
Jihun
J
Mun
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
Michael Cai
MC
Wang
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
Ali
A
Ashraf
Vacuum Center, Korea Research Institute of Standards and Science , Daejeon, 34113, Republic of Korea.|Department of Advanced Device Technology, University of Science and Technology , Daejeon 34113, Korea.
Sang-Woo
SW
Kang
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
SungWoo
0000-0002-9719-7203
S
Nam
Molybdenum disulfide (MoS2); crumples; hierarchical patterning; nanoflowers; surface coatings; tunable wettability; two-dimensional (2D) materials