Lotus-Like Water Repellency of Gas-Phase-Synthesized Graphene

Abstract

The ability of lotus leaves to repel water is desired in numerous applications, such as self-cleaning surfaces, biomedical devices, and naval vessels. Creating materials that mimic the hierarchical structure and surface chemistry of lotus leaves requires multistep processes that are impractical for the mass production of nonwettable products. Superhydrophobic surfaces have been created using graphene. However, graphene sheets obtained through graphite exfoliation or deposition on substrates are not superhydrophobic and require additional processes to achieve lotus-like water repellency. In this work, we show that graphene produced in the gas phase is inherently superhydrophobic. Gas-phase-synthesized graphene (GSG) and lotus leaves have fundamentally different structures, yet water droplets on both materials exhibit comparable contact angles, roll-off angles, and bouncing characteristics. Furthermore, hydrophilic surfaces become superhydrophobic when covered with GSG. The substrate-free synthesis of GSG is straightforward and sustainable, which could enable the manufacturing of a diverse range of water-repellent technologies.

Graphene Properties, Synthesis and Applications: A Review

“… 136 Gas phase synthesized graphene Single to few-layer graphene Water contacts 153.0° ± 3.0° Superhydrophobic coating Ref. 137 Electrophoretic deposition Graphene nanosheets Tensile strength 518 MPa, and bending strength 477 MPa Supercapacitor Ref. 138 Mechanical exfoliation Graphene flakes Mobility 130,000 cm 2 /Vs Spintronics Ref.…”

“… 154 A recent study by Miler et al holds exciting potential for creating water-repellent coatings using gas-phase synthesized graphene, with a water contact angle of 153° ± 3°. 137 The graphene grown by their reported method immediately can repel water without any chemical modifications. In another study, the use of the matrix material PDMS and rGO produced a robust superhydrophobic surface with a water contact angle of 159° ± 2°, which had self-cleaning, antifouling, and anticorrosion properties, indicating its potential applications in the marine industry 154 (Fig.…”

Straightforward Fabrication of Double Roughness Structures on a Microcrystalline Film of a Diarylethene Derivative

“…Recently, biomimetic superhydrophobic surface structures have received much attention. − The development of superhydrophobic materials mimicking these structures is rapidly increasing. − In particular, binary structures, which include micro- and nanostructures, are attracting attention because they provide the capability of superhydrophobicity in most natural life forms as well as artificial materials. − A highly representative example of double roughness structures (DRSs) having micro/nanosized roughness is the surface of a lotus leaf (Figure S1). This surface is covered with protrusions of about 10 μm in diameter and 14 μm in height. , All such protrusions are covered with wax tubes with a diameter of about 0.2 μm and a height of about 0.6 μm .…”