Structure dependent hydrogen induced etching features of graphene crystals

Abstract

H2 induced etching of graphene is of significant interest to understand graphene growth process as well as to fabricate nanoribbons and various other structures. Here, we demonstrate the structure dependent H2 induced etching behavior of graphene crystals. We synthesized graphene crystals on electro-polished Cu foil by an atmospheric pressure chemical vapor deposition process, where some of the crystals showed hexagonal shaped snowflake-dendritic morphology. Significant differences in H2 induced etching behavior were observed for the snowflake-dendritic and regular graphene crystals by annealing in a gas mixture of H2 and Ar. The regular graphene crystals were etched anisotropically creating hexagonal holes with pronounced edges, while etching of all the dendritic crystals occurred from the branches of lobs creating symmetrical fractal structures. The etching behavior provides important clue of graphene nucleation and growth as well as their selective etching to fabricate well-defined structures for nanoelectronics.

Fractal microgeometry of original and hydgrogen-charged graphene multilayer films surface: research by the low-temperature sorption of nitrogen method

“…The ambiguousness in the determination of the nitrogen molecules -hydrogen-charged graphene surface interaction revealed in the present research, may prove the fact that the hydrogen sorption process is the complex one and comes with graphene surface erosion due to dehydrogenation [9,19,20]. It can be presumed that formation of new nano-/micropores on the hydrogenated graphene surface takes place as the result both of such erosion and hydrogen evolution.…”

Impact of the in situ rise in hydrogen partial pressure on graphene shape evolution during CVD growth of graphene

“… 14 The flakes are also similar to those reported in post-growth hydrogen-assisted etching. 17 , 18 A comparison of these reports, in terms of morphology, size of the flakes and main processes is tabulated in Table 1 .…”

“… 16 Remarkably, similar dendritic shapes were achieved by etching the CVD grown graphene after growth (post-etching). 17 , 18 In those experiments, graphene is first grown following a standard procedure using a CH 4 in Ar/H 2 gas mixture, then the CH 4 is switched off and, finally, graphene is etched with Ar/H 2 . In other reports, gaseous oxidants were considered to be the main responsible for graphene etching, giving place to lines and holes with hexagonal shapes.…”

Carbon Nanomaterials as Versatile Platforms for Biosensing Applications

“…This “segregation” process is depicted clearly in Figure 9 A [ 66 ]. For metals such as Cu with low carbon solubility, carbon atoms tend to nucleate and laterally expand around the core nucleus to create graphene domains through the decomposition of a hydrocarbon, which is catalyzed by the substrates at high temperature ( Figure 9 B) [ 70 ]. Specifically, Figure 9 C,D show, respectively, a schematic diagram and optical image of the growth mechanism of graphene during the carbon segregation and precipitation on Ni (111).…”