Nanoscale imaging of oxidized copper foil covered with chemical vapor deposition‐grown graphene layers

Abstract

Characterization of the geometrical and structural characteristics of oxidized Cu area in high resolution is crucial for tracking the change in morphology, exploring interactions between graphene layers and Cu substrates and revealing the mechanism for the orientation‐dependent oxidation of Cu. Here, we reported experimental results on nanoscale imaging of natural oxidation of the polycrystalline Cu substrate coated by partial‐coverage chemical vapor deposition (CVD)‐grown graphene stored in dryer under ambient conditions for up to 10 months. Scanning electron microscope (SEM), together with atomic force microscope (AFM), Raman, and X‐ray photoelectron spectroscopy (XPS), was used for systematically studying the morphological and compositional changes at nanoscale during oxidation. The appearance of oxidized Cu substrates could be unambiguously distinguished from the unoxidized regions based on their distinctly different morphologies in SEM images, and the underlying mechanism was discussed in detail. By analyzing a millimeter‐seized polycrystalline Cu substrate, we found that the oxidation of polycrystalline Cu substrate depends sensitively on both orientation of graphene layers and Cu substrates. Furthermore, the time‐dependent oxidation evolution of Cu substrate was also established, and the oxidation rate was readily determined. The findings reported here will have important implications for developing protection coatings for Cu.

Putting High-Index Cu on the Map for High-Yield, Dry-Transferred CVD Graphene

“…Single-crystal-prepared Cu(111) shows this lack of oxidation as well, with our tests (similar graphene islands on single-crystal Cu(111) in the same humidified environment described in Experimental Details) showing no propagation of oxidation beneath graphene grown on Cu(111) even after several weeks of oxidation. This holds true for many Cu orientations . This lack of oxidation is consistent with prior literature, which suggests that Cu(111) inhibits extended oxidation beneath graphene and speculates that this links to the close commensurate matching and thus coupling of in-plane graphene and Cu(111) .…”

“…This holds true for many Cu orientations. 26 This lack of oxidation is consistent with prior literature, which suggests that Cu(111) inhibits extended oxidation beneath graphene 22 and speculates that this links to the close commensurate matching and thus coupling of in-plane graphene and Cu(111). 27 However, by examining the Cu regions not covered by graphene (see Figure S13 in the Supporting Information), we reveal that there is in general a strong correlation (0.770 Pearson correlation coefficient) between the oxidation of Cu facets beneath the graphene and of the uncovered Cu.…”

Substrate‐dependent enhancement of the durability of EPD graphene coating as a macroscale solid lubricant

“…Graphene film exhibits a relatively rough surface, with a mean surface roughness about 1.3–1.4 μm (Figure S1). Raman spectra of all graphene films demonstrated two distinct peaks at ~1575 cm −1 (G peak) and ~ 2721 cm −1 (2D peak), as shown in Figure 1A3–D3 30 . Besides, there is also a very weak peak at 1354 cm −1 , assigned to the D peak.…”

“…Raman spectra of all graphene films demonstrated two distinct peaks at $1575 cm À1 (G peak) and $ 2721 cm À1 (2D peak), as shown in Figure 1A3-D3. 30 Besides, there is also a very weak peak at 1354 cm À1 , assigned to the D peak. The intensity ratios of D and G peaks for the four samples are below 0.05, which suggests that the number of structural defects in the asfabricated graphene film is relatively small.…”

Nanoscale characterization of the heterogeneous interfacial oxidation layer of graphene/Cu based on a SEM electron beam induced reduction effect

“…A similar observation that oxidation of Gr/Cu did not progress uniformly from the edges into the interior has been reported, 28,59,60 and at the same time, we notice different reports that oxidation of Gr/Cu progress uniformly from the edges into the interior. 61,62 Further studies will be required for further understanding of the oxidation and corrosion mechanism of Gr/Cu.…”