Identification of Copper Surface Index by Optical Contrast

Abstract

With the rise of 2D materials, copper (Cu) is revealed as good surface catalyst, especially in the self‐limited growth of graphene. In the regime of surface catalyst, the catalytic activities and functionalities of Cu should be highly dependent on its surface type. Traditional methods to determine the surface index are mainly high‐vacuum based surface science techniques and are typically of low throughput and in small scale. A method to fast detect the surface index of Cu in large scale is still lacking. Here, the authors report an effective optical contrast method to identify the Cu surface index in large area. This method is based on the Cu2O‐thickness dependent color of Cu surface after a mild oxidation in hot air. It is revealed that different Cu surfaces (Cu(111), Cu(100), and Cu(110) as examples) have various oxidation barriers and would exhibit distinct color evolution with heating time. It is also showed that graphene grown on Cu surfaces with varied orientations has totally different growth behaviors. The results would greatly facilitate the high‐throughput determination of Cu surface index and accelerate the large‐scale facet‐dependent catalytic research of Cu, such as in single‐crystal graphene growth.

Bottom‐Up‐Etching‐Mediated Synthesis of Large‐Scale Pure Monolayer Graphene on Cyclic‐Polishing‐Annealed Cu(111)

“…Our experiments showed that different colors in Figure 3a are associated with different Cu grains that have different oxidization rates (Figure S3, Supporting Information). [ 23 ] This technique is capable of rapidly identifying grains, and positions of GBs before and after their movement. For example, adjacent light and dark lines indicating the possible positions of GBs can be found in the optical image in Figure 3a, which were also observed in the corresponding SEM image (Figure 3b).…”

Epitaxial growth of a 100-square-centimetre single-crystal hexagonal boron nitride monolayer on copper

“…The large-area Cu(110) surface can be easily observed by optical imaging after mild oxidization in air (Fig. 1a), as different surfaces have different oxidization rates to form Cu2O and show fingerprint colours 29 . The sharp Cu(220) peak in X-ray diffraction (XRD) pattern in the 2q scan ( Fig.…”

Color of Copper/Copper Oxide

“…[11,12] Another strategy to obtain wide color selectivity in a metal film is the construction of sophisticated nanostructures to realize various colors by means of polarization conversion. [13] Despite numerous attempts to modulate color by oxidation and nanostructuring efforts, [14][15][16] the complexity associated with conversion of the Cu lattice into an oxide remains an obstacle for coherent control of the interface between metal and metal oxide, which is necessary to obtain a full, well-defined color spectrum.…”