Figure 1. TEM images of (a-b) CuO NS, OD-Cu NSs (c) Cu-30, and (d) Cu-100 (the marks of white circles mean the nano-domains.), respectively. (e) XRD patterns of CuO NS, Cu-30, and Cu-100 (the label of star (*) and hashtag (#) represent metallic Cu and CuO phase, respectively)