Fig. 1: Characterization of a-CoO NSs.

a XRD patterns of a-CoO NSs and c-CoO NSs. b TEM, c AFM, and d HAADF-STEM images of a-CoO NSs. e ED pattern of a-CoO NSs. f HAADF-STEM image and corresponding EDS element mapping of a-CoO NSs: Co (red), O (yellow), and C (green).