“…As shown in Figure ci,ii, the organic ligand (2-methylimidazole) and the transition metal cation (Co) show an orthorhombic structure with intense and sharp peaks, while the as-prepared ZIF-67_NPs (Figure ciii) evidently show their crystalline structure. In the ZIF-67_NPs XRD spectrum, the broad peak region at 25° corresponds to (002) plane of the organic linker (ZIF) showing the existence of carbon, which is line with a previous report . The peaks at 2θ for the as-prepared ZIF-67_NPs are associated with (011), (002), (112), (022), (013), (222), (114), (233), (134), and (044) and confirm the successful incorporation of cobalt ions into the organic matrix and form a rhombic dodecahedral shape.…”