## 3 Results and Discussion  
The preparation process for CZIF-8/CNTs/CCBs involved three steps, as illustrated in the schematic diagram in Figure 1. Firstly, the 3D interconnected network structure of the CBs was fully wetted by the solution of 2-methylimidazole, which can result in active sites on the surface of the CBs for ZIF-8 growth. In this process, CBs were not only used as the support to adsorb the 2-methylimidazole but also acted as the porous structure for the loading of ZIF-8 and CNTs in the next step. Secondly, after adding a certain amount of CNTs and the solution of zinc nitrate, ZIF-8/CNTs/CBs was successfully prepared based on an in situ synthesis method, producing a color change from white to black. The addition of CNTs can not only enhance the cross-linking action of ZIF-8 but can also effectively improve the adsorption performance during the oil-water separation process. In the meantime, the prepared ZIF-8 was tightly adhered in the 3D interconnected network structure of the CBs, also improving the adsorption capacity due to its porous structure. Finally, ZIF-8/CNTs/CBs was carbonized in nitrogen at 600 \({}^{\circ}\)C, leading to the formation of CZIF-8/CNTs/CCBs with a superhydrophobic surface. The surface microstructure of the samples was observed using FE-SEM images of different magnifications and TEM images. As depicted in Figure 2a,d, the pristine CBs exhibit a 3D interconnected network structure and a relatively smooth surface. After the in situ synthesis process, ZIF-8 and CNTs are fully loaded into the porous structure of the CBs (Figure 2b). The ZIF-8 clusters are composed of ZIF-8 nanoparticles intercalated with abundant CNTs (Figure 2e), which is consistent with the TEM result (Figure 3a). As shown in Figure 2c,f, the ZIF-8 clusters disappear from the surface of the as-synthesized CZIF-8/CNTs/CCBs. The TEM image (Figure 3b) clearly shows that the ZIF-8 clusters are decomposed into ZIF-8 nanoparticles after carbonization. XPS, EDS, and FTIR were used to investigate the surface chemical composition of the samples. The XPS results in Figure 4a confirm the existence of the elements C (284.8 eV), N (399.9 eV), O (532.8 eV), and Zn (1022.3 eV) in the ZIF-8/CNTs/CBs and CZIF-8/CNTs/CCBs. It is worth noting that the proportion of Zn on the surface of CZIF-8/CNTs/CCBs is clearly higher than for ZIF-8/CNTs/CBs. As can be seen from the data in Figure 4b, the XPS spectra for each element of the ZIFs/CNTs/CBs were obtained and fitted. The C 1s spectrum can be divided into four peaks at 284.5, 284.8, 285.4, and 286.6 eV, corresponding to C\(-\)C (sp\({}^{2}\)), C\(-\)C (sp\({}^{3}\)), C\(-\)OH, and C\(-\)N, respectively. The N 1s spectrum of ZIF-8/CNTs/CBs reveals three peaks located at 399.5, 400.0, and 401.0 eV,  
Figure 1: Schematic illustration of the preparation of CZIF-8/CNTs/CCBs. ascribed to pyridinic N, pyrrolic N, and pyridine N oxide, respectively. The O 1s spectrum of ZIF-8/CNTs/CBs shows three peaks, corresponding to carboxyl C=O bonds at 532.2, and 532.8 eV and hydroxyl oxygen at 533.6 eV [32; 33]. The Zn 2p\({}^{3}\) spectrum of ZIF-8/CNTs/CBs contains two individual component peaks at 1022.2 and 1045.3 eV, assigned to the Zn 2p\({}^{3/2}\) and Zn 2p\({}^{1/2}\) electronic states, respectively. This result confirms the presence of zinc oxide, which is consistent with previous work [34]. The EDS elemental mappings shown in Figure 5a reveal that the main elements present are C and O on the surface of the CBs. After the in situ synthesis process, the elements N and Zn were detected on the surface of ZIF-8/CNTs/CBs, which corresponds to the XPS results (Figure 4a). In addition, the EDS result for CZIF-8/CNTs/CCBs reveals that the relative content of Zn showed a marked increase (Figure 4a,b). These results demonstrate that ZIF-8 particles are not only homogeneously deposited but are also abundant on the substrate. FTIR spectra were acquired to further confirm the composition of the CBs, ZIF-8/CNTs/CBs, and CZIF-8/CNTs/CCBs.