## 3 Results and Discussion
This hydrophobicity slows water diffusion, suppressing the competing hydrogen evolution reaction (HER), while the interconnected porous network ensures rapid CO\({}_{2}\) transport to active sites. The hierarchical porosity, combining micropores and mesopores, balances high surface area for CO\({}_{2}\) adsorption with efficient mass transfer, promoting enhanced CO\({}_{2}\)RR activity. The larger mesopores (>2 nm) mitigate diffusion limitations, while the smaller micropores enhance CO\({}_{2}\) trapping near catalytic centers. Together, these structural features optimize CO\({}_{2}\) enrichment near active sites, accelerate gas diffusion, and inhibit water-induced HER, leading to improved selectivity and reaction kinetics for CO\({}_{2}\). The as-prepared Ni-MOF@ZIF-L heterojunction was further characterized by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) to probe the electronic interaction between Ni-MOF and ZIF-L. XPS survey and high-resolution spectra (Figure 3a-d) reveal the chemical states of nitrogen and oxygen, as well as their interactions in Ni-MOF, ZIF-L, and Ni-MOF@ZIF-L. In Ni-MOF@ZIF-L, the N 1s binding energy increases due to charge delocalization through Van der Waals interactions with ZIF-L methyl groups, while the IC-N/IC-NH-ratio decreases from 6.0 to 3.4, confirming nitrogen species redistribution. O 1s spectra show the Imenta-O/IO-C=O ratio increases from 5.2 to 5.5 after Ni-MOF compositing, indicating ZIF-L optimizes the oxygen coordination environment. As is shown in Figure 3e, the Ni 2p spectrum exhibits two fitting peaks at 872.3 and 854.4 eV, along with two shakeup satellites at 878.4 and 860.1 eV, being characteristic spin-orbit peaks of Ni\({}^{2+}\)[44]. In the Co 2p region, peaks located at 782.8 and 781.5 eV are assigned  
Figure 2: (**a**) XRD of Ni-MOF, ZIF-L, and Ni-MOF@ZIF-L. (**b**) SEM image of Ni-MOF@ZIF-L nanoarray. (**c**) TEM and (**d**) Mapping analysis images of Ni-MOF@ZIF-L heterojunction. (**e**) N\({}_{2}\) adsorption/desorption (inset: pore size distribution) and (**f**) CO\({}_{2}\) adsorption of Ni-MOF, ZIF-L, and Ni-MOF@ZIF-L at 298 K. (**g**) Photograph and contact angle of Ni-MOF and Ni-MOF@ZIF-L nanoarray. to Co\({}^{2+}\) and Co\({}^{3+}\) species (Figure 3f). It is worthy of note the Ni 2p for this heterojunction apparently shifts to higher binding energy compared to pure Ni-MOF. In contrast, the Co 2p peaks for heterojunction are shifted to lower binding energy relative to the corresponding peaks of ZIF-L. Thus, the opposite shifts of \(\sim\)0.4 eV for Ni and Co suggest the partial electron transfer from Ni to Co in this heterojunction through oxygen bridges between metal ions, leading to an increase in Ni\({}^{2+}\) and Co\({}^{3+}\). These speculations are further supported by the K-edge XANES spectra of Ni and Co in Figure 4a. Interestingly, compared with pure Ni-MOF and ZIF-L, the K-edge oscillation curves of Ni and Co in this heterojunction show significant differences, indicating the existence of different atomic arrangements. Compared with pure Ni-MOF, the introduced Co can enhance the K-edge peak of Ni, which suggests that there is a partial electron transfer from Ni to Co in this heterojunction. Conversely, compared with ZIF-L, the K-edge peak of Co in the heterojunction shifts to the right (towards the higher energy direction), and its intensity changes. The coordination information of Ni and Co atoms can be confirmed by the Fourier-transform (FT) k\({}^{3}\)-weighted EXAFS spectra (Figure 4b). Compared with the R-space of Ni in Ni-MOF (about 1.5 A, Ni-O bond) and Co in ZIF-L (about 1.5 A, Co-N bond), peaks appear at different positions in this heterojunction. For Ni in the heterojunction, the shift of the peak indicates the shortening of the Ni-O bond; for Co in the heterojunction, the shift of the peak indicates the elongation of the Co-N bond, which reflects the changes in the electron density around Ni and Co atoms.