We sought to elucidate how interactions of CoPc with CNTs might affect catalysis. Due to π-π stacking and through-space orbital interactions, the electron delocalization should increase the absorption wavelength . This is validated by the UV-vis spectra of the catalysts, showing a red shift at the Q band of the CoPc molecules after deposition on CNTs (Supplementary Fig. ) . X-ray photoelectron spectroscopy (XPS) for both the Co 2p1/2 and Co 2p3/2 of CoPc/CNTs shift to higher binding energies (Fig. ), reaching a maximum difference of 1.2 eV for CoPc/SWCNT. The signal evolution is even more prominent for the N 1s peak (Fig. ). Previous reports studied the interactions of MPc with various substrates such as TiO2, Au, and other semiconductors . It was thought that the strong molecule-substrate interaction would induce a peak splitting, while a weak interaction would cause only a peak shift. Indeed, we observe a new peak at >400 eV for all the CoPc/CNT samples. CoPc/SWCNT shows the most intense new peak at ~400.5 eV, implying strong CoPc-SWCNT interactions. The peak splitting of CoPc/SWCNT is ~1.3 eV, attributed to the deviated N 1s energies according to theoretical calculations discussed below. To understand the CoPc/CNTs' local structures, we performed X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses of Co. As shown in Fig. , the Co K-edge XANES spectra exhibits an obvious peak at 7715 eV; this 1s→4pz transition is indicative of the Co-N4 structure . A decline in the 1s→4pz transition is observed when CNTs are introduced, likely due to the decreased symmetry (D4h to C4v). The peaks near 7725 eV result from the 1s→4px,y transition, with the exact peak position dependent on Co's valency . The peak position of CoPc/CNT shifts slightly to lower energy compared to CoPc, indicating charge transfer between CoPc and the CNT. The Fourier transform (FT) of the EXAFS spectra shows the coordination environment around Co sites (Fig. and Supplementary Fig. ). The signal can be cataloged into three groups: . In addition, the peak intensities increase with smallerdiameter CNTs; this increased Co coordination number is a result of stronger interaction of CoPc with the CNT, as inferred from signal fitting. The fitted EXAFS signals (Fig. and Supplementary Fig. and, Supplementary Table ) imply molecular bending around the CNT. The high degree of molecular bending for CoPc/SWCNT leads to elongated Co-N1 and Co-C1 ) compared to the 1.9 mA cm -2 for CoPc/15 and 1.5 mA cm -2 for CoPc/50. To confirm that MeOH is derived from CO2 rather than other impurities, isotopic-labelling experiments were conducted in 13 CO2-saturated 0.5 M KH 13 CO3 while under continuous 13 CO2 flow. The peak splitting of 1 H NMR at 3.32 ppm and the obvious C NMR peak at 49.11 ppm verifies that the produced MeOH originates from the CO2 input (Supplementary Fig. ). The bare CoPc, SWCNT, and MWCNT/15 samples show negligible electrocatalytic CO2RR activity with little CO produced throughout the potential window (Supplementary Fig. ). In the durability test, the CoPc/SWCNT maintained ~30% FEMeOH for 10 h at an operating total current density of 16 mA cm -2 (Supplementary Fig. ). Supplementary Fig. shows the relation of FEMeOH with CoPc loading on SWCNT. Increasing the CoPc:SWCNT ratio from 1:50 to 1:3 and 1:1 did not increase FEMeOH. This could be explained by CoPc-CoPc stacking at high loadings that weakens the support effect. High CoPc loading also leads to catalyst leaching during chronoamperometry.