Scanning transmission electron microscopy (TEM) was carried out using the Linköping double corrected and monochromated FEI Titan 3 60-300 (S)TEM equipped with a high brightness Schottky field emission gun (XFEG) and operated at 300 kV. The achieved resolution was measured to 0.7 Å on a Au/Pd nanoparticle reference grating. A Wien type monochromator was used to control the beam current to 40 pA. Electron energy-loss spectroscopy (EELS) mapping was performed using a Gatan GIF Quantum ERS 966 dual EELS spectrometer with 1.2 eV energy resolution in non-monochromated mode at 300 kV and at 0.25 eV dispersion. DualEELS mapping was carried out using high speed acquisition mode to limit the dose. Scanning TEM (STEM) images were acquired with an annular dark field (ADF) detector using a 21.5 mrad convergence semi-angle and with a camera length corresponding to 60-180 mrad collection angles. STEM cross-section samples were prepared by delaminating membranes fixed to SiN frames in pure ethanol followed by float deposition on a Cu TEM ring. Image and spectrum processing was carried out using Gatan Microscopy Suite (GMS) 3.52 with licensed plugins for EELS spectrum imaging and elemental quantification. EELS quantification was carried out using the Hartree-Slater scattering cross-section model with low-loss corrected plural scattering deconvolution and near edge exclusion of 20 eV. X-ray reflectivity measurements were used to measure the thin film thickness on polished Si substrates and to calibrate the deposition process to deposit very thin and uniform films. The measurements were performed by utilizing Cu Kα radiation with the Cu Kβ component filtered out by a nickel filter. The data were recorded using an X'Pert MRD diffractometer with a 1/32⁰ divergence slit and a 0.27° plate collimator, followed by analysis for film thickness and density using PANAlytical X'Pert Reflectivity software. A scanning electron microscope (SEM) specifically Zeiss Sigma 300 model was used to study the morphology of the composite membrane. The in-lens secondary electron detector with 15 keV accelerating voltage and 30 µm aperture was used to study the CNT membranes. X-ray diffraction analysis was conducted with a PANAlytical X'Pert Pro diffractometer. The incident beam side featured a Cu Kα X-ray source, which was outfitted with a Bragg-Brentano HD and had ½° divergence slit as primary optics. On the diffracted beam side, the apparatus includes an X'celerator detector that functioned in scanning mode, accompanied by a 5 mm antiscatter slit. The 002 peak of the diffraction curve was extracted, background subtracted and fitted with basic gaussian function to estimate the full width at half maximum (FWHM). X-ray photoelectron spectroscopy (XPS) was employed to investigate the chemical environment within the films using an AXIS Ultra DLD instrument from Kratos Analytical.