Transient capacitance simulations: The out-of-plane concentration gradients were calculated by assuming Fickian diffusion in a plane sheet with infinitely large lateral dimensions compared to its thickness (<1 µm). Unobstructed diffusion from the top surface (without surface barriers) and no diffusion from the bottom surface were taken as boundary conditions. The diffusivity of the adsorbent was 10 -14 m 2 s -1 . The local capacitance was calculated from the concentration profiles using effective medium approximation (Bruggeman model) and exhibited a linear relationship. The measured (macroscopic) capacitance was approximated by slicing the nanoporous film into individual layers (1000 in total) and calculating impedance by using an equivalent circuit consisting of capacitors connected in series.