The pore size distributions calculated from the N2adsorption isotherms (Figure 4) bring more details about the alterations in the porous texture of our materials. As expected from the structure of UiO-66, the predominant pore sizes should be ~ 0.6 nm and ~ 0.9 nm, which represent tetrahedral and octahedral cavities [19]. Defects such as missing linkers and missing clusters are expected to increase the sizes of these latter pores [6, 12, 37]. The striking difference between UiO-66 and the composites is the appearance, in the latter materials, of pores smaller than 0.5 nm and an increase in the volume of pores wider than 1.1 nm in their size. This effect is especially seen for the composite with the smallest amount of nGr. A detailed comparison of the change in the predominant pore sizes based on the PSDs is presented in Figure 5, where it is clearly seen that the greatest effect is an increase in pores wider than 0.7 nm upon the composite formation. This increase in the porosity is due to both, the pores of diameter between 0.7 and 1.1 nm, which represent the octahedral cavities, and to pores wider than 1.1 nm, which are assigned to defects such as missing linkers [12, 37] and clusters [6]. Pores smaller than 0.5 nm might represent the interface between nGr and UiO-crystal deposited on the nGr particles and thus, the smallest amount of nGr added might result in the highest dispersion of this phase and therefore in a more extended interface.