Figure 4. Differential pore size distributions calculated from
N2 isotherms using the 2D-NLDFT up to 2 nm (A) and
cumulative pore volume (B).
This increase in the level of defects should be reflected in an
increased porosity. The nitrogen adsorption isotherms and the pore size
distributions calculated from them [33] are presented in Figures 3
and 4, respectively. The addition of nGr increased the volume of
N2 adsorbed, and the calculated surface areas of the
composites increased by about 30 % compared to that of UiO-66 (Table
1). This increase in the surface area is consistent with the decrease in
the numbers of linkers per node discussed above. Interestingly, no trend
in the porosity development was found with an increase in the nGr
content, and the S BET of all composites remained
at the level of about 1600 m2/g. The volumes of
ultra-, micro-, mesopores and the total pore volumes of the composites
are also higher than those of UiO-66.
Table 1. Textural parameters calculated from N2adsorption isotherms at – 196°C.