## 3 Results
### Characterization of rGO/CeO\({}_{2}\)/Polymer Monoliths
#### 3.2.3 N\({}_{2}\) Adsorption-Desorption  
To better understand the structural properties and porosity of these materials, experiments of N2 adsorption-desorption were conducted. In Table 3, these results can be found. According to the adsorption isotherms (Figure 10), an increase in the N\({}_{2}\) adsorbed at a high relative pressure could be observed, indicating a high microporosity. The morphologies found via SEM could be directly connected with the adsorptions. It seems that the GCe had a higher specific surface area (SSA) compared with the other monoliths. It is interesting to see that the addition of polymer brushes to CeO\({}_{2}\) particles led to different SSAs. This could be expected since the polymers affect how particles are aggregated and thus dispersed inside the monolith. This is already something that can be extracted from the SEM images in Figure 7, where the monolithic structures are different. Based on the results presented, it can be found that the different polymeric brushes affected the structuring of the monoliths differently. The addition of PAA in CeO\({}_{2}\) led to almost half of the SSA compared with the GCe. In addition, the total pore volume was affected, showing a lower total volume than the GCe. This can also be seen from the higher average pore size of the GCePA sample, which increased by 23%. We can hypothesize that the addition of PAA on the CeO\({}_{2}\) led to monoliths that had less volume but with broader pore sizes. In the other two cases of GCePN and GCePM, the SSA was smaller but closer to that of the GCe. The pore volume among the monoliths with the other polymers of PNVCL and PMETAC have a very similar value and close to sample GCe The average pore size was relatively smaller for the GCePN than GCePA but still higher than that of the GCe. Interestingly, the GCePM monolith had very similar characteristics to the GCe. The SSA was very close to the total pore volume, and the average pore size was the same. The other important part of these results is the micropore percentage (volume area) of these monoliths. The GCePM sample had the highest percentage in the volume of micropores (7.0%) but also one of the smallest percentages in the area (9.9%). The other three monoliths had very similar micropore percentages in terms of volume, ranging from 5.1 to 5.6%. Differences were observed when these percentages were calculated for the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Samples**} & **SSA a** & **Total Pore** & **Average Pore** & **Percentage of Micropores [FOOTNOTE:]Footnote : Calculated with BET.[ENDFOOTNOTE]** \\  & **(m\({}^{2}\)/g)** & **Volume b** & **Size c** & **(Volume)** & **(Area)** \\  & **(cm\({}^{3}\)/g)** & **(nm)** & **(\%)** & **(\%)** & **(\%)** \\ \hline GCe & 95.1 & 0.175 & 7.4 & 5.1 & 11.1 \\ \hline GCePA & 52.6 & 0.120 & 9.1 & 5.6 & 13.2 \\ \hline GCePN & 77.5 & 0.166 & 8.6 & 5.5 & 7.4 \\ \hline GCePM & 89.7 & 0.165 & 7.4 & 7.0 & 9.9 \\ \hline \hline \end{tabular}  
\end{table} 
Table 3: Textural properties of the monoliths with different polymers. area of the micropores; GCe had 11.1%, and then the sample with GCePA had the highest at 13.2%. For the sample, GCePN had the smallest one at 7.4%. The combination of the micropore percentage (volume and area) and the total pore volume with the average pore size would create a different pore system that could influence CO\({}_{2}\) adsorption. For sure, an impact would also have the different functionalities of the decorated CeO\({}_{2}\) particles. In Figure 10, the adsorption-desorption isotherms of all four monoliths can be found, where the hysteresis typical for mesoporous materials was obviated. In Figure 10, it can be seen that the GCe, GCePN, and GCePM monoliths had an H3 hysteresis loop typical for slit-shaped pores. In contrast, for the GCePA monolith, the hysteresis loop was more similar to H4, which is typical for narrow, slit-shaped pores [42; 43].