## 2 Materials and Methods
### Characterization  
The surface morphology of the monolithic composites was examined using a scanning electron microscopy (SEM): a Hitachi TM3030 tabletop model (Krefeld, Germany) at an accelerating voltage of 15 kV after the samples were coated with a thin layer of gold. FTIR measurements were conducted with a Thermo Scientific(tm) Nicolet(tm) iS20 FTIR Spectrometer at RT with a spectra resolution better than 0.25 cm\({}^{-1}\) and 32 scans from 500 cm\({}^{-1}\) to 4000 cm\({}^{-1}\). Characterization for solid 13C-NMR conducted by a Bruker 400 AVANCE III WB spectrometer (9.40 T) for 64 h at a resonance frequency of 100.6 MHz using the standard  
\begin{table}
\begin{tabular}{c c c c} \hline
**Sample** & **Temperature** (°C) & **GO/AsA wt Ratio** & **Functionalization** \\ \hline rGO0.0.5 & 60 & 10.5 & - \\ \hline rGO0.2 & 60 & 12 & - \\ \hline rGO0.0.5 & 90 & 10.5 & - \\ \hline rGO90.2 & 90 & 12 & - \\ \hline
560,0.5 & 60 & 10.5 & TMOS \\ \hline
560,2 & 60 & 12 & TMOS \\ \hline
590,0.5 & 90 & 10.5 & TMOS \\ \hline
590,2 & 90 & 12 & TMOS \\ \hline No0.0.5 & 60 & 10.5 & TMON \\ \hline No0.2 & 60 & 12 & TMON \\ \hline No0.0.5 & 90 & 10.5 & TMON \\ \hline No0.2 & 90 & 12 & TMON \\ \hline SN60,0.5 & 60 & 10.5 & TMOSN \\ \hline SN60,2 & 60 & 12 & TMOSN \\ \hline SN80,0.5 & 90 & 10.5 & TMOSN \\ \hline SN90,2 & 90 & 12 & TMOSN \\ \hline \end{tabular}
\end{table}
Table 1: Monolith abbreviations, synthesis conditions, and functionalization.  
Figure 1: Schematic representation of the functionalization and formation of the rGO monolith.  
Bruker double-resonance magic-angle spinning (MAS) sample probe. The samples were packed into a cylindrical zirconia rotor (4 mm external diameter) and then spun at a MAS frequency of 10 kHz. The spectra of the solid samples were recorded using the high-power decoupled 13C pulse sequence, a time-domain of 2 s, a spectral width of 55 kHz, and an interpulse delay of 5 s.  
The porous texture of the monoliths was characterized by employing N\({}_{2}\) adsorption-desorption at -196 \({}^{\circ}\)C in a Micromeritis ASAP2010 apparatus (Madrid, Spain). Before the analysis, materials were degassed at 150 \({}^{\circ}\)C under vacuum for 8 h. From N\({}_{2}\) adsorption-desorption isotherms, the specific surface area (SBET) was calculated with the Brunauer-Emmett-Teller (BET) equation. Moreover, used the t-plot method for estimating the micropore volume (V\({}_{\rm micr}\)) and the external surface (S\({}_{\rm ext}\)). The mesopore volume (V\({}_{\rm mes}\)) was computed by differences between the total pore volume (VT) and micropore volume. Finally, the pore size distribution (PSD) and average pore diameter (d\({}_{\rm p}\)) were calculated using the method proposed by [PERSON] (BJH method).  
To determine the adsorption capacity of the monolithic composites to absorb CO\({}_{2}\), a TGA/DSC 3+ (Perkin Elmer, Waltham, MA, USA) was used. The mass resolution of the equipment was 0.001 mg with a precision of 0.0025% with an accuracy of 0.005%. The temperature resolution was 0.001 K with a precision of \(\pm\)0.2 K and accuracy of \(\pm\)0.3 K. Before the measurements, the materials were placed in an N\({}_{2}\) atmosphere at 100 \({}^{\circ}\)C for 30 min. Afterward, CO\({}_{2}\) adsorption measurements were performed at 25 and 60 \({}^{\circ}\)C at atmospheric pressure and a 50 mL/min gasses flow rate.