(187f) Carbon Dioxide Capture Using PEI /Mxene Composite

Carbon dioxide is a major greenhouse gas whose atmospheric concentration has been shown to correlate strongly with global temperature rise since late 19^th century. Thus, effective carbon dioxide mitigation technologies are essential. MXenes (M_n+1X_nT_x,), where M is a transition metal, X is C or N, and T_x represents terminal functional groups (e.g., F, O, OH), are novel 2D materials that have large surface areas and porous structures, and these properties make them promising materials for carbon dioxide capture. Amine chemistries have been used to capture carbon dioxide with excellent results. In this study, we combined the structural benefits of MXene with the amine chemistry for carbon dioxide capture. Polyethyleneimine (PEI) was added to MXene in different amounts (5-50 wt%) and analyzed using X-ray scattering (SAXS and WAXS). The d-spacing for the pure MXene was 1.20 nm and increased to 1.25 nm with the addition of 20 wt% PEI. Further loading of PEI to 50 wt% completely disrupted the MXene layered structure. The 20% sample was further characterized using scanning electron microscopy (SEM) to visualize the structure and thermogravimetric analysis (TGA) to measure carbon dioxide uptake. SEM images confirmed retention of the MXene layered structure after addition of 20 wt% PEI. TGA analysis showed the 20 wt% PEI loaded MXene sample captured more carbon dioxide (0.69 mmol/g) than pure MXene (0.05 mmol/g) and pure PEI (0.19 mmol/g). These results provide evidence that PEI/MXene composites may be effective materials for carbon dioxide capture.