CO₂ Sensing by in-situ Raman spectroscopy using activated carbon generated from mesocarp of babassu coconut

Herein an activated carbon (AC) with high surface area and microporosity was synthesized from the starch-rich mesocarp of the babassu coconut, an abundant biomass from north and northeastern Brazil. The synthesis of AC was realized by chemical activation using potassium hydroxide (KOH) coupled with pyrolysis at 750 °C and the produced material was further characterized by scanning (SEM) and transmission electron (TEM) microscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis. SEM and TEM showed the formation of a thin-layer porous morphology of AC; whereas the nitrogen (N₂) and carbon dioxide (CO₂) adsorption experiments identified a high surface area and microporosity. Raman spectra obtained by various laser lines revealed that AC has graphite-like microstructures with characteristic bands with features dependent on laser excitation energy. The amorphous nature from AC was further proven by XRD whereas FTIR showed the presence of surface-active oxygen functional groups. This AC material, produced from Brazillian Biomass showed a great potential as a CO₂ sensor using a optical technique, In-situ Raman spectroscopy and their D and G vibrational modes shifting in the presence of CO₂.