Triethanolamine-modified layered double oxide for efficient CO₂ capture with low regeneration energy

Various adsorbents for CO₂ capture have been developed to mitigate the greenhouse effect. In this work, a novel CO₂ adsorbent was fabricated by depositing triethanolamine (TEOA) onto the surface of nickel-cobalt-aluminum layered double oxide (NiCoAl-LDO) via the impregnation method. The CO₂ capacity of the TEOA-LDO composite reached 1.27 mmol/g at 0 °C and 100 kPa, which was twice that of unmodified NiCoAl-LDO. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that the hydroxyl groups (-OH) on the surface of NiCoAl-LDO played a significant role in facilitating CO₂ adsorption, similar to CO₂ adsorption in the presence of H₂O, where CO₂ is not converted to carbamates but to bicarbonates through base-catalyzed hydration. This bicarbonate pathway doubles the theoretical amine efficiency, increases the CO₂ capacity, and reduces the energy consumption during CO₂ desorption. The work provides valuable insights into the development of CO₂ adsorbents with high capacity, excellent cycling stability, and low regeneration energy.