This work focuses on the development of green and energy-efficient sorbents for CO2 optimized for different carbon capture applications. Our preliminary results indicate that Ca-based layered double hydroxides (Ca-LDHs) can be tailored to outperform state-of-the-art sorbents. Here we propose to investigate the adsorption mechanism of CO2 on phase-pure Ca-LDHs of different chemical composition using in situ pair distribution function (PDF) analysis as a function of relative humidity and pCO2. PDF analysis is especially suited to uncover this mechanism due to (1) its potential to unravel short-range order of disordered materials / adsorbates; and (2) the occurrence of amorphous intermediates after the conversion of CO2 to CO32-. The specific binding location(s) of CO2 within the Ca-based LDHs will be determined based on the description of the short-range order structure provided by the PDF, aided by additional experimental data and computational simulations.