We present molecular dynamics simulations of the adsorption of mixed CO2-water vapors on a graphene flakes substrate, a model inspired by the microporous structure of activated carbons. Adsorption strength is quantified through a reduced energy measure that avoids ambiguities associated with defining adsorption regions. We find that CO2 adsorbs more strongly and more rapidly than water across all temperatures studied. Adsorption from wet vapors was observed to result in higher CO2 uptake compared with dry vapors at temperatures below 375 K. At intermediate temperatures, water molecules were seen to form clusters that interact with both the substrate and CO2, potentially promoting CO2 adsorption. Additionally, we observe that the GF substrate inhibits the formation of large water clusters, altering water aggregation dynamics near the surface. These findings highlight a cooperative adsorption mechanism in humid environments and suggest that graphene-flakes-based materials may perform effectively for carbon capture under realistic, moisture-containing conditions.
