Adsorption properties of seaweed-based biochar with the greenhouse gases (CO2, CH4, N2O) through density functional theory (DFT)

Since the industrial revolution, greenhouse gas (GHG) emissions have increased dramatically, which has become a global concern. In this study, the interaction between biochar and GHG was calculated by building different models of seaweed-based biochar through density functional theory (DFT). The adsorption mechanism of biochar was then analyzed by structural parameters, adsorption energy, charge transfer, and surface electronic properties. The results showed that the biochar with N and O heteroatom doping had better adsorption performance, and results also show that biochar is more sensitive to CO2 and N2O. In particular, the adsorption energies of CO2 and N2O on N-doped biochar were increased by 58.1% and 21.4%, respectively. Finally, quantitative conformational relationships (QSAR) with GHG adsorption energy were constructed using representative electronic properties of biochar model surfaces as descriptors. The results showed that the electrostatic potential on the surface of biochar, ELOMO and ΔEgap of α orbitals showed a good linear relationship with the adsorption energy, which can be used for the preliminary screening of GHG adsorbents. This contribution provides an insight into the mechanism of GHG adsorption at the molecular level and may help in the design of more efficient materials for environmental remediation.