Ambient Carbon Dioxide Capture Using Boron-Rich Porous Boron Nitride: A Theoretical Study

The development of highly efficient sorbent materials for CO₂ capture under ambient conditions is of great importance for reducing the impact of CO₂ on the environment and climate change. In this account, strong CO₂ adsorption on a boron antisite (B_N) in boron-rich porous boron nitrides (p-BN) was developed and studied. The results indicated that the material achieved larger adsorption energies of 2.09 eV (201.66 kJ/mol, PBE-D). The electronic structure calculations suggested that the introduction of B_N in p-BN induced defect electronic states in the energy gap region, which strongly impacted the adsorption properties of the material. The bonding between the B_N defect and the CO₂ molecule was clarified, and it was found that the electron donation first occurred from CO₂ to the B_N double-acceptor state then, followed by electron back-donation from B_N to CO₂ accompanied by the formation of a B_N-C bond. The thermodynamic properties indicated that the adsorption of CO₂ on the B_N defect to form anionic CO₂^δ- species was spontaneous at temperatures below 350 K. Both the large adsorption energies and the thermodynamic properties ensured that p-BN with a B_N defect could effectively capture CO₂ under ambient conditions. Finally, to evaluate the energetic stability, the defect formation energies were estimated. The formation energy of the B_N defects was found to strongly depend on the chemical environment, and the selection of different reactants (B or N sources) would achieve the goal of reducing the formation energy. These findings provided a useful guidance for the design and fabrication of a porous BN sorbent for CO₂ capture.