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

The development of highly efficient sorbent materials for CO2 capture at 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 boron antisite (BN) 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 BN in p-BN induced defect electronic states in the energy gap region, which strongly impacted the adsorption properties of the material. The bonding between BN defect and CO2 molecule was clarified, and found that the electron donation first occurred from CO2 to BN double-acceptor state then followed by electron back-donation from BN to CO2 accompanied by the formation of a BN-C bond. The thermodynamic properties indicated that the adsorption of CO2 on BN defect to form anionic CO2?- species was spontaneous at temperatures below 350 K. Both the large adsorption energies and the thermodynamic properties ensured that p-BN with BN defect could effectively capture CO2 at ambient conditions. Finally, to evaluate the energetic stability, the defect formation energies were estimated. The formation energy of BN 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 porous BN sorbent for CO2 capture.