B–O Bonds in Ultrathin Boron Nitride Nanosheets to Promote Photocatalytic Carbon Dioxide Conversion

Abstract

Limited by the chemical inertness of CO₂ and the high dissociation energy of the C═O bond, photocatalytic CO₂ conversion is highly challenging. Herein, we prepare ultrathin oxygen-modified h-BN (O/BN) nanosheets containing B-O bonds. On the O/BN surface, CO₂ can be chemically captured and is bonded with the B-O bond, leading to the formation of an O-B-O bond. This new chemical bond acting as an electron-delivery channel strengthens the interaction between CO₂ and the surface. Thus, the reactants can continuously obtain electrons from the surface through this channel. Therefore, the majority of gaseous CO₂ directly converts into carbon active species that are detected by in situ DRIFTS over O/BN. Moreover, the activated energies of CO₂ conversion are significantly reduced with the introduction of the B-O bond evidenced by DFT calculations. As a result, O/BN nanosheets present an enhanced photocatalytic CO₂ conversion performance with the H₂ and CO generation rates of 3.3 and 12.5 μmol g^-1 h^-1, respectively. This work could help in realizing the effects of nonmetal chemical bonds in the CO₂ photoreduction reaction for designing efficient photocatalysts.