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

Limited by the chemical inertness of CO2and the high dissociation energy of the C═O bond, photocatalytic CO2conversion is highly challenging. Herein, we prepare ultrathin oxygen-modified h-BN (O/BN) nanosheets containing B–O bonds. On the O/BN surface, CO2can 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 CO2and the surface. Thus, the reactants can continuously obtain electrons from the surface through this channel. Therefore, the majority of gaseous CO2directly converts into carbon active species that are detected by in situ DRIFTS over O/BN. Moreover, the activated energies of CO2conversion 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 CO2conversion performance with the H2and CO generation rates of 3.3 and 12.5 μmol g–1h–1, respectively. This work could help in realizing the effects of nonmetal chemical bonds in the CO2photoreduction reaction for designing efficient photocatalysts.