Unveiling the Activity Origin of Ultrathin Bi2MoO6 Nanosheets for Photocatalytic CO2 Reduction
Bismuth-based layer semiconductors have attracted particular attention for various photocatalytic applications,owing to their unique surface properties.However,the changes of photocharge migration and surface/interface structure during photocatalytic reactions are rarely reported.Herein,we first observe the dynamic evolution of photocharge migration and surface/interface structure over ultrathin Bi2MoO6 nanosheets during photocatalytic CO2 reduction via quasi in situ X-ray photoelectron spectroscopy.Specifically,under the ground state,CO2 molecules adsorbed on the Bi activity site of the(010)exposed facet,owing to the strong electron-attraction of CO2 molecules,leading to the high-valance Mo(6+x)+in the inner layer increase significantly.Upon light irradiation,the characterization peak of*CO2 significantly decreased,while the peak of CO evidently increased,indicating that CO2 molecules were activated,and reacted with the photogenerated electrons to form*CO,which increased the proportion of high-valance Mo(6+x)+species.By virtue of the above unique characteristic changes,ultrathin Bi2MoO6 nanosheets exhibit excellent CO2 reduction to CO activity(41.8 μmol·g-1·h-1),which is nearly 4.2 times higher than that of bulk Bi2MoO6 nanosheets.Thus,this case provides new possibilities for photocatalyst design using two-dimensional materials with high solar-driven photocatalytic activity.
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