Spatial Separation of Photogenerated Charges on Well-Defined Bismuth Vanadate Square Nanocrystals

Crystal facet engineering has been recognized as a powerful strategy to finely modulate the charge separation behavior in semiconductor photocatalysis; however, disclosing the intrinsic roles that the morphologies and crystal facets play on photogenerated charge separation of semiconductor nanocrystals remains elusive. Herein, exemplified on the typical visible-light-responsive photocatalyst bismuth vanadate (BiVO4), for the first time, the successful fabrication is reported of well-defined BiVO4 square nanocrystals with precisely controllable (040)/(200) facet proportion, which undergo a dissolution-recrystallization-facet growth process accompanied with tetragonal to monoclinic phase transition. Spatial separation of photogenerated electrons and holes has been evidently demonstrated to take place between (040) and (200) facets of BiVO4 nanocrystals, on which the charge separation efficiency is verified to definitely depend on the facet proportion of (040)/(200). Further theoretical simulation reveals that the matching degree of charge collection length and crystal configuration is considered to be the major factor determining charge separation efficiency of BiVO4 nanocrystals. This study presents a strategy to fabricate morphology-tailored semiconductors, which will be favorable to advance the understanding of spatial charge separation in semiconductor photocatalysis.