BiVO₄ {010} and {110} Relative Exposure Extent: Governing Factor of Surface Charge Population and Photocatalytic Activity

The {010} and {110} crystal facets of monoclinic bismuth vanadate (m-BiVO₄) has been demonstrated to be the active reduction and oxidation sites, respectively. Here, we show using dual-faceted m-BiVO₄ with distinctly different dominant exposed facets, one which is {010}-dominant and the other {110}-dominant, contrary to prediction, the former m-BiVO₄ exhibits superior photooxidation activities. The population of photogenerated electrons and holes on the surface are revealed to be proportional to the respective surface areas of {010} and {110} exposed on m-BiVO₄, as evidenced by steady-state photoluminescence (PL) measurements in the presence of charge scavengers. The better photoactivity of {010}-dominant m-BiVO₄ is attributed to prompt electron transfer facilitated by the presence of more photogenerated electrons on the larger {010} surface. Additionally, the greater extent of electron trapping in {110}-dominant m-BiVO₄ also deteriorates its photoactivity by inducing electron-hole pair recombination.