Insight into the Crystal Facet Effect of {101} and {100} Facets of CeVO₄ in the Photochemical Property and Photocatalysis

Abstract

To investigate the photochemical property of specific crystal facets, two well-defined CeVO₄ dodecahedrons with exposed {101} and {100} facets are prepared, which have distinguishing appearances and unequal {101}/{100} area ratios (<i>A</i>_<i>{101}</i><i>/A</i>_<i>{100}</i>), <i>i.e</i>., compressed dodecahedra (CeVO₄ CD, <i>A</i>_<i>{101}</i><i>/A</i>_<i>{100}</i> ≈ 1) and elongated dodecahedra (CeVO₄ ED, <i>A</i>_<i>{101}</i><i>/A</i>_<i>{100}</i> ≈ 0.3). During the visible-light-irradiated process, the {101} and {100} facets are certified to selectively deposit photogenerated holes (h⁺) and electrons (e^-), thus exhibiting the photooxidability and photoreducibility, respectively. Meanwhile, a surface heterojunction could form at the adjacent facet interface and facilitate the spatial separation of carriers. Benefiting from the large exposure extent of the {101} facet and the rational <i>A</i>_<i>{101}</i><i>/A</i>_<i>{100}</i> (∼1), the CeVO₄ CD shows a superior photocatalytic performance for the degradation of tetracycline to the CeVO₄ ED. Finally, simulation calculations reveal that the energy deviations of the valence band (VB) and conduction band (CB) between CeVO₄{101} and CeVO₄{100} impel the photogenerated h⁺ and e^- to transfer in opposite directions, resulting in the facet-dependent photoactivity of the CeVO₄ dodecahedron.