Tuning the Anisotropic Facet of Lead Chromate Photocatalysts to Promote Spatial Charge Separation

A crucial issue in artificial photosynthesis is how to modulate the behaviors of photogenerated charges of semiconductor photocatalysts. Here, using lead chromate (PbCrO4 ) as an example, we conducted the morphology tailoring from parallelepiped (p-PbCrO4 ) to truncated decahedron (t-PbCrO4 ) and elongated rhombic (r-PbCrO4 ), resulting in exposed anisotropic facets. The spatial separation of photogenerated charges closely correlates to the anisotropic facets of crystals, which can only be realized for t-PbCrO4 and r-PbCrO4 . The charge-separation efficiencies exhibit a quasilinear relation with the surface photovoltage difference between anisotropic facets. The r-PbCrO4 gives an apparent quantum efficiency of 6.5 % at 500 nm for photocatalytic water oxidation using Fe3+ ions as electron acceptors. Moreover, the oxidation reverse reaction from Fe2+ to Fe3+ ions was completely blocked with ∼100 % of Fe3+ conversion achieved on the anisotropic PbCrO4 crystals.