AgI Microplate Monocrystals with Polar {0001} Facets: Spontaneous Photocarrier Separation and Enhanced Photocatalytic Activity

Elucidating the facet‐dependent photocatalytic activity of semiconductor photocatalysts is important in improving the overall efficiency of photocatalysis. Furthermore, combining facet control with selective deposition of oxidation and/or reduction cocatalysts on specific faces of semiconductor photocatalysts is potentially an effective strategy to synergistically optimize the functionality of photocatalysts. In the present study, high‐purity wurtzite‐type β‐AgI platelet microcrystals with polar {0001} facets were prepared by a facile polyvinylpyrrolidone‐assisted precipitation reaction. The polar‐faceted AgI microplates were used as archetypes to demonstrate preferential diametric migration (i.e., effective separation) of photogenerated electrons and holes along the c axis. Such vectorial electron–hole separation stems from the asymmetric surface structures, which give rise to distinct photoexcited reaction behaviors on the ±(0001) polar facets of wurtzite‐type semiconductors. Furthermore, on selective deposition of Ag and MnO_x (1.5<x<2) cocatalysts on the reductive (0001) and oxidative (000$bar 1$ ) facets, respectively, photocatalytic activity of the AgI microplates in degrading organic pollutants was dramatically enhanced thanks to the broad light‐absorption range, strong dye‐adsorption ability, and effective spatial separation of photocarriers.