Quantitative Study of Charge Carrier Dynamics in Well-Defined WO₃ Nanowires and Nanosheets: Insight into the Crystal Facet Effect in Photocatalysis

Abstract

Photocatalysts with different morphologies and specific exposed facets usually exhibit distinguished activities. Previous researches have focused on revealing the essence of the facet effect in photocatalysis; however, quantitative analyses on the differences of carrier dynamic between different facets are scarce. Herein, we successfully synthesized WO₃ nanosheets and nanowires with dominant exposed facets of {001} and {110}, respectively. The lower hole effective mass on {110} (0.94<i>m</i>₀) than on {001} (1.28<i>m</i>₀) calculated by density functional theory leads to the higher hole mobility on {110} (4.92 cm² V^–1 s^–1) than on {001} (3.14 cm² V^–1 s^–1). Combined with the Einstein equation and the lifetime of the hole, the calculated hole diffusion length on {110} (74.8 nm) is larger than on {001} (53.4 nm). Overall, the lower hole effective mass, higher hole mobility, and greater hole diffusion length on {110} collectively result in a photocatalytic activity on benzyl alcohol oxidation 2.46 times as high as that on {001}