Facet-controlled synthesis and facet-dependent photocatalytic properties of SnO₂ micropolyhedrons

The facet-dependent properties of SnO₂ are of fundamental and practical importance. In this study, by adjusting the deposition temperature during chemical vapor deposition, octahedral SnO₂ with the exposed (1 0 1) facet and two other kinds of SnO₂ polyhedrons with (1 0 1) and (1 0 0) facets with different ratios are fabricated controllably based on the vapor-solid growth mechanism. A slight increase in the deposition temperature from 1030 to 1070 °C decreases the surface energy of the reduced (1 0 1) facet with Sn termination, leading to the formation of polyhedrons with different area ratios of (1 0 1) to (1 0 0) facets. By adopting the terephthalic acid fluorescent method, the SnO₂ octahedrons are demonstrated to have the strongest photocatalytic activity due to the formation of surface states induced by 5s electrons of bivalent Sn on the (1 0 1) surface. The results reveal that the photocatalytic properties of SnO₂ microcrystals can be enhanced by facet-controlled synthesis.