Effects of exposed facets on photocatalytic properties of WO₃

Hexagonal WO₃ (h-WO₃) was prepared by using Na₂SO₄ and (NH₄)₂·SO₄ as capping agents under different hydrothermal conditions. XRD, SEM and TEM results indicated that three types of morphologies, including h-WO₃ rods with exposed (2 0 0) facets, h-WO₃ nanosheets with exposed (0 0 2) facets and h-WO₃ with corn cob-like structure and no preferred direction, could be obtained by tuning the capping agents and pH. Specifically, h-WO₃ nanosheets with exposed (0 0 1) facets have the best visible photocatalytic properties due to its high specific surface area and charge separation nature on the (0 0 2) high energy facets.