Hierarchical PbMoO4 microspheres: hydrothermal synthesis, formation mechanism and photocatalytic properties

Abstract

Hierarchical PbMoO₄ microspheres were synthesized via a simple nitric acid-assisted hydrothermal process without the addition of a template or an organic directing reagent. The scheelite-type tetragonal PbMoO₄ with various hierarchical microstructures can be controllably fabricated by adjusting the experimental conditions such as hydrothermal temperature, time and nitric acid concentration. Experimental results indicate that hierarchical PbMoO₄ microspheres with a size of 5–10 μm, which are assembled by plate-like microcrystals with an average thickness of ∼230 nm, can be obtained from a hydrothermal treatment at 160 °C for 24 h in the presence of HNO₃ solution, whereas only irregular particles and aggregations are obtained without HNO₃ solution. The hierarchical PbMoO₄ microspheres show better photocatalytic activity than the irregular PbMoO₄ particles and the commercial photocatalyst (P25) for the degradation of rhodamine B (RhB) under UV light irradiation. Furthermore, a possible nitric acid-assisted formation mechanism for the hierarchical PbMoO₄ microspheres is proposed, which might represent a new fabrication strategy for other nano/microstructures with desired morphologies.