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

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 mu m, which are assembled by plate-like microcrystals with an average thickness of similar to 230 nm, can be obtained from a hydrothermal treatment at 160 degrees 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.