Hydrothermal Synthesis of a CaNb2O6 Hierarchical Micro/Nanostructure and Its Enhanced Photocatalytic Activity

A novel CaNb2O6 hierarchical micro/nanostructure was successfully fabricated under mild hydrothermal conditions in the absence of templates or organic additives. In this hierarchical micro/nanostructure, the nanosheets grow vertically on the surface of the one-dimensional microneedles whose axial direction is along the c-axis, and the single crystalline nanosheets are parallel to the (020) planes. A two-step nucleation-growth mechanism is proposed to explain the formation of the CaNb2O6 hierarchical micro/nanostructure, based on the observation of a time-dependent morphology evolution process. The hierarchically structured CaNb2O6 exhibits a stronger enhancement of photocatalytic activity in the degradation of rhodamine B (RhB) than other morphological CaNb2O6 samples, such as nanoparticles, nanoribbons, and microneedles. This simple hydrothermal method provides a new general approach for the synthesis of potentially useful niobates.