PbMoO 4 micro-octahedrons were prepared by the coprecipitation method at room temperature without the presence of surfactants and processed in a conventional hydrothermal at different temperatures (from 60 to 120 °C) for 10 min. These micro-octahedrons were structurally characterized by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy, and its morphology was investigated by field-emission gun scanning electron microscopy (FEG-SEM). The optical properties were analyzed by ultraviolet-visible (UV-vis) absorption spectroscopy and photoluminescence (PL) measurements. XRD patterns and MR spectra confirmed that the PbMoO 4 micro-octahedrons are characterized by a scheelite-type tetragonal structure. FEG-SEM micrographs points out that these structures present a polydisperse particle size distribution in consequence of a predominant growth mechanism via aggregation of particles. In addition, it was observed that the hydrothermal conditions favored a spontaneous formation of micro-octahedrons interconnected along a common crystallographic orientation (oriented-attachment), resulting in self-organized structures. An intense blue PL emission at room temperature was observed in these micro-octahedrons when they were excited with a 350 nm wavelength. The origin of the PL emissions as well as its intensity variations are explained by means of a model based on both distorted [MoO 4 ] and [PbO 8 ] clusters into the lattice.

A complimentary combination of experimental work and first principle calculations, based on the Density Functional Theory (DFT) method, has been used to increase our limited understanding of the enhanced photocatalytic activity of PbMoO 4 powders with predominant (111), (100), (011), and (110) facets.In this work, PbMoO 4 powders were prepared by the co-precipitation method and processed on a hydrothermal reactor at 100 o C/10 minutes. The variation of different types of modifier such as acetylacetone (acac) or polyvinylpyrrolidone (PVP) is found to play a crucial role in controlling the particle size and morphology of products and their photocatalytic properties.The structure and morphology of these crystals were characterized by X-ray diffraction (XRD), micro-Raman (MR) spectroscopy, field-emission gun scanning electron microscopy (FEG-SEM), and ultraviolet visible (UV-vis) absorption spectroscopy. Furthermore, the assynthesized PbMoO 4 micro-octahedrons without presence of (001) surface exhibit enhanced activity for the photodegradation of rhodamine B (RhB) under ultraviolet-visible light irradiation.Based on the theoretical and experimental results, we provide a complete assignment of the micro-Raman spectra of PbMoO 4 , while a growth mechanism for the formation of PbMoO 4 micro-octahedrons was systematically discussed, and a schematic illustration of the probable formation of morphologies in the whole of the synthetic process was also proposed, which reveals that the high photocatalytic activity is attributed to the absence of (001) facet.

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