Photocatalytic performance of β-Ag2MoO4 microcrystals at different experimental conditions

Abstract

In this present work, we report the photocatalytic activity of microcrystals of silver molybdate (β-Ag2MoO4) synthesized at 120 °C for 2 h by hydrothermal method. These microcrystals have been structurally characterized by X-ray diffraction (XRD), Rietveld refinement and micro-Raman (MR). The optical properties and the structure of the band gap were studied using diffuse reflectance spectroscopy of UV–vis (UV–vis) and photoluminescence (PL). The morphology and semiquantitative analysis of elements were investigated by field emission scanning electron microscopy (FE-SEM) images. The photocatalytic properties of these microcrystals have been investigated in the degradation of rhodamine B (RhB) and methyl orange (MO) dyes under UV-light. XRD patterns, Rietveld refinement data and Raman spectrum indicate that all microcrystals exhibit spinel-type cubic structure with space group of Fd3¯m and point group of symmetry O7h composed by tetrahedral [MoO4] and distorted octahedral [AgO6] clusters. The optical band gap found was Egap =3.30 eV for β-Ag2MoO4 microcrystals, associated with the indirect allowed electronic transitions. FE-SEM images have revealed that microcrystals have potato-like morphology. The photoluminescent properties (PL) verified can be explained by the distortions of the clusters present in the structure of β-Ag2MoO4 microcrystals. Moreover, these microcrystals exhibit high photocatalytic performance at pH > 8. Where, the photo-induced holes (h+) are one of the main reactive species involved in the degradation of RhB and MO dyes.