Synthesis, surface and optical properties of Ag₂CaV₄O₁₂ nanoparticles for dye removal under visible irradiation

Ag-containing compounds are regarded as potential candidates for the efficient photocatalyst driven by visible-light. In this work, nano-sized Ag₂CaV₄O₁₂ was prepared via a modified Pechini synthesis. The detailed structural refinement of X-ray diffraction (XRD) pattern indicates that the Ag₂CaV₄O₁₂ crystallizes in tetragonal system with the space group of P4/nbm (125), Z = 2. The surface property of this vanadate was measured by the scanning electron microscope (SEM), energy dispersive spectra (EDS), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherm. The sample has an efficient optical absorption in the wavelength from UV to visible region characterized by its narrow band-gap energy of 2.231 eV with an indirect allowed property. The valence band maximum is composed of multiple states of Ag-d and O-p resulting in a narrow band. The excellent photocatalytic activity of Ag₂CaV₄O₁₂ nanoparticles was tested by the photodegradation of rhodamine B (RhB), methylene blue (MB) and phenol solutions excited by visible-light. The photocatalytic mechanism was suggested according to experimental results and the band energy positions. © 2016 Elsevier B.V.