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

• A new visible-light-driven photocatalyst of Ag2CaV4O12 was developed.
• It has a narrow band gap of 2.231 eV with an indirect allowed characteristic.
• Ag2CaV4O12 shows high activity in the MB degradation under visible light.
• The photocatalytic ability is mainly driven by the OH radicals.

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.

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