Hydrothermal synthesis of β-ZnMoO4 crystals and their photocatalytic degradation of Victoria Blue R and phenol

In this paper, the hydrothermal reaction with Na2MoO4·2H2O and Zn(NO3)2·6H2O as a precursor was investigated for the synthesis of β-ZnMoO4 crystals. The β-ZnMoO4 crystals were characterized by the X-ray diffraction (XRD), field emission scanning electronic microscopy-energy dispersive spectroscopy (FE-SEM-EDS), field emission transmission electronic microscopy-energy dispersive spectroscopy (FE-TEM-EDS), X-ray photoelectron (XPS), ultraviolet-visible (UV-vis), and Fourier transform infrared spectroscopy (FT-IR). Diffuse UV-vis spectra show that the β-ZnMoO4 crystals have an indirect semiconductors with an optical bandgap of 2.48-2.69 eV. The photocatalytic efficiencies of powder suspensions were evaluated by measuring the Victoria Blue R (VBR) and phenol concentration. The as-prepared β-ZnMoO4 crystals obtained at 280 °C for 24 h showed the best photocatalytic activity for VBR under UV irradiation and showed the best photocatalytic activity for VBR and phenol under visible-light irradiation. This is the first study to reveal excellent activities of β-ZnMoO4 crystals are a promising visible-light-responsive photocatalyst.