Structure and effective visible-light-driven photocatalytic activity of α-NiMoO4 for degradation of methylene blue dye

alpha-NiMoO4 powders were prepared by the Pechini method. The sample was investigated by X-ray powder diffraction (XRD) measurement, structural refinement, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). The average size of alpha-NiMoO4 powders was measured to be 250 nm. The optical absorption spectrum of alpha-NiMoO4 confirmed an efficient absorption in the UV-visible light wavelength region. The sample presents a narrowed band-gap energy of 2.23 eV, and the effective photocatalytic activity was evaluated by the photodegradation of methylene blue (MB). The effective photocatalytic activity was discussed on the base of the crystal structure characteristics such as heavily distorted NiO6, activated optical centers and good electric conductivity. These results indicate that the hexagonal tunnel-structure alternately connected by MoO4 and the heavily distorted NiO6 is the dominated superiority for high photocatalytic capacity. (C) 2015 Published by Elsevier B.V.