A new copper molybdate-doped aluminium phosphate nanocomposite heterostructure for photoreduction of aqueous 2-NA and 4-NA

Abstract

Metal molybdate-doped aluminium phosphate (M_xMo_xAl_1−xP_1−xO₄; M = Cu, Ni, and Co) heterostructures have been prepared by a solid solution method and found to be efficient catalysts for the photoreduction of o-nitroaniline (o-NA) and p-nitroaniline (p-NA). A comparative investigation of the different metal molybdate-doped aluminium phosphate materials shows the photocatalytic activity of various proportions of copper/nickel/cobalt–molybdenum–aluminium–phosphorous oxides in the reduction of o-nitroaniline (o-NA) and p-nitroaniline (p-NA) under both UV and visible light. Among the three types of metal systems, the copper heterostructure is very effective (Cu_xMo_xAl_1−xP_1−xO₄)(x = 0.5) (CuMAP2), showing good results with very effective catalytic activity, photoluminescence (highest intensity peak at 271 nm) and semiconductor (E_g 4.21 eV) properties. Therefore, our main investigation focused on the copper system. The nanocomposites were characterized using UV-vis spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and PL spectroscopy. The average crystallite and particle sizes of CuMAP2 were found to be 21.23 ± 1 and 45 ± 5 nm, respectively. Among the studied compositions, CuMAP2 showed the highest catalytic activity in the reduction of o-NA or 2-NA and p-NA or 4-NA under visible light. XRD analysis clearly explained the phase formation temperature and showed that different metal ions are present in the composition, which was also supported by FTIR spectroscopy. Photocatalytic parameters, including dopant concentration, catalyst loading, and p-NA and o-NA concentrations, have also been investigated.