Morphology-controllable synthesis of novel Bi25VO40 microcubes: optical properties and catalytic activities for the reduction of aromatic nitro compounds

Abstract

In the present paper, novel Bi₂₅VO₄₀ microcubes with relatively good dispersion have been fabricated via a facile, fast and mild hydrothermal synthesis strategy. The morphology and compositional characteristics of the Bi₂₅VO₄₀ sample were characterized by various testing techniques including powder X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), FT-IR spectroscopy, energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). Several experimental parameters including synthesis temperature, time and the amount of additives (e.g., polyacrylamide, sodium citrate and sodium hydroxide) were discovered to play vital roles in the construction of these Bi₂₅VO₄₀ microcrystals. From the UV-vis diffuse reflectance spectrum (DRS) of the Bi₂₅VO₄₀ its band gap was calculated to be 2.42 eV. The photoluminescence (PL) spectrum showed that Bi₂₅VO₄₀ microcubes had two obvious emission peaks centered at 458 and 639 nm. Moreover, catalytic experiments showed that the as-prepared Bi₂₅VO₄₀ microcubes possessed superior catalytic performance for the conversion of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) in the presence of excess NaBH₄ solution.