Influence of phase stabilization and perovskite vanadate oxygen vacancies of the BINIVOX catalyst on photocatalytic degradation of azo dye under visible light irradiation

Abstract

Mureish (2014) Influence of phase stabilization and perovskite vanadate oxygen vacancies of the BINIVOX catalyst on photocatalytic degradation of azo dye under visible light irradiation, A layered Aurivillius-perovskite-type BINIVOX system with the general formula Bi 2 Ni (II)x V 1−x O 5.5−(3x/2) was developed as a novel photocatalyst for degradation of organic dyes. A series of the BINIVOX.x catalysts in the compositional range 0 ≤ x ≤ 0.20 were successfully synthesized by the standard solidstate reaction and characterized using X-ray powder diffraction, differential thermal analysis, UV-vis diffuse reflectance spectroscopy and Brunauer-Emmett-Teller BET surface area. Then, the photocatalytic activities of prepared catalysts were investigated for the first time through the degradation of a new azo dye named sodium 4-[(E)-(4,5-dimethyl-1H-pyrazolo [3,4-c] pyridazin-3-yl) diazenyl] naphthalen-1-olate and denoted as 4-SPPN in aqueous solution under visible light irradiation. Adsorption efficiency and photocatalytic activity of BINIVOX.x catalysts were correlated well with the variation in phase crystal structures stabilized at room temperature as a function of composition. The stabilized γ -BINIVOX phases in the tetragonal crystal system with space group I4/m mm exhibited the best photocatalytic performance which can be attributed to their higher specific surface area, narrower band-gap energy and higher oxygenvacancy concentration in the perovskite vanadate layers. In addition, the possible photocatalytic degradation mechanism of aqueous 4-SPPN dye was proposed under visible light irradiation.

Recent Advances in Heterogeneous Photocatalytic Decolorization of Synthetic Dyes

“…The aromatic ring system of the dyes helps to strengthen the Van-der-Waals forces between dye and fibers [203]. Most synthetic dyes have significant structural variations and are extremely stable in performance under light and washing and most severely are resistant to aerobic biodecolorization by bacteria [204, 205].…”

“…The azoic dyes that are normally used on industrial scale have characteristics that are dependent on one or more azo bonds (–N=N–) with aromatic rings [ 167 , 200 – 202 ]. The aromatic ring system of the dyes helps to strengthen the Van-der-Waals forces between dye and fibers [ 203 ]. Most synthetic dyes have significant structural variations and are extremely stable in performance under light and washing and most severely are resistant to aerobic biodecolorization by bacteria [ 204 , 205 ].…”

A Novel Visible– Light Driven Photocatalyst: Ethylene Glycol–Citrate Sol–Gel Synthesis, Microwave–Assisted Calcination, and Photocatalytic Efficiency

“…UV-vis absorption spectra of BIMNVOX.x photocatalyst for various compositions are presented in Figure 5. The intrinsic band-gap absorption of Bi 4 V 2 O 11 is clearly seen at ~ 559 nm, resulting from the electronic transitions from Bi6s/O2p orbitals of the bismuthate (Bi 2 O 2 ) 2+ layers (valence band) to V3d orbitals of the (VO 3.5 0.5 ) 2-perovskite-like slabs (conduction band) [14,15], where represents an oxygen vacancy in vanadate polyhydra. The absorption edges of the BIMNVOX.x photocatalysts are found to shift toward longer wavelengths as the concentration of Mn dopant increases.…”

“…Very recently, a layered perovskite-type Bi 4 V 2 O 11 oxide and its metal-doped analogues, designated as BIMEVOX.x ; l=Me oxidation state) belonging to the Aurivillius family, have attracted considerable attention due to their interesting propriety, such as in peculiar polymorphic structure and stability [8,9,10], very low electrical conductivity below 300 o C [11], reasonable scaleelectronic and ferroelectric contribution at low dopant concentrations [12,13], and remarkably narrow band gap with a potential visible light photocatalytic efficiency [14,15]. BIMEVOX materials, such as BIALVOX, BIGAVOX [14] and BINIVOX [16] have shown enhanced photocatalytic degradation of some organic dyes in the visible spectral range as a consequence of band gap narrowing of the doped photocatalysts.…”