Nonaqueous Synthesis of a Bismuth Vanadate Photocatalyst By Using Microwave Heating: Photooxidation versus Photosensitized Decomposition in Visible‐Light‐Driven Photocatalysis

Abstract

A new synthetic route to monoclinic bismuth vanadate using a concept adapted from a nonaqueous synthesis strategy for nanostructured organic–inorganic hybrid materials and metal oxides, introduced recently as twin polymerization, is reported. Microwave‐assisted synthesis starting from bismuth(III) tert‐butoxide and vanadium(V) oxytri(tert‐butoxide) in the presence of 2‐methoxybenzyl alcohol, 2,4‐dimethoxybenzyl alcohol, and 2‐(2‐thienyl)iso‐propyl alcohol gave hybrid materials, which were characterized by solid‐state 13C NMR spectroscopy, CH analysis, atomic absorption spectroscopy, and energy dispersive X‐ray spectroscopy. Subsequent pyrolysis resulted in nanoscale monoclinic bismuth vanadate that showed a high photocatalytic activity. The photocatalytic decomposition of model pollutants such as rhodamine B (RhB), methyl orange, methylene blue, and orange G under visible‐light irradiation using the as‐prepared bismuth vanadate samples was studied with a focus on the influence of the agglomeration behavior. The interplay between the photooxidation of RhB, induced by the excitation of the catalyst using visible light, and the photosensitized decomposition pathway is demonstrated by degradation experiments in solution and the solid state.

The Power of Non-Hydrolytic Sol-Gel Chemistry: A Review

“…Bismuth vanadate represents another interesting material with a novel composition prepared via the non-hydrolytic microwave-assisted approach based on the concept of twin polymerization [187]. Reactions were performed with the use of bismuth(III) t butoxide and vanadium(V) oxytri( t butoxide) precursors.…”

“…An important feature of these materials is their high adsorption capacity. Finally, the photocatalytic properties of bismuth vanadate (BiVO 4 ) prepared by a non-hydrolytic microwave assisted reaction were described by Hofmann et al [187]. BiVO 4 showed a very high degradation efficiency (>99%) of rhodamine B after 150 min under visible light irradiation.…”

Bismuth vanadate-based semiconductor photocatalysts: a short critical review on the efficiency and the mechanism of photodegradation of organic pollutants

“…Despites the works attempting to discuss photocatalytic mechanism based on experimental observations in presence of BiVO 4 , many other published works often base their discussion on assumptions, calculations, already published data or even speculations (Hofmann et al 2015;Liu et al 2015). But without further experimental data to complete these theoretical results, a reliable mechanism cannot be determined.…”

“…To date, the most commonly used synthesis methods for the preparation of BiVO 4 in the form of film and powder are metal organic decomposition (MOD), precipitation and hydrothermal methods(Galembeck and Alves 2000;Hubert- Pfalzgraf 2003;Ke et al 2008;Park et al 2013;Sayama et al 2003;Thurston et al 2004;Xu et al 2011). Other techniques can be also used such as electrochemical and sol-gel processes but they are less common(Hofmann et al 2015;Pookmanee et al 2012;Seabold and Choi 2012;Wang et al 2016). Most of these preparation methods allow the use of dopants and/or surfactants into the reactive mixture in order to tune the chemical composition and to control the morphology of BiVO 4 materials(Park et al 2013).…”

Co2+ substituted for Bi3+ in BiVO4 and its enhanced photocatalytic activity under visible LED light irradiation

“…Monoclinic scheelite bismuth vanadate (m-s BiVO 4 ), a p-type semiconductor with a direct band gap (E g ) of 2.4 eV, has generated considerable interest as a visible light-responsive photocatalyst. [1][2][3][4] Reportedly, different morphologies of monoclinically structured BiVO 4 crystallites, such as nanospheres, 5 nanorods, 6,7 nanoowers, 8 nanosheets, 9 nanotubes, [10][11][12] olive, 13,14 and hyperbranched, 15 have been clearly created by the hydrothermal or solvothermal technique. Nevertheless, the poor charge transport and weak surface adsorption properties associated with pristine BiVO 4 could cause prompt recombination of photogenerated electron-hole pairs, reducing its overall photocatalytic efficiency.…”