Nano-Structuration of WO3 Nanoleaves by Localized Hydrolysis of an Organometallic Zn Precursor: Application to Photocatalytic NO2 Abatement

Abstract

WO3 is a known photocatalytic metal oxide frequently studied for its depollution properties. However, it suffers from a high recombination rate of the photogenerated electron/holes pair that is detrimental to its performance. In this paper, we present a new chemical method to decorate WO3 nanoleaves (NLs) with a complementary metal oxide (ZnWO4) in order to improve the photocatalytic performance of the composite material for the abatement of 400 ppb NO2 under mild UV exposure. Our strategy was to synthesize WO3·2H2O nanoleaves, then, to expose them, in water-free organic solution, to an organometallic precursor of Zn(Cy)2. A structural water molecule from WO3·2H2O spontaneously decomposes Zn(Cy)2 and induces the formation of the ZnO@WO3·H2O nanocomposite. The material was characterized by electronic microscopy (SEM, TEM), TGA, XRD, Raman and solid NMR spectroscopies. A simple thermal treatment under air at 500 °C affords the ZnWO4@WO3 nanocomposite. The resulting material, additionally decorated with 1% wt. Au, presents a remarkable increase (+166%) in the photocatalytic abatement of NO2 under UV compared to the pristine WO3 NLs. This synthesis method paves the way to the versatile preparation of a wide range of MOx@WO3 nanocomposites (MOx = metal oxide).

Gas Sensing Properties of CuWO4@WO3 n-n Heterojunction Prepared by Direct Hydrolysis of Mesitylcopper (I) on WO3·2H2O Nanoleaves

“…Although they are rather homogeneously distributed on the support, some aggregates can be observed as well. Such an agglomeration has not been noticed for the ZnO@WO 3 •H 2 O nanocomposite [22].…”

“…Some of them have been used as gas-sensitive layers and exhibited remarkable gas-sensing properties [28][29][30][31]. Recently, a modification of this approach led to the formation of new nanocomposites where zinc oxide nanoparticles were grown on WO 3 •2H 2 O nanoleaves [22]. Thanks to the water molecules incorporated in the crystal lattice of the WO 3 •2H 2 O, the hydrolysis of the zinc precursor (dicyclohexyl zinc (II)) was performed directly on the nanoleaves support without further addition of water and surfactants.…”

“…According to the results described before we have concentrated our study on the reaction of CuMes (Cu(I)) with WO 3 •2H 2 O NLs only [22]. The yellow suspension of the NLs rapidly turns green after the addition of the CuMes solution (0.5 molar equivalent CuMes/W atom) (Figure 2).…”

“…The Cu 2 O nanoparticles (NPs) have been produced by controlled hydrolysis of mesitylcopper (I) (CuMes) at room temperature under argon atmosphere and in the presence of an organic solvent (anisole). The Cu 2 O@WO 3 •H 2 O nanocomposite (NCs) has been synthesized by modifying a method described by Castello-Lux [22]. The latter is based on the in situ hydrolysis of an organometallic precursor (here mesitylcopper (I)) in a dry organic solvent directly on a suspension of WO O) was purchased from Sigma Aldrich (Darmstadt, Germany) and used without further purification.…”

“…The present manuscript describes a simple route for the preparation of Cu 2 O@WO 3 •H 2 O nanocomposite by modifying a synthesis protocol we have recently developed [22]. The method is based on direct hydrolysis of metal-organic precursor on WO 3 •2H 2 O nanoleaves.…”