Nano-Structuration of WO 3 Nanoleaves by Localized Hydrolysis of an Organometallic Zn Precursor: Application to Photocatalytic NO 2 Abatement.

WO 3 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 WO 3 nanoleaves (NLs) with a complementary metal oxide (ZnWO 4 ) in order to improve the photocatalytic performance of the composite material for the abatement of 400 ppb NO 2 under mild UV exposure. Our strategy was to synthesize WO 3 ·2H 2 O nanoleaves, then, to expose them, in water-free organic solution, to an organometallic precursor of Zn(Cy) 2 . A structural water molecule from WO 3 ·2H 2 O spontaneously decomposes Zn(Cy) 2 and induces the formation of the ZnO@WO 3 ·H 2 O 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 ZnWO 4 @WO 3 nanocomposite. The resulting material, additionally decorated with 1% wt. Au, presents a remarkable increase (+166%) in the photocatalytic abatement of NO 2 under UV compared to the pristine WO 3 NLs. This synthesis method paves the way to the versatile preparation of a wide range of MOx@WO 3 nanocomposites (MOx = metal oxide).