The photocatalytic activity of hexagonal (h-) WO3 nanoparticles (NPs) and nanowires (NWs) was investigated and compared with the
performance of monoclinic (m-) WO3 nanoparticles in the aqueous photo-bleaching reaction of methyl orange (MO) under UV irradiation.
It has been known that the m-WO3 is better photocatalyst than the h-WO3, but due to the advantageous morphology we investigated
whether the h-WO3 NWs can reach the photo-efficiency of the m-WO3 NPs. The h-WO3 was successfully synthesized in NW and NP
morphology using a microwave (MW) assisted hydrothermal procedure starting from Na2WO4 and thermal annealing of hexagonal
ammonium tungsten bronze (HATB), (NH4)0.33-xWO3, respectively. We found that the h-WO3 NWs exhibited almost three times higher
photoactivity than the h-WO3 NPs. The improved performance of the NWs can be attributed to the enlarged surface area and the good
charge carrier ability of the nanowire morphology. The catalytic tests also confirmed that the morphological effect could lead to as high
photoactivity in the case of h-WO3 NWs as exhibited by the m-WO3 NPs.
Key words: WO3, hexagonal, monoclinic, nanoparticle, nanowire, photocatalysis
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