According to reports, researchers have prepared yellow tungsten oxide (tungsten trioxide/WO3) by air annealing of various W precursors, and examined the effects of W precursor type and pretreatment conditions on the physical properties and photocatalytic activity of the obtained yellow tungsten oxide powder.
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In this reports, the photooxidation of water to oxygen and protons in the presence of reducible additives Ce4+, using the luminous and near IR illumination was used as a test reaction to evaluate the activity of the powders. Increasing annealing temperatures gave materials with a high degree of crystallinity and red-shifted the onset of light absorption. The photocatalytic activity of tungsten trioxide powders depended on the type of W precursor used, annealing conditions, and the physicochemical characteristics of the resulting powders. The activity as a ding of annealing temperature and duration of W precursors goes through a maximum at 700–800°C and 4–8 h, respectively. Increasing the specific surface area of WO3 powders, did not alter the activity significantly. Small amounts of hydrogen were also produced from photochemical reactions involving the photoexcitation of Ce3+.
