WO3/TiO2 Photocatalyst Towards Indoor Air Purification Using APT

Vehicle emissions by burning fossil fuels had produce serious air pollutions. Some major pollutants include itrogen oxides (NOx), sulfur dioxide (SO2) and volatile organic compounds (VOC). As the indoor environment has attracted more attentions, the indoor air purification device is becoming more popular in the market. 

The best approach is by applying photocatalytic materials to reduce indoor air pollutants using solar light. Currently, the most relevant photocatalyst from an application point of view is titanium dioxide (TiO2). Unfortunately, its disclosed drawbacks such as large band gap energy, which can only be activated under ultra-violet light illumination.

To overcome the disadvantages, nanocomposite of WO3 and TiO2 (WO3/TiO2) has been synthesized, surface modified with Fe(III) nanoclusters. It is considered that the TiO2 supported WO3 is extending the population of photogenerated charge carriers due to a synergistic interaction.

The preparation approach of the modified WO3/TiO2 photocatalysts applying ammonium paratungstate (APT) as precursors is as below:

Calculated amount of APT was used to reach final weight fraction of 1–2.5 wt% WO3 relative to TiO2 was dissolved in hot (90 °C) deionized water under stirring for 4 h. The appropriate amount of TiO2 powder was dispersed in ethanol with the weight ratio of 1:10 and a specific volume out of the stock solution of the tungsten precursor was added into this suspension, which was then vigorously stirred for 3 h at 50 °C. The suspension was dried at 70 °C and the obtained residue was calcined at 500 °C for 3 h to form heterogeneous WO3/TiO2 composites. The obtained material was grinded into fine powders and washed with a 6 M HCl for 3 h under stirring at 90 °C, centrifuged 3 times with a copious amount of distilled water and dried at 110 °C for 24 h. The thus obtained samples were labeled as 1WT and 2.5WT with 1 and 2.5 referring to the 1 wt% and 2.5 wt% fraction of WO3 in TiO2, respectively.

In conclusion, the modified WO3/TiO2 photocatalysts had been successfully produced applying APT as precursors. The Fe(III) nanoclusters (0.005 wt%) had been grafted on the surface of sWO3/TiO2 composite.  Supported WO3 and surface grafted iron nanoclusters extremely improved its photocatalytic response under UV as well as visible light. highest performance for the degradation of acetaldehyde and nitric oxide at a composition of 0.05 wt%.

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