Diethyl phthalate (DEP) is an odorless, colorless, oily liquid. It is used to make plastics, pesticides, cosmetics, and aspirin, as well as toothbrushes, auto parts, toys, tools and food packaging. At the same time, DEP has a negative impact on human health and causes environmental problems.

Combustion equipment and automobiles are the major sources of NOx gas including nitrogen dioxide (NO2). These gases have negative effects on the human health and can also cause acid rain. Therefore, effective adsorption materials should be used to sense and detect these gases in the atmosphere.

In the past decade, the application of semiconductor powder as a photocatalytic degradation of organic pollutants in water has received widespread attention. Titanium dioxide (TiO2) suppresses amazing photocatalytic properties, including high activity, chemical stability, and low cost. However, the photocatalytic activity of TiO2 (with a band gap of 3.2 eV, excited by photons with a wavelength of less than 387 nm) is still limited by UV wavelength irradiation, so the photocatalytic process cannot effectively occur during sunlight irradiation. 4% of the total solar spectrum radiation is in the ultraviolet region.

Oxide nanomaterials are used to develop advanced photovoltaic materials, photocatalysts, and smart devices. Among metal oxides, tungsten oxide (WO3) is an n-type semiconductor with a small bandgap of 2.6 eV and unique thermal, optical, physical, chemical, and electrical properties. These properties have led to many applications in chemical and selective catalysis, sensors, fuel cells, color change, and pollutant adsorption. WO3 is considered a suitable candidate for the photodegradation of organic pollutants in the visible light region.