With an extension of the absorption band toward visible light, plasmonic photocatalysts directly harvest energy from solar light without compromising the activity, offering a desirable way to address energy and environmental issues. Here we demonstrate photocatalytic oxidation of formaldehyde in air over plasmonic Au/TiO 2 catalyst under visible light in a single-pass continuous flow reactor. Compared to that under dark, a significant enhancement of up to 5 times the reaction rate at 13% RH under visible light is achieved. Au/TiO 2 catalyst exhibits very high activity, a complete conversion of formaldehyde of 83.3% under visible light at 44% RH, but is completely inactive in dry air even under visible light. Also, the plasmonic Au/TiO 2 is efficient for photocatalytic oxidation of formaldehyde under visible light, which is evidenced by a slight difference of conversion between UV light and visible light. To disclose the underlying mechanism, in situ diffuse reflectance infrared Fourier transform (DRIFT) spectra studies are conducted. The contributions of TiO 2 and Au (supported on TiO 2 ), moisture, and visible light are identified. It is ascertained that moisture is indispensable to carbonate decomposition and also accelerates dioxymethylene (DOM) oxidation to formate. Visible light enhances the rate-determining steps of formate oxidation to carbonate and carbonate decomposition. It appropriately illustrates the remarkable difference in activities. On the basis of the spectra experiments, such a pathway of formaldehyde oxidation is proposed, which undergoes four sequential reaction steps (k 1 , k 2 , k 3 , k 4 ) with reaction conditions dependent on moisture and visible light over Au/TiO 2 catalyst. On the basis of the approximately identical spectra, which indicate the same reaction pathways under visible light or under dark, the insights into the mechanism for photocatalytic oxidation of formaldehyde in air under visible light over Au/TiO 2 , are obtained.
A facile and fast CVD method for the deposition of TiO 2 films, under atmospheric pressure and at room temperature, onto glass and polyethylene terephthalate (PET) substrates is explored. The hydrolysis reaction of titanium tetraisopropoxide (TTIP) is employed for the deposition of TiO 2 film, and the corresponding deposition rate determined. The surface morphology of the as-deposited TiO 2 films is observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In order to confirm the structure, composition, and optical properties of the films, X-ray diffraction (XRD), Raman spectroscopy (RS), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV-Vis absorption spectroscopy are employed. The as-deposited TiO 2 films are amorphous with a band gap energy of around 3.42 eV and rich in surface OH groups, which exhibit very high photocatalytic activity for complete oxidation of HCHO in simulated air under UV-C irradiation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.