UV-LED photocatalytic oxidation of carbon monoxide over TiO2 supported with noble metal nanoparticles

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2017-04, Vol.314, p.600-611
• Main Authors: Kolobov, N.S., Svintsitskiy, D.A., Kozlova, E.A., Selishchev, D.S., Kozlov, D.V.
• Format: Article
• Language: English
• Subjects: CO oxidation; Nanoparticles; Noble metals; Photocatalytic oxidation; TiO2; UV LED
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2016.12.018

[Display omitted] •CO is oxidized to CO2 over UV-LED irradiated TiO2 supported with Pt, Pd or Au.•Thermal catalytic and photocatalytic oxidation pathways are proposed for M/TiO2.•Domed dependence of carbon monoxide PCO rate on the metal content is observed.•CO oxidation rate for Pt/TiO2 is up to 11 times higher than for Pd/TiO2 or Au/TiO2.•Chemically reduced 1wt% Pt/TiO2 is found to be the most active catalyst. The TiO2 catalysts supported with 0.01–4wt% Pt, Pd, or Au were prepared via chemical reduction of inorganic precursors with NaBH4 or their photoreduction in water-ethanol solution under UV irradiation. The samples were characterized by the means of X-ray fluorescence, N2 adsorption, TEM, XPS and UV-Vis spectroscopy and investigated in the processes of dark catalytic and UV-LED photocatalytic oxidation of carbon monoxide at room temperature. UV-LED irradiation of all the synthesized catalysts resulted in an increase in CO oxidation rate compared to the oxidation without UV. Two parallel pathways including thermal catalytic oxidation on metal particles and photocatalytic oxidation by the action of UV light were proposed for the M/TiO2 catalysts. The domed dependence of photocatalytic oxidation rate on the metal content was observed for all the metal deposited catalysts and had a maximum at 1wt% for Pt and 0.05wt% for Pd and Au. The activity of the 1wt% Pt/TiO2 catalyst was 7 and 11 times higher than that of the 0.05wt% Pd- and Au-loaded samples, respectively. For the 1wt% Pt/TiO2 sample, the deposition method via chemical reduction with NaBH4 resulted in a much higher activity than the photoreduction method. The effects of the metal nature, its content and the preparation method on CO photocatalytic oxidation rate are discussed in the terms of metal particle size and charge state based on the data from TEM and XPS analyses.