Correlation study between photo-degradation and surface adsorption properties of phenol and methyl orange on TiO2 Vs platinum-supported TiO2

• Photocatalytic oxidation of phenol and methyl orange over TiO2and Pt–TiO2.
• FT-IR study of the substrate-photocatalysts surface interaction.
• High influence of Pt particle size on substrate-TiO2 adsorption.
• Small Pt deposits promote phenolates formation on Pt–TiO2 photocatalysts surfaces.
• Large Pt deposits favour the methyl orange-TiO2 surface interaction.

Adsorption of phenol and methyl orange on the surface of TiO2 and Pt–TiO2 photocatalysts was investigated by FT-IR spectroscopy. It was found that platinum plays an important role in the adsorption properties of the studied substrates on TiO2. Platinum deposits modified the phenol-photocatalyst interaction providing new adsorption sites on TiO2 surface. On Pt–TiO2 photocatalysts, phenol mainly interacts via formation of adsorbed phenolates species. It was also found that the adsorption of methyl orange on titania and Pt–TiO2 photocatalysts occurs via interaction of the azo group with surface Ti4+. Pt photodeposition significantly increases the TiO2 photoreactivity in phenol and methyl orange photo-degradation; however, this increase depends on the properties of the Pt deposits. Moreover, it was observed that platinum content is the main factor determining the substrate-photocatalyst interaction and therefore the Pt–TiO2 photocatalytic performance.

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