TiO2/graphene-like photocatalysts for selective oxidation of 3-pyridine-methanol to vitamin B3 under UV/solar simulated radiation in aqueous solution at room conditions: The effect of morphology on catalyst performances

• TiO2/graphene-like composites were tested in the oxidation of 3-pyridine methanol.
• Two different forms of graphene layers were used to produce TiO2 composites.
• Morphology of TiO2 composites strongly influences the photocatalytic performances.
• Photocatalytic activity is depending on the generated stable free-radical species.

Graphene-like layers, synthesized through a two-step oxidation/reduction wet treatment of a high surface carbon black, have been used to prepare composites with TiO2 nanoparticles by liquid phase deposition, followed by calcination at 200 °C. The photocatalytic activity of the TiO2/graphene-like composites has been tested for the selective conversion of 3-pyridine methanol to 3-pyridine carboxyaldehyde and nicotinic acid (vitamin B3), under de-aerated and UV/solar simulated conditions, in the presence of cupric ions. Two different composite morphologies have been explored and a dependence of the photocatalytic activity has been assessed. An enhanced photocatalytic activity, with respect to the neat TiO2, has been observed and attributed to the broader variety of stable free-radical species generated, at a given photo-catalyst morphology, within the delocalized π-electron systems.

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