Effect of the irradiation wavelength on the performance of nanoporous carbon as an additive to TiO2

• Superior performance of TiO2/carbon catalysts compared to bare TiO2.
• The photoactivity of the carbon component is boosted using light at λ > 200 nm.
• Quinones are dominant intermediates on irradiation using light at λ > 360 nm.
• Regioselectivity towards ortho position is favored by the nanoporous carbon.

We report the dependence of the photochemical activity of titania/carbon hybrid catalysts toward the degradation of phenol from solution using polychromatic light and filters. In all cases larger photooxidative efficiencies were obtained using light at 200 nm < λ < 600 nm. The incorporation of a carbon additive to TiO2 increased the photocatalytic performance regardless the illumination conditions, although, the effect was more pronounced at λ > 200 nm. The photocatalytic runs carried out with the nonporous carbon alone confirmed a certain level of intrinsic photoactivity under both irradiation conditions. Nevertheless, a clear deactivation was evident after 60 min of irradiation suggesting that the photoactive sites in the carbon are either consumed or deactivated in the course of the reaction. The composition of the catalyst and the illumination conditions also have a strong effect on the nature of the degradation intermediates, with a marked regioselectivity toward ortho-substitution at high energy photons and when the carbon component is added to the catalyst composition.

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