Impact of different TiO2 samples and porphyrin substituents on the photocatalytic performance of TiO2@copper porphyrin composites

- Carboxylporphyrin dimers existed on the low surface area of cTiO2.
- Carboxylporphyrin easily interacts with the hydroxyl group on the high surface area of pTiO2.
- The anchoring modes of carboxylporphyrin have a positive impact on the photocatalytic activity.

In this manuscript, the preparation and the comparison of the photocatalytic activity of novel TiO2@copper porphyrin composites obtained by impregnation of (5-(4-hydroxy) phenyl-10,15,20-triphenyl copper porphyrin 1a, 5-(4-ethylacetatatomethoxy) phenyl-10,15,20-triphenylcopper porphyrin 1b, and 5-(4-carboxylatomethoxy) phenyl-10,15,20-triphenyl copper porphyrin 1c respectively onto the surface of different TiO2 samples, commercial (cTiO2) and home-prepared (pTiO2), has been reported. The TiO2@copper porphyrin composites were characterized by XRD, BET, UV-vis, FT-IR and SEM-EDS techniques.For the first time, the formation of aggregated porphyrin, most likely in form of dimers 1a-1a, 1b-1b and 1c-1c, were detected on the lower and less hydroxylated surface area of cTiO2.The photocatalytic activity of the samples was evaluated on the basis of the photodegradation of 4-nitrophenol (4-NP) in aqueous solution under metal halide lamp irradiation.The highest photocatalytic efficiency in the degradation of 4-NP, observed by using the carboxylporphyrin 1c as sensitizer supported onto the surface of both pTiO2 or cTiO2, was ascribed to the optimal combination of the anchoring mode with the efficient electron injection in the conduction band that carboxylic group produced at the surface of the TiO2 samples.

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