Spectroscopic investigations on the simulated solar light induced photodegradation of 4-nitrophenol by using three novel copper(II) porphyrin–TiO2 photocatalysts

Three porphyrins containing different functional groups (OH, CO2C2H5, COOH), 5-(4-hydroxy) phenyl-10,15,20-triphenyl porphyrin (1a), 5-(4-ethylacetatatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1b), 5-(4-carboxylatomethoxy) phenyl-10,15,20-triphenyl porphyrin (1c), were synthesized and characterized spectroscopically. The CuPp(2a, 2b, 2c)–TiO2 photocatalysts were then prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis-DRS), Fourier-transform infrared spectroscopy (FT-IR). The photocatalytic activities of the photocatalysts were investigated by carrying out the photodegradation of 4-nitrophenol in aqueous solution under simulated solar irradiation. It was found that the CuPp(2a, 2b, 2c)–TiO2 enhanced the photocatalytic efficiency of bare TiO2 in photodegrading the 4-NP due to the interaction between CuPp(2a, 2b, 2c) and TiO2, resulted in the enhancement of the photogenerated electron–hole separation. The reasons of this enhanced photocatalytic activity were also discussed. Based on the present study, it could be considered as a promising photocatalyst for the further industrial application.

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► The CuPp and CuPp(2a, 2b, 2c)–TiO2 were prepared and studied by XRD, TEM, UV–vis-DRS, FI-IR, XPS and PL spectroscopies.
► Higher photocatalytic activity of the CuPp(2a, 2b, 2c)–TiO2 than bare TiO2 was observed under simulated solar irradiation.
► The photocatalytic activity of CuPp(2a, 2b, 2c)–TiO2 is related closely to the interaction between CuPp and TiO2.