Preparation, characterization, and photocatalytic properties of composite materials of copper(II) porphyrin/TiO2

Three new CuPp–TiO2 composite materials were prepared by impregnating copper(II) porphyrin with different peripheral substituent (–OH, –COOC2H5, and –COOH) onto the surface of polycrystalline TiO2 at room temperature and characterized by SEM, energy-dispersive X-ray spectrometry, X-ray diffraction, FT-IR, UV–Vis DRS, and photoluminescence. The effects of metalloporphyrins on the surface of TiO2 have been detected by the photodegradation of 4-nitrophenol (4-NP) and rhodamine B (RhB). The loading of metalloporphyrins onto TiO2 results in strong visible light absorption by the composite and, more importantly, a 1.47–2.47 times increase in visible light photocatalytic activity in the degradation of RhB. The metalloporphyrins dispersed on the TiO2 surface can act as a small-band-gap semiconductor to absorb visible light, giving rise to electron–hole separation. What’s more, these CuPp–TiO2 with different peripheral substituent (–OH, –COOC2H5, and –COOH) in meso-sites of porphyrin ring displayed different catalytic activities in the degradation of 4-NP and RhB, the CuPp containing –OH and –COOH showed better catalytic activity due to their strong interaction with TiO2. A possible mechanism of these higher photocatalytic efficiencies was proposed based on the relative experiments.