Enhanced photocatalytic degradation of rhodamine B by surface modification of ZnO with copper (II) porphyrin under both UV–vis and visible light irradiation

In this paper, a new organic–inorganic CuPp–ZnO photocatalyst was achieved by copper (II) 5-mono-[4-(2-ethyl-p-hydroxybenzoate)ethoxyl]-10,15,20-triphenylporphyrin (CuPp) impregnated onto the surface of ZnO with an effective mixing method. Then the CuPp–ZnO photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR) spectroscopy and photoluminescence spectra (PL). The results revealed that CuPp successfully impregnated onto the surface of ZnO and there existed an interaction between ZnO and CuPp. The photocatalytic activities of the CuPp–ZnO photocatalyst were evaluated in the photocatalytic degradation of rhodamine B (RhB) both under UV–vis and visible light (λ ≥ 420 nm) irradiation. It was found that the CuPp–ZnO photocatalyst showed much higher photodegradation efficiency than bare ZnO, which improved the separation of photogenerated electrons and holes. The active species during the photocatalytic reaction were detected by using different types of active species scavengers. Finally, the photocatalytic mechanisms both under UV–vis and visible light irradiation were proposed. In addition, the repetition test demonstrated that the CuPp–ZnO still maintained high photocatalytic activity over five recycles. Based on the present study, it could be considered as a promising photocatalyst for future applications.

Graphical abstractA new CuPp–ZnO photocatalyst was prepared and characterized firstly. Then the CuPp–ZnO exhibited excellent photocatalytic activity and stability for the photodegradation of RhB under light irradiation. Based on the present study, the possible photodecatalytic mechanisms both under visible and UV–vis light irradiation were proposed by adding different types of active species scavengers.Figure optionsDownload full-size imageDownload high-quality image (335 K)Download as PowerPoint slideHighlights► A new CuPp–ZnO photocatalyst was successfully achieved and characterized. ► The CuPp–ZnO photocatalyst exhibited excellent photocatalytic activity and stability for the photodegradation RhB. ► A higher visible photocatalytic degradation of RhB was observed on CuPp–ZnO compared with CuPp–TiO2. ► Photocatalytic mechanisms both under visible and UV–vis light irradiation were proposed.