Photodegradation of dyes in batch and continuous reactors by Cu2O-CuO nano-photocatalyst on Cu foils prepared by chemical-thermal oxidation. (October 2020)

• Record Type: Journal Article
• Authors: Behjati, Sara; Sheibani, Saeed; Herritsch, Jan; Gottfried, J. Michael
• Is Part Of: Materials research bulletin. Volume 130(2020)
• Publication Date: 2020-10
• Subjects: Cu2O-CuO nano-photocatalyst -- Chemical-thermal oxidation -- X-ray photoelectron spectroscopy -- Continuous reactor; Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2020.110920
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: Highlights: CuO-Cu2 O photocatalyst on Cu foils was synthesized by chemical-thermal oxidation. Photocatalytic activity was investigated in two new batch and continuous reactors. The continuous reactor has faster kinetics and higher water purification capacity. After degradation CuO/Cu2 O ratio and adsorbed oxygen on the surface were increased. The maximum photonic efficiency was obtained for the blue color. Abstract: In this study, CuO-Cu2 O nanocomposite photocatalyst on Cu foils was synthesized by chemical-thermal oxidation. In the chemical step Cu(OH)2 forms and in the thermal step, it turns to CuO and Cu2 O. The X-ray diffraction (XRD) analysis and field emission scanning electron microscopy (FESEM) showed the synthesized Cu/CuO-Cu2 O nanocomposite contains nanorods distributing on the polyhedral copper oxide matrix. One-step thermal oxidation of Cu(OH)2 at 500 °C under nitrogen atmosphere has a denser distribution of the nanorods on the truncated octahedral matrix. Transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS) showed the formation of a heterostructure of CuO nanorods on the Cu2 O matrix with the band gap energy of 1.35 eV. Photoluminescence spectroscopy (PL) indicated higher electron-hole separation efficiency in the presence of more nanorods. The photocatalytic activity was investigated by Methylene blue (MB) and Methyl orange (MO) degradation in two new batch and continuous reactors with and without air bubble flow under visible light irradiation. The continuous reactor not only was closer to the real application but also has faster kinetics and higher water purification capacity. The degradation in this reactor for 300 mL of 2 mg L −1 MB solution was 55 % within 5 h with 0.8 cm 2 mL −1 of photocatalyst. X-ray photoelectron spectroscopy (XPS) revealed the increase in the CuO/Cu2 O ratio and the adsorbed oxygen on the surface after the degradation process. Different colors of light-emitting diodes (LED) were used as an illumination source. The maximum photonic efficiency was obtained for the blue color.